Experimental study of a diesel engine heat pump in heating mode for domestic retrofit application

An engine driven heat pump (ENHP) can provide better efficiency compared to electric heat pump (EHP) considering primary energy consumption. The present work aimed to find suitability of diesel engine heat pump as a domestic retrofit application for off or weak gas/electricity network area. For this work, water-to-water heat pump test facility was developed which consisted heat pump, diesel engine and heat recovery arrangements. The system performance was evaluated for 65 °C flow temperature from condenser at three different engine speeds (1600, 2000 and 2400 rpm) and four evaporator water inlet temperatures (0, 5, 10 and 15 °C). The system performance was evaluated by heating capacity, isentropic efficiency, coolant heat recovery, exhaust gas heat recovery and PER. Performance analyses showed that heat recovery contributed 33% in total heat output where heat recovery was in a range of 1.7 to 3.7 kW. PER varied in the range of 0.9 to 1.4 showing good potential in terms of 35-65% primary energy saving and 23-42% CO2 emissions reduction compared to conventional systems. DEHP optimisation showed ability to meet water flow temperature requirement of 65-73 °C by speed variations and heat recovery providing good potential to meet heating demand during winter and summer periods in retrofit settings.