Chapter 9, Problem 9.71P

4. An evaporator has R-410A at -20°C and quality 80% flowing in. The exit flow is saturated vapor at -20°C. a. Consider the heating to be a reversible process and find the specific heat transfer from the entropy balance. (Answer: 48.7 kJ/kg) b. If the heat source was at -10°C and the inlet and outlet streams still have the same properties as in a), calculate the specific entropy generation? (Answer: 7.33 J/(kg K))

A Factory uses a vapor absorption refrigerator to cool its products, the heat is supplied to generator by steam at 150 C (hfg=2500kJ/kg) and 90% dry. The temperature of the evaporator is to be maintained at -5 C. the refrigeration capacity is 20 Tonnes and actual COP is 70% of the maximum, atmospheric Pressure is 1 bar and ambient temperature 30 C. find the maximum COP. mass of steam per hour

9. An air compressor takes in air at 105 Pa and 27°C having volume of 1.5 m3/kg and compresses it to 4.5×105 Pa. Find the work done, heat transfer and change in internal energy if the compression is isothermal.

In an absorption refrigeration system, heating cooling and refrigeration takes place at 140°C, 25°C and -15°C. Find theoretical COP of the system. Now heating temp. is increased to 180°C and refrigeration temp is decreased to -30°C. Find percentage change in theoritical COP.

In an engine, the air in a piston-cylinder arrangement has a compression ratio of 0.1. It starts from 100kPa and 20degC. Find the temperature at state 2. You can assume an adiabatic process and the ideal gas law applies.

A refrigeration system has a heat rejected of 430 kw.If COP is 7,find the mass chilled water in the evaporator for a temperature decrease of 16°℃.

An amount of 4000 BTU of heat is transferred from a reservoir at 800 deg. F to a reservoir at 200 deg. F. Find the entropy change of the system.

A piston/cylinder receives (control mass system) R-134a at 300 kPa and compresses it in a process where the entropy does not change. to a state of 1000 kPa, 60° C. Find the initial temperature, AND THE CHANGE IN INTERNAL ENERGY.

Refrigerant R-410a inters a refrigerator compressor at a pressure of 150 kPa, -10 c° and leaves at 1200 kPa, 50 c° with mass flow rate of 3 kg/s. the compressor is water cooled and the heat loss to the water Qloss is 20 kW. Determine the compressor input work W.. Note: Neglect potential and kinetic energy in your calculations. 1 2 CN Compressor cool