RAC & I.C. Engine - 1 - Mechanical Engineering MCQ

The refrigerant commonly used in vapour absorption system is

In a lithium Bromide absorption refrigeration system

A cold storage is to be maintained at –5°C while the surroundings are at 35°C. The heat leakage from the surrounding in to cold storage is estimated to be 29 kW. The actual COP of refrigeration plant is one third of an ideal pant working between the same temperature limit. Power required to drive the plant will be

A refrigerating machine working on reversed Carnot cycle takes out 2 kW from the system while operating between temperature limits of 300 K and 200 K. COP and power consumed by the cycle will be respectively:

A refrigeration system operating on reversed brayton cycle has a temperature of 250 k at inlet to the compressor. If the temperature at the end of constant pressure cooling is 300 k and rise in temperature of air in refrigerator is 50 k. Then the net work of compression will be _______ kJ/kg (for air c_p = 1 kJ/kg K)

A vapour absorption refrigeration system works with generator, ambient and evaporator temperature as 360 K, 310 K and 260 K respectively. If the evaporator temperature falls to 250 K what should be the generator temperature in order to operate the system with same COP

In aqua ammonia absorption system the heat is supplied to generator by condensing steam at 0.2 MPa and 90% dryness fraction. The temperature to be maintained in refrigeration is –10°C and the ambient temperature is 30°C. The actual COP is the 40% of the maximum COP and the refrigeration effect is 20 TR. The required flow rate will be (Given: at 0.2 MPa saturation, temperature = 120.2°C = 2201.9 kJ/kg)

Maximum possible COP of a solar absorption refrigeration system with generator temperature of 360 K, absorber temperature of 300 K, condenser temperature of 300 K and evaporator temperature of 270 K is ___________.

A refrigerator based on ideal vapour compression cycle operates between the temperature limits of –20°C and 40°C. The refrigerant enters the condenser as saturated vapour and leaves as saturated liquid. The enthalpy and entropy values for saturated liquid and vapour at these temperature are given in the table below.

Q. 

If refrigerant circulation rate is 0.025 kg/s, the refrigeration capacity is equal to

A refrigerator based on ideal vapour compression cycle operates between the temperature limits of –20°C and 40°C. The refrigerant enters the condenser as saturated vapour and leaves as saturated liquid. The enthalpy and entropy values for saturated liquid and vapour at these temperature are given in the table below.

Q. 

The COP of the refrigerator is 

A vapour absorption refrigeration system is a heat pump with three thermal reservoirs as shown in the figure. A refrigeration effect of 100 W is required at 250 K when the heat source available is at 400 K. Heat rejection occurs at 300 K. The minimum value of heat required (in W) is ___________.

Moist air at a pressure of 100 kPa is compressed to 500 kPa and then cooled to 35°C in an aftercooler. The air at the entry to the aftercooler is unsaturated and becomes just saturated at the exit of the aftercooler. The saturation pressure of water at 35°C is 5.628 kPa. The partial pressure of water vapour (in kPa) in the moist air entering the compressor is closest to