Multistage compressors are used in industry, because they
(A) Reduce the cost of compressor
(B) Reduce the size requirement
(C) Resemble closely to isothermal compression
(D) Are easy to control

1 Answer

Answer :

(C) Resemble closely to isothermal compression

Related questions

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

Description : In multi stage compressor, the isothermal compression is achieved by A. Employing intercooler B. By constantly cooling the cylinder C. By running compressor at very slow speed D. By insulating the cylinder

Last Answer : ANSWER : C

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

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

Description : Which of the statement is True for centrifugal compressors? a) The compressor should not be operated at full load b) The compressor should be operated at shut off pressure c) The ... operated with inlet-guide vane control d) The compressor should not be operated close to the surge point 

Last Answer : d) The compressor should not be operated close to the surge point

Description : Interstage coolers are provided in a multistage compressor to (A) Save power in compressing a given volume to a given pressure (B) Cool the delivered air (C) Achieve the exact delivery pressure (D) None of these

Last Answer : (A) Save power in compressing a given volume to a given pressure

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

Description : Which one of the following is correct? A. In a multistage compressor adiabatic efficiency is less than stage efficiency B. In a multistage turbine adiabatic efficiency is less than the stage ... compressor is greater than one D. Preheat factor does not affect the multistage compressor performance

Last Answer : ANSWER : A

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

Description : Multistage compression of air as compared to single stage compression offers the advantage of (A) Power saving per unit weight of air delivered (B) Moisture elimination in the inter-stage cooler (C) Increased volumetric efficiency (D) All (A), (B) & (C)

Last Answer : (D) All (A), (B) & (C)

Description : What Is The Difference Between A Rotary Screw Compressor And A Reciprocating Compressors?

Last Answer : A rotary screw compressor is one that utilizes two intermeshing helical rotors to trap a volume of air, then compress it to a higher pressure. Rotary screw compressors can be run at lower ... piston compressor (aka reciprocating) uses pistons driven by a crankshaft to deliver air at high pressure.

Description : If Carrier develops a new air conditioning compressor that lasts twice as long as existing compressors but only uses half the electricity, it will probably establish its pricing based on: A)cash flow. B)product quality. C)survival. D)return on investment. E)market share.

Last Answer : B)product quality.

Description : From base load operation and from achieving best specific energy consumption point of view, which of the following compressors are suitable? a) Single stage reciprocating compressors b) Centrifugal compressors c) Two stage reciprocating compressor d) Multi stage reciprocating compressor

Last Answer : b) Centrifugal compressors

Description : From the point of lower specific energy consumption, which of the following compressors are suitable for part load operation? a) Two stage reciprocating compressors b) Centrifugal compressors c) Two stage screw compressor d) Single stage screw compressor

Last Answer : a) Two stage reciprocating compressors

Description : Which of the following type does Screw compressor belongs to? a) Positive displacementcompressor b) Dynamic compressors c) Both a & b d) None of the above 

Last Answer : a) Positive displacementcompressor

Description : How closely do you think a planetary environment would have to resemble that of our Earth in order for life to exist there?

Last Answer : answer:I never understand why we seek out only earthlike planets to look for life. Who says alien life has to look anything at all like earth life? Life on other planets would go through ... we're used to, but it is entirely possible it could adapt to environments we consider inhospitable.

Description : In which way did the early printed books closely resemble the manuscripts? -SST 10th

Last Answer : They were written on the leaves . They were fragile and took a lot of time to write. They were tough to handle .

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

Description : Give the advantages of multistage compression.

Last Answer : 1.Saving in work is obtained 2.There is little chance of lubrication trouble as the maximum temperature is reduced. 3.it improves the volumetric efficiency. 4.the leakage loss is reduced ... 5. it provide more uniform torque and thus smaller size flywheel is required. 6.lighrter cylinders.

Description : Multistage operation (as in the case of catalytic oxidation of SO2 ) is not carried out for NH3 synthesis, because of (A) Comparatively higher pressure drop (B) High cost of the high pressure ... for the reactor (C) Higher pumping cost (D) Chances of entrainment and disturbance of catalyst bed

Last Answer : (B) High cost of the high pressure vessel used for the reactor

Description : The compression ratios for axial flow compressors are ____. a) Lesser b) Higher c) moderate d) None 

Last Answer : b) Higher

Description : The ratio of indicated power to shaft power of the engine required to drive the compressor is called A. Compressor efficiency B. Volumetric efficiency C. Isothermal efficiency D. Mechanical efficiency

Last Answer : ANSWER : D

Description : The ratio of isothermal power to actual measured input power of a compressor is known as: a) Isothermal efficiency b) Volumetric Efficiency c) Barometric efficiency d) None 

Last Answer : a) Isothermal efficiency

Description : Define (i) I.P (ii) B.P (iii)Volumetric efficiency (iv)Isothermal efficiency of air compressor

Last Answer : i) I.P. - It is the ratio of polytrophic work into speed of compressor in revolution per second.   ii) B.P. - It is the power required to drive the compressor or power delivered to ... the ratio of isothermal power to the shaft power or brake power of motor required to drive the compressor  

Description : Define isothermal efficiency of compressor.

Last Answer : Isothermal Efficiency of compressor: It is the ratio of isothermal work (or power) required to drive compressor to the actual work required to drive compressor for the same pressure ratio. Mathematically isothermal efficiency is given as the ratio of isothermal power to shaft or brake power. 

Description : Pick out the correct statement. (A) The available energy in an isolated system for all irreversible (real) processes decreases (B) The efficiency of a Carnot engine increases, if the sink temperature is decreased ... condition is the change in Helmholtz free energy (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Description : In case of an __________ process, the temperature of the system increases. (A) Isothermal compression (B) Isothermal expansion (C) Adiabatic expansion (D) Adiabatic compression

Last Answer : (D) Adiabatic compression

Description : The work done in isothermal compression compared to that in adiabatic compression will be (A) Less (B) More (C) Same (D) More or less depending upon the extent of work done

Last Answer : (B) More

Description : For an isothermal reversible compression of an ideal gas (A) Only ΔE = 0 (B) Only ΔH =0 (C) ΔE = ΔH = 0 (D) dQ = dE

Last Answer : C) ΔE = ΔH = 0

Description : Which of the following non-flow reversible compression processes require maximum work? (A) Adiabatic process (B) Isothermal process (C) Isobaric process (D) All require same work

Last Answer : (A) Adiabatic process

Description : The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition. (A) Internal energy (B) Enthalpy (C) Gibbs free energy (D) Helmholtz free energy

Last Answer : (C) Gibbs free energy

Description : A two stage compressor is used to compress an ideal gas. The gas is cooled to the initial temperature after each stage. The intermediate pressure for the minimum total work requirement should be equal to ... final pressures respectively) (A) Logarithmic (B) Arithmetic (C) Geometric (D) Harmonic

Last Answer : (C) Geometric

Description : Capacity & power requirement for an air compressor working at high altitude compared to sea-level will be (A) More (B) Less (C) Same (D) Either more or less; depends on the climatic conditions

Last Answer : (B) Less

Description : Which of the following has the maximum compression ratio? (A) Blower (B) Compressor (C) Vacuum pump (D) Fan

Last Answer : (C) Vacuum pump

Description : Which of the following can be used to create a flow of gas, where no significant compression is required? (A) Reciprocating compressor (B) Blower (C) Axial flow compressor (D) Centrifugal compressor

Last Answer : (B) Blower

Description : Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)? (A) Freon (B) Liquid sulphur dioxide (C) Methyl chloride (D) Ammonia

Last Answer : (A) Freon

Description : Which of the following processes cannot be made reversible even under ideal condition of operation? (A) Free expansion of a gas (B) Compression of air in a compressor (C) Expansion of steam in a turbine (D) All (A), (B) & (C)

Last Answer : (A) Free expansion of a gas

Description : Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = Cp/Cv = 7/5) and the process to be reversible, is (A) 300 × (32/7) (B) 300 × (33/5) (C) 300 × (333/7) (D) 300 × (35/7)

Last Answer : A) 300 × (32/7)

Description : Which of the following units is not present in both the vapor compression refrigeration system and absorption refrigeration system? (A) Expansion valve (B) Condenser (C) Refrigerator (D) Compressor

Last Answer : (D) Compressor

Description : With increase in compression ratio, the volumetric efficiency of air compressor (A) Increases (B) Decreases (C) Remain same (D) May increase or decrease (depends on the suction pressure)

Last Answer : Option A

Description : For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it (A) Occupies smaller space (B) Is more economical (C) Is easy to operate and maintain (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Description : The propagation of sound waves in a gas involves – (1) Adiabatic compression and rarefaction (2) Isothermal compression and rarefaction (3) Isochoric compression and rarefaction (4) Isobaric compression and rarefaction

Last Answer : (1) Adiabatic compression and rarefaction Explanation: Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the ... . Through solids, however, it can be transmitted as both longitudinal waves and transverse waves.

Description : The propagation of sound waves in a gas involves – (1) Adiabatic compression and rarefaction (2) Isothermal compression and rarefaction (3) Isochoric compression and rarefaction (4) Isobaric compression and rarefaction

Last Answer : (1) Adiabatic compression and rarefaction Explanation: Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within ... is transmitted through gases, plasma, and liquids as longitudinal waves, also called compression waves.

Description : Which of the following engines is the most efficient?  a. Isobaric expansion  b. Adiabatic compression  c. Adiabatic expansion  d. Isothermal expansion

Last Answer : Isobaric expansion

Description : When the expansion of compression of gas takes place without transfer of heat to or from the gas the process is called  a. reversible  b. adiabatic  c. polytropic  d. isothermal

Last Answer : adiabatic

Description : When the expansion of compression of gas takes place without transfer of heat or from the gas the process is called;  a. Isometric process  b. Isothermal process  c. Isobaric process  d. Adiabatic process

Last Answer : Adiabatic process

Description : During which of the following process does heat rejection takes place in Carnot cycle?  A. Isothermal expansion  B. Isentropic expansion  C. Isothermal compression  D. Isentropic compression

Last Answer : Answer: C

Description : A process, in which the temperature of the working substance remains constant during its expansion or compression, is called  A. isothermal process  B. hyperbolic process  C. adiabatic process  D. polytropic process

Last Answer : Answer: A

Description : The index of compression n tends to reach ratio of specific heats y when  (a) flow is uniform and steady  (b) process is isentropic  (c) process is isothermal  (d) process ... specific heat does not change with temperature  (e) process is isentropic and specific heat changes with temperature.

Last Answer : Answer : d

Description : The propagation of sound waves in a gas involves (1) adiabatic compression and rarefaction (2) isothermal compression and rarefaction (3) isochoric compression and rarefaction (4) isobaric compression and rarefaction

Last Answer : adiabatic compression and rarefaction