Chapter 5, Problem 5.40P

A Carnot heat pump to heat a house in the winter and keep the interior temperature of the house at 25 ° C. is used. The heat losses of the house in a day when the outdoor temperature is 2 ° C are approximately 55000 kJ / hour. determined. If the heat pump is drawing 6.6 kW of power from the grid while it is running a) How many hours the heat pump has been running on the specified day (outdoor temperature is 2oC) b) By accepting that the electricity price is 0.085 dollars / kWh c) Calculate the cost of heating the same day if a direct electric heater was used.

3.0 A cold storage is to be maintained at -5°C while the surroundings are at 35°C. The heat leakage from the surroundings into the cold storage is estimated to be 30 kw. The actual C.O.P. of the refrigeration plant used is one third that of an ideal plant working between the same temperatures. Find the power required to drive the plant.

3.0 A cold storage is to be maintained at -5°C while the surroundings are at 35°C. The heat leakage from the surroundings into the cold storage is estimated to be 28 kW. The actual C.O.P. of the refrigeration plant used is one fourth that of an ideal plant working between the same temperatures. Find the power required to drive the plant.

A refrigerator working between 283 K to 310K and extracting 340 J of heat. How much work required to run the refrigerator.

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the energy transffered by heat from an engine during one cycle is 500J. how much energy must be added to the engine so that it can operate at 30 %

A heat pump is used to heat a house. When the outside air temperature is 266K and the inside is maintained at 293K, the heat loss from the house is 195 kW. a. What is the minimum electric power (kW) required to operate the heat pump? b. What is the rate of heat transfer to the heat pump? C. What is the COP for an ideal heat pump operating between these temperatures?

A bio-reactor is kept at 42°C by a heat pump driven by a motor of 2 kW. The reactor loses energy at a rate of 0.5 kW per degree difference to the colder ambient. The heat pump has a COP that is 50% that of a Carnot heat pump. What is the minimum ambient temperature for which the heat pump is sufficient?

An irreversible heat pump with COP of 2.4 is used to heat water to 80°C for cleaning purposes. This heat pump absorbs heat from surrounding at 30°C and received the entire power, W from a Carnot heat engine operating between 250°C and 30°C. The Canot heat engine received 6.3 kW of heat from the high temperature source. i) Draw the schematic diagram of the above system. ii) Determine the power received by the heat pump, W from Carnot heat engine, kW. i1) Calculate the rate of heat supplied to the water by the heat pump, kW. iv) Determine the COP of the heat pump if it operates on a reversed Carnot cycle.