A heating system must maintain the interior of a building at TH = 20°C when the outside temperature is TC = 2°C. If the rate of heat transfer from the building through its walls and roof is 16.4 kW, determine the electrical power required, in kW, to heat the building using (a) electrical-resistance heating, (b) a heat pump whose coefficient of performance is 3.0, (c) a reversible heat pump operating between hot and cold reservoirs at 20°C and 2°C, respectively.

A heat pump cycle delivers energy by heat transfer to a dwelling at a rate of 40,000 Btu/h. The coefficient of performance of the cycle is 2.8. Evaluating electricity at $0.085 per kW•h, determine the cost of electricity during the heating season when the heat pump operates for 2000 hours.

In a given process, a heat engine requires 2500J of energy and exhausts 1200J of heat. What is its efficiency?

Steam at 140 ° C flows in a pipe having an inner radius of 50 mm and an outer radius of 55 mm. The convective heat transfer coefficient between the steam and the inner pipe wall is 2500 W / (m² ° C). The outer surface of the pipe exposed to ambient air is 20 ° C with a convective heat transfer coefficient of 10 W / (m² ° C). Assuming steady state, calculate the rate of heat transfer per meter of pipe from steam to air. Assume that the thermal conductivity of stainless steel is 15 W / (m ° C.). Steps of work according to example 4.16 Singh. a. Find the overall heat transfer coefficient = Answer W / m² ° C. b. Heat transfer rate per meter of pipe = Answer W / m.

The food compartment of a refrigerator is maintained at 4°C by removing heat from it at a rate of 347 kJ/min. If the required power input to the refrigerator is 3 kW, determine the rate of heat rejection to the room that houses the refrigerator.   Select one: a. 480 kJ/min b. 610 kJ/min c. 394 kJ/min d. 527 kJ/min

An inventor claims to have developed a resistance heater that supplies 1.2 kWh of energy to a room for each kWh of electricity it consumes. Is this a reasonable claim, or has the inventor developed a perpetual-motion machine? Explain.

heat pump with a coefficient of performance of 2.5 supplies energy to a house at a rate of 60,000 Btu/h. Determine (a) the electric pwer drawn by the heat pump and (b) the rate of heat absoption from the outside air.

The thermal effiency of a general heat engine is 35 percent, and it produces 60 hp. At what rate is heat transferred to this engine, in kJ/s?

“Heat can never pass from a colder to warmer body without another concurrent change within.” What is the concurrent change (or work) done by the modern refrigerator allowing heat to flow to a warmer body?     1st law of thermodynamics     Expansion and cooling     Compression and heating of refrigerant     3rd law of thermodynamics     Expansion and heating

Please give the detailed solution. Mechanical -thermo