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 lose heat at a rate of 55 000 kJ/h. If the heat pump consumes 4.8 kW of power while operating, determine: (a). how long the heat pump ran on that day (b). The total heating costs, assuming an average price of R 2.35/kWh for electricity, and (c). The heating cost for the same day if resistance heating is used instead of a hea

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 lose heat at a rate of 55 000 kJ/h. If the heat pump consumes 4.8 kW of power while operating, determine: (a). how long the heat pump ran on that day (b). The total heating costs, assuming an average price of R 2.35/kWh for electricity, and (c). The heating cost for the same day if resistance heating is used instead of a hea

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter8: Natural Convection

Section: Chapter Questions

Problem 8.46P

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By supplying energy to a house at a rate of 25,000 kJ/hr, a heat pump maintains the temperature of the dwelling at 20 C when the outside air is at -10 C. If electricity costs 8 cents per kW-hr, determine the minimum theoretical operating cost to heat the house for 24 hours. $1.97 O $1.37 $1.75 O $1.51 O$1.64
b) On a winter day when the average outdoor temperature remains at about 4 ° C, the house is estimated to lose heat at a rate of 62,000 kJ / h. For this reason a Carnot heat pump is used to heat a house and maintain it at 23 ° C. If the heat pump consumes 6 kW of power while operating, determine (a) how long the heat pump ran on that day; (b) the amount of heat removed from surrounding (Q.); and (c) the total heating costs, assuming an average price of 6.5 ¢ / kWh for electricity (d) the heating cost for the day if resistance heating is used instead of a heat pump assuming an average price of 6.5 € / kWh for electricity .
A heat pump with a COP of 3.2 is used to heat a perfectly sealed house (no air leaks). The entire mass within the house (air, furniture, etc.) is equivalent to 1200 kg of air. When running, the heat pump consumes electric power at a rate of 5 kW. The temperature of the house was 7°C when the heat pump was turned on. If heat transfer through the envelope of the house (walls, roof, etc.) is negligible, the length of time the heat pump must run to raise the temperature of the entire contents of the house to 22°C is (a) 13.5 min (b) 43.1 min (c) 138 min (d) 18.8 min (e) 808 min
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b) On a winter day when the average outdoor temperature remains at about 4°C, the house is estimated to lose heat at a rate of 62,000 kJ/h. For this reason a Carnot heat pump is used to heat a house and maintain it at 23°C. If the heat pump consumes 6 kW of power while operating, determine (a) how long the heat pump ran on that day; (b) the amount of heat removed from surrounding (QL); and (c) the total heating costs, assuming an average price of 6.5¢/kWh for electricity (d) the heating cost for the day if resistance heating is used instead of a heat pump assuming an average price of 6.5¢/kWh for electricity.
A heat pump is used to extract heat from the outside atmosphere to heat the inside of a building. On a day when the outside air temperature is Tc°C, the heat pump is operating to a COP of 3.7, maintaining the inside temperature of the building at Th°C. If the building is losing heat at the rate of 53,709 kJ/hour in these conditions, determine how much power (kW) must be supplied to a heat pump? Keep two decimal places
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