Performance modelling of an ammonia-water absorption-compression heat pump for steam generation in food processing

At the present time, fossil fuel is still the primary energy source for steam production in food processing. To mitigate climate change and promote sustainable development, there is an urgent need for eco-friendly steam boilers. The absorption-compression heat pumps (ACHP) using an ammonia-water mixture as the working fluid can provide high heat sink temperature up to 140°C at low discharge pressure levels and with temperature glides in absorption and desorption processes. The present study investigated the performance of the ACHP for hot water and steam production. The simulation model was established based on the ACHP prototype in the NTNU lab. A case of 150 kW heating capacity was simulated with a high pressure of 23.65 bar and a low pressure of 4 bar. The ACHP system COP was 2.85 for a pressurized hot water supply temperature of 105 °C. The effects of heat sink outlet temperature and part-load and overload conditions on the system performance were investigated.