Thermal Optimization of a Solar Thermal Cooling Cogeneration Plant at Low Temperature Heat Recovery

Abstract

A simple cooling cogeneration has been developed by coupling a Kalina cycle system (KCS) with a vapor absorption refrigeration (VAR) system. The working fluid used in this theoretical thermodynamic evaluation is ammonia water mixture. A low temperature heat recovery (150 آ°C–200 آ°C) from engine exhaust gas, solar collectors, or similar can be used to operate the plant. A controlling facility is provided to set the required amount of power or cooling to meet the variable demand. In this proposed plant, the liquid refrigerant absorbs more amount of heat from evaporator surroundings with a flow control located in between power and cooling cycles. The extra included components are condenser, heat exchanger and throttling device over KCS plant. Due to possibility of more cooling, it offers high energy utilization factor (EUF). The coupled plant characteristics are studied with changes in mass split ratio, separator vapor fraction, separator temperature, and turbine concentration to develop efficient working conditions. The power mass split ratio is varied from 80% to 100% to run the coupled plant at nearly full load conditions. The separator vapor fraction and temperature are optimized at 45% and 150 آ°C, respectively. It is recommended to maintain the turbine concentration above 0.85 for optimum power and cooling. The maximum cycle EUF and plant EUF are 0.15 and 0.06, respectively, at 80% power mass split ratio. The specific power and specific cooling at these conditions are 62 kW/kg and 72 kW/kg, respectively.