本文選題：內(nèi)嵌換熱面　切入點：雙層多孔介質(zhì)　出處：《浙江大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：多孔介質(zhì)燃燒技術(shù)作為一種高效、清潔能源利用方式,具有燃燒速率高,負(fù)荷調(diào)節(jié)范圍寬、污染物排放量低等優(yōu)點。本文通過試驗和模擬相結(jié)合的手段,對內(nèi)嵌換熱面雙層多孔介質(zhì)中的氣體燃燒特性和換熱面?zhèn)鳠釞C(jī)理進(jìn)行了研究,為內(nèi)嵌受熱面多孔介質(zhì)燃燒裝置的設(shè)計運行提供指導(dǎo)。主要的研究內(nèi)容如下:(1)試驗研究可燃?xì)怏w在具有內(nèi)嵌換熱面泡沫型多孔介質(zhì)中的燃燒、傳熱特性。搭建多孔介質(zhì)燃燒熱態(tài)試驗系統(tǒng),將換熱面內(nèi)嵌布置于雙層泡沫型多孔介質(zhì)下游碳化硅泡沫陶瓷中,試驗研究甲烷/空氣預(yù)混氣體在其中的溫度分布、穩(wěn)燃范圍、燃燒產(chǎn)物排放特性,并分析了燃燒器熱效率和換熱面在多孔介質(zhì)內(nèi)的傳熱過程。結(jié)果表明,在泡沫型多孔介質(zhì)燃燒系統(tǒng)中內(nèi)嵌換熱面后燃燒器溫度水平降低,仍具有較寬的穩(wěn)燃范圍;相較于無內(nèi)嵌換熱面情況,燃燒器出口 NOx排放量下降,試驗工況范圍內(nèi)低于35mg/m3;燃燒器熱效率隨入口氣流速度下降并保持在60%～80%范圍內(nèi);換熱管外壁與多孔介質(zhì)氣固兩相的傳熱相較于傳統(tǒng)的氣流橫向沖刷管束,平均傳熱系數(shù)增幅逾150%;基于MATLAB軟件擬合得到內(nèi)嵌換熱面?zhèn)鳠嵯禂?shù)半經(jīng)驗公式,公式計算值與試驗值誤差低于10%。(2)試驗研究不同換熱面布置對于內(nèi)嵌換熱面多孔介質(zhì)燃燒器性能的影響。結(jié)果表明:內(nèi)嵌換熱面多孔介質(zhì)燃燒器CO排放量隨著橫、縱向管間距的升高均降低,為降低CO排放,在實際設(shè)計內(nèi)嵌換熱面時,應(yīng)盡量避免換熱面過于密集的布置方式;不同橫縱向管間距下,氮氧化物排放量均低于20mg/m3。(3)以CFD商業(yè)軟件FLUENT6.3為平臺,數(shù)值模擬甲烷、空氣預(yù)混氣體在內(nèi)嵌換熱面雙層多孔介質(zhì)中的燃燒、傳熱,重點分析了換熱面與多孔介質(zhì)間的傳熱機(jī)理。結(jié)果顯示:模型可以較好的預(yù)測甲烷、空氣預(yù)混氣體在內(nèi)嵌換熱面雙層多孔介質(zhì)中燃燒特性,溫度預(yù)測值與試驗結(jié)果誤差低于20%;三排換熱面?zhèn)鳠崃侩S布置位置與氣體反應(yīng)區(qū)距離的增加依次降低;第二、三排換熱面與多孔介質(zhì)氣固兩相間的傳熱以高溫固體輻射傳熱為主,輻射傳熱占總傳熱量的55.4%,第一排換熱面以導(dǎo)熱為主,達(dá)42.6%;燃燒器熱效率隨下游材料消光系數(shù)升高而降低。
[Abstract]:As a kind of efficient and clean energy utilization technology, porous media combustion technology has the advantages of high combustion rate, wide load regulation range and low pollutant emission. The combustion characteristics of gas and the heat transfer mechanism of heat transfer surface in bilayer porous media with embedded heat transfer surface are studied. The main research contents are as follows: 1) Experimental study on combustion of combustible gases in porous media with embedded heat transfer surface. Heat transfer characteristics. A heat transfer test system for combustion of porous media was set up. The heat transfer surface was embedded in silicon carbide foam ceramics downstream of bilayer porous media. The temperature distribution of methane / air premixed gas was studied and the combustion range was stabilized. The characteristics of combustion product emission are analyzed, and the heat transfer process of the burner and the heat transfer surface in porous media are analyzed. The results show that the temperature level of the burner decreases after the heat transfer surface is embedded in the foam porous medium combustion system. Compared with no intercalation surface, the NOx emission from the burner outlet decreases, and is lower than 35 mg / m ~ 3 under the test conditions, and the thermal efficiency of the burner decreases with the inlet flow velocity and remains within the range of 60% or 80%. The average heat transfer coefficient between the outer wall of the heat transfer tube and the gas-solid two-phase heat transfer in porous media is increased by more than 150, compared with that of the traditional air flow, and the semi-empirical formula of the heat transfer coefficient of the embedded heat transfer surface is obtained based on the fitting of the MATLAB software. The effect of different heat transfer surface arrangement on the performance of porous media burners with intercalation surface is studied. The results show that the CO emission from porous media burners with intercalated heat transfer surfaces is transversely. In order to reduce CO emission, the arrangement of heat transfer surface should be avoided when the heat exchange surface is designed in practice. Using CFD commercial software FLUENT6.3 as a platform, numerical simulation of combustion and heat transfer in a bilayer porous medium with a heat exchanger surface of methane and air premixed gases, The heat transfer mechanism between heat transfer surface and porous media is analyzed emphatically. The results show that the model can predict the combustion characteristics of methane and air premixed gas in a bilayer porous medium with heat transfer surface. The error between the temperature prediction value and the test results is less than 20. The heat transfer rate of the three rows of heat transfer surfaces decreases with the increase of the location of the arrangement and the distance between the gas reaction zone. Secondly, the heat transfer between the three rows of heat transfer surfaces and the gas-solid phase of porous media is dominated by high temperature solid radiation heat transfer. Radiation heat transfer accounts for 55.4% of the total heat transfer, and the first heat transfer surface is mainly heat conduction, reaching 42.6.The thermal efficiency of the burner decreases with the increase of the extinction coefficient of the downstream materials.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ038.1

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