Chapter 8, Problem 8.51P

A binary vapor power cycle consists of two ideal Rankine cycles with steam and Refrigerant 134a as the working fluids. The mass flow rate of steam is 2 kg/s. In the steam cycle, superheated vapor enters the turbine at 8 MPa, 560°C, and saturated liquid exits the condenser at 50 kPa. In the interconnecting heat exchanger, energy rejected by heat transfer from the steam cycle is provided to the Refrigerant 134a cycle. The heat exchanger experiences no stray heat transfer with its surroundings. Superheated Refrigerant 134a leaves the heat exchanger at 600 kPa, 30°C, which enters the Refrigerant 134a turbine. Saturated liquid leaves the Refrigerant 134a condenser at 100 kPa.Determine:(a) the net power developed by the binary cycle, in kW.(b) the rate of heat addition to the binary cycle, in kW.(c) the percent thermal efficiency of the binary cycle.(d) the rate of entropy production in the interconnecting heat exchanger, in kW/K.

4. An ideal vapor-compression heat pump cycle with Refrigerant 134a as the working fluid provides heating at a rate of 15 kW to maintain a building at 20°C when the outside temperature is 5°C. Saturated vapor at 2.4 bar leaves the evaporator, and saturated liquid at 8 bar leaves the condenser. Calculate (a) The power input to the compressor, in kW. (b) The coefficient of performance. (c) The coefficient of performance of a Carnot heat pump cycle operating between thermal reservoirs at 20 and 5 °C.

An ideal vapor-compression heat pump cycle with Refrigerant 134a as the working fluid provides 15 kW to maintain a building at 200°C when the outside temperature is 50°C. Saturated vapor at 2.4 bar leaves the evaporator, and saturated liquid at 8 bar leaves the condenser. Calculate (a) The power input to the compressor, in kW (b) The coefficient of performance. (c) The coefficient of performance of a reversible heat pump cycle operating between thermal reservoirs at 20 and 50°C. (h, = 244.09kJ/ke, 5 = 0.9222 kJ/kg -K; h, = 268.97 kJ/ kg; h, = 93.42 kJ/ kg)