Numerical analysis of the system: Vapour compressor heat pump - Vertical ground heat exchanger

Thermal processes in a heat pump system are the subject of numerical analyses in the paper. The system considered consists of vapour compressor heat pump collaborating with a vertical ground heat exchanger and heated space. Particularly, it is equipped with a piston compressor, and the ground heat exchanger containing a row of Field pipes. The worked out numerical model of coupled thermal processes in the system is described in the paper. The model contains both the characteristic equations for heat pump unit elements and equations for the ground heat exchanger. The second ones are used for calculating unsteady temperature field in the ground and temperature distribution of intermediate heat carrier inside the pipes of the exchanger. It was assumed that the heat pump system capacity is big enough to satisfy the daily demand for heat. The heat pump compressor works within successive days as long as the daily demand for heat in the heated space is achieved. Exemplary results of calculations are also presented and analysed. The results confirm strong correlation between characteristic parameters of the heat pump unit and the ground heat exchanger. There are also visible distinct changes of some of these parameters both during the heating season as well as during daily working time of the compressor.