Verification and analysis of a TRNSYS model of a demonstration house equipped with a solar assisted ground coupled heat pump system

A TRNSYS model of a demonstration house equipped with a solar assisted ground coupled heat pump system (SAGCHPS) has been built. Besides using a built-in vertical ground heat exchanger (VGHE) module in TRNSYS, the model also uses a newly developed VGHE module which considers coupled heat and moisture transfer in ground with variable soil properties and phase change of soil moisture. The TRNSYS model with the new VGHE module (which has three simulation modes) is verified to produce better simulation results than the one with TRNSYS´s built-in VGHE module, comparing with the field data of an actual and successful project. Coupled heat and moisture transfer effect in ground plays a more important role than variable soil properties and phase change of soil moisture. However, the result of considering all of them is the best. It is found that a simulation with pure heat transfer in ground (i.e., without moisture transfer and latent heat effect) can be considered in an early stage of a VGHE design. However, for better results and study of long-term effects, coupled heat and moisture transfer in ground with variable soil properties and phase change of soil moisture is recommended.