Q: A heat pump is used to heat a house and maintain it
A heat pump is used to heat a house and maintain it at 24°C. On a winter day when the outdoor air temperature is –5°C, the house is estimated to lose heat at a rate of 80,000 kJ/h. Determine the minim...
See AnswerQ: A commercial refrigerator with refrigerant-134a as the working fluid is
A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at –35°C by rejecting waste heat to cooling water that enters t...
See AnswerQ: The performance of a heat pump degrades (i.e.,
The performance of a heat pump degrades (i.e., its COP decreases) as the temperature of the heat source decreases. This makes using heat pumps at locations with severe weather conditions unattractive....
See AnswerQ: A heat pump is to be used for heating a house in
A heat pump is to be used for heating a house in winter. The house is to be maintained at 78°F at all times. When the temperature outdoors drops to 25°F, the heat losses from the house are estimated t...
See AnswerQ: A completely reversible heat pump has a COP of 1.6
A completely reversible heat pump has a COP of 1.6 and a sink temperature of 300 K. Calculate (a) the temperature of the source and (b) the rate of heat transfer to the sink when 1.5 kW of power is su...
See AnswerQ: A Carnot heat pump is to be used to heat a house
A Carnot heat pump is to be used to heat a house and maintain it at 25°C in winter. On a day when the average outdoor temperature remains at about 2°C, the house is estimated to...
See AnswerQ: A Carnot heat engine receives heat from a reservoir at 900°
A Carnot heat engine receives heat from a reservoir at 900°C at a rate of 800 kJ/min and rejects the waste heat to the ambient air at 27°C. The entire work output of the heat engine is used to drive a...
See AnswerQ: A hydraulic lift is to be used to lift a 1900-
A hydraulic lift is to be used to lift a 1900-kg weight by putting a weight of 25 kg on a piston with a diameter of 10 cm. Determine the diameter of the piston on which the weight is to be placed.
See AnswerQ: The structure of a house is such that it loses heat at
The structure of a house is such that it loses heat at a rate of 4500 kJ/h per °C difference between the indoors and outdoors. A heat pump that requires a power input of 4 kW is used to maintain this...
See AnswerQ: Derive an expression for the COP of a completely reversible refrigerator in
Derive an expression for the COP of a completely reversible refrigerator in terms of the thermal energy reservoir temperatures, TL and TH.
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