An industrial heat pump operates between the temperature of 27°C and –13°C. The rates of heat addition and heat rejection are 750 W and 1000 W, respectively. The COP for the heat pump is ____.
In an ideal vapour compression refrigeration cycle, the specific enthalpy of refrigerant (in kJ/kg) at the following states is given as:
Inlet of condenser : 283
Exit of condenser : 116
Exit of evaporator : 232
The COP of this cycle is
In a cascade refrigeration system the COP of lower cycle is COP1 and that of upper cycle is COP2 , COP of combined cycle will be
A refrigerator operates between the temperature of –23°C and 27°C. If one TR = 3.5 kW, the minimum power required per TR to operate the refrigerator is
In a vapour compression refrigeration plant, the refrigerant leaves the evaporator at 195 kJ/kg and the condenser at 65 kJ/kg. For 1 kg/s of refrigerant, the refrigeration effect is ___________ kW.
The wet bulb depression is zero, when relative humidity is equal to
The atmospheric air at 760 mm of Hg, dry bulb temperature 15°C and wet bulb temperature 11°C enters a heating coil whose temperature is 41°C. If the by-pass factor of the heating coil is 0.5, then what will be the dry bulb temperature of the air leaving the coil?
Water at 42°C is sprayed into a stream of air at atmospheric pressure, dry bulb temperature of 40°C and a wet bulb temperature of 20°C. The air leaving the spray humidifier is not saturated. Which of the following statements is true?
Given, water spraying temperature = 42°C
Dry bulb temperature, Td = 40°C
Wet bulb temperature, Tw = 20°
Here we see that, water spraying temperature > Td
During the adiabatic cooling of moist air
An air-conditioned room of volume 10 m3 has infiltration of air equivalent to 3 air changes per hour. Density of air is 1.2 kg/m3, specific heat Cp is 1 kJ/kgK and temperature difference between room and ambient air is 20 K. The sensible heat load due to infiltrated air is
In diesel engine, the suction consists of
In petrol engine, ignition takes place
The ratio of shaft horse power to the energy supplied by the fuel is called
Indicated horse power of a four-stroke engine is given by
The expression denotes the following efficiencies of an I.C. engine
The compression ratio for a diesel engine as compared to petrol engine is
A moist air sample has dry bulb temperature of 30°C and specific humidity of 11.5 g water vapour per kg dry air. Assume molecular weight of air as 28.93. If the saturation vapour pressure of water at 30°C is 4.24 kPa and the total pressure is 90 kPa, then the relative humidity (in %) of air sample is
Atmospheric air at 1.013 bar and 35°C has relative humidity 60%. The saturation pressure of water vapour at 35°C is 5.628 kPa. The specific humidity of water vapour in kg vapour per kg dry air will be
Moist air enters the cooling coil with mass flow rate of 10 kg-da/s at dry bulb temperature of 30°C and humidity ratio of 0.017 kg v/da. It leaves the cooling coil at dry bulb temperature of 16°C and humidity ratio of 0.008 kg v/da. If specific heat of humid air is 1.02 kJ/kg da K and latent heat of water vapour is 2500 kJ/kg v. The sensible and latent heat transfer of cooling coil are, respectively
In a sample of moist air at saturated atmospheric pressure of 101.325 kPa and 26°C the partial pressure of water vapour is 1.344 kPa. If the saturation pressure of water vapour is 3.36 kPa at 26°C, then what are the humidity ratio and relative humidity of moist air sample?