Thermodynamic investigation of integrated organic Rankine cycle-ejector vapor compression cooling cycle waste heat recovery configurations for cooling, heating and power production
Konstantinos Braimakis, Sotiriοs Karellas
Abstract
The present work focuses on vessel engine waste heat recovery (WHR) architectures for cooling, heating and power production based on the combination of an Organic Rankine Cycle (ORC) and a thermally assisted ejector cooling cycle-vapor compression cycle (EVCC), integrated into an ORC-EVCC. Their advantages and disadvantages are analyzed and their performance is evaluated using numerical models developed according to boundary conditions corresponding to a vessel diesel engine WHR micro-scale (100 kWth thermal input) application considering R1233zd(E), R1234yf and R1234ze as working fluids. Ultimately, a parallel ORC- parallel/serial EVCC layout operating with R1233zd(E) is determined as the most promising configuration, considering its superior thermodynamic performance and practical aspects (simplicity, space and weight requirements and cost). The ORC and EVCC are integrated in parallel and operate with the same fluid. Furthermore, the EVCC compressor and ejector are connected in a parallel/serial layout. Under the design point, the net power output of the system is 10.30 kWe in electricity-only mode and 7.68 kWe in CHP mode. In CHP mode, the heating output is 88.97 kWth. In the two cooling modes, electricity and cooling are produced simultaneously by the ORC and EVCC, respectively. The cooling output ranges between approximately 4.48 and 7.82 kWc.