To study the performance and selection of the working fluid pump in organic Rankine cycle (ORC) waste heat recovery system for vehicle engines

a test bench of a multistage centrifugal pump was constructed using R123 as working fluid in a condition of simulative ORC waste heat recovery system for vehicle engines. Experimental results of the multistage centrifugal pump under various operating conditions were obtained based on controlled working rotational speed (870-2900 r·min-1) and working fluid flow rate (0.20-5.00 m3·h-1). The interaction of the key pump parameters and their effect on the ORC performance were analyzed in this paper. In addition

the feasibility of the multistage centrifugal pump applied to the ORC waste heat recovery system for vehicle engines was verified and the optimal working point parameters were also determined. Results showed that the overall pump efficiency of multistage centrifugal pump was between 15.00% and 65.70%. The outlet pressure

pump efficiency and ORC thermal efficiency increased with the increase of the rotating speed of the pump. The flow rate needed to be regulated as the frequency became increasingly high. The maximum thermal efficiencies of the ORC system corresponding to various working frequencies of the pump were observed. Furthermore

the practical back work ratio (BWR) can reach up to 0.45 with the increase of the evaporating temperature of the ORC system. And the thermal efficiency can reach up to 10.50% when the rotating speed of multistage centrifugal pump was 2900 r·min-1. Pumping power should not be neglected for small-scale ORC applications

and pump efficiency assumptions should be dependent on experiments. Low pump efficiency affected the increase of the thermal efficiency and net power of the ORC system.