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  本文關鍵詞：R290和R1234ze在水平微通道內(nèi)流動凝結換熱的實驗研究　出處：《清華大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： 微細通道 流動凝結 對流換熱 R290 R1234ze

【摘要】：微通道換熱器由于緊湊高效的特點,在空調(diào)制冷行業(yè)提高能效方面發(fā)揮著重要作用。隨著HCFCs類制冷劑面臨逐步淘汰,低GWP值的制冷劑成為了當下研究的熱點。本文選取R290和R1234ze作為研究對象,實驗研究了其在水平微通道中流動凝結的兩相摩擦壓降及換熱特性,并與R22的實驗結果進行比較。實驗中選取了圓管與方管兩種管型,圓管內(nèi)徑為1.085mm,方管當量直徑為0.952mm。實驗工質的飽和溫度為40℃和50℃。R22的質量流率為200~1200kg/(m2·s),R290的質量流率為200~650kg/(m2·s),R1234ze的質量流率為200~800kg/(m2·s)。干度范圍為0~1.0�；趯嶒灲Y果分析了質量流率、干度、飽和溫度及斷面形狀對摩擦壓降和凝結對流換熱系數(shù)的影響。對比了三種制冷劑在相同工況下摩擦壓降與換熱系數(shù)的大小,將壓降與換熱的實驗數(shù)據(jù)與現(xiàn)有的關聯(lián)式進行了比較。結果表明,摩擦壓降及換熱系數(shù)均隨著質量流率及干度的增加而增加,隨飽和溫度的升高而降低;方管中的摩擦壓降及換熱系數(shù)大于圓管中的;R290的摩擦壓降與換熱系數(shù)均為最大,R1234ze的次之,R22的最小;Garimella、Kim關聯(lián)式對壓降的數(shù)據(jù)預測較好,Sun和Mishima、Lopez Belchi關聯(lián)式的預測偏高。Kim、Koyama、Wang對換熱的數(shù)據(jù)預測較好,Shah關聯(lián)式只對R1234ze的實驗數(shù)據(jù)預測較為準確,Bohdal關聯(lián)式對實驗中的三種制冷劑的預測都偏高。
[Abstract]:Because of its compact and efficient characteristics, microchannel heat exchanger plays an important role in improving energy efficiency in the air conditioning and refrigeration industry. With the gradual elimination of HCFCs refrigerants, low GWP refrigerants have become a hot spot in the present research. In this paper, R290 and R1234ze were chosen as the research object. The frictional pressure drop and heat transfer characteristics of flow and condensation in horizontal microchannel were experimentally studied, and compared with the experimental results of R22. In the experiment, two tubes with circular tube and square tube are selected. The inner diameter of the circular tube is 1.085mm, and the equivalent diameter of the square tube is 0.952mm. The saturated temperature of the experimental working fluid is 40 and 50. The mass flow rate of R22 is 200~1200kg/ (m2. S), and the mass flow rate of R290 is 200~650kg/ (m2. S), and the mass flow rate of R1234ze is 200~800kg/ (M2 s). The dry range is 0~1.0. Based on the experimental results, the effects of mass flow rate, dry degree, saturation temperature and section shape on the friction pressure drop and the convective heat transfer coefficient are analyzed. The friction pressure drop and heat transfer coefficient of three refrigerants under the same working conditions were compared, and the experimental data of pressure drop and heat transfer were compared with the existing correlations. The results show that the frictional pressure drop and heat transfer coefficient with the mass flow rate and dry degree increased with the rise of saturation temperature decreases; the tube frictional pressure drop and heat transfer coefficient is greater than the circular pipe; the frictional pressure drop and heat transfer coefficient of R290 were the largest, the second is R1234ze, the minimum of R22 Garimella, Kim; data correlation on the pressure drop prediction is good, high Sun, Lopez and Mishima predicted Belchi correlations. Kim, Koyama and Wang predict the heat transfer data better. Shah correlation is only more accurate for the experimental data of R1234ze, and Bohdal correlation is more predictive for the three refrigerants in the experiment.
【學位授予單位】：清華大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TK124

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本文編號：1338847