Experiment Study On Discharging Characteristics Of Heat Storage Unit Based On Supercooling Of Salt Hydrate

In this paper, the heat storage unit based on supercooling of salt hydrate phase change material is design and the properties of the unit are studied experimentally. First, three different structures of the heat storage unit (rectangle with filleted corner, rectangular, cylindrical) are designed, and a seasonal heat storage system based on both the dimension of the heat storage unit and the purpose of the experiment is build. The experiment results indicate that the heat storage unit whose structure is rectangle with filleted corner can not only better achieve stable supercooling, but also has better economic benefits. Thus the heat storage unit whose structure is rectangle with filleted corner is regarded as the optimum seasonal heat storage unit.Then, a series of experiments are conducted to study the effect of different factors on the crystallization induction period according to the supercooling mechanism of hydrated salt. Results show that:supercooling can be achieved easily by lengthening the heating time, decreasing the cooling rate, diminishing the roughness as well as reducing the amount of CMC.In addition, knocking is selected as the way of inducing. The effects of different factors on the crystallization induction period are investigated by changing the experimental parameters. The results showed that:knocking is a stable method to induce. And we can shorten the induction period of crystallization by enlarging knocking intensity, diminishing the roughness, prolonging supercooling time and reducing heating temperature.Particularly, ultrasonic which is more controllable and complicated is selected as another way of inducing. The feasibility of ultrasonic is investigated. Experiment results indicate that:ultrasound is a viable option to achieve trigger crystallization. The frequency region is different for different solutions. Additionally, it can be inferred that we can shorten the induction period of crystallization by increasing ultrasonic power and reducing ultrasonic frequency. Moreover, crystallization can be realized as long as local intensity meets crystallization driving conditions.