Absorption-based heat pumps for decarbonization of industrial process heating: performance, current status, and new developments

• Water/LiBr AHP technology for up to 100 °C heat supply and 70 MW capacity (TRL 9) • Water/LiBr AHT technology for up to 185 °C heat supply and 15 MW capacity (TRL 9) • Ammonia/water ACHP technology for up to 160 °C heat supply and 10 MW capacity (TRL 8 − 9) • High heat supply temperature and large temperature lift potential using AHT system. • Large sink and source temperature glide matching potential using ACHP system. In industry, there is a huge demand for process heat to produce, process, or finish products. Industrial process heat originates mainly from the combustion of fossil fuels, so industries need to use sustainable heat supplies if they are to reduce their carbon footprints. In this context, absorption-based heat pumps can offer a viable solution to mitigating the environmental impact of industrial heat consumption. This article reviews and discusses the state of the art of three types of absorption-based heat pumps for industrial heating applications (≥80 °C): absorption-compression heat pumps, absorption heat pumps (Type I heat pumps), and absorption heat transformers (Type II heat pumps). The water/LiBr Type I heat pump technologies currently available are restricted to a maximum heat supply temperature of 100 °C and a temperature lift up to 50 °C with thermal COPs of 1.65–1.80. The water/LiBr Type II heat pumps have a maximum heat supply temperature of 185 °C and a temperature lift of up to 50 °C with thermal COPs of 0.33–0.48. The ammonia/water absorption-compression heat pumps have a maximum heat supply temperature of 160 °C and a temperature lift of up to 110 °C with electrical COPs of 2.7–7.3. However, to fully exploit the potential of these heat pumps in process industries, research and development should focus on increasing heat supply temperature and temperature lift beyond the current limits. The use of these heat pumps to recover industrial waste heat will make a considerable contribution to the decarbonisation of the process industries.