Dynamic thermal analysis of a residential ground-source heat pump

We present the dynamic thermal analysis of a residential ground-source heat pump (GSHP) with the following objectives: (1) to present a comprehensive GSHP model accounting for the dynamic behavior of a vapor compression unit, lumped serviced space, and the ground heat exchanger (GHE); (2) to identify a set of GHE temperature, mass flow rate, and evaporator area fraction (alpha) improving the time-averaged coefficient of performance ((COP) over bar) while retaining thermal comfort in the serviced space; and (3) to propose a GHE design satisfying the desired design and operating conditions determined in (2). For a 4-ton residential GSHP considered herein, we verified the existence of a critical GHE mass flow rate of 1 kg/s after which the (COP) over bar hardly varied. Furthermore, we observed a design trade-off between cooling and heating modes wherein a smaller alpha was preferred in cooling mode while the heating mode favored a higher alpha. Cooling (COP) over bar was sensitivity to both alpha and GHE temperature (T-B), whereas that in heating mode was insensitive to T-B as long as both and L-t were sufficiently high. The optimal alpha impartial to bothmodes was 0.29 and the peak (COP) over bar = 5.49 and 3.6 in cooling and heating mode, respectively.