Description : The compression ratio in a Spark Ignition (SI) engine is generally in between a. 7 to 10 b. 10 to 14 c. 14 to 18 d. 18 to 22 (Ans:a)
Last Answer : Which of the following is not true for two stroke engine as compared to four stroke engine? a. Less cooling is required b. Greater lubrication is required c. More uniform torque on crankshaft d. Complete exhaust of products of combustion (Ans:a)
Description : If the compression ratio of an engine working on Otto cycle is increased from 5 to 7 the percentage increase in efficiency will be a. 2% b. 4% c. 8% d. 14%
Last Answer : ANSWER d. 14%
Description : An ideal air standard Otto cycle has a compression ratio of 8.5. If the ratio of the specific heats is 1.4, then what is thermal efficiency (in percentage) of the Otto cycle? a. 57.5% b. 45.7% c. 52.5% d. 95%
Last Answer : ANSWER a. 57.5%
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
Description : HUCR is the highest compression ratio at which the A. engine can be run B. engine gives maximum output C. engine is most efficient D. fuel can be used in a test engine without detonation
Last Answer : ANSWER : D
Description : The accumulation of carbon in a cylinder results in increase of A. clearance volume B. volumetric efficiency C. ignition time D. effective compression ratio
Description : In compression ignition (CI) engine, the compression ratio is a. Cylinder volume / Clearance volume b. Swept Volume / Cylinder Volume c. Clearance volume / Cylinder volume d. Cylinder volume / Swept volume (Ans:a)
Last Answer : In two stroke engine there is one power stroke in _____ of crankshaft rotation. a. 90° b. 180° c. 270° d. 360° (Ans:d)
Description : In spark ignition engines, the knocking tendency can be decreased by a) decreasing compression ratio b) controlling intake throttle c) controlling ignition timing d) adding dopes like tetraethyl lead and ethylene dibromide
Last Answer : Answer: d Explanation: None.
Description : The knocking tendency in CI engines increases with (a) Increase of coolant water temperature (b) Increase of temperature of inlet air (c) Decrease of compression ratio (d) Increase of compression ratio
Last Answer : Ans :c
Description : Which of the following factors increases the tendency of knocking in the CI engines? (a) Increasing both the r and coolant temperatures (b) Increasing both the speed and the injection advance (c) Increasing the speed, injection advance and coolant temperature (d) Increasing the compression ratio
Description : In SI engines knocking can be reduced by (a) Increasing the compression ratio (b) Increasing the cooling water temperature (c) Retarding the spark advance (d) Increasing the inlet air temperature
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 : 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 : The accumulation of carbon in a cylinder results in increase of a. clearance volume b. volumetric efficiency c. ignition time d. effective compression ratio
Last Answer : ANSWER d. effective compression ratio
Description : In diesel engine, the compression ratio as compared with the expansion ratio is a. same b. less c. more d. variable
Last Answer : ANSWER c. more
Description : The tendency of a diesel engine to knock increases if a. engine speed is increased b. engine power is increased c. cetane number of the fuel is increased d. compression ratio is increased
Last Answer : ANSWER d. compression ratio is increased
Description : Detonation can be controlled by a. varying the compression ratio b. using lean mixture c. retarding the spark timing d. reducing the rpm
Last Answer : ANSWER c. retarding the spark timing
Description : The thermal efficiency of a diesel cycle having fixed compression ratio with increase in cut-off ratio will a. increase b. decrease c. independent d. increase or decrease depending upon other factors
Last Answer : ANSWER b. decrease
Description : A diesel engine is usually more efficient than a spark ignition engine because a. Diesel being a heavier hydrocarbon, release more heat per kg than gasoline b. The air standard efficiency of diesel ... an Spark ignition engine d.Self ignition temperature of diesel is higher than that of gasoline.
Last Answer : ANSWER c. The compression ratio of a diesel engine is higher than that of an S.I engine
Description : For same compression ratio and heat input a. Otto cycle is more efficient b. Diesel cycle is more efficient c. Both are equally efficient d. None of the above
Last Answer : ANSWER a. Otto cycle is more efficient
Description : For the same capacity engines, the compression ratio of diesel engine a. is lower than the compression ratio of SI engine b. is higher than the compression ratio of SI engine c. is same as the compression ratio of SI engine d. cannot say
Last Answer : ANSWER b. is higher than the compression ratio of SI engine
Description : Use of gasoline blend like tetraethyl lead in internal combustion engine a. increases the octane rating of the fuel b. allows engine to operate at higher compression ratio c. avoids auto-ignition of fuel d. all of the above
Last Answer : ANSWER d. all of the above
Description : The compression ratio cannot be increased beyond certain limit as it results in a. auto-ignition of fuel b. detonation c. engine knocking d. all the above
Last Answer : ANSWER d. all the above
Description : What is the relation between compression ratio (rk) and the efficiency of the Otto cycle? a. efficiency decreases with increase in compression ratio b. efficiency increases with increase in compression ratio c. efficiency is not affected by change in compression ratio d. none of the above
Last Answer : ANSWER b. efficiency increases with increase in compression ratio
Description : What is the formula for compression (rk) ratio of the Otto cycle? a. rk = Volume of cylinder at the beginning of compression / Volume of cylinder at the end of compression b. rk = Volume of cylinder ... c. rk = Volume of cylinder at the end of compression / clearance volume d. none of the above
Last Answer : ANSWER a. rk = Volume of cylinder at the beginning of compression / Volume of cylinder at the end of compression
Description : For same compression ratio a. Diesel cycle has lower efficiency than Otto cycle b. Diesel cycle has higher efficiency than Otto cycle c. Diesel cycle and Otto cycle have equal efficiencies d. Depends upon the load on engine
Last Answer : Answer a. Diesel cycle has lower efficiency than Otto cycle
Description : The efficiency of the Otto cycle is independent of a. Heat supplied b. Compression ratio c. Ratio of specific heats d. None of the above
Last Answer : Answer a. Heat supplied
Description : The condition of refrigerant before entering the expansion or throttle valve, in a vapour compression system (a) dry vapour (b) wet vapour (c)liquid-vapour mixture (d) high pressure saturated liquid
Description : The COP of a vapour compression plant in comparison to vapour absorption plant is (a) more (b) less (c) same (d) more/less depending on size of plant
Last Answer : Ans: a
Description : Most of the domestic refrigerators work on the following refrigeration system (a) vapour compression (b) vapour absorption (c) carnot cycle (d) electrolux refrigerator
Description : The advantage of dry compression is that (a) it permits higher speeds to be used (b) it permits complete evaporation in the evaporator (c) it results in high volumetirc and mechanical efficiency (d) all of the above
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 : The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy-diagram represents (a) condensation of the refrigerant vapour (b) evaporation of the refrigerant liquid (c) compression of the refrigerant vapour (d) metering of the refrigerant liquid
Last Answer : Ans: b
Description : Where does the lowest temperature occur in a vapour compression cycle ? (a) condenser (b) evaporator (c) compressor (d) expansion valve
Description : Aqua ammonia is used as refrigerant in the following type of refrigeration system (a) compression (b) direct (c) indirect (d) absorption
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
Description : The value of COP in vapour compression cycle is usually (a) always less than unity (b) always more than unity (c) equal to unity (d) any one of the above
Description : The higher temperature in vapour compression cycle occurs at (a) compressor discharge. (b) expansion valve (c) evaporator (d) condenser discharge
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
Description : Domestic refrigerator working on vapour compression cycle uses the following type of expansion device (a) electrically operated throttling valve (b) manually operated valve (c) thermostatic valve (d) capillary tube
Description : The vapour compression refrigerator employs the following cycle (a) Rankine (b) Carnot (c) Reversed Carnot. (d) Brayton
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
Description : In vapour compression cycle the condition of refrigerant is superheated vapour (a) after passing through the condenser (b) before passing through the condenser (c) after passing through the expansion or throttle valve (d) beforeentering the expansion valve
Description : In vapour compression cycle, the condition of refrigerant is high pressure saturated liquid (a) after passing through the condenser (b) before passing through the condenser (c) after passing through the expansion or throttle valve (d) before entering the expansion valve
Description : In vapour compression cycle, the condition of refrigerant is very wet vapour (a) after passing through the condenser (b) before passing through the condenser (c) after passing through the expansion or throttle valve (d) before entering the expansion valve
Description : In vapour compression cycle, the condition of refrigerant is saturated liquid (a) after passing through the condenser (b) before passing through the condenser (c) after passing through the expansion throttle valve (d) before entering the expansion valve
Description : Ammonia-absorption refrigeration cycle requires (a) very little work input (b) maximum work input (c) nearly same work input as for vapour compression cycle (d) zero work input
Description : Vapour compression refrigeration is some what like (a) Carnot cycle (b) Rankine cycle (c) reversedCamot cycle (d) reversed Rankine cycle
Last Answer : Ans: C
Description : Most high speed compression ignition engine operate on A. dual cycle B. otto cycle C. diesel cycle D.Carnot cycle
Last Answer : ANSWER : A
Description : In four stroke engine which of the following is also known as power stroke a. Suction stroke b. Compression stroke c. Expansion stroke d. Exhaust stroke (Ans:c) Measurements of fuel and air ... into IC engine,___________its efficiency A. increase B. decrease C. does not alter D. unpredictable on
Last Answer : ANSWER : B