Modeling, Verification and Optimization of Hybrid Ground Source Heat Pump Systems in Energyplus

Abstract

Hybrid Ground Source Heat Pump system simulation capability was added to EnergyPlus. Program was modified to handle multi-year simulation capability. New supervisory controls were added and a plate heat exchanger model developed to configure realistic systems. The models were verified by comparing to the published results in literature by Yavuzturk et al. (2000). GenOpt was used to investigate the optimal design, control strategies and configuration. Life cycle cost of the system was used as objective function. Effects of using first year operating cost and 20th year operating cost on optimization results were studied. The modifications and addition of new models successfully modeled HGSHP systems in EnergyPlus. The results obtained from EnergyPlus model agreed well within the modeling differences with Yavuzturk results. Optimization proceeded to decrease the GLHE length to the minimum possible, since it was the highest contributor towards cost. Optimization of HGSHP systems was found to be system specific and highly affected by the load imbalance. Use of 20th year operating cost instead of first year operating cost to calculate the life cycle cost affected the results of optimization.