Experimental study on the matching characteristics of working fluid types and heat sources based on the organic Rankine cycle system

Organic substances with low boiling points can be easily converted into high-pressure gases when heated, making them suitable for ORC (organic Rankine cycle) systems to recover low-temperature waste heat. This study investigated the recycling process of a LTHS (low-temperature heat source) using a kW-scale ORC experimental system with hydrofluorocarbon as the working fluids. The system performance under various operating conditions was explored by changing the type of working fluids and WFFQ (working fluids filling quantity), as well as HST. When the WFFQ increased from 5 to 10 kg at a HST of 100 °C, the theoretical shaft power of the expander ranged from 0.332 to 1.341 kW for R134a, 0.555–1.9147 kW for R245fa, and 0.372–1.067 kW for R227ea. Corresponding thermal efficiency ranged from 2.084 to 4.739 %, 3.136–5.878 %, and 4.525–6.448 %, respectively. At a HST of 120 °C, the theoretical shaft work of the expander ranged from 0.517 to 1.569 kW for R134a, 0.703–2.165 kW for R245fa, and 0.445–1.158 kW for R227ea; thermal efficiency ranged from 3.500 to 5.563 %, 3.889–6.303 %, and 5.446–6.454 %, respectively.