Environmental performance is playing an increasingly important role alongside energy efficiency and safety considerations when designing new heat pumps, argue Miquel Pitarch et al in their paper ‘High Efficiency Heat Pump with Subcooling for Sanitary Hot Water Production Working with Propane’, presented at Purdue Conferences 2016 at West Lafayette in the U.S. state of Indiana.
A heat pump “needs a working fluid (refrigerant) in order to absorb heat from one area and reject it into another,” Pitarch’s paper explains.
With global efforts to phase down HFCs underway, natural refrigerants – which the researchers point out are “harmless to the ozone layer, with no influence upon greenhouse effect or very less than traditional refrigerants” – are ready replacements.
CO2 and propane have already been successfully harnessed for residential heat pump systems.
The University of Valencia researchers set about designing a propane heat pump based on a water-to-water system to heat or cool as necessary, using the water inlet as a temperature reference point.
By operating in a subcritical cycle for sanitary hot water production and harnessing sub-cooling, their system has been shown to be 31% more efficient than conventional technology.
“Heating COP is improved by adding sub-cooling in the propane cycle. The benefits obtained from producing sub-cooling are higher than the COP degradation due to the increase of condensing temperature,” the researchers explain.
