Description : When the humidity ratio of air increases the air is said to be A. dehumidified B. humidified C. heated D. cooled
Last Answer : ANSWER : B
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
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
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
Description : What is the perfect condition for dehumidification of air? A. air is heated above its dew point temperature B. air is cooled up to its dew point temperature C. air is heated below its dew point temperature D. air is cooled below its dew point temperature
Description : In centrifugal compressor terminology, vaneless space refers to the space between A. The inlet and blade inlet edge B. Blades in the impeller C. Diffuser exit and volute casing D. Impeller tip and diffuser inlet edge
Description : Volumetric efficiency of a compressor without clearance volume A. Increases with increase in compression ratio B. Decreases wit increase in compression ratio C. Not dependent upon compression ratio D. Unpredictable
Last Answer : ANSWER : C
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
Description : In reciprocating air compressor the clearance ratio is given by A. B. C. D.
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
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
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.
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
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
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
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
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
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
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
Description : The maximum delivery pressure in a rotary air compressor is A. 10 bar B. 20 bar C. 30 bar D. 50 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
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.
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
Description : Air can be cooled and dehumidified by A. circulating chilled water in tube across air flow B. placing evaporator coil across air flow C. spraying chilled water to air D. all of the mentioned
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
Description : In a gas-liquid shell and tube heat exchanger, the (A) Presence of a non-condensable gas decreases the condensing film coefficient (B) Gases under high pressure are routed through the tube side, because high pressure ... water or steam condensate remain localised to the tubes (D) All 'a', 'b' & 'c'
Last Answer : (D) All 'a', 'b' & 'c'
Description : The critical spark energy required to ignite a given mixture A. decreases with decreasing sparking voltage B. increases with decreasing sparking voltage C. increases with increasing sparking voltage D. decreases with increasing sparking voltage
Description : When humidity ratio of air ____ air is said to be dehumidified. A. increases B. decreases C. remains constant D. none of the mentioned
Description : In a simple carburetor, the air-fuel ratio increases when the A. density of air increases B. velocity of air increases C. velocity of air decreases D. density of air decreases
Description : The stoichiometric air fuel ration for petrol is 15:1 . What is the air fuel ratio required for maximum power? (a) 16:1 – 18:1 (b) 15:1 (c) 12:1 – 14:1 (d) 9:1 – 11:1
Last Answer : Ans :c
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.
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
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
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
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%
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
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
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
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
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
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
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
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
Description : Compressor at high altitude will draw A. More power B. Less power C. Same power D. Unpredictable
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 : In a 4 S diesel engine, the term ‘squish’ refers to the (a) Injection of fuel in the precombustion chamber (b) Discharge of gases from the precombustion chamber (c) Entry of air into the combustion chamber (d) Stripping of fuel from the core
Description : Air at dry bulb temperature Td1 is passed through the heating coil and some amount of air is by passed unaffected and leaves with dry bulb temperature Tb2 and the temperature of heated air is Td3 (where Td2 < Td3), what is the ... - Td1) / (Td2 - Td3) D. Bypass Factor = (Td2 - Td3) / (Td2 - Td1)
Description : Choose the wrong statement (a) Temperature of medium being cooled must be below that of the evaporator (b) Refrigerant leaves the condenser as liquid (c) All solar thermally operated absorption systems are capable only of intermittent operation (d) frost on evaporator reduces heat transfer
Description : In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be (a) high, of the order of 25° (b) as low as possible (3 to 11°C) (c) zero (d) any value
Description : In a vapour compression cycle, the refrigerant immediately after expansion valve is (a) liquid (b) sub-cooled liquid (c) saturated liquid (d) wet vapour