Study on the Optimun Operation of High Performance Cold Thermal Storage System Using Liquid Ice

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1. Design and construction of the compact scale liquid-ice thermal storage systemA design and construction of the compact scale thermal storage system for home-use have been carried out to determine the optimum operation mode of the system. The experimental system consists mainly of production and storage unit, transporting loop, and consumption unit of the liquid ice. Production and storage unit of the liquid ice consists of refrigerator, evaporator, and storage tank. The evaporator was installed in the storage tank with its surface being coated with polyolefin tube. Liquid ice was produced by cooling aqueous binary solution in the tank. Liquid ice, which was produced in the tank, is derived to the thermal load unit by the circulating pump through the piping system with 20m long, and then returns to storage tank after its cold energy consumed. In the kexperiment, a variety of operation modes of the system, namely the combination of the time of production, storage, and consumption of the liquid ice, were set as the test parameters. Then the measurements of power-input of the refrigerator, thermal load, and ice-packing factor were carried out, and then the optimum operation mode was determined.2. RESULTS AND REMARKS(1) In the heat release operation mode, both the exit air temperature and released heat were kept almost constant until the ice particles in the liquid-ice finish to melt. Furthermore, after the ice particles in the liquid-ice has melt, cooling capacity remains enough to keep the operation by the sensible heat of aqueous solution.(2) Long-time opration in the production mode produces much more ice packing factor, while it reduces the temperature of the liquid-ice yielding the reduction of the performance of the refrigerator. Therefore, by taking all the factors, namely, power input to the refrigerator, cooling capacity, efficiency o heat-release mode, into the account, the optimum operation mode in the present study has been determined.