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 : The refrigerant for a refrigerator should have (a) high sensible heat (b) high total heat (c) high latent heat (d) low latent heat
Last Answer : Ans: c
Description : At lower temperatures and pressures, the latent heat of vaporization of a refrigerant (a) decreases (b) increases (c) remains same (d) depends on other factors
Description : ick out the undesirable property for a good refrigerant. (A) High thermal conductivity (B) Low freezing point (C) Large latent heat of vaporisation (D) High viscosity
Last Answer : (D) High viscosity
Description : Why high latent heat of vaporisation is desirable in a refrigerant ?
Last Answer : A high latent heat of vaporisation of refrigerant results in small amount of refrigerant and thus lesser circulation system of refrigerant for same tonnage.
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 : 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 vapourization
Last Answer : has high specific heat
Description : High __________ is an undesirable property for a good refrigerant. (A) Specific heat (B) Latent heat of vaporisation (C) Viscosity (D) Specific vapor volume
Last Answer : (C) Viscosity
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
Last Answer : Ans: a
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
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 : 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
Last Answer : ANSWER : B
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 : 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 : 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 : 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
Description : The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will (a) increase (b) decrease (c) remain unaffected (d) may increase or decrease depending on the type of refrigerant used
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 : In a refrigeration cycle, the flow of refrigerant is controlled by (a) compressor (b) condenser (c) evaporator (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 : A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure ofabout 67 kg/cm. The refrigerant used is (a) Ammonia (b) Carbon dioxide (c) Freon (d) Brine
Description : Highest pressure encountered in a refrigeration system should be (a) critical pressure of refrigerant (b) much below critical pressure (c) much above critical pressure (d) near critical pressure
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 : Accumulators should have adequate volume to store refrigerant charge at least (a) 10% (b) 25% (c) 50% (d) 75%
Description : In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to (a) collect liquid refrigerant and prevent it from going to compressor (b) detect liquid in vapour (c) superheat the vapour (d) increase refrigeration effect
Description : Condensing temperature in a refrigerator is the temperature (a) of cooling medium (b) of freezing zone (c) of evaporator (d) at which refrigerant gas becomes liquid
Description : One of the purposes of sub-cooling the liquid refrigerant is to (a) reduce compressor overheating (b) reduce compressor discharge temperature (c) increase cooling effect (d) ensure that only liquid and not the vapour enters the expansion (throttling) valve
Description : Absorption system normally uses the following refrigerant (a) Freon-11 (b) Freon-22 (c) C02 (d) ammonia.
Last Answer : Ans: e
Description : In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is (a) less than 2 kg (b) more than or equal to 3.65 kg (c) more than 10 kg (d) there is no such consideration
Description : Highest temperature encountered in refrigeration cycle should be (a) near critical temperature of refrigerant (b) above critical temperature (c) atcritica. temperature (d) much below critical temperature
Description : The bank of tubes at the back of domestic refrigerator are (a) condenser tubes (b) evaporator tubes (c) refrigerant cooling tubes (d) capillary tubes
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 : 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 : Refrigeration in aeroplanes usually employs the following refrigerant (a) Co2 (b) Freon-11 (c) Freon-22 (d) Air
Description : Presence of moisture in a refrigerant affects the working of (a) compressor (b) condenser (c) evaparator (d) expansion valve.
Description : The moisture in a refrigerant is removed by (a) evaporator (b) safety relief valve (c) dehumidifier (d) driers
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 : Which of the following cycles uses air as the refrigerant? (a) Ericsson (b) Stirling (c) Carnot (d) Bell-coleman
Description : Entrainer used in Azeotropic distillation should (A) Form a low boiling azeotrope with one of the constituents of the mixture (B) Form a new azeotrope of low relative volatility with one of the ... (C) Have high latent heat of vaporisation (D) Have high viscosity to provide high tray efficiency
Last Answer : (A) Form a low boiling azeotrope with one of the constituents of the mixture
Description : The boiling point of ammonia is (a) -100°C (b) -50°C (c) - 33.3°C (d) 33.3°C.
Description : With rise of boiling point of a water, what will be the latent heat of steam? -Do You Know?
Last Answer : answer:
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.