NH3-H2O water source absorption heat pump (WSAHP) for low temperature heating: Experimental investigation on the off-design performance

- An NH3-H2O water source absorption heat pump was tested under different conditions.
- For generator inlet of 110-140 °C, COP is 1.43-1.55, capacity is 32.23-88.35 kW.
- For produced hot water of 30-45 °C, COP is 1.65-1.45, capacity is 94.55-60.37 kW.
- For evaporator inlet of −10-30 °C, COP is 1.20-1.61, capacity is 39.51-79.72 kW.
- Compared with former works, it can work under an evaporator inlet as low as −18 °C.

Heat supply systems based on absorption heat pump were assessed to have great potentials on energy savings and emissions reduction. A prototype of NH3-H2O water source absorption heat pump (WSAHP) designed for low temperature heating was experimentally investigated under different working conditions. The effects of driving source, hot water and source fluid temperature on the heating performance were studied. As driving source increases from 110 °C to 140 °C with 15 °C evaporator inlet and 45 °C hot water, COP increases from 1.429 to 1.552 and then decreases to 1.495, while the heating capacity increases from 32.23 kW to 88.35 kW. As hot water increases from 30 °C to 45 °C with 130 °C generator inlet and 15 °C evaporator inlet, COP decreases from 1.653 to 1.449, while the heating capacity drops from 94.55 kW to 60.37 kW. As the source fluid increases from −10 °C to 30 °C with 130 °C generator inlet and 45 °C hot water, COP increases from 1.203 to 1.609, while the heating capacity increases from 39.51 kW to 79.72 kW. Comparisons with former work indicate that the developed prototype can operate under evaporator inlet temperatures as low as −18 °C, which is significant to improve heating applicability in colder conditions.