An evaluation of the performance of a scroll machine in a reversible high-temperature heat pump - organic Rankine cycle system using R1233zd (E) as the working fluid.

A reversible high-temperature heat pump (HTHP) - Organic Rankine cycle (ORC) system can effectively recover industrial waste heat in the lower temperature band (<100 ◦C). This system can provide upgraded heat in HTHP mode or generate electrical power in ORC mode. For a compact reversible HTHP-ORC system, it is essential to utilise a volumetric machine that can function as both a compressor (HTHP mode) and an expander (ORC mode). This paper presents a performance analysis of an open-drive scroll machine operating in both modes, using R1233zd(E) as the working fluid. Steady-state models developed for this analysis were validated against data from previous experimental tests and subsequently used to evaluate the performance of the scroll compressor/ expander under extended operating conditions. The model predictions indicated that the scroll compressor could achieve an overall isentropic efficiency of 73 % (Tsf,ev,in = 90 ◦C, Ncp = 2,000 RPM) and a volumetric efficiency of 92.3 % (Tsf,ev,in = 90 ◦C, Ncp = 2,500 RPM). In expander mode, the overall isentropic efficiencies were lower than in compressor mode, reaching a maximum value of 57.7 %. The results also demonstrated that the scroll machine could produce a gross power output of 1.01 kW (rp = 3.6, Tsf,ev,in = 90 ◦C) at higher pressure ratios in expander mode.