Chapter 5, Problem 5.95EP

A building is being heated through the help of a Carnot heat pump and is required to be maintained at 20 degrees C always. When the temp outside drops to -10 degrees C, the rate at which heat is lost from the building is 25kW. What is the minimum electrical power required (kW) in order to drive the heat pump?

Since Lucas is an engineer familiar with thermodynamics. He decided to create his own heat engine at home to avoid paying for electricity. He created a small, makeshift heat engine for trial. The combustion of his fuel. diesel, reaches a temperature of 750°C, while waste heat is disposed to the atmosphere at 50°C. He, then connected a generator and a heat pump to the heat engine to check the amount of power being produced. Assume that the heat pump will be used to warm his room to 25°C, while the outside temperature is at 5°C. Lucas' rooms loses 85,000 kJ/hr of heat. And, 25% of the heat engine's power output goes to the heat pump. How much diesel (in kg) needs to be burned by the heat engine to maintain the temperature in Lucas' room? Assume carnot heat engine and heat pump. If the natural gas has a heating value of 22,000 BTU/lb.

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

A geothermal heat pump with a coefficient of performance of 1.3 supplies a building with 48000 BTU/hr of heat. Assuming a $0.20/kWh electricity rate. Provide responses to the following questions about this system: a. How much would it cost per month to supply heat at a rate of 48000 BTU/hr using a basic electrical resistance heater? b. In that month, how much heat is extracted from the earth by the heat pump, in kWh? c. What is the monthly savings associated with using this heat pump vs a basic electrical resistive heater?

A heat pump is used to meet the heating requirements of a house and maintain it at 20°C. On a day when the outdoor air temperature drops to -2°C, the house is estimated to lose heat at a rate of 63,000 kJ/h. If the heat pump under these conditions has a COP of 1.8, determine the rate at which heat is absorbed from the cold outdoor air. Select one: a. 28,000 kJ/h b. 58,000 kJ/h c. 38,000 kJ/h d. 48,000 kJ/h  NEED ASAP. I WILL UPVOTE

The heat loss from a chicken coop (chicken house) is K(Tnside - Totside) during the winter, where K is 1.5 kW/K. The chicken coop temperature can vary between 15 °C and 25 °C without harming egg production. A heat pump with a coefficient of performance of 40% of that of a reversible heat pump is used to heat the chicken coop. What are the minimum power requirements if the outside temperature is -5 °C? .

A heat pump with a motor of 2 kW is used to keep a chicken hatchery at 30°C. This latter 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% of a Carnot heat pump. a- Draw a sketch for the entire system showing all energy transfers. b- Illustrate a heat pump operating between two constant-temperature energy reservoirs showing all energy transfers. c- What is the minimum ambient temperature for which the heat pump is sufficient?

A heat pump with COP of 2.0 is used to heat water to 90 oC for cleaning purpose. This heat pump absorb heat from surrounding at 30 oC and received the entire power, ̇ from a Carnot heat engine operating between 200 oC and 25 oC. The Carnot 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, ̇ from Carnot heat engine, kW. iii) 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.

2. Between 300K and 600K is the operating temperature of a pair of heat pumps connected in series. The efficiency of the second heat pump is three times that of the first. Find the input work for the first and second heat pumps if the second heat pump absorbs 20kW of heat and the heat release in the first heat pump is the same.