A cascade heat pump for water heating
Heat pumps offer considerable energy cost and energy-related environmental benefits. However the high temperature required for domestic hot water limits energy efficiency, especially if heat-source temperatures are low.
A team including Professor Don Cleland worked to design a heat pump to overcome these limitations. This system uses ambient air as the heat source, a heat pump configuration involving two refrigerants in a cascade arrangement, and is coupled to a stratified hot water cylinder.
Laboratory performance testing, combined with analysis using climate data and field tests, suggests the system would achieve seasonal heating efficiencies of more than 300% (more than 3 units of heat for each unit of energy input) at most New Zealand locations.
Contact Don Cleland