Description : Alcohols alone cannot be used in CI engines as a) their self ignition temperature is high b) latent heat of vaporization is high c) all of the mentioned d) none of the mentioned
Last Answer : Answer: c Explanation: None.
Description : Choose the correct statement (a) A refrigerant should have low latent heat (b) If operating temperature of system is low, then refrigerant with low boiling point should be used (c) Pre-cooling and sub-cooling bf refrigerant are same (d) Superheat and sensible heat of a. refrigerant are same
Last Answer : Ans: b
Description : Which of the following is not a desirable property of a refrigerant (a) highmisibility with oil (b) low boiling point (c) good electrical conductor (d) large latent heat
Last Answer : Ans: c
Description : The refrigerant for a refrigerator should have (a) high sensible heat (b) high total heat (c) high latent heat (d) low latent heat
Description : Vegetables are cooked in lesser time by adding a pinch of salt while cooking because (1) boiling point of water increases (2) latent heat of vaporization of water decreases (3) latent heat of vaporization of water increases (4) boiling point of water decreases
Last Answer : (1) boiling point of water increases Explanation: Adding salt raises the boiling point of water, which allows food to cook at higher temperature. The higher the temperature, the higher the rate of heat transfer between the food and water, thus it cooks more quickly.
Last Answer : boiling point of water increases
Description : Under-cooling in a refrigeration cycle (a) increases COP (b) decreases COF (c) COP remains unaltered (d) other factors decide COP
Last Answer : Ans: a
Description : Superheating in a refrigeration cycle (a) increases COP (b) decreases COP (c) COP remains unaltered (d) other factors decide COP
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
Description : When air passes through silica gel, A. it absorbs water vapour molecules B. latent heat of condensation is released C.dbt of air increases D. all of the mentioned
Last Answer : ANSWER : D
Description : With the increase in speed of the vehicle, the back pressure will a. decrease b. increase c. remains unaffected d. depends on other factors
Last Answer : ANSWER b. increase
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
Last Answer : Ans :c
Description : Consider the following statements 1. Large cold storage plants use ammonia as refrigerant while domestic refrigerators use chlorofluorocarbons. 2. Ammonia can be liquefied at ambient temperatures and at low pressures. 3. Chlorofluorocarbons are ... 3 only (b) 2 and 3 only (c) 1, 2 and 3 (d) 3 only
Last Answer : Ans:(a)
Description : In sensible cooling process the relative humidity: A. decreases B. increases C. remains constant D. none of the above
Last Answer : ANSWER : B
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 : Which law states that the specific heat of a gas remains constant at all temperatures and pressures (a) Charles’ Law (b) Joule’s Law (c) Regnault’s Law (d) Boyle’s Law (e) there is no such law.
Last Answer : Answer : c
Description : For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphereis high, then (a) bigger cabinet should be used (b) smaller cabinet should ... tight vapour seal should be used (d) refrigerant with lower evaporation temperature should be used
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
Description : The vapour pressure of refrigerant should be (a) lower than atmospheric pressure (b) higher than atmospheric pressure (c) equal to atmospheric pressure (d) could be anything
Description : For same power output and same r, as compared to 2- stroke engines, four stroke SI engines have (a) Higher fuel consumption (b) Lower thermal efficiency (c) Highest exhaust temperatures (d) Higher thermal efficiency
Last Answer : Ans :d
Description : The heat absorbed by a unit mass of a material at its holding point in order to convert the material into a gas at the same temperature. a. Latent Heat of Sublimation b. Latent Heat of Vaporization c. Latent Heat of Fusion d. Latent Heat Of Condensation
Last Answer : Latent Heat of Vaporization
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 : 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 : With increase in pump speed, its NPSH requirement (A) Decreases (B) Increases (C) Remains unaltered (D) Can either increase or decrease; depends on other factors
Last Answer : (B) Increases
Description : Humidification is the process of addition moisture in air at A. constant wet bulb temperature B. constant dry bulb temperature C. constant latent heat D. none of the above
Description : Describe any two sources of air leak in surface condenser. Also describe effect of air leak on latent heat of steam and cooling water requirements.
Last Answer : ✓ The main sources of air leakage found in condenser are given below: 1) There is leakage of air from atmosphere at the joint of the parts which are internally under a pressure less ... hence evaporation enthalpy of steam increases therefore more amount of cooling water required in the condenser.
Description : The condensing pressure due to the presence of non-condensable gases, as compared to that actually required forcondensing temperatures without non-condensable gases, (a) will be higher (b) will be ... remain unaffected (d) may be higher or lower depending upon the nature of non-condensable gases
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
Description : How the efficiency of the SI engine is affected by the specific heat ratio (γ) of the working fluid? a. the efficiency of the engine increases with increase in specific heat ratio (γ) of the working ... not affected by change in specific heat ratio (γ) of the working fluid d. none of the above
Last Answer : ANSWER a. the efficiency of the engine increases with increase in specific heat ratio (γ) of the working fluid
Description : What is the temperature at which the water vapour in the mixture of water vapour in air, starts condensing called? A. condensation temperature B. dew point temperature C. vaporization temperature D. all of the above
Description : The process of breaking up or liquid into fine droplets by spraying is A. vaporization B. atomization C. condensation D. evaporation
Description : The process of breaking up a liquid into fine droplets by spraying is called a. vaporization b. carburetion c. injection d. atomization
Last Answer : ANSWER d. atomization
Description : Vapour lock is a. complete or partial stoppage of fuel supply due to vaporization of the fuel b. locking of carburetor due to high vapor pressure c. excess fuel supply to the engine d. supply of liquid fuel to the engine
Last Answer : ANSWER a. complete or partial stoppage of fuel supply due to vaporization of the fuel
Description : If the temperature of intake air in internal combustion engine is lowered, the efficiency will a. increase b. decrease c. remains same d. increases upto certain limit and then decrease
Last Answer : ANSWER a. increase
Description : If the intake air temperature of Internal combustion engine increases, its efficiency will a. increase b. decrease c.remains same d unpredictable
Last Answer : ANSWER b. decrease
Description : What does the latent heat of vaporization represents?
Last Answer : The amount of energy required to turn a mole of a liquid into agas
Description : What does the heat latent heat of vaporization measure?
Last Answer : The energy required to boil a substance
Description : Steam at 100°C causes more severe burns than water at 100° C because – (1) steam has no specific heat capacity (2) steam has latent heat of vaporization (3) water has no specific heat capacity (4) water has latent heat of fusion
Last Answer : (2) steam has latent heat of vaporization Explanation: It is because steam releases its latent heat as it condenses, which is substantial. The heat of vaporization of steam is over 2000 J per gram. And when it releases that it's then 100 degree water, the same as boiling water.
Description : Water is not suitable as a calorimetric substance because it – (1) has high specific heat (2) is a good conductor (3) has high boiling point (4) low latent heat of vaporization
Last Answer : (1) has high specific heat Explanation: The specific heat of water is higher than all other common substances. Hence, water is used for heating purposes (as in hot water bottles) and for cooling ... the liquids, mercury has the lowest specific heat due to which it is used as a thermometric liquid.
Description : What is the latent heat of vaporization of water at 1 atm? A. 2314.8 kJ/kg B. 2257.1 kJ/kg C. 2511.7 kJ/kg D. 2429.8 kJ/kg
Last Answer : 2257.1 kJ/kg
Description : What refers to the amount of energy absorbed or released during a phase-change process? A. Molar heat B. Latent heat C. Vaporization heat D. Condensation heat
Last Answer : Latent heat
Description : The self-ignition temperature of diesel oil compared to petrol is a. higher b. lower c. same d. depends on the quality of fuel
Last Answer : ANSWER a. higher
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 : Common rail injection system uses injection pressures of the order a) 100-200 bar b) 200-400 bar c) 400-600 bar d) 1500 bar
Last Answer : Answer: d Explanation: Generally, common rail injection system uses injection pressures of the order 1500 bar.
Description : With increase in the concentration of the adsorbate, the integral heat of adsorption (A) Increases (B) Decreases (C) Remains unchanged (D) May increase or decrease; depends on the type of adsorbate
Last Answer : (B) Decreases
Description : Latent heat of dry steam at atmospheric pressure is 539 Kcal/kg; which __________ with increase in the pressure of steam. (A) Decreases (B) Increases (C) Remain same (D) May increase or decrease
Last Answer : (A) Decreases
Description : In milk chilling plant, the usual secondary refrigerant is (a)ammonia (b)sodium silicate (c) glycol (d) brine
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 C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperatureconstant, will (a) increase (b) decrease (c) may increase or decrease depending on the type of refrigerant used (d) remain unaffected