PERFORMANCE MODEL OF A WASTE HEAT DRIVEN TURBO-COMPRESSION CHILLER
Waste heat recovery systems can offer performance and economic benefits for power generation systems, including power plants and diesel generators. One method of waste heat recovery is to use a turbo-compressor to convert low grade waste heat into a cooling effect. The turbo-compression cooling system (TCCS) functions by using low grade waste heat to operate a recuperative Rankine or supercritical cycle to directly power a compressor in a vapor-compression cycle. The TCCS has a similar coefficient of performance (COP) to high efficiency absorption systems, but is less complex and can potentially be manufactured at a lower cost. The cooling effect from the vapor compression cycle can be used to offset cooling loads, provide air conditioning, or offer alternate cooling uses. This study determines the COP of a TCCS at a 250kWth output scale with realistic turbine and compressor geometry designed for a low temperature lift while the system provides much colder 7°C chilled water under various ambient conditions (i.e., from 15°C to 30°C). To analyze this system, a method for determining the performance of the TCCS using compressor and turbine efficiency maps that account for the change in fluid properties, pressure differential, and rotation speed is described. This method is applicable to different sized systems and allows for scaling of the TCCS to various cooling requirements and waste heat sources.