Analysis of CO2 heat pump for low energy residential building
In low energy buildings heat loss is reduced through energy-saving measures
like heat recovery of ventilation air and a well-insulated building
envelope. Consequently the demand for domestic hot water often makes
up a larger share of the annual heating demand than in traditional buildings.
For this application heat pumps using CO2 as a working fluid are
seen as a promising alternative to conventional heat pumps. In the current
study a transcritical CO2 heat pump model for use in building simulations
was developed. Some challenges related to the development and
implementation of the model were pointed out.
A preliminary study of the model was performed in order to determine
the optimal input parameters for the heat pump in the building of interest.
The performance of the heat pump was analyzed over a range of
operating conditions. Sizing recommendations for the main heat pump
components were made, and a strategy for optimal control of the gas
cooler pressure was presented.
The model was implemented into EnergyPlus and used for energy simulations
of a low energy residential building consisting of three apartments.
The heat pump performance was analyzed for different building usage
patterns including ?normal? use, increased demand for domestic hot water
and night-time reduction of the indoor temperature. Simulation results
showed and increase in overall system SPF from 2.51 to 2.64 in the
case of increased domestic hot water demand because of more favorable
operating conditions for the heat pump. Results further suggested that
energy savings in the case of night-time temperature reduction would be
minimal due to an increased demand for supplementary heating when
reheating the building. In the latter case the overall system SPF was
reduced to 2.43. Recommendations for achieving a better performance
were made based on the simulations results.
Place, publisher, year, edition, pages
Institutt for energi- og prosessteknikk , 2013. , 98 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-21999Local ID: ntnudaim:9504OAI: oai:DiVA.org:ntnu-21999DiVA: diva2:646737
Nord, Natasa, Førsteamanuensis