High-temperature heat pumps: Fundamentals, modelling approaches and applications

In March 2023, the European Parliament and Council reached a consensus to increase the binding renewable energy target (RES) to a minimum of 42.5 % by 2030, effectively doubling the proportion of RES from the 2020 baseline. This significant development aligns the EU more closely with the objectives of the European Green Deal and the REPowerEU initiative. High-temperature heat pumps (HTHP), due to their appropriateness for industrial-scale applications, integrate perfectly within this progressive trajectory. They enable waste heat generated by various production processes to be recovered (temperatures typically ranges from around 50 °C–100 °C) and subsequent use at temperatures above 100 °C, thus reducing the consumption of fossil fuels and greenhouse gas emissions. The high operating temperatures and pressures of HTHPs are challenging. They require an in-depth analysis of the system processes involved, taking into account refrigerants, efficient heat pump cycles and key components. One possibility for a preliminary analysis of vapour compression HTHP system performance without incurring the costs associated with manufacturing and testing the device is modelling. However, there is no comprehensive review of research work on possible software. Commonly, the researchers report on one chosen methodology and the tools used. This paper provides a comprehensive review of modelling approaches. It also discusses aspects related to the principles of operation, refrigerants and system components. Additionally, the paper presents an overview of vapour compression heat pump applications in various sectors. The literature review conducted indicates the need for further research and development of HTHP covering not only technological aspects but also software development.