Paper No 363 – Thermodynamic analysis of the cascade economization cycle for high temperature heat pump applications – 14th IEA Heat Pump Conference, Chicago, USA
High-temperature heat pumps (HTHP), supply temperatures > 100°C, have received significant traction in recent years due to the high total energy usage by processing industries and the phasing down of hydrocarbons. However, despite their potential to significantly reduce greenhouse gas emissions, electrically driven HTHPs suffer considerable performance losses at temperature lifts greater than 60 °C. However, multiple industrial sectors require supply temperature > 120°C while at the same time high temperature high-capacity waste heat sources are often not readily available. Currently, the most widely used cycle for HTHPs with a large temperature lift is the cascade arrangement with different refrigerants on the high side and low side. In this work, we propose staging either the high-side or the low-side compressor, and as such, we investigated different types of economization through a thermodynamic simulation in EES. The refrigerants selected were R-32 and R-1233zd(E). It was found that by using open economization on the high side and by optimizing the cascade temperature, performance enhancements in the order of 25% are achievable over the baseline cascade cycle.