Ground source heat pumps for heating: Parametric energy analysis of a vapor compression cycle utilizing an economizer arrangement

Reductions in fossil fuel use and increases in system efficiency are required to make space heating more environmentally benign. Ground loop heat pumps offer a heating option that is more environmentally benign than conventional methods. Past studies of these heat pumps have usually focused on basic system arrangements, but new advanced systems are being developed. Here, energy analyses are reported for an advanced heat pump arrangement comprised of a vapor compression cycle with an economizer. A parametric analysis is performed to identify and quantify the influence of condenser pressure, evaporator pressure, intermediate pressure, degree of subcooling at the condenser outlet and degree of super heating at the evaporator outlet on system performance and ground loop requirements. The results show that, of the operating conditions investigated, condenser pressure has the greatest effect on the coefficient of performance (COP). The effect on COP of the other parameters, ranked from highest to lowest, are evaporator pressure, degree of subcooling, intermediate pressure and degree of superheating within this study. ► Heat pumps with economizers have potential for high COP values. ► Condenser pressure has the greatest effect on COP. ► To maximize COP the intermediate pressure should be maximized. ► The ground loop pump plays a small role system COP. ► COP is dependent on condenser and evaporator pressures not pressure ratio between them.