Experimental study and CFD approach for scroll type expander used in low-temperature organic Rankine cycle

• Scroll expanders with various built-in volume ratios were experimentally studied.
• ORC efficiency of 7.77% was obtained at system temperature difference of 60.6 °C.
• The internal behaviors of scroll expander have been numerically investigated.

This study focuses on experimental test of scroll type expanders in low-temperature organic Rankine cycle (ORC) system. In this circuit, lubricant has been mixed with R245fa as working fluid. In this experiment, two scroll expanders with different built-in volume ratio have been experimentally tested. Main test parameters considered are the pressure difference and the rotational speed of the expanders. It is found that the expander performance could be significantly improved when bigger built-in volume ratio is used. However the internal leakage and friction loss are vital factors to influence expander performance. The maximum shaft power output by expander of 1.77 kW and deliver electricity by generator of 1.375 kW. A Computational Fluid Dynamics approach (CFD) has been employed for preliminary investigation on the thermal-hydraulic behavior of the scroll type expanders. The simulation result shows that unbalance pressure distribution were occurred in the expander by means of top scroll wrap has been modified.