Heat pumps may be used in drying processes to recover low-grade heat contained in moist exhaust air and supply the dryer. The heat pump design is limited technically by the level of process temperature and its performance optimization depends strongly on the difference between both temperature levels of process and effluents.

Using an exergy optimization methodology for heat pump integrations in industrial processes, a high temperature transcritical heat pump using the R-32 as working fluid was earlier proposed by the authors and experimentally demonstrated a 120°C hot air supply temperature.

In this paper, HFO’s are considered to increase the air supply temperature to reach up to 150°C. Architecture technical options are also studied in order to improve the COP depending on the heat source and sink properties.

The prototype developed for the R-32 is adapted and used to validate the predicted performances. Its performance, when heating air from 90°C or 100°C to 150°C, is presented. The effluents are available at 82°C with different absolute humidities. The observed COP of the heat pump reached up to 3.72.