Heat pumps employ the same principles as are found in fridges and air conditioning, pumping heat from one part of their machinery to another to make one part colder and another hotter, but are used specifically for heating rather than for cooling. They can be much more efficient than using electricity directly for heating. Even when using electricity generated by fossil fuels the overall conversion of fossil fuel energy to useful heat can be similar to or better than using the fossil fuel directly. It is also possible to build a heat pump which runs directly from natural gas but there are very few commercially available.
The ratio of heat output from a pump to primary power (usually electricity) consumed is its Coefficient of Performance and depends on the difference between the output and input temperatures, and other factors.
For space heating applications heat pumps commonly draw their input heat either from outside air (air source) or from the ground, via pipes laid under an outdoor area or boreholes sunk outside. Where a body of either fresh or sea water is available this can be used as the heat source.
Transcritical CO2 Air Source Heat Pump for Average UK Domestic Housing with High Temperature Hydronic Heat Distribution System VENKATA SATISH DUDDUMPUDI; University of Strathclyde, Depertment of Mechanical Engineering (PhD thesis); 25 Dec 2010
- The main purpose of this project is to develop a platform to investigate the performance of an Air to water residential CO2 heat pump which reduces the severe environmental problems causing by synthetic refrigerants, for Space heating and domestic hot water, in an average UK domestic house with high temperature hydronic heat distributing system.
- For this a numerical simulation model of Air source Transcritical CO2 heat pump system was developed based on thermodynamic equations using Engineering Equation Solver (EES). Then factors to be considered in components selection in the construction of CO2 heat pump cycle and numerical simulator and the modifications that improve the performance of the heat pump cycle were studied and analyzed, the values of the model parameters are estimated based on measured data for existing devices for the optimum output from the simulation system. The equations developed to estimate the performance and the behaviour of the components used in the heat pump cycle were based on the thermodynamic relations and laws. And then to validate the model, its performance was compared with Dr Jørn Stene’s CO2 Heat Pump simulation model at similar operating and design conditions.
- Finally, the simulation code for CO2 heat pump was developed in such a way that, the performance of the heat pump can be evaluated when retro-fitted in any domestic housing by running the code with heat demand (space heating and domestic hot water demand) input. In this project heat loads for average UK domestic house and the climatic data were taken from ADEPT developed by ESRU, University of Strathclyde were chosen to find the performance of the CO2 heat pump when retro-fitted as future research with few modifications to the heating distribution and heat generation system.