| Summary: | 博士 === 南臺科技大學 === 機械工程系 === 105 === With the innovation of science and technology, improved life quality results from many new and convenient electric appliances innovation. This leads to explosive growth of electricity consumption. In the premise of ease to use, energy storage technology and devices become more user-friendly. As a result, how to develop and design devices within a smaller volume to increase higher energy density turns into the prior task. However, the applications of energy storage devices are often limited by ambient temperature. Ambient temperature is prone to heat failure of energy storage devices and even explosion. With extreme low ambient temperature, solidification of liquid materials in energy storage devices results into sudden drop in voltage, and they cannot work for the time being. The goal of this research is set to explore energy storage devices for thermal energy and electric energy under low temperature environment still being able to work normally as well as the possibility of improving their efficiency. Super capacitor is chosen for electric energy storage device. Its positive electrode was prepared by using the nickel foam as the substrate, and the electrochemical deposition on the substrate to form the MnCoOx film, in order to obtain better chemical reaction and conversion efficiency. After a series of tests, the best parameters for the positive electrode is the deposition voltage 0.6V and the deposition time 450s. Four materials with low temperature eutectic temperatures tested by DSC, including LiNO3, Mg(NO3)2, NH4Cl and SrCl2, were chosen and formulated into aqueous solutions of appropriate concentration by weight to serve as the electrolytes. The capacitance packages were tested under different ambient temperatures ( 30℃, 5℃, -10℃, -25℃). The results show that the capacitance with the Mg(NO3)2 solution as the electrolyte is better than others.
Besides, this research proposed a theoretical model of cold energy storage for low temperature logistic systems in accordance with the energy conservation law. Two type of thumb rules for cold storage keeping time were derived for cold energy storage model. Three materials, Mg(NO3)2, NH4Cl and SrCl2, were chosen for testing the thermal and aging performance of cold energy storage. After compared with the experimental results regarding cold storage keeping time, the second type thumb rule was better than the first type thumb rule. Furthermore, the results predicted by both two type thumb rules were inferior to the that from the numerical results simulated by SolidWorks Flow Simulation 2010.
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