Study On Waste Heat Recovery Using Phase Change Heat Story In The Hige Temperature Manganese Sulfate Process

Lots of high-temperature waste gases will be produced during the process of high-temperature manganese sulfate,this can not only wasting energy but also polluting our environment. This paper aims to do study on recycling polluted gases and reduce the cost. Among energy storage technologies, phase change storage technology has gradually become a focus of current study due to its large heat-storage density, temperature constancy as well as hardly any container pressure change during heat storage and heat release. PCM is the key point of heat storage and release. However, most PCMs possess poor heat conductivity. Therefore, to deal with this problem, heat transfer enhancement technology is applied so as to improve the heat transfer coefficient of PCM area. Based on the actual situation, the author conducted a simulation research about the influence of fin parameters on heat transfer efficiency by using mannitol as PCM, finned tubes as heat enhancement structure and FLUENT software and wrote this thesis. The main contents of this thesis are as follows:1.The author built phase-change storage models under the first boundry conditon, compared the results with previous research data, verifed calculation methods and the feasiblity of phase-change storage models and analysed the laws of heat storage with mannitol as PCM in unfinned heat storage units. The simulation research shows that the heat storage process with two sides:(a)mannitol consists of three stages, namely: sensible heat storage phase before heat storage phase, latent heat storage phase and sensible heat storage phase after heat storage phase.(b)The heat transfer coefficient of mannitol decreases with the increase of heat storage time.2.With finned tubes as heat storage units, the heat storage rate of phase-change storage system can be improved through fins. First, the author established mannitol-finned tubes as heat storage units. Then the author conducted the simulated calculation of heat storage units by FLUENT software, analysed the influence of fin height, depth and pitch on the melting rate of PCM area, made a comparison between3.heat storage processes with finned heat storage units and unfinned ones and finally figured out the optimal design parameters of mannitol heat storage units: height 20 mm, pitch 15 mm, depth 5mm. The heat storage time of finned units is 2.9 times less than the unfinned ones of the same volume. The total heat storage capacity is 2088.3k J.4.Based on the optimal parameters of heat storage units, the author designed a phase-change accumulator suitable for this research and hopes this phase-change accumulator can provide certain reference value for engineering application.