Study On Thermal Properties And Characteristics Of Cool Charge And Discharge Of Nanofluids

Cool storage technology is an important measure to realize shifting electrical energy demand from peak period to off-peak period. At present, cool storage technology is applied mainly to air-conditioning. It is expected to enlarge it's application scope with technical development, Therefore, the research and developement of industrial low-temperature cool storage has important theoretical and practical significance. An effective way of improving the thermal conductivity of flulds is to suspend small solid Particles in the carrier fluids in order to change transport properties. A low-temperature phase change material for cool storage is developed for beer industry. The basic way to abtain nanofluids is suspend a little nanoTiO2 particals with 20nm in BaCl2-H2O solution,and make use of disperse technology. The purpose of the paper is to demonstrate experimentally and theoretically the feasibility of nanocomposite material,the main studies are indicated from the following aspects: 1. Supercooling research of nanofluids In order to research the crystal effect of nanoparticals to eutectic salt solution, the freezing/melting experiment with the sample fluids is developed, as a result, show that nanofluids can reduce nuclear degree of supercooling, and along with the increase of particle volume fraction, its degree of supercooling is linear to drop. With 1.13 vol % volume fraction , it can eliminate degree of supercooling basically. 2. Latent heat ,phase change temperature and specific heat of nanofluids Latent heat ,phase change temperature and specific heat of nanofluids are measured with Differential Scanning Calorimetry ( DSC ). The value of latent heat is 254.2～279.5kJ/kg,and phase change temperature is about –8.5℃.During the fifty cool charge/discharge experiment, its latent heat and phase change temperature are very steady,it shows that the material's stability is good. 3. Thermal conductivity measurement of nanofluids In this paper,the transient hot-wire instrument for measuring the thermal conductivity of nanofluids is developed.Experiment reault shows that nanoparticals enhance thermal conductivity of eutectic salt solution. The theoretical study of the thermal conductivity of nanocomposite material is introduced to explain possible mechanisms contributing to enhancement of the thermal conductivity of nanofluids 4. Characteristics of Cool Charge and discharge of nanofluids Compared with utectic salt solution through the Cool Charge and discharge experiment in the condition,the experiment result shows that the time for freezing of nanofluids is much less than eutectic salt solution,the charge/discharge capacity,charge/discharge late and heat transfer coefficient of nanofluids are higher than eutectic salt solution.