本文選題：空冷器 + 傳熱　； 參考：《華中科技大學(xué)》2015年碩士論文

【摘要】：水膜蒸發(fā)空冷器具有的高效傳熱、節(jié)能和節(jié)水特點(diǎn)使其應(yīng)用日益廣泛,但由于水風(fēng)耦合作用的復(fù)雜性,其管外傳熱傳質(zhì)系數(shù)的確定一直以來(lái)都是設(shè)計(jì)計(jì)算的難點(diǎn)。本文在水膜蒸發(fā)空冷器小型實(shí)驗(yàn)臺(tái)上,搭建了3管程的水膜蒸發(fā)空冷管束,配置了流量計(jì)、風(fēng)速儀、干濕球溫度計(jì)等傳感器,并自主設(shè)計(jì)和配置了測(cè)量管外水膜溫度的72個(gè)熱電偶。在125個(gè)工況(5個(gè)熱水流量×5個(gè)熱水溫度×5個(gè)迎面風(fēng)速)下,測(cè)量了熱水溫度、管外空氣溫濕度和壓力沿管程的分布,測(cè)量了管外水膜溫度沿管程、管束寬度和管束高度的分布。根據(jù)測(cè)量數(shù)據(jù),分析了不同工況對(duì)各管程空氣狀態(tài)的影響,對(duì)空氣進(jìn)出口比焓差、噴淋水平均溫度和設(shè)備總壓降的影響,以及對(duì)管內(nèi)外平均傳熱系數(shù)的影響;描述了管外水膜溫度場(chǎng)和傳熱傳質(zhì)系數(shù)場(chǎng),探討了工況參數(shù)對(duì)水膜溫度場(chǎng)的影響,研究了從熱水溫度分布和水膜溫度分布到熱流密度,再到壁水傳熱系數(shù)的計(jì)算方法。實(shí)驗(yàn)及分析表明:水膜蒸發(fā)空冷器中,水膜溫度沿流動(dòng)方向呈鋸齒狀分布,且在上管程的波動(dòng)幅度較大,在下管程波動(dòng)趨于平緩;上管程的壁水傳熱系數(shù)和水風(fēng)傳質(zhì)系數(shù)較大,下管程的水風(fēng)傳熱系數(shù)較大;水膜蒸發(fā)空冷器的空氣吸熱量中蒸發(fā)潛熱占85%左右,上管程和中管程主要為蒸發(fā)傳熱,下管程對(duì)流傳熱和蒸發(fā)傳熱大體相當(dāng);水膜溫度峰值位置主要受迎面風(fēng)速影響,風(fēng)速越大,峰值越靠近管束頂部迎水面;熱水溫度對(duì)水膜溫度的影響大于熱水流量對(duì)水膜溫度的影響;管外各處壁水傳熱系數(shù)hw(x,z)可由水膜溫度場(chǎng)算得。
[Abstract]:Water film evaporative air cooler is widely used because of its high efficiency heat transfer, energy saving and water saving. However, due to the complexity of water-wind coupling, the determination of heat transfer coefficient of water film evaporator has always been a difficulty in design and calculation.In this paper, a water film evaporative air cooling tube bundle with 3 tubes is built on a small experimental bench of water film evaporator, with sensors such as Flowmeter, anemometer, dry-wet bulb thermometer and so on.72 thermocouples were designed and configured to measure the temperature of water film outside the tube.Under 125 working conditions (5 hot water flow rate 脳 5 hot water temperature 脳 5 direct wind speed), the distribution of hot water temperature, air temperature, humidity and pressure outside the tube was measured. The distribution of water film temperature along the tube side, the width of tube bundle and the height of tube bundle were measured.According to the measured data, the effects of different working conditions on the air state of each pipe, on the difference of specific enthalpy of air inlet and outlet, on the average temperature of spray level and on the total pressure drop of equipment, as well as on the average heat transfer coefficient inside and outside the pipe are analyzed.This paper describes the temperature field and heat and mass transfer coefficient field of water film outside the tube, discusses the influence of operating conditions on the temperature field of water film, and studies the calculation method of heat transfer coefficient from hot water temperature distribution and water film temperature distribution to heat flux, and then to wall water heat transfer coefficient.The experiment and analysis show that the water film temperature is sawtooth distribution along the flow direction in the water film evaporative air cooler, and the fluctuation amplitude in the upper tube is larger, and the fluctuation in the lower pipe tends to be gentle, and the wall water heat transfer coefficient and the water wind mass transfer coefficient of the upper tube side are larger.The heat transfer coefficient of the water wind in the lower tube side is larger, the latent heat of evaporation in the air of the water film evaporator is about 85%, the heat transfer between the upper and the middle pipe is mainly evaporative heat transfer, and the convection heat transfer and the evaporation heat transfer in the lower tube side are about the same.The peak position of water film temperature is mainly affected by the direct wind speed. The higher the wind speed is, the closer the peak value is to the water surface at the top of the tube bundle, the influence of hot water temperature on water film temperature is greater than the influence of hot water flow on water film temperature.The water heat transfer coefficient (HWX) can be calculated from the water film temperature field.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ021.3

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