Technical and economic working domains of industrial heat pumps: Part 2 – Ammonia-water hybrid absorption-compression heat pumps

• The working domain of the hybrid absorption-compression heat pump is investigated.
• Technical constraints based on commercial components are applied.
• Economic viability is determined based on net present value.
• Hybrid absorption-compression heat pumps allow heat supply temperatures up to 150 °C.
• At high temperatures the hybrid absorption-compression heat pump is economically favourable.

The ammonia-water hybrid absorption-compression heat pump (HACHP) has been proposed as a relevant technology for industrial heat supply, especially for high sink temperatures and high temperature glides in the sink and source. This is due to the reduced vapour pressure and the non-isothermal phase change of the zeotropic mixture, ammonia-water. To evaluate to which extent these advantages can be translated into feasible heat pump solutions, the working domain of the HACHP is investigated based on technical and economic constraints. The HACHP working domain is compared to that of the best available vapour compression heat pump with natural working fluids. This shows that the HACHP increases the temperature lifts and heat supply temperatures that are feasible to produce with a heat pump. The HACHP is shown to be capable of delivering heat supply temperatures as high as 150 °C and temperature lifts up to 60 K, all with economical benefits for the investor.