In order to meet the great demand for green grain storage and low carbon emissions, paraffin, high-density polyethylene (HDPE), and expanded graphite (EG) were used to produce shape-stabilized phase change material (SSPCM) plates, which were then used to reconstruct building walls for existing granaries. A new type of SSPCM plate was then prefabricated with different thermal conductivities and a high latent heat. This plate could be directly adhered to the existing granary walls. In order to evaluate the thermal regulation performance of these phase change granary walls, experiments and numerical methods were established, specifically for the summer condition. The thermal behavior of the SSPCM granary wall was compared with that of the common concrete granary wall to obtain the optimal parameters. It was concluded that increasing the thickness of the SSPCM layer can reduce the temperature rise of the wall. However, the maximum latent heat utilization rate and energy storage effects were obtained when the SSPCM thickness was at an intermediate level of 30 mm. The thermal conductivity of the SSPCM had a controversial effect on the thermal resistance and latent heat utilization behaviors of the SSPCM. Considering the temperature level and energy saving rate, a 30 mm thick SSPCM plate with a thermal conductivity of 0.2 W/m·K provided a superior performance. When compared to the common wall, the optimized energy-saving rate was greatly enhanced by 35.83% for the SSPCM granary wall with a thickness of 30 mm and a thermal conductivity of 0.2 W/m·K.

A ground heat exchanger (GHE) can efficiently exploit geothermal energy, and a ground source heat pump (GSHP) is an important type of geothermal application. The distributed thermal response test (DTRT) is widely used to measure layered ground thermal properties for shallow GHEs, but nowadays, there is a lack of studies applying the DTRT to deep coaxial GHEs (DCGHEs). This study proposes a new parameter estimation method (PEM) by adopting the DTRT data of a DCGHE to estimate layered ground thermal properties and applies the proposed PEM to simulated DTRTs under different boundary conditions, and the estimated values of the layered ground thermal properties are compared with the true values. Under heat output rate or inlet temperature boundary conditions, the relative errors of the thermal conductivities and heat capacities of ground estimated using the proposed PEM are basically within 2% and 4%, respectively, except for shallower layers with a depth range of 0–800 m. The larger errors for shallower layers may be caused by weaker heat transfer between the fluid and ground, and the errors are basically lower for higher heat output rates. The predicted fluid temperature distributions during 120 d using the estimated values of the layered ground thermal properties match well with those using the true values. The results show that the proposed PEM is viable for DCGHE DTRT interpretation under heat output rate and inlet temperature boundary conditions, is a cost-effective way to establish key parameters for GSHP design, and would promote geothermal development.