Thermodynamic and economic analysis of different cogeneration and trigeneration systems based on carbon dioxide vapor compression refrigeration systems

Abstract

Carbon dioxide vapor compression refrigeration cycles operating at low evaporator temperatures represent a substantial waste energy recovery potential to generate useful products using the high-temperature carbon dioxide leaving the compressor. Despite this remarkable potential, there are limited investigations about waste energy recovery from these cycles for different applications. Using this as a motivation, in this work, different novel integrated cogeneration and trigeneration configurations are proposed based on a carbon dioxide parallel compression economization-vapor compression refrigeration cycle with a 1000 kW capacity and evaporator temperatures of −35 °C to −45 °C. The major originality of this work is the proposal and detailed techno-economic evaluation of several feasible cogeneration and trigeneration configurations for different practical applications. Different cycles and components are integrated into the carbon dioxide cycle including single and double stages water-lithium bromide absorption chillers, a single stage ammonia-water absorption refrigeration, a carbon dioxide-water heat exchanger and an organic Rankine cycle. The thermo-economic findings demonstrate that recovering the available thermal energy of carbon dioxide exiting the compressor would be very attractive both thermodynamically and economically to produce several useful outputs. More than 478 kW and 147 kW cooling (air conditioning) and refrigeration effects can be generated using the cogeneration configurations. Also, between 59.52 kW and 185.8 kW power can be generated depending on the configurations and organic fluid used, improving the coefficient of performance up to 18.0%. Moreover, 7763–9360 m3/year of domestic hot water can be generated by the trigeneration configurations, reducing the levelized cost of cooling up to 13%.