漁船廢熱驅動噴射制冷系統(tǒng)中噴射器的性能研究
發(fā)布時間：2019-02-11 07:51
【摘要】：噴射式制冷系統(tǒng)主要包括加熱器、噴射器、冷凝器、蒸發(fā)器以及膨脹閥和循環(huán)水泵等設備。由于其具有構造簡單、造價低廉、運行可靠、操作方便和節(jié)約能源等優(yōu)點而被人們所青睞。然而其缺點主要為效率低下,通常難以滿足制冷需求,而對噴射式制冷系統(tǒng)效率起關鍵影響的部件是噴射器。噴射器是一種通過使用高壓流體來抽吸低壓流體的混合動力裝置,在工業(yè)領域中被廣泛使用,雖然噴射器結構較為簡單,但其內部的流場極為復雜,使得當前人們對噴射器的性能及流場分布規(guī)律的掌握情況較為有限�，F(xiàn)有的噴射器研究大都采用一維或二維的分析方法,這些方法不能很好的體現(xiàn)噴射器三維結構及其內部特殊的物理現(xiàn)象。本文以基于廢熱源制冷為目的的漁船噴射制冷系統(tǒng)的關鍵部件—噴射器為對象,通過采用CFD模擬與實驗相結合,以R236fa為工作流體,研究了噴射器性能,并著重分析了其結構對其性能的影響。模擬所需的噴射器幾何結構簡化為三維中心對稱結構,三維研究可以更加真實地反映噴射器內部的流動特性并得到更多的空間混合及流動信息。噴射器網(wǎng)格劃分采用全六面體結構化網(wǎng)格,并采用網(wǎng)格自適應技術捕捉激波,最大程度上提高網(wǎng)格質量及計算的準確性。計算模型選用Shear Stress Transport(SST)模型。通過搭建雙熱源雙極噴射制冷系統(tǒng)實驗臺,從實驗角度來分析噴射器性能,對與其中一組模擬結構相同的噴射器進行實驗分析,得出噴射系數(shù)隨冷凝器壓力變化的實驗數(shù)據(jù),并與模擬結果比較,發(fā)現(xiàn)兩者結果的平均相對誤差為9.6%,模擬結果具有較高的可靠性。經(jīng)研究表明:噴射器結構對其性能的影響非常明顯,在給定工作參數(shù)條件下,噴嘴出口端長度D1以及噴射器噴嘴出口與混合段出口之間距離D2均存在一個最佳值,此時噴射系數(shù)達到最大;而噴射器性能隨其擴散室出口角度?以及噴嘴喉部直徑d的增加而降低。該課題的研究,為中國中小型遠洋漁船上運用噴射制冷的可行性奠定基礎,同時為噴射器三維模擬研究提供思路。
[Abstract]:The ejector refrigeration system includes heater, ejector, condenser, evaporator, expansion valve and circulating water pump. It has the advantages of simple structure, low cost, reliable operation, convenient operation and energy saving. However, the main shortcomings of the system are inefficiency, which is usually difficult to meet the refrigeration requirements, and the ejector plays a key role in the efficiency of the ejector refrigeration system. Ejector is a hybrid power device which uses high-pressure fluid to pump low-pressure fluid. It is widely used in industrial field. Although the structure of ejector is relatively simple, its internal flow field is extremely complex. At present, the performance of ejector and the distribution of flow field are limited. Most of the existing researches on ejectors use one-dimensional or two-dimension analysis methods, which can not well reflect the three-dimensional structure of the ejector and its special physical phenomena. In this paper, the ejector, which is the key component of the fishing vessel ejector refrigeration system based on waste heat source refrigeration, is used as the object. The performance of the ejector is studied by using CFD simulation and experiment, using R236fa as the working fluid. The influence of its structure on its performance is analyzed. The geometry of the ejector needed for simulation is simplified to a three-dimensional centrosymmetric structure. The three-dimensional research can reflect the flow characteristics of the ejector more truly and obtain more spatial mixing and flow information. All hexahedron structured meshes are used in the mesh generation of ejector and the shock waves are captured by mesh adaptive technique. The mesh quality and accuracy of calculation are improved to the greatest extent. The Shear Stress Transport (SST) model is selected for the calculation model. The performance of the ejector is analyzed from the point of view of the experiment by setting up a double heat source bipolar ejector refrigeration system, and the experimental data of the ejector coefficient varying with the condenser pressure are obtained through the experimental analysis of the ejector with the same structure as one of the simulated ones. Compared with the simulation results, it is found that the average relative error of the two results is 9.6, and the simulation results have high reliability. The results show that the effect of ejector structure on its performance is very obvious. Under the given working parameters, there is an optimum value for the length of nozzle exit D1 and the distance between nozzle exit and mixing section exit D2. The jet coefficient reaches the maximum. And the ejector performance depends on the outlet angle of the diffuser chamber? And the nozzle throat diameter d increases and decreases. The research of this subject lays a foundation for the feasibility of using ejector refrigeration on Chinese small and medium-sized ocean-going fishing vessels, and provides a way of thinking for the three-dimensional simulation of ejector at the same time.
【學位授予單位】：太原科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U664.87;TB657
本文編號：2419536
[Abstract]:The ejector refrigeration system includes heater, ejector, condenser, evaporator, expansion valve and circulating water pump. It has the advantages of simple structure, low cost, reliable operation, convenient operation and energy saving. However, the main shortcomings of the system are inefficiency, which is usually difficult to meet the refrigeration requirements, and the ejector plays a key role in the efficiency of the ejector refrigeration system. Ejector is a hybrid power device which uses high-pressure fluid to pump low-pressure fluid. It is widely used in industrial field. Although the structure of ejector is relatively simple, its internal flow field is extremely complex. At present, the performance of ejector and the distribution of flow field are limited. Most of the existing researches on ejectors use one-dimensional or two-dimension analysis methods, which can not well reflect the three-dimensional structure of the ejector and its special physical phenomena. In this paper, the ejector, which is the key component of the fishing vessel ejector refrigeration system based on waste heat source refrigeration, is used as the object. The performance of the ejector is studied by using CFD simulation and experiment, using R236fa as the working fluid. The influence of its structure on its performance is analyzed. The geometry of the ejector needed for simulation is simplified to a three-dimensional centrosymmetric structure. The three-dimensional research can reflect the flow characteristics of the ejector more truly and obtain more spatial mixing and flow information. All hexahedron structured meshes are used in the mesh generation of ejector and the shock waves are captured by mesh adaptive technique. The mesh quality and accuracy of calculation are improved to the greatest extent. The Shear Stress Transport (SST) model is selected for the calculation model. The performance of the ejector is analyzed from the point of view of the experiment by setting up a double heat source bipolar ejector refrigeration system, and the experimental data of the ejector coefficient varying with the condenser pressure are obtained through the experimental analysis of the ejector with the same structure as one of the simulated ones. Compared with the simulation results, it is found that the average relative error of the two results is 9.6, and the simulation results have high reliability. The results show that the effect of ejector structure on its performance is very obvious. Under the given working parameters, there is an optimum value for the length of nozzle exit D1 and the distance between nozzle exit and mixing section exit D2. The jet coefficient reaches the maximum. And the ejector performance depends on the outlet angle of the diffuser chamber? And the nozzle throat diameter d increases and decreases. The research of this subject lays a foundation for the feasibility of using ejector refrigeration on Chinese small and medium-sized ocean-going fishing vessels, and provides a way of thinking for the three-dimensional simulation of ejector at the same time.
【學位授予單位】：太原科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U664.87;TB657
【參考文獻】
相關期刊論文 前1條
1 楊新宇;王金鋒;謝晶;;喉部面積比對噴射器性能的影響分析[J];低溫與超導;2011年06期
，本文編號：2419536
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