發(fā)布時(shí)間：2018-04-08 21:46

  本文選題：熱化學(xué)儲(chǔ)熱　切入點(diǎn)：水合鹽　出處：《華北電力大學(xué)(北京)》2016年碩士論文

【摘要】：跨季節(jié)儲(chǔ)熱技術(shù)中,水合鹽熱化學(xué)吸附具有儲(chǔ)熱密度高、長(zhǎng)周期存儲(chǔ)無(wú)熱損、清潔環(huán)保、成本低廉等優(yōu)勢(shì),逐漸成為國(guó)內(nèi)外儲(chǔ)熱領(lǐng)域的研究熱點(diǎn)。本文對(duì)基于水合鹽熱化學(xué)吸附的跨季節(jié)儲(chǔ)熱技術(shù)的發(fā)展進(jìn)行了深入調(diào)研,對(duì)比分析不同水合鹽儲(chǔ)熱材料的儲(chǔ)熱特性和反應(yīng)器選型的優(yōu)劣。由于低溫運(yùn)行條件下,儲(chǔ)熱材料MgCl_2·6H_2O表現(xiàn)出優(yōu)良的反應(yīng)性能,結(jié)合本文數(shù)值模擬的需求,選擇以MgCl_2·6H_2O顆粒材料構(gòu)成的堆積床反應(yīng)器作為模擬對(duì)象。針對(duì)MgCl_2·6H_2O堆積床反應(yīng)器中固體顆粒吸附劑表面發(fā)生的熱化學(xué)儲(chǔ)熱過(guò)程進(jìn)行理論建模,建立與熱化學(xué)反應(yīng)耦合的多孔介質(zhì)多尺度傳輸理論模型,闡明反應(yīng)器內(nèi)多尺度熱質(zhì)傳輸規(guī)律及與熱化學(xué)動(dòng)力性能的作用機(jī)制。采用計(jì)算流體力學(xué)軟件FLUENT對(duì)于MgCl_2·6H_2O堆積床反應(yīng)器中儲(chǔ)熱過(guò)程進(jìn)行數(shù)值模擬。自定義編寫(xiě)化學(xué)反應(yīng)過(guò)程中的質(zhì)量和能量源項(xiàng),用以描述反應(yīng)器內(nèi)熱化學(xué)吸附／脫附過(guò)程的物質(zhì)交換和能量傳輸過(guò)程。從FLUENT設(shè)置、模擬結(jié)果與實(shí)驗(yàn)對(duì)照、網(wǎng)格獨(dú)立性檢驗(yàn)等方面驗(yàn)證了熱化學(xué)吸附模型的可靠性。基于本文建立的熱化學(xué)反應(yīng)傳熱傳質(zhì)模型,對(duì)MgCl_2·6H_2O堆積床反應(yīng)器儲(chǔ)熱過(guò)程進(jìn)行了模擬分析,得到不同時(shí)刻反應(yīng)器中溫度場(chǎng)、組分濃度場(chǎng)、固體顆粒含水量場(chǎng)的分布規(guī)律。綜合分析了MgCl_2·6H_2O堆積床反應(yīng)器儲(chǔ)熱過(guò)程中顆粒吸附量與水蒸氣產(chǎn)率的變化特性,得出傳質(zhì)區(qū)的移動(dòng)是與化學(xué)反應(yīng)耦合的傳熱傳質(zhì)過(guò)程綜合作用的結(jié)果,也是影響顆粒吸附量及水蒸氣產(chǎn)率的關(guān)鍵因素。通過(guò)改變運(yùn)行工況包括空氣入口流速及反應(yīng)床溫度,對(duì)儲(chǔ)熱反應(yīng)器的不同運(yùn)行狀態(tài)進(jìn)行模擬分析。得出針對(duì)本文MgCl_2·6H_2O堆積床反應(yīng)器,入口空氣流速提高0.5倍,儲(chǔ)熱進(jìn)程縮短41%；降低0.5倍,儲(chǔ)熱進(jìn)程延長(zhǎng)45%。床體初溫降低20℃,脫附進(jìn)程延長(zhǎng)10%；床體初溫升高10℃,脫附進(jìn)程縮短8.5%。最后,本文總結(jié)了水合鹽熱化學(xué)吸附跨季節(jié)儲(chǔ)熱的技術(shù)特點(diǎn),并指出了該技術(shù)未來(lái)的主要研究方向。
[Abstract]:In the cross-season heat storage technology, the thermal chemisorption of hydrated salt has the advantages of high heat storage density, long period storage without heat loss, clean and environmental protection, low cost and so on, and has gradually become the research hotspot in the field of heat storage at home and abroad.In this paper, the development of cross-season heat storage technology based on hydrated salt thermal chemisorption was investigated, and the heat storage characteristics of different hydrated salt thermal storage materials and the advantages and disadvantages of reactor selection were compared and analyzed.Because of the excellent reaction performance of the thermal storage material MgCl_2 6H_2O under low temperature operation conditions, combined with the requirement of numerical simulation in this paper, the pile-up bed reactor composed of MgCl_2 6H_2O granular material was selected as the simulation object.The thermochemical heat storage process on the surface of solid particle adsorbent in MgCl_2 6H_2O packed bed reactor was modeled theoretically, and the multi-scale transport theory model of porous media coupled with thermal chemical reaction was established.The multiscale heat and mass transfer in the reactor and the mechanism of its interaction with the thermochemical dynamic properties are described.The heat storage process in MgCl_2 6H_2O packed bed reactor was numerically simulated by computational fluid dynamics software FLUENT.The mass and energy source terms in the chemical reaction process are customized to describe the material exchange and energy transfer in the thermochemical adsorption / desorption process in the reactor.The reliability of the thermochemical adsorption model was verified from the FLUENT setting, the comparison between the simulation results and the experimental results, and the grid independence test.Based on the thermal chemical reaction heat and mass transfer model established in this paper, the heat storage process of MgCl_2 6H_2O packed bed reactor was simulated and analyzed. The distribution of temperature field, component concentration field and water content field of solid particles in the reactor at different times were obtained.The variation characteristics of particle adsorption capacity and water vapor yield during heat storage in MgCl_2 6H_2O packed bed reactor are comprehensively analyzed. It is concluded that the movement of mass transfer zone is a comprehensive result of heat and mass transfer process coupled with chemical reaction.It is also a key factor to influence the adsorption capacity and water vapor yield.By changing the operating conditions, including air inlet velocity and reaction bed temperature, the different operating conditions of the heat storage reactor were simulated and analyzed.For MgCl_2 6H_2O packed bed reactor, the inlet air velocity is increased 0.5 times, the heat storage process is shortened by 41 times, and the heat storage process is prolonged by 45 times.The initial temperature of the bed decreased by 20 鈩，

本文編號(hào)：1723450