An Advanced Hybrid Ground Source Heat Pump System for a Multi-Family Residential Unit: Modeling and Optimization

Geothermal Heat Pumps use energy from the earth for space heating or cooling. During the heating process, a ground source heat pump takes thermal energy from a working fluid and delivers that heat into a space. This system can be efficient but sometimes can become electrically consumptive in the peak of the heating season. A hybrid ground source heat pump system for a small apartment building set in Birmingham Alabama was established in TRNSYS to model the resulting system in order to predict the gains. The system was optimized in order to maximize cost-effectiveness and efficiency for the systems heating application. The ground loop of the system was modified to include a large tank for water storage and a solar collector capable of delivering thermal energy directly into the working fluid. The size of the tank by volume, the size of the solar panel by area, and the size of the heat pump by heating tons were all modified to maximize the system based on cost. Simulation results showed that system sizing was much smaller than a standard heating system, and the addition of the tank and the solar panel cut down on the unmet hours of the system