The maximum delivery pressure in a rotary air compressor is A. 10 bar B. 20 bar C. 30 bar D. 50 bar

The maximum delivery pressure in a rotary air compressor is A. 10 bar B. 20 bar C. 30 bar D. 50 bar  
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In a two stage reciprocating air compressor, the suction and delivery pressure are 1 and 4 bar respectively. For maximum efficiency the intercooler pressure is A. 1.5 bar B. 2 bar C. 2.5 bar D. 3 bar

Description : In a two stage reciprocating air compressor, the suction and delivery pressure are 1 and 4 bar respectively. For maximum efficiency the intercooler pressure is A. 1.5 bar B. 2 bar C. 2.5 bar D. 3 bar

Last Answer : ANSWER : B

In a two stage reciprocating air compressor with a suction pressure of 2 bar and delivery pressure of 8 bar the ideal intercooler pressure will be A. 10 bar B. 6 bar C. 4 bar D. 3 bar

Description : In a two stage reciprocating air compressor with a suction pressure of 2 bar and delivery pressure of 8 bar the ideal intercooler pressure will be A. 10 bar B. 6 bar C. 4 bar D. 3 bar

Last Answer : ANSWER : C

In a four stage compressor, if the pressure at the first and third stage are 1 bar and 16 bar, then the delivery pressure at the fourth stage will be A. 1 bar B. 16 bar C. 64 bar D. 256 bar

Description : In a four stage compressor, if the pressure at the first and third stage are 1 bar and 16 bar, then the delivery pressure at the fourth stage will be A. 1 bar B. 16 bar C. 64 bar D. 256 bar

Last Answer : ANSWER : C

The volume of air delivered by the compressor is called A. Free air delivery B. Compressor capacity C. Swept volume D. Mean effective pressure

Description : The volume of air delivered by the compressor is called A. Free air delivery B. Compressor capacity C. Swept volume D. Mean effective pressure

Last Answer : ANSWER : B

In a single stage reciprocating air compressor, the work done on air to compressor is from suction pressure to delivery pressure will be minimum when the compression is A. Isothermal process B. Adiabatic process C. Polytropic process D. Constant pressure process.

Description : In a single stage reciprocating air compressor, the work done on air to compressor is from suction pressure to delivery pressure will be minimum when the compression is A. Isothermal process B. Adiabatic process C. Polytropic process D. Constant pressure process.

Last Answer : ANSWER : A

Which one of the following statement is not correct for the volumetric efficiency of a reciprocating air compressor? A. It decreases with increase in ambient temperature B. It increases with decrease in pressure ratio C. It increases with decrease in clearance ratio D. It decreases with increases in delivery pressure

Description : Which one of the following statement is not correct for the volumetric efficiency of a reciprocating air compressor? A. It decreases with increase in ambient temperature B. It increases with ... It increases with decrease in clearance ratio D. It decreases with increases in delivery pressure

Last Answer : ANSWER : A

In a single acting reciprocating compressor, the suction, compression and delivery of air takes place in A. One stroke B. Two stroke C. Three stroke D. Four stroke

Description : In a single acting reciprocating compressor, the suction, compression and delivery of air takes place in A. One stroke B. Two stroke C. Three stroke D. Four stroke

Last Answer : ANSWER : B

In vapour compression cycle using NH3 as refrigerant, initial charge is filled at (a) suction of compressor (b) delivery of compressor (c) high pressure side close to receiver (d) low pressure side near receiver

Description : In vapour compression cycle using NH3 as refrigerant, initial charge is filled at (a) suction of compressor (b) delivery of compressor (c) high pressure side close to receiver (d) low pressure side near receiver

Last Answer : Ans: c

A large clearance volume in a reciprocating compressor results in A. Reduced volume flow rate B. Increased volume flow rate C. Lower suction pressure D. Lower delivery pressure

Description : A large clearance volume in a reciprocating compressor results in A. Reduced volume flow rate B. Increased volume flow rate C. Lower suction pressure D. Lower delivery pressure

Last Answer : ANSWER : A

A large clearance volume in reciprocating compressor results in A. reduced volume flow rate B. Increased volume flow rate C. Lower suction pressure D. Lower delivery pressure

Description : A large clearance volume in reciprocating compressor results in A. reduced volume flow rate B. Increased volume flow rate C. Lower suction pressure D. Lower delivery pressure

Last Answer : ANSWER : A

The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is (a) bigger (b) smaller (c) equal (d) smaller/bigger depending on capacity

Description : The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is (a) bigger (b) smaller (c) equal (d) smaller/bigger depending on capacity

Last Answer : Ans: a

Volumetric efficiency of air compressor is of the order of A. 20% to 30 % B. 40% to 50% C. 60% to 70% D. 70% to 90%

Description : Volumetric efficiency of air compressor is of the order of A. 20% to 30 % B. 40% to 50% C. 60% to 70% D. 70% to 90%

Last Answer : ANSWER : D

Rotary compressors are used for delivering A. Small quantities of air at high pressure B. Large quantities of air at high pressure C. Small quantities of air at low pressure D. Large quantities of air at low pressure

Description : Rotary compressors are used for delivering A. Small quantities of air at high pressure B. Large quantities of air at high pressure C. Small quantities of air at low pressure D. Large quantities of air at low pressure

Last Answer : ANSWER : D

The clearance volume of the air compressor is kept minimum because A. It allows maximum compression to be achieved B. It greatly affects volumetric efficiency C. It results in minimum work D. It permits isothermal compression

Description : The clearance volume of the air compressor is kept minimum because A. It allows maximum compression to be achieved B. It greatly affects volumetric efficiency C. It results in minimum work D. It permits isothermal compression

Last Answer : ANSWER : B

A reciprocating compressor is not suitable for use as a supercharger because: A. it runs at lower rpm B. the pressure ratio is high C. volumetric efficiency is high D. it is bulky and can handle small quantity of air

Description : A reciprocating compressor is not suitable for use as a supercharger because: A. it runs at lower rpm B. the pressure ratio is high C. volumetric efficiency is high D. it is bulky and can handle small quantity of air

Last Answer : ANSWER : D

Which one of the following statements are correct for reciprocating air compressor? A. Its volumetric efficiency increases with increasing clearance ratio B. Its volumetric efficiency increases with pressure ratio C. Its volumetric efficiency does not vary with change in clearance ratio and pressure ratio D. Its volumetric efficiency decreases with increasing clearance ratio and pressure ratio

Description : Which one of the following statements are correct for reciprocating air compressor? A. Its volumetric efficiency increases with increasing clearance ratio B. Its volumetric efficiency increases ... ratio D. Its volumetric efficiency decreases with increasing clearance ratio and pressure ratio

Last Answer : ANSWER : D

The power required to drive a turbo compressor for a given pressure ratio decreases when A. Air is heated at entry B. Air is cooled at entry C. Air is cooled at exit D. Air is heated at exit

Description : The power required to drive a turbo compressor for a given pressure ratio decreases when A. Air is heated at entry B. Air is cooled at entry C. Air is cooled at exit D. Air is heated at exit

Last Answer : ANSWER : B

Reduction in the delivery pressure of a Compressor working at 7 bar, by 1 bar would reduce the power consumption by a) 6 to 10 % b) 2 to 3 % c) 12 to 14 % d) None of the above

Description : Reduction in the delivery pressure of a Compressor working at 7 bar, by 1 bar would reduce the power consumption by a) 6 to 10 % b) 2 to 3 % c) 12 to 14 % d) None of the above

Last Answer : a) 6 to 10 %

Adiabatic compression is one in which A. Temperature during compression remains constant B. No heat leaves or enters the compressor cylinder during compression C. Temperature rise follows a linear relationship D. Work done is maximum.

Description : Adiabatic compression is one in which A. Temperature during compression remains constant B. No heat leaves or enters the compressor cylinder during compression C. Temperature rise follows a linear relationship D. Work done is maximum.

Last Answer : ANSWER : B

Classification of air compressor

Description : Classification Of Air Compressor

Last Answer : Air compressors are classified in several different ways, depending on the specific characteristics and features of the compressor. Here are a few common ways that air compressors are classified: ... range of sizes and capacities, from small, portable units to large, industrial-sized compressors.

The area of actual indicator diagram on an air compressor as compared to area of ideal indicator diagram is A. Less B. More C. Same D. Unpredictable

Description : The area of actual indicator diagram on an air compressor as compared to area of ideal indicator diagram is A. Less B. More C. Same D. Unpredictable

Last Answer : ANSWER : B

In reciprocating air compressor the clearance ratio is given by A. B. C. D.

Description : In reciprocating air compressor the clearance ratio is given by A. B. C. D.

Last Answer : ANSWER : C

Work input to the air compressor with n as index of compression A. Increases with increase in value of n B. Decrease with increase in value of n C. remains same whatever the value of n D. first increase and then decreases with increase of value of n.

Description : Work input to the air compressor with n as index of compression A. Increases with increase in value of n B. Decrease with increase in value of n C. remains same whatever the value of n D. first increase and then decreases with increase of value of n.

Last Answer : ANSWER : A

Surging basically implies A. Unsteady, periodic and reversed flow B. Forward motion of air at a speed above sonic velocity C. The surging action due to the blast of air produced in a compressor D. Forward movement of aircraft

Description : Surging basically implies A. Unsteady, periodic and reversed flow B. Forward motion of air at a speed above sonic velocity C. The surging action due to the blast of air produced in a compressor D. Forward movement of aircraft

Last Answer : ANSWER : A

Which one of the following methods can be adopted to obtain isothermal compression in an air compressor? A. Increasing the weight of the compressor B. Inter-stage heating C. Atmospheric cooling D. Providing appropriate dimensions to the cylinder

Description : Which one of the following methods can be adopted to obtain isothermal compression in an air compressor? A. Increasing the weight of the compressor B. Inter-stage heating C. Atmospheric cooling D. Providing appropriate dimensions to the cylinder

Last Answer : ANSWER : A

In a reciprocating air compressor the compressor work per kg of air A. Increases as clearance volume increases B. Decreases as clearance volume increases C. Is independent of clearance volume D. Increases with clearance volume only of multistage compressor

Description : In a reciprocating air compressor the compressor work per kg of air A. Increases as clearance volume increases B. Decreases as clearance volume increases C. Is independent of clearance volume D. Increases with clearance volume only of multistage compressor

Last Answer : ANSWER : C

Reducing suction pressure in refrigeration cycle (a) lowers evaporation temperature (b) increases power required per ton of refrigeration (c) lowers compressor capacity because vapour is lighter (d) all of the above.

Description : Reducing suction pressure in refrigeration cycle (a) lowers evaporation temperature (b) increases power required per ton of refrigeration (c) lowers compressor capacity because vapour is lighter (d) all of the above.

Last Answer : Ans: d

For obtaining high COP, the pressure range of compressor should be (a) high (b) low (c) optimum (d) any value

Description : For obtaining high COP, the pressure range of compressor should be (a) high (b) low (c) optimum (d) any value

Last Answer : Ans: b

In a centrifugal compressor, an increase in speed at a given pressure ratio causes A. Increase in flow B. Decrease in flow C. Increase in efficiency D. Increase in flow and decrease in efficiency

Description : In a centrifugal compressor, an increase in speed at a given pressure ratio causes A. Increase in flow B. Decrease in flow C. Increase in efficiency D. Increase in flow and decrease in efficiency

Last Answer : ANSWER : D

The ratio of work done per cycle to the stroke volume of the compressor is known as A. Compressor capacity B. Compression ratio C. Compressor efficiency D. Mean effective pressure

Description : The ratio of work done per cycle to the stroke volume of the compressor is known as A. Compressor capacity B. Compression ratio C. Compressor efficiency D. Mean effective pressure

Last Answer : ANSWER : D

For a multistage compressor, the polytropic efficiency is A. the efficiency of all stages combined together B. the efficiency of one stage C. Constant throughout for all the stages D. a direct consequence of the pressure ratio

Description : For a multistage compressor, the polytropic efficiency is A. the efficiency of all stages combined together B. the efficiency of one stage C. Constant throughout for all the stages D. a direct consequence of the pressure ratio

Last Answer : ANSWER : C

In a centrifugal compressor an increase in speed at a given pressure ratio causes A. Increase in flow and increase in efficiency B. Increase in flow and decrease in efficiency C. Decrease in flow and increase in efficiency D. Decrease in flow and decrease in efficiency

Description : In a centrifugal compressor an increase in speed at a given pressure ratio causes A. Increase in flow and increase in efficiency B. Increase in flow and decrease in efficiency C. Decrease in flow and increase in efficiency D. Decrease in flow and decrease in efficiency

Last Answer : ANSWER : B

The pressure rise in the impeller of centrifugal compressor is achieved by A. the decrease in volume and diffusion action B. the centrifugal action and decrease in volume C. the centrifugal and diffusion action D. the centrifugal and push pull action

Description : The pressure rise in the impeller of centrifugal compressor is achieved by A. the decrease in volume and diffusion action B. the centrifugal action and decrease in volume C. the centrifugal and diffusion action D. the centrifugal and push pull action

Last Answer : ANSWER : D

For a two stage compressor, the ratio of diameter of low pressure cylinder to high pressure cylinder is equal to A. Square of the ratio of final pressure to initial pressure B. The ratio of final pressure to initial pressure C. The square root of the ratio of final pressure to initial pressure D. Cube root of the ratio of final pressure to initial pressure

Description : For a two stage compressor, the ratio of diameter of low pressure cylinder to high pressure cylinder is equal to A. Square of the ratio of final pressure to initial pressure B. The ratio of ... final pressure to initial pressure D. Cube root of the ratio of final pressure to initial pressure

Last Answer : ANSWER : C

In a constant pressure process steam is generated from 10 bar and 0.8 dry condition till it become dry and saturated. Determine amount of heat added per kg of steam. From steam table at 10 bar Tsat = 179.9°C hf = 762.6 kl/kg, hg = 2776.2 kJ/kg

Description : In a constant pressure process steam is generated from 10 bar and 0.8 dry condition till it become dry and saturated. Determine amount of heat added per kg of steam. From steam table at 10 bar Tsat = 179.9°C hf = 762.6 kl/kg, hg = 2776.2 kJ/kg 

Last Answer : Constant pressure process Final condition of steam is dry saturated Enthalpy of dry steam = hg= hf + hfg =2776.2 KJ/Kg .Given Latent heat of vaporization = hfg = hg - hf =2776.2-762.6 =2013.6 KJ/Kg Initial condition ... hfg = 762.6+0.8 X 2013.6 =2373.48 KJ/Kg Heat added = hg-hw = 402.72 KJ/kg

Intercooling in multistage compression is done A. To cool the air during compression B. To cool the air at delivery C. To enable compression in two stages D. To minimize the work of compression

Description : Intercooling in multistage compression is done A. To cool the air during compression B. To cool the air at delivery C. To enable compression in two stages D. To minimize the work of compression

Last Answer : ANSWER : D

With suction pressure being atmospheric, increase in delivery pressure with fixed clearance volume A. increase volumetric efficiency B. decrease volumetric efficiency C. does not change volumetric efficiency D. First increase volumetric efficiency and then decrease it

Description : With suction pressure being atmospheric, increase in delivery pressure with fixed clearance volume A. increase volumetric efficiency B. decrease volumetric efficiency C. does not change volumetric efficiency D. First increase volumetric efficiency and then decrease it

Last Answer : ANSWER : B

Continuous injection system usually has a) plunger pump b) rotary pump c) gear pump d) vane pump

Description : Continuous injection system usually has a) plunger pump b) rotary pump c) gear pump d) vane pump

Last Answer : Answer: b Explanation: In common use continuous injection system usually has rotary pump.

In compression ignition engines, swirl denotes a. Haphazard motion of the gases in the cylinder b. Rotary motion of the gases in the cylinder. c. Radial motion of the gases in the cylinder. d. None of the above

Description : In compression ignition engines, swirl denotes a. Haphazard motion of the gases in the cylinder b. Rotary motion of the gases in the cylinder. c. Radial motion of the gases in the cylinder. d. None of the above

Last Answer : ANSWER a. Haphazard motion of the gases in the chamber

The coefficient of performance is the ratio of the refrigerant effect to the (a) heat of compression (b) work done by compressor (c) enthalpy increase in compressor (d) all of the above

Description : The coefficient of performance is the ratio of the refrigerant effect to the (a) heat of compression (b) work done by compressor (c) enthalpy increase in compressor (d) all of the above

Last Answer : Ans: d

Where does the lowest temperature occur in a vapour compression cycle ? (a) condenser (b) evaporator (c) compressor (d) expansion valve

Description : Where does the lowest temperature occur in a vapour compression cycle ? (a) condenser (b) evaporator (c) compressor (d) expansion valve

Last Answer : Ans: b

In a refrigeration cycle, the flow of refrigerant is controlled by (a) compressor (b) condenser (c) evaporator (d) expansion valve

Description : In a refrigeration cycle, the flow of refrigerant is controlled by (a) compressor (b) condenser (c) evaporator (d) expansion valve

Last Answer : Ans: d

In vapour compression refrigeration system, refrigerant occurs as liquid between (a) condenser and expansion valve (b) compressor and evaporator (c) expansion valve and evaporator (d) compressor and condenser

Description : In vapour compression refrigeration system, refrigerant occurs as liquid between (a) condenser and expansion valve (b) compressor and evaporator (c) expansion valve and evaporator (d) compressor and condenser

Last Answer : Ans: c

In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to (a) collect liquid refrigerant and prevent it from going to compressor (b) detect liquid in vapour (c) superheat the vapour (d) increase refrigeration effect

Description : In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to (a) collect liquid refrigerant and prevent it from going to compressor (b) detect liquid in vapour (c) superheat the vapour (d) increase refrigeration effect

Last Answer : Ans: a

Formation of frost on evaporator in refrigerator (a) results in loss of heat due to poor heat transfer (b) increases heat transfer rate (c) decreases compressor power. (d) can be avoided by proper design

Description : Formation of frost on evaporator in refrigerator (a) results in loss of heat due to poor heat transfer (b) increases heat transfer rate (c) decreases compressor power. (d) can be avoided by proper design

Last Answer : Ans: a

One of the purposes of sub-cooling the liquid refrigerant is to (a) reduce compressor overheating (b) reduce compressor discharge temperature (c) increase cooling effect (d) ensure that only liquid and not the vapour enters the expansion (throttling) valve

Description : One of the purposes of sub-cooling the liquid refrigerant is to (a) reduce compressor overheating (b) reduce compressor discharge temperature (c) increase cooling effect (d) ensure that only liquid and not the vapour enters the expansion (throttling) valve

Last Answer : Ans: d

The higher temperature in vapour compression cycle occurs at (a) compressor discharge. (b) expansion valve (c) evaporator (d) condenser discharge

Description : The higher temperature in vapour compression cycle occurs at (a) compressor discharge. (b) expansion valve (c) evaporator (d) condenser discharge

Last Answer : Ans: a

Presence of moisture in a refrigerant affects the working of (a) compressor (b) condenser (c) evaparator (d) expansion valve.

Description : Presence of moisture in a refrigerant affects the working of (a) compressor (b) condenser (c) evaparator (d) expansion valve.

Last Answer : Ans: a

The domestic refrigerator uses following type of compressor (a) centrifugal (b) axial (c) miniature sealed unit (d) piston type reciprocating

Description : The domestic refrigerator uses following type of compressor (a) centrifugal (b) axial (c) miniature sealed unit (d) piston type reciprocating

Last Answer : Ans: d

In vapour compression cycle the condition off refrigerant is dry saturated vapour (a) after passing through the condenser (b) before passing through the condenser (c)before entering the expansion valve (d) before entering the compressor

Description : In vapour compression cycle the condition off refrigerant is dry saturated vapour (a) after passing through the condenser (b) before passing through the condenser (c)before entering the expansion valve (d) before entering the compressor

Last Answer : Ans: D