Analysis of Operation Characteristics of Phase-Change Temperature Maintenance System Heating by Solar Source and Sewage Source Heat Pump

To address the issues of high energy consumption and operating costs in the temperature maintenance and heating of floating roof oil tanks, a phase-change temperature maintenance simulation system using a solar source–sewage source heat pump was designed. Its operating characteristics and economic benefits were studied based on the TRNSYS platform. The study analyzed the effects of the solar energy guarantee rate, phase-change heat storage tank operating temperature, and sewage source heat pump operating temperature on various indicators, such as the heat storage and release efficiency of the phase-change heat storage tank, the heating capacity and energy proportion of crude oil, and the power consumption of the sewage source heat pump system. The economic benefits were also compared. The results indicate that when the solar energy guarantee rate is below 30%, the phase-change heat storage tank does not operate, while the sewage source heat pump operates at a higher efficiency, leading to increased system power consumption. However, when the solar energy guarantee rate exceeds 30%, the phase-change heat storage tank operates normally from April to December, while the sewage source heat pump ceases to function, resulting in reduced total system power consumption. Additionally, increasing the phase-change temperature from 38 °C to 54 °C boosts the heat storage and release efficiency of the phase-change heat storage tank from 87% to 94%, without affecting the heat pump’s heating capacity. Similarly, raising the temperature of the sewage source heat pump from 20 °C to 40 °C enhances the heat pump’s heating capacity and efficiency from 4.45 to 4.84, without impacting the heat storage and release efficiency of the phase-change heat storage tank.