Chapter 5, Problem 5.8P

An air conditioner using refrigerant 134a as work fluid It is used to keep the temperature of a room at 23 ° C by giving heat to the environment. The house from the walls and heat gain from windows is 250 kJ / min ; 900 W of heat from computer, TV and lamps to the room spreads. The refrigerant is 100 L / min in the form of saturated vapor at 400 kPa pressure to the compressor entering with flow and it left from the compressor 1200 kPa pressure and 70 ° C. a) real COP value b) max COP value c) Calculate the min volumetric flow rate for the refrigerant can have for the same compressor inlet and outlet conditions

.The thermal efficiency of a heat engine is 30%, the heat rejected from the engine is 30kJ, evaluate the heat input to the engine.

A reversible heat pump absorbs heat at a temperature of 25.00oC and produces heat at 61.00oC, The work input rate is 110.00 kW, determine the heat input rate. the answer is 2490.16kW

A system is proposed to generate power from wastewater of 54C. If the ambient temperature is 23C, what is the highest thermal efficiency of this system in %?

A carnot heat pump is operating to keep a room at 20C. The unit is taking in air from a -30C location. If it is pulling 5kW from the -30C location, what is the power input required to do this and how much heat is delivered to the 20C room?

A water cooler for drinking water should cool 25 L/h water from 18 C to 10 C while the water reservoirs also gains 60 W from heat transfer. Assume that a small refrigeration unit with a COP of 2.5 does the cooling. Find the power input to the unit.

Through a combustion of a fossil fuel at 35000C, an engine receives energy at a rate of 3000Btu/s to heat a steam to 15000C. There is no energy loss during the combustion process, the steam in turn produces 1000Btu/s of work and rejects the remaining energy to the surrounding at 3000C, What is the thermal efficiency of the plant? What is the reversible work and Carnot efficiency? What is irreversibility?

A domestic food freezer maintains a temperature of-15°C. The ambient air temperature is 30°C. If heat leaks into the freezer at the continuous rate of 1.75 kJ/s what is the least power necessary to pump this heat our continuously?

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