Supercharger vs Turbocharger

In this post we will learn about Supercharger vs Turbocharger. Many times we have heard that, this car is supercharged or this is turbocharged. When we heard this, one question  arises in our mind what is supercharged and what is turbocharged engine. Which one is  better between them. What are functions of these units. Today I will tell you all these answers and the main differences between them.

Before discussing about difference between supercharger and turbocharger, first you should know about what is charge. When we talk about an engine the charge is used to identify amount of air and fuel mixture sucked into the cylinder during the intake stroke. So the charge is refereed as the mass of air-fuel mixture taken into the cylinder during intake stroke.

When we required more power than we need more charge into the cylinder. There are two ways of increasing charge of an engine.

  1. First one is to increases the engine size or cylinder size, so more air fuel mixture sucked and generate more power.



  1. The other one uses a compressor which increase the density of charge and  draws more charge into the cylinder at high pressure so the more mass of air fuel mixture comes into the cylinder which generate more power. 


The second one is more convenient because it uses an smaller size engine to generate same power as the big one. And the other benefit is that this can be implemented in the old cars by adding a compressor unit. Both supercharger and turbocharger are  worked on same principle i.e. by using compressor. Turbocharger and supercharger both compresses the air and forces this compressed air into the engine cylinder. According to the air, large amount of fuel is injected into the cylinder, which produces more power. It is the basic principle of both turbocharger and supercharger.

Supercharger is an air compressor which is used to increase the power of an engine. Basically supercharger is a rotary compressor which is driven by  the crankshaft through a belt drive. This compressor is connected at the inlet manifold of the engine. As the engine rotate it rotate the supercharger which forces compressed air into cylinder.

 

Turbocharger is basically a combination of a turbine and a rotary compressor. The turbine is connected to the compressor and driven by the hot exhaust gases of the engine. So a turbocharge is a compressor which is driven by exhaust gases of engine which forces the compressed gases into the cylinder.

 

 

Supercharger vs Turbocharger:


 

 















































SuperchargerTurbocharger
1. It is  directly driven by the engine through a belt drive.1. It is driven by the exhaust gas of engine.
2. It uses the useful power of engine to drive the compressor.2. Turbocharger uses  power of exhaust (waste power) gases to drive the compressor.
3. Because it uses useful power of engine so it decreases the engine efficiency.3. Because it uses exhaust gases to drive the compressor, resulting in increased efficiency.
4. Supercharger is connected by the crankshaft, so it starts working suddenly as the engine start.4. Turbocharger used exhaust gases to operate, so it does not work until a sufficient smoke is generated by the engine.
5. supercharger is a unit that is bolted to engine and connected with a belt drive between crankshaft and the supercharger unit.5. A turbocharger is similar to a supercharger, except it has an exhaust housing instead of a belt drive, and runs by exhaust gasses.
7. It increases the engine power about 30 to 40%.7. It also increases the engine power about 30 to 40%.
8. Supercharger is difficult to adopt in the car because it occupy large space.8. When we considered about design turbocharger is compact and easily adopted in the cars.
9. Supercharger is more costly than turbocharger.9. It is less costly.
10. It is not essential to use inter cooler in supercharger.10. Because turbocharger work by exhaust gases so inter cooler is essential.
11. It generate more noise.11. It generate less noise because it used exhaust gases.

 

Today we have discussed about Supercharger vs Turbocharger. If you have any query kindly ask by commenting below.

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Petrol Engine and Diesel Engine

Today we will discuss all main Difference Between Petrol Engine and Diesel Engine. We all love driving. We all have heard about the diesel engine and petrol engine. But most of us only know that the difference between both engine is that one is run by petrol and the other one is by diesel. But after this many question develop in our mind.

  1. If the diesel is cheaper than petrol, then why we make petrol engine vehicle?

  2. Why all heavy vehicles have diesel engine?

  3. Why diesel cars are so noisy?

  4. Why all sports vehicle and bikes have petrol engine?


 

 

Difference Between Petrol Engine and Diesel Engine:
















































































Diesel Engine or CI EnginePetrol Engine or SI Engine
1.The diesel engine work on diesel cycle.The petrol engine works on Otto engine.
        2.In this engine Diesel is used as fuel which is a non-volatile fuel.In this engine petrol which is a high volatile fuel is used as fuel.
3.In the diesel engine the air is sucked during the suction stroke and the fuel is injected into combustion chamber thru injector.In the petrol engine the air-fuel mixture sucked during the suction stroke.
4.The ignition is due to the heat generated during the compression stroke by the high compressed ratio. So it is called compression ignition (CI) engine.The spark is generated by the spark   plug into the combustion chamber so the ignition is due to the spark by external source so it is called spark ignition (SI) engine.
5.Due to high compression ratio it have large vibration so it develop more noise.Due to less compression ratio it has small vibration so it develop less noise.
6.To handle the high compression ratio it has heavy metal so it is heavier than petrol engine.It has low compression ratio so they   are light in weight.
7.This engine used injector to inject   the fuel in combustion chamber.This engine used spark plug to ignite the fuel in the combustion chamber.
    8.Due to heavy weight and also due to heterogeneous combustion, they are low speed engines. Due to light weight and also due to homogeneous combustion, they are high speed engines.
    9.Due to heterogeneous combustion and high compression ratio, it provides high torque. So it is used in heavy vehicle.Due to homogeneous combustion and comparatively low compression ratio, it provides low torque. So it is used in light vehicle.
10.In diesel engine there is no pre mixing of air and fuel so no need of carburetor.In the petrol engine air fuel mixture   is drawn into the combustion chamber so due to pre mixing of air fuel carburetor is required.
11.Due to high compression ratio the   diesel engine generate high torque which is driving force of vehicle. So high torque is required for heavy vehicle so this engine is used in heavy vehicle.Due to low compressed ratio it is not used in heavy vehicle.
12.Diesel is low volatile so it burns slowly. Due to slow burn it generates low speed so it is not used in sports car.Petrol is high volatile so it burns rapidly. Due to rapid burning it generates high speed so it is used in sports car.
13.This engine develops low speed at high torque.This engine develops high speed at low torque.
 

14.

.
Due to heavy metal and injector, it is have high pricesDue to light metal it has low prices.

Today we have discussed Difference Between Petrol Engine and Diesel Engine. If you have any query, ask by commenting below.

Impulse and Reaction Turbine

Today we will discuss about main difference between impulse and reaction turbine. In my last post we have learnt about main types of turbine. We know that turbines are widely used in power generation industries. Selection of proper hydraulic turbine is among the most important factor affecting the economic viability of hydraulic project.

 

The term impulse and reaction denote the basic type of turbine. The basic and main difference between impulse and reaction turbine is that there is pressure change in the fluid as it passes through runner of reaction turbine while in impulse turbine there is no pressure change in the runner. In the impulse turbine first all pressure energy of water convert into the kinetic energy through a nozzle and generate a high speed jet of water.  This water jet strikes the blade of turbine and rotates it. In the reaction turbine there is pressure change of water when it passes through the rotor of turbine. So it uses kinetic energy as well as pressure energy to rotate the turbine. Due to this it is known as reaction turbine.

 

Difference between Impulse and Reaction Turbine:





































Impulse TurbineReaction Turbine
1.  In impulse turbine only kinetic energy is used to rotate the turbine.1. In reaction turbine both kinetic and pressure energy is used to rotate the turbine.
2. In this turbine water flow through the nozzle and strike the blades of turbine.2. In this turbine water is guided by the guide blades to flow over the turbine.
3. All pressure energy of water converted into kinetic energy before striking the vanes.3. In reaction turbine, there is no change in pressure energy of water before striking.
4. The pressure of the water remains unchanged and is equal to atmospheric pressure during process.4. The pressure of water is reducing after passing through vanes.
5. Water may admitted over a part of circumference or over the whole circumference of the wheel of turbine.5. Water may admitted over a part of circumference or over the whole circumference of the wheel of turbine.
6. In impulse turbine casing has no hydraulic function to perform because the jet is at atmospheric pressure. This casing serves only to prevent splashing of water.6. Casing is absolutely necessary because the pressure at inlet of the turbine is much higher than the pressure at outlet. It is sealed from atmospheric pressure.
7. This turbine is most suitable for large head and lower flow rate. Pelton wheel is the example of this turbine.7. This turbine is best suited for higher flow rate and lower head situation.

Today we have discussed about Difference between impulse and reaction turbine. If you have any query kindly ask by commenting.

MIG and TIG Welding

Today we will discuss difference between MIG and TIG welding. These are two main types of welding. The term MIG is stand for Metal inert Gas welding and TIG is stand for Tungsten Inert Gas welding. These are widely use for joining a verity of shapes and material. Today we will learn the main difference between them.

Difference between MIG and TIG welding:


 























































MIG WELDINGTIG WELDING
1. This welding is known as metal inert gas welding.1. This is known as tungsten inert gas welding.
2. Metal rod is used as electrode and work piece used as another electrode.2. Tungsten rod is used as electrode.
3. It is gas shielded metal arc welding.3. It is gas shielded tungsten arc welding.
4. Continuous feed electrode wire is used which are fast feeding.4. Welding rods are used which are slow feeding.
5. The welding area is flooded with a gas which will not combine with the metal.5. Gas is used to protect the welded area form atmosphere.
6. MIG can weld materials such as mild steel, stainless steel and aluminum. A range of material thicknesses can be welded from thin gauge sheet metal right up to heavier structural plates.6. TIG weld things like kitchen sinks and tool boxes. Pipe welding and other heavier tasks can also be performed, you just need to have a unit that is capable of putting out the amount of power that you need.
7. MIG requires consumable metallic electrode.7. It used non consumable tungsten electrode
8. Electrode is feeded continuously from a wire reel.8. It does not require electrode feed.

 
9. DC with reverse polarity is used.9. It can use both A.C and D.C.
10. Filler metal is compulsory used.10. Filler metal may or may not be used.
11. It can weld up to 40 mm thick metal sheet.

 
11. Metal thickness is limited about 5 mm.

 
12. MIG is comparatively faster than TIG.12. TIG is a slow welding process.

Today we have learn about main difference between MIG and TIG welding. If you have any query regarding this article, ask by commenting below.

Automatic vs Manual Transmission

Today we will learn about automatic vs manual transmission. When you go out for buy a car, one question arise in your mind that which car is better Manual or Automatic. We all have heard about manual and automatic transmission and some of us used both of these transmissions. When we go to buy a car we have heard both these words manual car and automatic car. Before buying these cars we should have clear understanding about main differences about them. Both of these transmissions have those own advantages and disadvantages. One should choose the right one according to their uses, preference and habits. So today i am going to differentiate automatic vs manual which will help you to make right decision to buy a car.

 

Automatic vs Manual transmission:













































































Automatic TransmissionManual Transmission
1. In automatic transmission the gear shift automatically according to the driving condition and you are not responsible to shift it.1. In manual transmission you are responsible to shift the gear ratio. You have to shift gear through a lever manually.
2. Automatic transmission car are more costly than manual transmission cars.2. Manual transmission cars are less expensive than automatic transmission cars.
3. It is more expensive of maintenance of Automatic transmission cars.3. It is less expensive of maintenance of manual transmission cars.
4. This transmission uses a little more fuel and give less mileage.4. Manual transmission cars use less fuel and gives more mileage than automatic.
5. Automatic transmission cars are difficult to service. It has costly maintenance too.5. It is easier to service manual transmission cars. So it is less costly too.
6. The life of automatic transmission works less than manual transmission6. Manual transmission works thousands of kilometer without any problem
7. In the jam traffic city road automatic transmission is better than manual. You have not need to change gears.7. In the long distance highway road manual transmission is better which gives higher mileage.
8. Automatic transmission are heavier than manual.8. Manual transmissions are lighter than automatic.
9. Automatic transmissions are more luxury than manual.9. Manual transmissions are less luxury than automatic.
10. Automatic transmission uses torque converter which is automatically operated by speed.10. Manual transmission uses clutch to disengage the gearbox from engine.
11. From driver point of view these cars are easier to drive.11. Manual transmission cars are much difficult ti drive.
12. Automatic transmission required rapid cooling.12. Manual transmission does not require active cooling.
13. This transmission has better ability to control traction so it is easier to drive in climbing situation.13. Manual transmission cars are difficult to use on climbing hills.
14. As we told in automatic transmission you are not responsible for changing gear ratio so its acceleration is quite low.14. Manual transmission improves the acceleration of the car which give more fun to driver.
15. It has higher resale value.15. It has lower resale value.
16. Automatic transmission cars have only two paddle acceleration and brake.16. Manual transmission cars have three paddle clutch, brake and acceleration which are quite hard to operate.
17. For driving comfort automatic transmission is better than manual transmission.17. For sport point of view manual transmission gives more fun.

Today  we have discuss about advantages and disadvantages of automatic vs manual transmission. If you are still confuse about them ask by commenting.

 

 

Up Milling and Down Milling

Today we will discuss about difference between up milling and down milling. The milling is a machining process in which, a rotary cutter is used to remove the material from work piece in the direction perpendicular to the axis of rotation. The milling process is done by the machine, which hold both the tool and work piece in jig and fixture, known as milling machine. There are two ways to cut the material from the work piece through milling machine. First one is named as conventional milling or Up milling and the other one known as climb milling or down milling. The main and basic difference between up milling and down milling is the direction of rotation of cutter to the feed.

The milling operation is used to facing of those work piece, which are not symmetrical from its axis. It is also used to cut pockets, drill, slot and shape the work piece according to the requirement.

There are two ways to cut the material from the work piece through milling machine. First one is named as conventional milling or Up milling and the other one known as climb milling or down milling. The main and basic difference between up milling and down milling is the direction of rotation of cutter to the feed.

In up milling the cutter is rotate clockwise when cutting the work piece from right to left. In this type of milling the tool spins against the direction of feed. In this milling process, the cutting chips are carried upward by the tool.

 

In down milling, the cutter rotates clockwise while cutting the work piece from left to right. In this milling operation, the tool spins with the direction of feed. The cutting chips are carried downward by the tool.

Difference between Up milling and Down milling:

 





































































Up Milling


Down Milling

1.In up milling the cutter rotates against direction of feed.In Down milling, the cutter rotates with direction of feed.
2.It is also known as conventional milling.It is also known as climb milling.
3.In this, chip width size is zero at initial cut and increase with feed. It is maximum at the end of feed.In this cutting process, chip size is maximum at start of cut and decrease with the feed. It is zero at the end of feed.
4.In this process, heat is diffuse to the work piece which causes the change in metal properties.In down milling most of heat diffuse to the chip does not change the work piece properties.
5.In up milling, tool wear is more because the tool runs against the feed.In this, tool wear is less compare to the up milling, due to the cutter rotate with the feed.
6.Tool life is low.Tool life is high.
7.The cutting chips are carried upward by the tool so known as up milling.The chips are carried downward by the tool so known as down milling.
8.The cutting chips fall down in front of the cutting tool which again cut the chips cause less surface finish.The cutting chips fall down behind the tool. This gives better surface finish.
9.Due to upward force by tool, high strength zig and fixture required to hold the work piece.In down milling, downward force act on work piece normal zig and fixture required.
10.It is the traditional way of cutting the work piece.It is non-traditional way, but now days, down milling used more than up milling.
11.High quality cutting fluid is required because heat diffuse in the work piece.In this process heat does not diffuse in the work piece, so simple cutting fluid is required.
12.It required high cutting force compare to down milling.It required low cutting force.

 

Today we have learnt about difference between up milling and down milling. If you have any query or doubt, ask by commenting below.

 

Fire Tube Boiler and Water Tube Boiler

Today I am going to tell you difference between fire tube boiler and water tube boiler. The boiler is divided into two main types. One is known as fire tube boiler and the other one is known as water tube boiler. These boilers is largely used in power development and other industrial like sugar industries, cotton industries etc. for steam generation. The main difference between fire tube and water tube is that in fire tube boiler the flue gases flow in the tubes and water flows from the shell and in water tube boiler, water flows from the tubes and the flue gases from the shell or passes over the tubes. This is the key difference between these boilers.

Now I am going to tell you some hidden difference between these boilers.

 

Difference between Fire Tube Boiler and Water Tube Boiler:




















































































Fire Tube boiler Water Tube Boiler
1.Hot flue gases flow inside the tube and the water outside the tube.Water flows inside the tube and the flue gases outside the tube.
2.This boiler pressure is limited up to 20 bar. These boilers are generally low or medium pressure boiler.This boiler pressure is up to 70-100 bar. So these boilers are generally high pressure boiler
3.Fire tube boiler have lower rate of steam production compare to water tube.It has higher rate of steam production.
4.These boilers are almost internally fired. Furnace is placed at the one end of fire tube.These boilers are generally externally fired.
5.It is suitable for the production work like sugar mill, textile industries.It is suitable for large power plant.
6.Risk of explosion is lower due to low pressure.Risk of explosion is higher due to high pressure boiler.
7.This boiler occupies large floor space.It occupies less floor space compare to fire tube boiler.
8.It required less skill to operate.It required a skilled operator.
9.It is difficult to repair and cleaning.It is easily clean and repairable due to externally fired.
10.It required large shell diameter because the fire tube situated inside the shell.It required small shell diameter.
11.This boiler is difficult to construct.This is simple in construction.
12.The efficiency of fire tube boiler is less compare to water tube. It will increase by using other accessories.This boiler is more efficient.
13.The maintenance of this boiler is costly. It is required regular inspection.This boiler is easy to maintain.
14.The treatment of water is not necessary.The water flows through small diameter tube. So water is treated before entering into the tube otherwise it will jam the tube.
15.Example Lancashire boiler 

Example Babcock and Wilcox boiler


Today we have discussed about difference between fire tube boiler and water tube boiler. If you have any doubt or query regarding this article, ask by commenting.

arc welding and gas welding

Today I am going to tell you about difference between arc welding and gas welding. These are the two main types of welding used in different joining process. These joining processes are used in joining same or different metal by application of heat. We can differentiate these in following aspect.

Difference between Arc Welding and Gas Welding:


 









































































S.No.Arc WeldingGas Welding
  1.In the arc welding, electricity is used to generate heat.In gas welding, fuel gases like acetylene, hydrogen are used to generate heat.
 

2.
This welding generates higher temperature than gas welding. The temperature is about 6000C.This welding generates lower temperature than arc welding. The temperature is about 3600C.
  3.This welding generates stronger joint compare to gas welding.It gives weaker joint.
  4.It gives poor surface finish.This welding gives good surface finish.
 

5.
In arc welding consumable electrode is used.In gas welding non consumable electrode is used.
  6.The electrode is combined with the filler metal.A filler rod is used separately if required.
  7.It can be used in welding alone.It can be used in welding, brazing and soldering.
  8.There is risk of explosion due to high voltage.There is risk of explosion due to high pressure.
  9.It is mostly used to joint similar material.It is mostly use to join both similar and different metals.
  10.The heat is concentrate in arc welding.The heat is distributing according to the flame. There is higher loss of energy.
  11.It is more efficient.It is less efficient.
  12.Speed of welding is high.Speed of welding is low.
  13.The initial cost of arc welding is high.The setup cost of gas welding is low.

These are main difference between arc welding and gas welding. If you have any query ask by commenting.

 

Brazing vs Welding vs Soldering

Brazing vs Welding vs Soldering : Which is better?


Welding, Soldering and brazing are the most common joining process use in industries for joining same and different metal. Today we will learn about these processes and further we will compare welding vs soldering vs brazing. These all are joining processes but different process uses in different conditions. Welding is use in mechanical industries for jointing same or different metals. The main function of welding is to make a strong joint which can carry all mechanical stresses. Soldering are used in electrical and electronics industries. It is use to joint wire to panel. Main function to these processes to make a electrically strong joint which can withstand in any electrical condition. Brazing is use to joint dissimilar metal in automobile and aircraft industries.

Brazing vs Welding vs Soldering:


What is welding?


Welding is a most common joint process in mechanical industries. Two metals joint by using of heat energy with and without filler material or pressure is known as welding. It forms a permanent joint. In this process, both work pieces to be joint are heated until its plastic stage. These work piece bring close and allow to solidify. After solidification a strong joint is achieved. Sometimes filler material is use to joint metal, where filler material placed between work pieces in molten stage. As it solidifies, it makes a strong joint. The heat use to heat work pieces is achieved by burning gases like acetylene or by using electric arc. According to method of achieving heat, welding is divided into Gas welding and Arc welding. Sometimes welding is perform by using only pressure and friction without applying heat and filler material , known as pressure welding and friction welding.

 

Welding is use as permanent fastener, which can stand with working stresses. The main function of welding it to provide the strongest joint, which will not fail during working. A main disadvantage of welding joints is that it is brittle in nature so cannot stand with fatigue stress. One other big problem occurs due to uneven heating and cooling which increase internal stresses.

Advantages of welding:



  1. It is more suitable permanent joint.

  2. No hole is required, so stress concentration is less.

  3. No filler plate requires so overall weight of work piece is less.

  4. Welding joints have high efficiency.

  5. The rate of joint is high compare to other joining processes.

  6. Less labour required.


Disadvantages of welding:



  1. The welding joints are brittle witch cannot withstand with fatigue load.

  2. Due to uneven heating, internal stress develops in welding.

  3. Skill labour required

  4. It is difficult to inspect.


What is soldering?


Soldering is almost similar to welding except it use to joint wire in electrical and electronics industries. In welding process, a strong joint is making between two plates by using heat. This joint withstand with high mechanical stress and load. It is use to make good mechanical connection. Soldering is same as welding except it is use to make good electrical connection.

 

In the soldering process solder is use as the filler motel to join the wire or other small electrical component like resistor, capacitor to panel. Solder is a soft alloy of lead and tin. It is high electric conductor and has low melting point. A soldering iron is use to heat up the filler metal witch melts the solder over the joint. Soldering iron tip is use to place the solder over joint. As the solder solidified, it makes a good strong joint between the electric components like capacitor, resistor to the panel. Solder is a mechanical connection. It’s main function to provide a good electrical connection between these components. Soldering is use widely in electronics industries.

Advantages of soldering:



  1. it require less heat.

  2. Solder is good electric conductor so make a good electrical joint.

  3. It does not require skilled labour.


What is brazing?


Brazing is the most common joining process to join dissimilar metals. It is similar to soldering except high temperature is use in brazing. Brazing is a joining process of metal which is done at the lower temperature of melting of work piece. In this process silver based alloy is use as the filler metal which melting temperature is above 450C but below the melting temperature of base metal. The molten metal allow to flow between gapes by capillary action. One big advantage of this joint is gives similar strength for similar and dissimilar base metal.

 

Brazing is done into open atmosphere which can cause of forming oxide of metal. A flux is use to prevent the joint by oxygen.

Advantages of brazing:



  1. It does not melt base metals.

  2. Both similar and dissimilar metals can join.

  3. It does not form internal stress due to uneven heating.

  4. It can use in mass production.

  5. Brazing produces a clean joint.


Difference between Welding, Brazing and Soldering















































S. No.WeldingBrazingSoldering
1.It requires high temperature above melting point of base   metal. It is above 3000C.It requires temperature below melting point. It is up to 800C.It requires low temperature below 450C.
2.It forms strongest mechanical joint which can withstand with high working stress.Brazing joints are stronger than soldering but weaker than welding.It forms weakest mechanical joint. But this joints are highly electrical conductor so form a strong electrical joint
3.High skilled labour requiredLess skill require to join metal.Less skill requires.
4.Preheating of base metal does not require.Preheating of base metals require.Preheating of base metal is essential.
5.The properties of base metal may change.No change in mechanical properties.No change in mechanical properties.
6 .It is not required to clean the work piece before weld.The work piece is clean before joining.It is essential to clean the work piece.

Today we have discussed about welding, soldering and brazing. We have also compared brazing vs welding vs soldering. If you have any query regarding this article, ask by commenting.

 

Welding and Brazing

Today we will discuss about difference between welding and brazing. In my last post we have discussed about welding vs brazing vs brazing. We know that these both are jointing processes but used in different condition. The knowledge of both processes is required to better efficiency of joint.

 

Welding and brazing denote the common joining processes used in metal industries. The main and basic difference between these two processes is that Welding used to join metal above the melting temperature but brazing use to join metal below the melting temperature. These process can be differentiate according to following aspect in tabular form.






















































S. No.

Welding

Brazing

  1.It is the jointing process in which both piece of work piece melted together with or without application of filler materialBrazing is the joining process in which work piece is heated below its melting temperature and the joint is made by use of filler material known as braze.
  2.Temperature of welding is above the melting point of work piece. It is almost 3600oC
.
It is done much below the melting temperature which is almost 600oC.
  3.The properties of base metal may change after joining.The properties of base metals remain same after joining.
  4.It forms strongest joint.These joints are weaker than welding.
  5.The use of filler metal is not compulsory in welding.Filler metal is used compulsory in brazing.
  6.The work piece must be clean before welding.The work piece should clean but it is not compulsory.
  7.It mostly used to join similar metals.It is mostly use to join dissimilar metal.
  8.It is best suitable to join large assembly.It is best suited for join small assembly.
  9.Welded joints can withstand with high temperature.These joints cannot withstand with high temperature.

 

These are key difference between these two joining processes, welding and brazing. If you have any query regarding this article, ask by commenting.

Soldering and Welding

Today I am going to tell you main difference between welding and soldering. Welding and soldering both are metal joining processes but according to their uses, these are different form one another. Basically welding is used to make a joint which can carry all mechanical stresses and loads. It forms a very strong joint between metals. In the other hand soldering is used to joint small electrical component like capacitor, resistor, to the electronic panel. The main function of soldering is to make a electrically strong joint between metals which can withstand with the all electrical loads.

These processes can differentiate in following aspects.

 

Difference between Soldering and Welding:




























































S.No.WeldingSoldering
1.It is used in mechanical industries, like automotive, aerospace etc.It is used in electrical industries.
2.In welding, both work piece are melted together to form a mechanical joint. Sometimes filler material is used to make the joint.In soldering, a joint is made by use of filler material, known as solder. A rod is heated up to the melting temperature of filler metal. This melted filler metal used to make a joint.
3.The welding temperature is above the melting temperature of work piece which is above 3600CIt is done at much below the melting temperature of work piece which is below 400C
4.There is change in properties of work piece.There is no change in properties.
5.It forms strong mechanical joint.It forms strong electrical joint.
6.Filler material is not compulsory.Filler material is compulsory in soldering.
7.It can withstand with high temperature.It cannot withstand with high temperature.
8.The work piece should be clean below welding.It is not compulsory to clean work piece before joining.
9.Special training is required to perform the welding.No special training is required to perform it.
10.Preheating of work piece is not required.Preheating of work piece is not compulsory but it may give good result.

 

Today we have discussed about difference between welding and soldering. If you have any query, ask by commenting.

 

Soldering and Brazing

Soldering and brazing both are metal joining process used in different joining conditions. These processes are more confusing to differentiate because both process use filler material and done below critical temperature. Today I am gaining to tell you difference between soldering and brazing so you can understand these processes clearly. The basic and main difference between soldering and brazing is that soldering is used to make a electrically strong joint between metals which can withstand with all electric loads and brazing is used to make a mechanical strong joint which can withstand with all mechanic loads and stresses. These processes can be differentiating in following aspects.

 





















































S. No.SolderingBrazing
1.It is used in electrical industries to joint capacitor, resistor, wire etc. to the electronic plate.It is used to mechanical industries to joint different metals.
2.Soldering is done at temperature below  200 C.Brazing is done at temperature above 450C but below the critical temperature of metal.
3.These joints are weaker than brazing joints.It forms stronger joint.
4.In soldering an alloy of lead and tin is used known as solder.In brazing an alloy of copper and zinc is used as filler metal.
5.It does not need a special training to soldering.It needs special trading.
6.It is a cheaper process.It is a costly process.
7.Soldering does not need to preheat of base metal.This process needs preheating of base metal.
8.It is used to joint electronics component.It is used in automotive industries and pipe fitting.
9.This process is very flexible and easy to automate.It is not so easy for automation except automation is done at automotive industries.

These are the difference between soldering and brazing. If you have any query asks by comment.

centrifugal pump and reciprocating pump

Today we will discuss about difference between centrifugal pump and reciprocating pump. Both centrifugal and reciprocating pumps are most common type of pumps used to move fluid and increase its pressure. Centrifugal pump which is also known as rotary pump used kinetic energy of impeller to force the fluid and increase its kinetic energy. This kinetic energy suddenly converts into pressure energy which move fluid upward. These are used in household pumps for domestic water supply. Reciprocating pumps are one of the positive displacement pumps which contain a piston cylinder device. Water is trapped into the cylinder during suction stroke and force out during exhaust stroke. It is mostly used to pump high viscous fluids.

 

The basic and main difference between centrifugal pump and reciprocating pump is that centrifugal pump use kinetic energy of impeller so it continuously supply fluid but in reciprocating pump piston sucks the fluid and then pushes it out which does not gives continuous supply. There are some modified reciprocating pumps are available which gives continuous discharge. There are many other differences which are described as follow.

Difference between Centrifugal Pump and Reciprocating Pump:
















































































S. No.Centrifugal pumpReciprocating pump
1.It is one of the rotary pumps which used kinetic energy of impeller.It is a positive displacement type pump which is forced by piston.
2.It continuously discharges the fluid.It does not discharge the fluid continuously.
3.In centrifugal pump the flow rate decreases which increasing the pressure.The pressure does not affect flow rate in reciprocating pumps.
4.It is used for pumping high viscous fluid.It is used for pump low viscous fluid.
5.In this pumps discharge is inversely promotional to the viscosity of fluid.In reciprocating pump viscosity of fluid does not affect the discharge rate.
6.Efficiency of these pumps are low compare to reciprocating pump.Efficiency is high.
7.Centrifugal pump have problem of priming.It does not have any problem of priming.
8.It uses impellers to transfer energy to fluid.It uses piston cylinder device to transfer energy to fluid.
9.They are lighter than reciprocating pumps.These are heavier compare to centrifugal pump.
10.It gives higher discharge at low heads.These gives higher heads at low discharge.
11.It is less costly.These are costly.
12.These pumps required less maintenance.These required higher maintenance.
13.Centrifugal pumps are easy to install. These required less floor space.These pumps are difficult to install. These required more floor area.
14.It is mostly used for domestic purpose and where higher discharge at low head required.These are mostly used in industries and high viscous fluid pumped at a high head.

 

Today we have learnt about difference between centrifugal pump and reciprocating pump. If you have any query regarding this article, ask by commenting.

Motor and Engine

Today I am going to tell you about difference between motor and engine. We have heard the word motor and engine many times but most of us doesn't know significant difference between them. The term engine is use for any device or mechanical unit which converts heat energy into mechanical energy. Mostly heat is taken by burning of fuel. It is mostly used in automobile industries and many other industrial works. Motor is an electrical device which converts electric energy into mechanical energy. It is used in many household devices like fen, juicer etc.

 

The basic and main difference between motor and engine is that engine converts chemical energy of fuel into mechanical energy whereas motor converts electrical energy into mechanical energy. Both these devices used for develop mechanical motion. There are many other hidden differences which are described as follow.

Difference between engine and motor:














































S.No.



Engine



Motor


1.It converts chemical energy into mechanical energy.It converts electrical energy into mechanical energy.
2.It is run by fuel.It is run by electricity.
3.Engine needs lubrication for continuous running.It doesn't need lubrication.
4.It is generally a piston cylinder device.Motor is an arrangement of coil and rotor.
5.For the equal power engines are heavier then motor.Motor are lighter than engines.
6.It has less efficient.Efficiency of motor is high.
7.It generate lot of sound during converting energy.It develops less sound.

 

Today we have learnt about difference between motor and engine. If you have any query, ask by commenting.

Shaper and Planer

Difference between Shaper and Planer


When we talk about difference between shaper and planer, one thing strike our mind that both are different name of a same machine but this is not true. Both shaper and planner are used to make flat surfaces, cut slot and grooves and also use to make concave and convex geometry but there are some key differences which separate them from each other.

The basic and main difference between shaper and planer is that in shaper machine work piece is fixed at the table and tool is in reciprocating motion which rub the work piece and cut unwanted metal. It is used for small size work piece. But in planer machine tool is act like as stationary body and work piece move over it. It is used for large size work pieces. There are many other difference which are described below.

 

Difference between shaper and planer:




























































S.No.ShaperPlaner
1.Shaper is used to machine small work piece which can fit on the table.It can work with large size of work piece.
2.Tool is the moving part in shaper machine.Work piece is the moving part in planer.
3.Work piece remain stationary on this machine.Tool remains stationary on planer.
4.It is light duty machine.It is a heavy duty machine.
5.It can use only one cutting tool at a time.It is equipped more than one cutting tool at a time.
6.It uses single point cutting tool.It also used single point cutting tool but more than one tool can be used at same time.
7.Shaper is used quick return mechanism to drive the ram. In modern machine hydraulic drive is also used.Planer is driven by gear or hydraulic arrangement.
8.It gives poor accuracy compare to planer.It gives higher accuracy.
9.Shaper is smaller in size and gives slow cutting speed. It is not suitable where productivity is prime concern.It is larger in size and gives large productivity.
10.The stroke length can be adjustable.Stroke length can be adjusted.

Today we have learned about key difference between shaper and planer. If I have missed some, kindly inform me through commenting.

pump and compressor

Today we will learn about difference between pump and compressor. Pump and compressor both are hydraulic machines used to increase the energy of fluid. Both of these devices used in industries and for domestic work. Pump is a device which is used to move the fluid (water, liquid and gases) and increase its elevation. It is mostly used to supply fluid from low elevation to high elevation. A compressor is a device which is a mechanical device just like pump but it increases the potential energy of fluid by compressing it in a closed container.

 

The main difference between pump and compressor is that the pump is used to increase kinetic energy of fluid which further increases the elevation or pressure energy of it.  It moves the fluid from one place to another. But the compressor is mostly used to increase the potential energy (pressure energy) of fluid by pressuring it into a container. It is used to compress the fluid which increases its density and pressure. There are many other differences which are described below.

Difference between pump and compressor:













































S. No.PumpCompressor
1.It is used to move the fluid from one place to another at any height.It is used to increase pressure or potential energy of fluid. It increases density of fluid.
2.It increase pressure of fluid by move it at higher height.It increases pressure of fluid by compressing it.
3.There is no change volume from inlet to outlet of pump.There is change in volume from inlet to outlet from the compressor.
4.It is used to transport liquid like water, oil etc.It is used to transport gases.
5.The may or may not change in pressure of fluid.There must be change in pressure of fluid.
6.It is mostly used to increase energy of incompressible fluid.It is mostly used to increase energy of compressible fluid.
7.It does not have storage. It only sucks the fluid from one side and forced it out from other side.It has storage capacity. It can store gases and deliver it when required.

Today I have point out main difference between pump and compressor. If I forgot something, kindly inform me through comment.

 

Horsepower vs Torque

Today we will discuss about horsepower vs torque. These two terms are used to specify an engine or any rotary machine, but lot of people doesn’t know the accurate meaning of these both terms.  Horsepower and torque are very useful when you buy a vehicle of a rotary machine. Before discussing on this topic, first you should learn about the meaning of torque, horsepower and RPM.

What are Torque, RPM and Horsepower?


Torque:


Torque is measure of rotary force. It is works as force works in linier motion. When a torque is applied on a shaft it rotates or tends to rotate if the torque is not sufficient. In simple words, the rotary force applied on a shaft to rotate it is known as torque.

In mathematically torque is the product of tangential force applied on a shaft and the radius of shaft. The SI unit of torque is N-m (Newton per meter).

 

RPM:


RPM is the unit or measure of speed in rotary motion. The rpm is stand for rotation per minute. If a shaft rotate 50 cycle per minute mean it has 50 rpm speed. Larger rpm means larger speed.

 

Horsepower:


Horsepower is the unit or measure of power. Power is the capacity of do work. Larger power means, more work can do in smaller time.

Mathematically work done per unit time is called power or product of force and velocity is called power. But in rotary motion Torque is stand for force and RPM for velocity so the product of torque and RPM is called power. The SI unit of power is Watt ( J/s). It is equal to the power needed to move 1N weight bar to one meter in one second. Watt is a very smaller unit so we used KW and Horsepower (HP) to specify a machine power. One horsepower is equal to the 735 Watt.

 

Horsepower vs Torque:


As we know that horsepower is a unit or measure of power and torque is measure of force in rotary motion. In any rotary machine power is measured at highest rpm and the torque is at lowest rpm. If a vehicle is specified 400 HP @ 2000RPM means its maximum power is 400HP. If The same engine is specified as 2000 N-m @ 1300rpm means it give maximum torque is 2000 N-m.

The torque is measure of force applied to move the vehicle and the Horsepower is measure of rate of work done.

Torque plays a very important role while choosing a vehicle. Suppose two vehicles one is a truck and other one is a sports car. Both have same Horsepower 400 HP but both vehicles are with different each other. Sports car can't pull a heavy load like 1MT or a truck can't run on speed like 200Kph. The main difference between these machines is torque. A truck has a higher torque compare to sport vehicle so it can pull more load but due to power is function of product of torque and RPM so it has low RPM or speed. In the other hand the sport car has high RPM but low torque which gives it high speed. Both machines have same power but gives different uses.

It is seen like that a 1 kg block is move 10 meter or a 10 kg block is move one meter. Both have same power but have different pull force. These are key difference between them.

The more torque gives high starting power or gives more pickup to vehicle. So next time, when you go for buy a vehicle considered both Horsepower and torque and remember torque is pulling force and power means product of torque and RPM.

Today we have discussed horsepower vs torque. I think now you have better understanding between these. If you have any doubt regarding this article, ask by commenting.

Fan vs Blower

Today we will learn about difference between fan and blower. The fan and blower are two different kind of machines belong to the same group. Both these machines are used to flow a gas or mostly air in a large area but the main difference between fan and blower is that the fan is operate at low pressure while blower is operate at high pressure.  These machines are used in many industrial machines for air conditioning or cooling purpose.

The fan consist a rotor witch is equipped with some blades. This rotor is rotate by a electric motor or sometimes by a mechanical machine. It is primary used to flow the air into a large space. Mostly fans used to blow the air axially or the direction of the air flow along the axis of the rotor. Fans blow large volume of air with minor change in pressure. It has specific pressure ratio is 1.1.

Blower is different from fan. It is a centrifugal unit which blows the air radially. It consist a impeller equipped with series of blades which are designed to flow air radially. It blow the air or gas with a moderate pressure change. The change in specific pressure ratio is 1.11 to 1.2.

 

Difference between fan and blower:








































S.No.FanBlower
1.The pressure change in fan is about 1.1The change in pressure in blower is about 1.1 to 1.2
2.It is used to flow of gas or air in open space.It is mostly used to flow of gas in specific direction.
3.It blows gases or air in every direction.Blower is used to point the air in specific direction.
4.It is smaller than blower.Blowers are mostly larger than fan
5.It consumes less energy.It consist more energy.
6.It does not have moving blades.It may have moving blades to pointed air in specific direction.

Today we have learned about difference between fan and blower. If you have any query regarding this article, ask by commenting.

Carnot Cycle vs Rankine Cycle

Today I am going to tell you difference between Carnot cycle and Rankine cycle. Both Carnot cycle and Rankine cycle are air standard cycles. Carnot cycle is an ideal cycle of heat engine which gives highest efficiency between given temperature difference but it is a theoretical cycle and actually no engine works on Carnot cycle. Rankine cycle is an ideal cycle of vapor or steam power generation. All steam power plant work on this cycle. It used water as the working substance. Both these cycle have different features which I will describe below.

Carnot cycle has two isothermal processes and two isentropic processes. Heat is added and rejected isothermally and compression and expansion take place at constant entropy. It is a theoretical cycle but actually it is difficult to achieve isothermal heat addition and rejection. It gives highest efficiency between given temperature difference.

As I told Rankine cycle is a ideal vapor power generation cycle used in steam turbine. It consist two isobaric and two isentropic processes. Heat is added and rejected at constant pressure and expansion and compression of gas takes place isentropically. In practically, first water is pumped to a boiler where heat is added at constant pressure which converts water into steam. This high temperature steam rotates the turbine. This expansion of gas takes places isentropically. Now the heat is rejected into condenser at constant pressure which converts it into water. Now the water is pumped isentropically which complete the cycle. This cycle runs continuously which generate power.

The basic and main difference between Carnot and Rankine cycle is that in Carnot cycle heat is added and rejected at constant pressure and in Rankine cycle heat addition and rejection take place at constant pressure. The other main difference is that the Rankine cycle use water as working substance and Carnot cycle used air as working substance. There are many other differences which are describe below in tabular form.

 

Difference between Carnot Cycle and Rankine cycle:



































Sr. No.Carnot CycleRankine Cycle
1.It is a theoretical cycle. . It gives maximum efficiency between two temperature differenceThis one is a practical cycle of steam engine and turbine.
2.Heat is added and rejected at constant temperature.Heat is added and rejected at constant pressure.
3.It has highest efficiency between two temperature differences.Rankine cycle has lower efficiency than Carnot cycle.
4.Carnot cycle uses air as the working substance.Rankine cycle uses water as working substance.
5.Carnot cycle is ideal cycle for heat engine.It is ideal cycle for vapor power engine.

Today we have discussed about main difference between Carnot cycle and Rankine Cycle. If you have any query regarding this article, ask by commenting.

Forging vs Casting

Today I am going to tell you about difference between Forging vs Casting. Casting and forging are both industrial processes of metal forming and shaping. Different process used in different conditions. The main difference between casting and forging is that the metal is compulsory to heat and convert into liquid stage in casting but in forging metal is converted into desire shape by applying pressure with or without applying heat. If the metal is preheated into forging it does not convert into liquid stage. But before differentiate this both terms; you have to know about what is casting and what is forging. So first I am going to tell you about these terms.

Forging vs Casting:



What is casting?


Casting is a process in which metal is heated until molten stage and pour this liquid metal into a mold or cavity where it is allow solidifying. This process converts the metal into desire shape. It is useful to make complex structure. Most of the industrial structures parts are like lathe machine bed, milling machine bed make big base of other machinery part, IC engine components etc. are made by this process.

Advantages of Casting



  • This process can form very large structure which is impossible to form by other process.

  • It can make any complex and unsymmetrical structure.

  • The structure formed by this process has high compressive strength.

  • It can attain wide range of properties.

  • This process can attain high accuracy.


 

What is forging?


On the other hand forging is the process of converting metal into desire shape by applying pressure and with or without heat. When the metal is heated before applying pressure the process is called hot forging. In forging metal is heated before below critical temperature or below molten stage. Rolling, pressing, Wire drawing etc. is various types of forging. All sheets, small component, wire etc are formed by this process.

Advantages of Forging:



  • It produces tougher product compare to other.

  • The product made by forging has high impact or tensile strength.


Tabular form of Difference between Forging vs Casting


















































S. No.CastingForging
1.The metal is heated until it converts into molten stage.The metal is heated below recrystallization temperature.
2.The product produce by it have high compressive strength compare to forging.It has low compressive strength.
3.It has low fatigue strength.It has high fatigue strength.
4.Imperfection or directional defecates does not improve in casting.Directional defect are refined in forging.
5.It is less reliable or has low strength.It is high reliable.
6.It is costly sometime and has high lead time.It has low lead time and cheap compare to casting.
7.The product has low tensile strength.This produces high tensile strength.
8.It required a secondary finishing operation.It does not require a secondary operation.

Today we have learned about difference between. Casting and forging. If you have any query regarding this article, ask by commenting.

 

2 Stroke vs 4 Stroke Engine

Today I am going to tell you about main difference between 2 strokes vs 4 stroke engines. We all heard about both of these engines but few of us know the basic differences between them. Before discussing on this topic first you should know about stroke. The stroke in an engine is the distance covered by the piston from top dead center to the bottom dead center. In simple words, stroke is the distance of cylinder between piston moves. If a piston moves 2 times in the cylinder, that means, engine is known as two stroke engine and if it moves 4 times in a four stroke engine. The crankshaft rotates one time between 2 strokes.

 

The basic and main difference between two stroke and four stroke engine is that the crankshaft complete one revolution in one power stroke in 2 stroke engine and complete 2 revolution in one power stroke in four stroke engine. So the 2 stroke engine give high power compare to 4 stroke engine but the 4 stroke engine is more fuel efficient. There are many other differences which are given below.

Difference between 2 Stroke vs 4 Stroke Engine


























































































S. No.Two Stroke EngineFour Stroke Engine
1.It has one revolution of crankshaft within one power stroke.It has two revolution of crankshaft between one power strokes.
2.It can generate high torque compare to 4 strokes engine.It generates less torque due to 2 revolution of crankshaft between one power strokes.
3.It used port to inlet and outlet of fuel.It used valve to inlet and outlet.
4.2 stroke engines require lighter flywheel compare to other engines because it generates more balanced force due to one revolution for one power stroke.It requires heavy flywheel because it generates unbalance force due to two revolutions for one power stroke.
5.The charge is partially burn and mix with the burn gases during inlet. It is due to port mechanism.In four stroke engine charge is fully burn and does not mix with burn charge in ideal condition.
6.Easy lubrication due to lubrication oil mix with the fuel.Comparatively complicated lubrication.
7.More lubricating oil requires because some oil burns with fuel.Comparatively less lubricating oil requires.
8.These engines give less thermal efficiency.These engines give more thermal efficiency.
9.It has high power to weight ratio compare to others.4 stroke engines have less power to weight ratio.
10.It creates more noise.It is less noisy.
11.Two stroke engines are less efficient and generate more smoke.Four stroke engines are more efficient and generate less smoke.
12.These engines are comparatively cheaper.These engines are expansive due to valve and lubrication mechanism.
13.These engines are easy to manufacture.These engines are comparatively hard to manufacture.
14.These engines are generally lighter.These engines are comparatively heavier than 2 strokes due to heavy flywheel and valve mechanism.
15.These are mostly used in ships, scooters etc.These engines mostly used in car, truck, and other automobiles.
16.Due to poor lubrication more wear and tear occursLess wear and tear occurs.

 

These are all about between difference between 2 stroke and 4 stroke engine. If you have any query regarding this article, asks by commenting.

LPG Engine vs Petrol Engine

#LPG Engine vs Petrol Engine

Today we will learn about main difference between LPG vs Petrol powered engine. We know that both petrol and LPG are used as fuel in SI engine. Mainly SI engine are power by petrol but due to low cost of LPG and negligible effect on power, most of people convert their Petrol Power engine into LPG power engine.

 

There are many other differences between these two engines except cost. These are as follow.

Difference between LPG vs Petrol Engine:



















































S.No.



Petrol Engine



LPG Engine


1.Fuel Consumption in Petrol engine is less when compared to LPG.Engine running on LPG results 10% increase in consumption compare to petrol engine.
2.Petrol has odour or it smell badly.LPG is odourless or it has no smell. But due to identified leakage Ethyl Mercaptan added in it which also smell badly.
3.Octane rating of petrol is 81.Octane rating of LPG is 110 which is more than petrol, So there e is less possibility of detonation.
4.Compare to LPG Engine, petrol engines are not smooth running.Due to higher octane number less knocking LPG engines are running smoothly compare to petrol engines.
5.Lead is added in petrol engine to increase octane rating, which is harmful for environment.LPG is lead free so it is ecofriendly.
6.When petrol passes over the oil rings, it washes out the lubricant film from the upper cylinder surface. It causes lack of lubricant which increases wear and tear. So the life of petrol engine is less compare to LPG engine.LPG does not wash out lubricant film, hence the life of LPG engine is increased by 50%.
7.It forms carbon deposit on the spark plugs, so the life of spark plug is shorter.LPG does not deposits carbon on spark plug so the life of spark plug is more than petrol engine.
8.Carburetor is used to mix air fuel mixer in proper ratio in petrol engine.Vaporizer used to mix air fuel in proper ratio in LPG engine. It reduce the LPG pressure, vaporize it and supply it according to engine requirement.

 

This is all about LPG vs Petrol engines. If you have any query regarding this article, ask by commenting. If you like this article don’t forget to share it on social networks.

Top 100 Mechanical Engineering Interview Questions & Answer

[su_heading]Top 100  Mechanical Engineering Interview Questions & Answer[/su_heading]


mechanical engineering interview questions and answers pdf free download 


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1. What is the difference between scavenging and supercharging ?

Ans: Scavenging is process of flushing out burnt gases from engine cylinder by introducing fresh air in the cylinder before exhaust stroke ends. Supercharging is the process of supplying higher mass of air by compressing the atmospheric air.

 

2. What are the names given to constant temperature, constant pressure, constant volume, constant internal energy, constant enthalpy, and constant entropy processes.Ans: Isothermal, isochroic, isobaric, free expression, throttling and adiabatic processes respectively.

 

3. In a Rankine cycle if maximum steam pressure is increased keeping steam temperature and condenser pressure same, what will happen to dryness fraction of steam after expansion ?Ans: It will decrease.

 

4. Why entropy change for a reversible adiabatic process is zero ?

Ans: Because there is no heat transfer in this process.

 

5. What are two essential conditions of perfect gas ?

Ans: It satisfies equation of state and its specific heats are constant.

 

6. Enthalpy and entropy are functions of one single parameter. Which is that ?

Ans: Temperature.

 

7. Why rate of condensation is higher on a polished surface compared to rusty surface ?

Ans: Polished surface promotes drop wise condensation and does not wet the surface.

 

8. How much resistance is offered to heat flow by drop wise condensation ?

Ans: Nil

 

How are these questions - please do add comments and if you like them please do share this post on facebook, linkedin, twitter and google plus.

 

9. What is the relationship between COP of heating and cooling ?

Ans: COP of heating is one(unity) more than COP of cooling.

 

10. How much is the work done in isochoric process ?

Ans: Zero.

 

11. When maximum discharge is obtained in nozzle ?

Ans: At the critical pressure ratio.

 

1. Under what condition the work done in reciprocating compressor will be least ?

Ans: It is least when compression process approaches isothermal. For this purpose, attempts are made to cool the air during compression.

 

13. What is the difference between stalling and surging in rotary compressions ?

Ans: Stalling is a local phenomenon and it occurs when How breaks away from the blades. Surging causes complete breakdown of flow and as such it affects the whole machine.

 

14. Why the electric motor of a fan with backward curved blades is never got overloaded under any condition ?

Ans: The maximum power is consumed at about 70% of maximum flow in case'of fan with backward blades. For higher flow, power consumption gets lower.

 

15. Why the work per kg of air flow in axial flow compressor is less compared to centrifugal compressor for same pressure ratio ?

Ans: Isentropic efficiency of axial flow compressor is higher.

 

16. What is the name given to portion of thermal energy to be necessarily rejected to environment ?

Ans: Anergy.

 

17. What is pitting ? How it is caused ?

Ans: Non uniform corrosion over the entire metal surface, but occuring only in small pits is called pitting. It is caused by lack of uniformity in metal.

 

18. What is caustic embrittlement ?

Ans: It is the actual physical change in metal that makes it extremely brittle and filled with minute cracks. It occurs particularly in the seams of rivetted joints and around the rivet holes.

 

19. Which impurities form hard scale and which impurities soft scale ?

Ans: Sulphates and chlorides of lime and magnesium form hard scale, and carbonates of lime and magnesium form soft scale.

 

20. What is the difference between hard water and soft water ?

Ans: Hard water contains excess of scale forming impurities and soft water contains very little or no scale forming substances.

 

21. Which two elements in feed water can cause corrosion of tubes and plates in boiler ? '

Ans: Acid and oxygen in feed water lead to corrosion.

 

22. What should be done to prevent a safety valve to stick to its seat ?

Ans: Safety valve should be blown off periodically so that no corrosion can take place on valve and valve seat.

 

23. Why large boilers are water tube type ?

Ans: Water tube boilers raise steam fast because of large heat transfer area and positive water circulation. Thus they respond faster to fluctuations in demand. Further single tube failure does not lead to catastrophy.

 

24. What type of boiler does not need a steam drum ?

Ans: Super-critical pressure boiler.

 

25. Why manholes in vessels are usually elliptical in shape ?

Ans: Elliptical shape has minimum area of opening and thus plate is weakened the least. Further it is very convenient to insert and take out the cover plate from elliptical opening.

 

26. Low water in boiler drum is unsafe because it may result in overheating of water tubes in furnace. Why it is unsafe to have high water condition in boiler drum ?

Ans: High drum level does not allow steam separation to be effective and some water can be carried over with steam which is not desirable for steam turbine.

 

27. Why boiler is purged everytime before starting firing of fuel ?

Ans: Purging ensures that any unburnt fuel in furnace is removed, otherwise it may lead to explosion.

 

28. What is the principle of mechanical refrigeration ?

Axis. A volatile liquid will boil under the proper conditions and in so doing will absorb heat from surrounding objects.

 

29. Why high latent heat of vaporisation is desirable in a refrigerant ?

Ans: A high latent heat of vaporisation of refrigerant results in small amount of refrigerant and thus lesser circulation system of refrigerant for same tonnage.

 

30. What is the critical temperature of a refrigerant ?

Ans: Critical temperature is the maximum temperature of a refrigerantrat which it can be condensed into liquid and beyond this it remains gas irrespective of pressure applied.

 

31. Maximum combustion temperature in gas turbines is of the order of 1100 to 10°C whereas same is around 00°C in I.C. engine ? Why ?

Ans: High temperature in I.C. engine can be tolerated because it lasts for a fraction of second but gas turbines have to face it continuously which metals can't withstand.

 

32. Why efficiency of gas turbines is lower compared to I.C. engines ?

Ans: In gas turbines, 70% of the output of gas turbine is consumed by compressor. I.C. engines have much lower auxiliary consumption. Further combustion temperature of I.C. engines is much higher compared to gas turbine.

 

33. What do you understand by timed cylinder lubrication ?

Ans: For effective lubrication, lub oil needs to be injected between two piston rings when piston is at bottom of stroke so that piston rides in oi during upward movement. This way lot of lub oil can be saved and used properly.

 

34. What is IIUCR in relation to petrol engine ?

Ans: HUCR is highest useful compression ratio at which the fuel can be used in a specific test engine, under specified operating conditions, without knocking.

 

35. In some engines glycerine is used in place of water for cooling of engine. Why ?

Ans: Glycerine has boiling point of 90°C which increases its heat carrying capacity. Thus weight of coolant gets reduced and smaller riadiator can be used.

 

36. Why consumption of lubricating oil is more in two-stroke cycle petrol engine than four-stroke cycle petrol engine ?

Ans: In two-stroke engine lub oil is mixed with petrol and thus some lub oil is blown out through the exhaust valves by scavenging and charging air. There is no such wastage in four stroke petrol engine.

 

37. As compression ratio increases, thermal n increases. How is thermal n affected by weak and rich mixture strength ?

Ans: Thermal n is high for weak mixture and it decreases as mixture strength becomes rich.

 

38. How engine design needs to be changed to burn lean mixture ?

Ans: Engine to burn lean mixture uses high compression ratio and the highly turbulent move¬ment of the charge is produced by the geometry of the combustion chamber.

 

39. Horse power of I.C. engines can be expressed as RAC rating, SAE rating, or DIN rating. To which countries these standards belong ?

Ans: U.K., USA and Germany respectively.

 

40. What is the use of flash chamber in a vapour compression refrigeration cycle to improve the COP of refrigeration cycle ?

Ans: When liquid refrigerant as obtained from condenser is throttled, there are some vapours. These vapours if carried through the evaporator will not contribute to refrigerating effect. Using a flash chamber at some intermediate pressure, the flash vapour at this pressure can be bled off and fed back to the compression process. The throttling process is then carried out in stages. Similarly compression process is also done in two separate compressor stages.

 

41. Why pistons are usually dished at top ?

Ans: Pistons are usually hollowed at top to (i) provide greater spa'e for combustion, (ii) increase surface for flue gases to act upon, and (iii) better distribution of stresses.

 

42. What is the function of thermostat in cooling system of an engine ?

Ans: Thermostat ensures optimum cooling because excessive cooling decreases the overall efficiency. It allows cooling water to go to radiator beyond a predetermined temperature.

 

43. What are the causes of failure of boiler tubes ?

Ans: Boiler tubes, usually are made from carbon steel and are subject to (a) high rates of heat transfer,( b ). bending stresses due to uneven heating, especially at expanded or welded joints into headers or drums, © external erosion from burners and flue gas, (d) possible corrosion on the boiler side, and (e) occasional manufacturing defects.

Failure may occur due to following reasons :

(a) High thermal ratings may lead to rapid failure if the internal fluid flow is reduced for any reason. The resultant overheating leads to a failure by creep, characterised by the bulging of the tube with the eventual development of a longitudinal split.

(b ) Fatigue cracking due to bending stresses occur. These are associated with change of section and/or weld undercut, where tubes are expanded or welded into headers.

© Failure may arise due to overstressing of a reduced section of metal.

(d) Sudden failure of the boiler tube due to corrosion arises from embrittlement of the carbon steel due to interaction between atomic hydrogen from the corrosion process and the iron carbide present in the steel.

(e) Defects in tube manufacture, although far from being a regular occurrence, can be a cause of serious trouble. Lamination in boiler tubes or score marks arising from the cold drawing of tubes, give rise to premature failure and may promote corrosion at these regions.

 

44. What are the causes of failure of superheater tubes ?

Ans: Superheater tubes are subjected to the most severe combination of stress, temperature and corrosive environment. In addition to high-temperature strength, resistance to corrosion is also important. For example, low-alloy ferritic steel such as -1/% Cr, 1% Mo would not be used at metal temperatures above 580°C because of inadequate resistance to corrosion and oxidation over a full service life of 100,000/150,000 hr.

Failures in superheater tubes may arise from :

(a) Prior fabrication history (b ) Faulty heat treatment

© Consequences of welding (d) Overheating of the tube metal

(e) Gas-side corrosion (f) Stress corrosion (austenitic steels).

 

45. Why supercritical boilers use less amount of steel compared to non-supercritical boilers ?

Ans: Supercritical boilers do not head heavy drum for separation of steam from mixture of water and steam.

 

46. Out of electric heater and heat pump, which is economical in operation ?

Ans: Heat pump.

 

47. Which furnace burns low-ash fusion coal and retains most of the coal ash in the slag?

Ans: Cyclone furnace.

 

48. How the thickness of thermal boundary layer and thickness of hydrodynamic boundary layer related ?

Ans: Ratio of their thickness = (Prandtl number)-1/3.

 

49. What is the effect of friction on flow of steam through a nozzle ?

Ans: To decrease both mass flow rate and wetness of steam.

 

50. Why gas turbine power plant needs efficient compressor ?

Ans: Because a large portion of turbine work is eaten away by compressor and its inefficiency will affect net power output and cost of generation.

 

51. Why rockets using liquid hydrogen have higher specific impulse compared to liquid hydrocarbon ?

Ans: Liquid hydrogen has higher burning velocity.

 

52. Why axial flow compressor is preferred for gas turbines for aeroplanes ?

Ans: Because it has low frontal area.

 

53. What is the effect of inter cooling in gas turbines ?

Ans: It decreases thermal efficiency but increases net output.

 

54. Why iso-octane is chosen as reference fuel for S.I. engines and allotted 100 value for its octane number ?

Ans: Iso-octane permits highest compression without causing knocking.

 

55. Why thermal efficiency of I.C. engines is more than that of gas turbine plant ?

Ans: In I.C. engine maximum temperature attained is higher than in gas turbine.

 

56. Which are the reference fuels for knock rating of S.I. engines ?

Ans: n-heptane and ISO-octane.

 

57. When effect of variations in specific heats is considered then how do maximum temperature and pressure vary compared to air standard cycle ?

Ans: Temperature increases and pressure decreases.

 

58. Quantities like pressure, temperature, density, viscosity, etc. are independent of mass. What are these called ?

Ans: Intensive properties.

 

59. The amount of radiation emitted per scm per sec is called .... ?

Ans: Emissive power.

 

60. In convection heat transfer, if heat flux intensity is doubled then temperature

difference between solid surface and fluid will ?

Ans: Get doubled.

 

61. How you can define coal ?

Ans: Coal is a naturally occurring hydrocarbon that consists of the fossilised remains of buried plant debris that have undergone progressive physical and chemical alteration, called coalification, in the course of geologic time.

 

62. Which pollutant is major greenhouse gas and what is its effect ?

Ans: CO is major greenhouse gas and it traps the radiation of heat from the sun within earth's atmosphere.

 

63. In order to increase efficiency and reduce CO emissions and other emissions, clear coal technologies are receiving major attention. What are these ?

Ans: (i) Advanced pulverised and pressurised pulverised fuel combustion.

(ii) Atmospheric fluidised bed combustion and pressurised fluidised bed combustion.

(iii) Supercritical boilers.

(iv) Integrated gasification combined cycle systems.

(v) Advanced integrated gasification, including fuel cell systems.

(vi) Magneto hydrodynamic electricity generation.

 

64. What are the important operational performance parameters in design of fuel firing equipment ?

Ans: Fuel flexibility, electrical load following capability, reliability, availability, and maintenance ease.

 

65. What is the differenc between total moisture and inherent moisture in coal ?

Ans: The moisture content of the bulk as sampled is referred to as total moisture, and that of the air dried sample is called inherent moisture.

 

66. Proximity analysis of coal provides data for a first, general assessment of a coal's quality and type. What elements it reports ?

Ans: Moisture, volatile matter, ash and fixed carbon.

 

67. Ultimate analysis of coal is elementary analysis. What it is concerned with ?

Ans: Carbon, hydrogen, nitrogen, and sulphur in coal on a weight percentage basis.

 

68. Explain the difference between AFBC, BFBC, PFBC and PCFB in regard to fluidised bed technologies.

Ans: AFBC (Atmospheric fluidised bed combustion) process consists of forming a bed of inert materials like finely sized ash or ash mixed with sand, limestone (for sulphur removal), and solid fuel particles in a combustor and fluidising it by forcing combustion air up through the bed mixture. The gas flows thorugh bed without disturbing particles significantly but gas velocity is high enough to support the total weight of bed (fluidisation). At slightly higher velocity excess gas passes through the bed as bubbles (fluidised bed) and gives the bed the appearance of a boiling liquid.

Bubbling fluidised bed combustion (BFBC) has a defined height of bed material and operates at or near atmospheric pressure in the furnace.

Pressurised fluidised bed combustion (PFBC) system operates the bed at elevated pressure. Exhaust gases have sufficient energy to power a gas turbine, of course, gases need to be cleaned.

In fluidised combustion, as ash is removed some unburned carbon is also removed resulting in lower efficiency. In circulating fluidised bed combustion (CFBC) system, bed is operated at higher pressure leading to high heat transfer, higher combustion efficiency, and better fuel feed. Circulating fluidised beds operate with relatively high gas velocities and fine particle sizes. The maintenance of steady state conditions in a fast fluidised bed requires the continuous recycle of particles removed by the gas stream (circulating bed). The term circulating bed is often used to include fluidised bed sys¬tems containing multiple conventional bubbling beds between which bed material is exchanged.

 

69. What for Schmidt plot for is used in heat transfer problems ?

Ans: Schmidt plot is a graphical method for determining the temperature at any point in a body at a specified time during the transient heating or cooling period.

 

70. In which reactor the coolant and moderator are the same ?

Ans: Pressurised water reactor.

 

71. Which reactor has no moderator ?

Ans: Fast breeder reactor.

 

72. What are thermal neutrons ?

Ans: Thermal neutrons are slow neutrons (having energy below 1 eV) which are in thermal equilibrium with their surroundings.

 

73. What is big advantage of fast breeder reactor ?

Ans: It has rapid self breeding of fissile fuel during the operation of the reactor, and thus, it offers about sixty times the output with same natural uranium resources through ordinary non-breeder nuclear reactor.

 

74. What is the purpose of biological shield in nuclear plants ?

Ans: Biological shield of heavy concrete prevents exposure to neutrons, beta rays and gamma rays which kill living things.

 

75. Which two elements have same percentage in proximate and ultimate analysis of coal?

Ans: Moisture and ash.

 

76. On which analysis is based the Dulong's formula for the heating value of fuel ?

Ans: On ultimate analysis.

 

77. Which element causes difference in higher and lower heating values of fuel ?

Ans: Hydrogen.

 

78. Which heating value is indicated by a calorimeter and why ?

Ans: Gross heating value because steam is condensed and heat of vapour formed is recovered.

 

79. State the difference between ultimate and proximate analysis of coal ?

Ans: In ultimate analysis, chemical determination of following elements is made by weight: Fixed and combined carbon, H, O, N, S, water and ash. Heating value is due to C, H and S.

In proximate analysis following constituents are mechanically determined by weight. Moisture, volatile matter, fixed carbon and ash. Heating value is due to fixed carbon and volatile matter.

 

80. What is fuel ratio ?

Ans: Fuel ratio is the ratio of its % age of fixed carbon to volatile matter.

 

81. How the analyses and calorific values of fuels can be reported ?

Ans: It may be reported as

(a) as received or fired (wet) basis

(b ) dry or moisture free basis

© combustible or ash and moisture free basis

 

82. What is the difference between nuclear fission and fission chain reaction.

Ans: The process of splitting of nucleus into two almost equal fragments accompanied by re¬lease of heat is nuclear fission. Self sustained, continuing, sequence of fission reactions in a con¬trolled manner is fission chain reaction.

 

83. Explain difference between fissile and fertile materials.

Ans: The materials which can give nuclear fission e.g. U 35, Pu 39, U 33 are fissile materi¬als. Fertile material itself is not fissionable, but it can be converted to a fissionable material by irradiation of neutrons in a nuclear reactor.

 

84. What do you understand by fuel cycle in nuclear plants ?

Ans: Fuel cycle a series of sequential steps involved in supplying fuel to a nuclear power reactor. The steps include : Mining, refining uranium, fabrication of fuel elements, their use in nuclear reactor, chemical processing to recover remaining fissionable material, re-enrichment of fuel from recovered material, refabrication of new fuel elements, waste storage etc.

 

85. What is heavy water and what is its use in nuclear plants ?

Ans: Water containing heavy isotopes of hydrogen (Deuterium) is known as heavy water. Heavy water is used as a moderator. Heavy water has low cross section for absorption of neutrons than ordinary water. Heavy water slows down the fast neutrons and thus moderates the chain reaction.

 

86. What is a converter reactor ?

Ans: A reactor plant which is designed to produce more fuel than it consumes. The breeding is obtained by converting fertile material to fissile material.

 

87. Explain nuclear reactor in brief.

Ans: A plant which initiates, sustains, controls and maintains nuclear fission chain reaction and provides shielding against radioactive radiation is nuclear reactor.

 

88. What is the difference between conversion and enrichment ?

Ans: The process of converting the non fissile U 38 to fissile U-35 is also called "Conversion". The material like U 38 which can be converted to a fissile material by the neutron flux is called "fertile material". The conversion is obtained within the nuclear reactor during the chain reaction.

Enrichment is the process by which the proportion of fissile uranium isotope (U-35) is increased above 0.7% (original % in natural uranium).

The concentration of U-35 in the uranium hexafluoride is increased from the 0.7% in natural uranium to to 4%. This is called enrichment and is accomplished in an enrichment plant.

 

89. Disposal of radioactive waste materials and spent fuel is a major and important technology. How the waste radioactive material is disposed off ?

Ans: Nonusable fission products are radioactive and take short/medium/long time for radioactive decay to reach safe level of radioactivity. Accordingly three methods of disposal are :

(a) Zero or low radioactivity material is dispersed or stored without elaborate shielding.

(b ) Medium radioactivity material is stored for short duration of about 5 years to allow decay of radioactivity.

© High radioactive material. They are stored in water for several months to permit radioactive decay to an accepetable low level.

 

90. Which nuclear reactor uses water as a coolant, moderator and reflector ?

Ans: Pressurised water reactor.

 

91. Which reactor produces more fissionable material than it consumes ?

Ans: Breeder reactor.

 

92. Which reactor uses natural uranium as fuel ?

Ans: Gas cooled reacator.

 

93. Which reactor uses heavy water as moderator ?

Ans: CANDU.

 

94. Which reactor requires no moderator ?

Ans: Breeder reactor.

 

95. Which reactor uses primary coolant as fluoride salts of lithium, beryllium, thorium and uranium ?

Ans: Molten salt breeder reactor.

 

96. Why an increase in area is required to produce an increase of velocity in case of supersonic flow ?

Ans: Increase in area for increase in velocity for supersonic flow is required because the density decreases faster than velocity increases at supersonic speeds and to maintain continuity of mass, area must increase.

 

97. Under what circumstances would there be an increase in pressure in a diver¬gent nozzle ?

Ans: For subsonic flow at inlet section of a diffuser a lower velocity and higher pressure will exist at the exit section. For supersonic isentropic flow at the inlet section a higher velocity and lower pressure will exist at the exit but if a shock wave occurs in the diffuser then a higher pressure will exist at the exit.

 

98. Why water can't be used as refrigerant for small refrigerating equipment ?

Ans: The refrigerant should be such that vapour volume is low so that pumping work will be low. Water vapour volume is around 4000 times compared to R- for a given mass.

 

99. Which parameter remains constant in a throttling process ?

Ans: Enthalpy.

 

100. What is the difference between isentropic process and throttlinglprocess ?

Ans: In isentropic process, heat transfer takes place and in throttling process, enthalpy before and after the process is same.

 

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