Theoretical research of seasonal performance testing for ground-source heat pump systems

Taking the measured water temperature of buried pipe in a typical summer condition for example, according to Fourier series approximation algorithms and sampling theorem, determines the minimum number of test points to restore the outlet water temperature fluctuation profile during the entire summer running process, and presents the seasonal performance testing method for ground-source heat pump systems. The results show that the water temperature profile of buried pipe during the entire summer running process can be restored by uniformly testing outlet water temperature four times, and by using second order harmonic Fourier series, the restored results and the measured results are in good agreement. Through magnifying the phase of second order harmonic Fourier series by 2.3 times, the restored error can be reduced to ±1%.