In situ optimization methodology for the water circulation pumps frequency of ground source heat pump systems

Abstract

[EN] This paper presents an experimental study of the influence of the water circulation pumps frequency atthe indoor and outdoor loops in the overall system performance of a ground source heat pump moni-tored plant, and describes a three steps new methodology to optimize the system energy performanceand obtain the values of the optimal frequencies when ON/OFF regulation is employed. The first stepconsists of several experimental tests of pseudo-random sequence of frequency steps for both, internaland external circulation pumps, carried out during a single day. The second step is the characterization ofthe quasi-steady state system performance as a function of circulation pumps frequencies. The final stepconsists of, by means of an analytical expression, the extrapolation of results to any partial load ratio,what allows finding the optimal frequency as a function of the instantaneous thermal load. The advantageof the proposed methodology is that it can be carried out on site and is able to consider the phenomenaoccurring at the heat pump and the ground source heat exchanger when the flow rates are varied. Themethodology can be applied to any installation incorporating variable speed circulation pumps. Resultsindicate large energy savings potential for this kind of installation.