1) Adiabatic compression is one in which___________________? a. temperature during compression remains constant b. no heat leaves or enters the compressor cylinder during cornpression c. temperature rise follows a linear relationship d. work done is maximum e. entropy decreases
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2) The- most efficient method of compressing air is to compress it_________________? a. isothermally b. adiabatically c. isentropically d. isochronically e. as per law pV
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3) Isothermal compression effeicency can be attained by running the compressor__________________? a. at very high speed b. at very slow speed c. at average speed d. at zero speed e. isothermally
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4) Isothermal compression efficiency, even when running at high speed, can be approached by using A. multi-stage compression B. cold water spray C. both A. and B. above D. fully insulating the cylinder E. high stroke_________________?
Isothermal compression efficiency, even when running at high speed, can be approached by using a. multi-stage compression b. cold water spray c. both A. and B. above d. fully insulating the cylinder e. high stroke
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5) The overall isothermal eiffciency of compressor is defined as the ratio of_______________? a. isothermal h.p. to the BHP of motor b. isothermal h.p. to adiabatic h.p. c. power to drive compressor to isothermal h.p. d. work to compress air isothermally to work for actual compression e. isothermal work to ideal work
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6) 1 m of air at atmospheric condition weighs approximately__________________? a. 0.5 kg b. 1.0 kg c. 1.3 kg d. 2.2 kg e. 3.2 kg
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7) Free air is the air at________________? a. atmospheric conditions at any specific location b. 20°C and 1 kg/cm2 and relative humidity of 36% c. 0°C and standard atmospheric conditions d. 15°C and 1 kg/cm2 e. 25°C, 1 kg/cm2 and relative humidity of 50%
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8) The capacity of a compressor is 5 m /mih. 5 m /min refers to_______________? a. standard air b. free air c. compressed air d. compressed air at delivery pressure e. air sucked
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9) Maximum work is done in compressing air when the compression is_________________? a. isothermal b. adiabatic c. polytropic d. any one of the above e. none of the above
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10) Standard air is the air at_____________________? a. atmospheric conditions at any specific location b. 20°C and 1 kg/cm2 and relative humidity 36% c. 0°C and standard atmospheric conditions d. 15°C and 1 kg/cm2 e. 25°C, 1 kg/cm2 and RH of 60%.
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11) The compressor capacity with decrease in suction temperature_________________? a. increases b. decreases c. remains unaffected d. may increase or decrease depending on compressor capacity e. increases upto certain limit and then decreases
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12) Inter cooling in compressors__________________? a. cools the delivered air b. results in saving of power in compressing a given volume to given pressure c. is the standard practice for big compressors d. enables compression in two stages e. prevents compressor jacket running very hot
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13) Isothermal compression though most efficient, but is not -practicable because_________________? a. ityrequires very big cylinder b. it does not increase pressure much c. it is impossible in practice d. compressor has to run at very slow speed to achieve it e. it requires cylinder to be placed in water
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14) What will be the volume of air at 327°C if its volume at 27°C is 1.5 m3/mt ? a. 3 m3/mt b. 1.5 m3/mt c. 18 m3/mt d. 6 m3/mt e. 0.75 m3/mt
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15) An ideal air compressor cycle without clearance on p-v diagram can be represented by following processes________________? a. one adiabatic, two isobaric, and one constant volume b. two adiabatic and two isobaric c. two adiabatic, one isobaric and one constant volume d. one adiabatic, one isobaric and two constant volume e. two isobaric, two adiabatic and one constant volume
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16) The work done per unit mass of air in compression will’be least when n is equal to______________? a. 1 b. 1.2 c. 1.3 d. 1.4 e. 1.5
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17) An ideal air compressor cycle with clearance on p-v diagram can be represented by following processes_______________? a. one adiabatic, two isobaric, and one constant volume b. two adiabatic and two isobaric c. two adiabatic, one isobaric and one constant volume d. one adiabatic, one isobaric and two constant volume e. two isobaric, two adiabatic and one constant volume
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18) Compression efficiency is compared against_____________________? a. ideal compression b. adiabatic compression c. botii isothermal and adiabatic compression d. isentropic compression e. isothermal compression
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19) Aeroplanes employ following type of compressor_______________? a. radial flow b. axial flow c. centrifugal d. combination of above e. none of the above
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20) Ratio of indicated H.P. and brake H.P. is known as_________________? a. mechanical efficiency b. volumetric efficiency c. isothermal efficiency d. adiabatic efficiency e. relative efficiency
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