Multiphysics Modelling of Standing Column Well and Implementation of Heat Pumps Off-Loading Sequence Presented at the 2012 COMSOL Conference in Boston

A simplified but fully coupled multiphysics model involving heat transfer and groundwater flow within a SCW and its surrounding ground was implemented in COMSOL Multiphysics 4.2a with MATLAB to simulate a 24-hour heating operation. The heat pumps were modeled using interpolation functions thereby allowing the effect of the pumped water temperature on the capacity and coefficient of performance of the heat pumps to be accounted for. In the model presented here, a three level bleed control is applied when the temperature of the pumped water drops to 7, 6 and 5°C. If the pumped water temperature drops below 4°C, an off-loading sequence implemented via a MATLAB function allows the heat pumps to automatically shut down one by one at 10 minute intervals. Results demonstrate that the numerical model developed in this paper can successfully evaluate the EWT over time and that both bleed and off-loading sequence played a key role in maintaining the EWT within the heat pump's operational range.