Novel multi-condenser hybrid ground source heat pump system incorporated to vapour compressor refrigeration cycle with internal heat exchanger assessed with multi-objective genetic algorithm

Ground-source systems take advantage of the stability of the ground temperatures, allowing for performance levels higher than those of air-source systems. Nevertheless, in areas where cooling is the major requirement, the constant rejection of heat eventually depletes the ground's thermal capacity, gradually degrading the performance of ground-source systems. Internal heat exchangers also contribute to the problem by increasing the compressor's superheat, thereby accelerating the saturation of the ground. In addition, GSHPs suffer from thermal saturation during operation in hot climates. Therefore, there is a need for a heat-rejection system that minimizes heat transfer to the ground while maintaining GSHP performance. This study has proposed a multi-condenser vapour compression refrigeration system approach for solving the condenser load management problems in GSHPs using ground heat exchangers. The conventional GSHP has a reduced COP due to the integration of IHX. Furthermore, the VCR system integrated with the IHX has a greater load on the condenser. Therefore, three theoretical models are proposed and analyzed for the GSHP coupled with the GHE. The load management strategies for the GSHP are classified into air-assisted condenser (AAC) and ground heat exchanger-assisted condenser (GHEAC). Three models are developed for the GSHP coupled with the GHE. These include the baseline model coupled with the GHE, the conventional GSHP coupled with the IHX, and the conventional GSHP coupled with the GHE. The load management strategies for the GSHP are classified into air-assisted condenser (AAC) and ground heat exchanger-assisted condenser (GHEAC). The models are developed as permutations of the two condensers. The AAC model performs best under standard conditions, followed by the GHEAC model. For the AAC model, the amount of heat transferred to the ground is reduced by 63.44% relative to the baseline model. In addition, the exergy efficiency improves by 12.62%, while the COP decreases by 1.25%. In terms of COP, the baseline model performs best, followed by the model in which the ambient air is pre-cooled using the GHE before it is supplied to the condenser to cool the superheated refrigerant.