Diesel engine heat pump performance analysis for a domestic retrofit application.

An engine driven heat pump (ENHP) uses an engine rather than electric motor and heat is recovered from engine coolant and exhaust gas. ENHP arrangement could have great potential where gas/electricity network are weak or not in existing. The aim of this work is to find the suitability of Diesel engine heat pump (DEHP) for domestic application comparing with the conventional technologies such as gas/oil boiler and electric heat pump (EHP). DEHP system was tested to provide high flow temperature as a retrofit technology to replace existing gas boiler at four-evaporator water inlet temperature and three engine speeds. Primary energy ratio (PER) and CO2 saving potential have been compared. Test results showed that DEHP system has 39-65% higher heat output and 26-62% higher PER compared to EHP. Heat recovery share in total heat output varies from 28-39%. DEHP system annual performance compared with conventional system which showed that DEHP system has potential of 35-65% primary energy savings, 23-42% CO2 emission saving and 26-42% annual fuel-cost savings compared to oil boiler with possible use of bio fuel with high retrofit potential in the UK.