Set Thermal Evaporation/storage/integration Of Solar Energy Heat Pump Water Heater System Performance Research

In view of the normal solar heat pump couldn’t operate efficiently and steady all day long, a novel solar heat pump water heater integrated with solar collector, energy storage and evaporation (SHPWHICSE) was proposed. The special design of collector/storage/evaporator could reduce heat exchanging losses and manufacturing cost. By adding phase change materials (PCM) into the collector/storage/evaporator, the solar energy on sunny days could be absorbed and storied as latent heat of solid-liquid phase materials, and the operating unstableness of the heat pump system caused by interval solar energy could be drastically solved.Firstly, a prototype of solar heat pump water heater integrated with collector, storage and evaporation was designed and built based on theoretical analysis of the schematic diagram. The appropriate PCM could be chosen according to operating temperature, suitable using conditions and characteristics of PCM. Then, the prototype which was respectively injected into two kinds of PCM decanoic acid and paraffin, was experimentally investigated comprehensively and thoroughly. The linear curve of heat got efficiency was fitted through the influence of solar radiation, ambient temperature and the temperature of the collector surface. What’s more, temperature variation rule of the PCM in the vacuum tubes with the solar radiation, and temperature distribution of the PCM during the endothermic and exothermic process before and after staring the system were analyzed. The result showed that the storied energy could meet the heat load to run this system normally from the point of the theory and experiment.Then, taking decanoic acid as thermal storage materials, experiments were carried out on the prototype and data collected and calculated in typical working conditions in both the transition seasons and winter in Nanjing. The performance characteristic of this system changing with the solar radiation, the factors impacting on the coefficient of performance (COP) and the stability were analyzed on sunny days, on rainy days and at night. The experimental results showed that the average heat got efficiency of the system being4.02, was far more efficient than that of the common solar heat pomp systems. The average COP being5.26, was significantly higher the solar-air source heat pump water heater. Even in the worst weather condition during the whole year, COP could reach4.03. The unstable variation of the intensity of solar radiation had much less impact on the SHPWHICSE system than on the normal direct-expansion solar heat pump water heater.Finally, the operating characteristics of the system regarding paraffin as the thermal storage materials were compared to those of the system mentioned above. The results showed that in the same weather condition, heating time of the paraffin system was significantly shortening by11.11%, and energy efficiency ratio was increasing by11.41%comparing to decanoic acid system. It could be concluded that the paraffin system had higher and more stable coefficient heat got efficiency and heating rate. The replacement of the PCM could match the SHPWHICSE system much better.