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U型毛細管網輻射板頂板輻射供冷空調系統(tǒng)研究

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【摘要】:毛細管網輻射供冷空調系統(tǒng)作為一種低能耗、高舒適性的新型空調方式得到了越來越廣泛的研究和工程應用,但是在實際推廣中也遇到了一些瓶頸,主要是結露問題、供冷能力不足問題和一次性投資問題。當輻射板表面溫度低于室內空氣露點溫度時,會出現(xiàn)結露現(xiàn)象,因而也制約了輻射板的供冷能力,并導致一次性投資增加。 影響毛細管網輻射板供冷能力的因素主要有輻射板自身的結構性因素、運行因素、室內環(huán)境溫度等,本文針對這三種因素對毛細管網輻射板供冷能力的影響展開研究,建立了U形石膏毛細管網輻射板的三維流-固耦合模型,采用數(shù)值模擬軟件Fluent模擬毛細管網輻射板表面溫度分布規(guī)律,通過改變席長、管間距、石膏層厚度等參數(shù),找出影響該種輻射板換熱性能的關鍵性結構因素,通過大量模擬計算,探尋有利于提高石膏毛細管網輻射板供冷能力的最佳結構參數(shù)或范圍;并在此基礎上,研究供水溫度、供水流速、室內溫度等因素對石膏毛細管網輻射板供冷性能的影響。模擬研究表明:(1)結構性因素中,U型毛細管網石膏輻射板的單位面積供冷量隨管間距和石膏層厚度的增大而降低,受席長影響很小,管間距由10mm增加到40mm,,輻射板單位面積供冷量減少18.5W/m~2;石膏層厚度由10mm增加到25mm,輻射板單位面積供冷量減少27.61W/m~2;席長增加1000mm,輻射板單位面積供冷量只減少1.14W/m~2;側邊界條件對輻射板供冷量也有一定影響,側面絕熱比側面直接接觸空氣時輻射板下表面溫度低0.3℃。(2)運行因素中,U型石膏毛細管網輻射板的單位面積供冷量隨供水溫度降低而增大,改變供水流速對輻射板單位面積供冷量影響很小,供水12℃比供水20℃時輻射板單位面積供冷量增大64.89W/m~2;供水流速0.1m/s比供水流速0.5m/s時,輻射板單位面積供冷量只降低了1.48W/m~2。(3)毛細管網輻射板單位面積總供冷量隨室內溫度的升高而增大,室內溫度28℃比室內溫度23℃時,輻射板單位面積供冷量增大42.28W/m~2。 本研究搭建了毛細管網頂板輻射供冷空調系統(tǒng)實驗臺,將石膏毛細管網輻射板制作成模塊化結構,吊裝于實驗小室頂部,采用輻射吊頂+置換通風/貼附射流模式,通過LabVIEW程序自動控制,以優(yōu)先控制結露為原則,實驗測試了U10石膏毛細管網輻射板在不同供水溫度、不同送風方式下,輻射板表面溫度分布情況和室內溫度分布;并比較了在相同測試條件下U型石膏毛細管網輻射板和U型金屬毛細管網輻射板在輻射板表面溫度分布和供冷效果方面的差異。實驗結果表明:金屬輻射板表面溫度分布的不均勻度比石膏輻射板;金屬輻射板表面溫度最不利點位于輻射板供水口附近,石膏輻射板表面溫度最不利點位于輻射板中心部位,應以最不利點溫度為依據控制結露;輻射板制冷量受管密度影響較大,相同供水溫度下, U10石膏毛細管網輻射板的單位面積供冷量比U20毛細管網金屬輻射板高15W/m~2左右;降低供水溫度可以顯著提高輻射板供冷量,在沒有結露危險時,可通過降低供水溫度使室內溫度在短時間內降低,四十分鐘左右即有明顯效果;在室溫控制方面,金屬毛細管網輻射板較石膏毛細管網輻射板反應迅速,在相同條件下,安裝金屬輻射板的房間比安裝石膏輻射板的房間可提前十分鐘左右達到設定溫度,金屬輻射板由于對水溫變化反應迅速,可以達到很好的控制精度;石膏輻射板較金屬輻射板具有一定的蓄冷能力,可在夜間向室內釋放剩余冷量,使空調關閉后室溫升高緩慢。模擬結果和實驗結果比較吻合。本研究所得結果可以為毛細管網輻射供冷空調系統(tǒng)的設計施工以及進一步研究提供理論依據。
[Abstract]:As a new type of air conditioning system with low energy consumption and high comfort, capillary network radiation cooling air conditioning system has been more and more widely studied and applied in engineering. However, some bottlenecks have also been encountered in the practical popularization, such as condensation problems, insufficient cooling capacity and one-time investment, when the surface temperature of the radiant plate is lower than that of indoor air Condensation occurs when the gas dew point temperature occurs, which also restricts the cooling capacity of the radiant panel and leads to an increase in one-time investment.
The factors affecting the cooling capacity of the capillary network radiant plate mainly include the structural factors of the radiant plate itself, the operating factors and the indoor environment temperature. In this paper, the influence of these three factors on the cooling capacity of the capillary network radiant plate is studied. The three-dimensional flow solid coupling model of the U shaped gypsum capillary network radiant plate is established, and the numerical simulation is used. The software Fluent simulated the surface temperature distribution of the capillary network radiant plate. By changing the parameters of the length, the distance of the tube and the thickness of the gypsum layer, the key structural factors affecting the heat transfer performance of the radiant plate were found. Through a large number of simulated calculations, the optimum structure parameters or scope were explored to improve the cooling capacity of the gypsum capillary network radiation plate. On this basis, the influence of water supply temperature, water supply velocity and indoor temperature on the cooling performance of the gypsum capillary network radiant plate is studied. The simulation study shows that (1) the cooling capacity per unit area of the U type capillary network gypsum radiation plate decreases with the increase of the tube spacing and the thickness of the gypsum layer, and the tube is influenced by the length of the tube very small. The spacing is increased from 10mm to 40mm, the unit area of the radiation plate is reduced by 18.5W/m~2, the thickness of the gypsum layer is increased from 10mm to 25mm, the cooling capacity of the radiation plate is reduced by 27.61W/m~2, the seat length is 1000mm, the unit area of the radiation plate is only 1.14W/m~2, and the side boundary conditions have some influence on the cooling capacity of the radiant plate, and the side adiabatic condition is also adiabatic. The lower surface temperature of the radiant panel is 0.3 degrees centigrade when the air is directly exposed to the air. (2) the cooling amount per unit area of the U type gypsum capillary network radiation plate increases with the decrease of the water supply temperature. The change of water supply velocity has little effect on the cooling amount per unit area of the radiant plate, and the cooling capacity of the radiation plate per unit area of the water supply at 12 C is 64 more than that of the water supply at 20 C. .89W/m~2; when the flow velocity 0.1m/s is 0.5m/s, the cooling amount per unit area of the radiation plate is only reduced by 1.48W/m~2. (3), the total cooling capacity per unit area of the capillary network radiation plate increases with the increase of the indoor temperature. The cooling capacity of the radiation plate unit area is increased by 42.28W/m~2. when the indoor temperature is 23 degrees centigrade than the indoor temperature.
In this study, the experimental platform of the capillaries radiation cooling air supply air conditioning system was set up. The gypsum capillary network radiation plate was made into a modular structure, which was hoisted to the top of the laboratory. The radiation ceiling + displacement ventilation / attached jet mode was adopted, and the LabVIEW program was automatically controlled to control the condensation as a priority, and the U10 gypsum capillary was tested. The temperature distribution of the radiant plate surface and the temperature distribution on the surface of the radiant plate at different water supply temperatures and air supply modes are compared. The difference between the surface temperature distribution and the cooling effect of the U type gypsum capillary net radiant plate and the U type metal capillary network radiant plate on the surface of the radiant plate under the same test conditions is compared. The surface temperature distribution of the metal radiant plate is smaller than that of the plaster plate; the most unfavorable point on the surface temperature of the metal radiant plate is located near the water supply port of the radiant plate, the most unfavorable point on the surface temperature of the gypsum radiant plate is located at the center of the radiation plate, and the condensation should be controlled on the basis of the most unfavorable point temperature; the cooling capacity of the radiant plate is greatly influenced by the tube density. Under the same water supply temperature, the unit area per unit area of U10 gypsum capillary network radiation plate is about 15W/m~2 higher than that of the U20 capillary metal plate. Reducing the water supply temperature can significantly increase the cooling capacity of the radiant plate. When there is no danger of condensation, the temperature of the water supply can be reduced in a short time by reducing the water supply temperature, which is about forty minutes or so. In the room temperature control, the metal capillary network radiant plate is more responsive than the gypsum capillary network radiant plate. Under the same condition, the room with metal radiant plate can reach the setting temperature about ten minutes earlier than that of the plaster radiation plate. The metal radiant plate can be achieved very well due to the rapid reaction of the water temperature change. The result of this study can be used for the design, construction and further study of the capillary network radiation cooling air conditioning system. Provide a theoretical basis.
【學位授予單位】:天津商業(yè)大學
【學位級別】:碩士
【學位授予年份】:2013
【分類號】:TU831.3

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