發(fā)布時(shí)間：2018-04-26 12:00

  本文選題：干式管殼式蒸發(fā)器 + 分液裝置��； 參考：《南京師范大學(xué)》2015年碩士論文

【摘要】：干式管殼式蒸發(fā)器因其制冷劑需求量小、運(yùn)行穩(wěn)定等優(yōu)點(diǎn)目前在制冷工業(yè)中應(yīng)用廣泛。目前制約其更大范圍應(yīng)用的一個(gè)瓶頸在于其換熱性能仍不夠理想,有研究認(rèn)為各管間的制冷劑分配不均是導(dǎo)致其性能不能大幅提升的主要原因。本文分別通過(guò)理論分析、實(shí)驗(yàn)研究和數(shù)值模擬的方法對(duì)管殼式蒸發(fā)器內(nèi)制冷劑的分液特性及分液對(duì)換熱的影響進(jìn)行了研究,并提出了改進(jìn)方法。首先,本文首先提出了干式管殼式蒸發(fā)器內(nèi)流量分配均勻度的評(píng)判標(biāo)準(zhǔn),通過(guò)理論分析的方法得到了單管換熱公式,研究了流量變化對(duì)換熱的影響。結(jié)果表明,換熱器內(nèi)制冷劑存在的分配不均會(huì)對(duì)換熱造成影響。流量分配均勻會(huì)帶來(lái)?yè)Q熱的增強(qiáng),濕周小于1的狀況下流量分配對(duì)換熱的影響更大。隨后,本文建立了流體分配實(shí)驗(yàn)裝置并開(kāi)展了實(shí)驗(yàn)。由于受到實(shí)驗(yàn)條件的限制,文中對(duì)實(shí)驗(yàn)進(jìn)行了簡(jiǎn)化和介質(zhì)替代：分管數(shù)目為25個(gè)、實(shí)驗(yàn)介質(zhì)為空氣-水。實(shí)驗(yàn)的開(kāi)展達(dá)到了以下兩個(gè)目標(biāo)：得到了流體分配的可視化結(jié)果；為同條件下的兩相流的數(shù)值模擬提供了有效性證明。建立了與實(shí)際尺寸一致的干式管殼式蒸發(fā)器的三維模型并進(jìn)行了數(shù)值計(jì)算。分析了換熱器內(nèi)分液不均的原因,認(rèn)為各管程入口處的壓力分布特點(diǎn)及分液裝置內(nèi)和管內(nèi)的渦流區(qū)域是影響分流的重要因素。提出了改善分液裝置內(nèi)分液的方案,即將分液裝置設(shè)計(jì)為為錐形分液裝置。用簡(jiǎn)化后的模型對(duì)改進(jìn)后的分液器進(jìn)行了數(shù)值模擬研究,研究中為避免特殊流速對(duì)分液的影響,對(duì)流速進(jìn)行了分析,認(rèn)為1.5m/s的進(jìn)口流速為適宜流速。在對(duì)13種不同錐形分液裝置數(shù)值計(jì)算和分析的基礎(chǔ)上,認(rèn)為一種錐角位于流體入口中心線下方的錐形分液裝置整體分液效果最好。針對(duì)該分液器,研究了不同的錐角高度h對(duì)流體分配的影響,結(jié)果表明,h=35mm時(shí)分液效果最好。本文的研究結(jié)果有望對(duì)干式殼管式蒸發(fā)器的性能改進(jìn)提供參考。
[Abstract]:Dry shell evaporator is widely used in refrigeration industry because of its low refrigerant demand and stable operation. At present, a bottleneck of its wider application is that its heat transfer performance is still not ideal. It is considered that the uneven distribution of refrigerant among different tubes is the main reason why the performance can not be greatly improved. In this paper, theoretical analysis, experimental study and numerical simulation are used to study the characteristics of the refrigerant in the tube and shell evaporator and the effect of the separation of the liquid on the heat transfer, and the improved method is put forward. First of all, the criterion of uniformity of flow distribution in dry tube and shell evaporator is put forward in this paper. The formula of single tube heat transfer is obtained by theoretical analysis, and the influence of flow rate on heat transfer is studied. The results show that the uneven distribution of refrigerant in the heat exchanger will affect the heat transfer. Uniform flow distribution will increase heat transfer, and the effect of flow distribution on heat transfer is greater when wet cycle is less than 1. Then, the experimental device of fluid distribution is established and the experiment is carried out. Due to the limitation of the experimental conditions, the experiment is simplified and the medium is replaced: the number of tubes is 25, and the experimental medium is air-water. The experimental results are as follows: the visualization results of fluid distribution are obtained, and the validity of numerical simulation of two-phase flow under the same conditions is proved. A three-dimensional model of dry tube-shell evaporator is established and numerically calculated. Based on the analysis of the reasons for the uneven distribution of liquid in the heat exchanger, it is considered that the pressure distribution characteristics at the entrance of each tube and the eddy current region in the separation unit and the pipe are the important factors affecting the flow distribution. The scheme of improving the internal separation of liquid is put forward, that is to say, the separation device is designed as a conical separation device. In order to avoid the influence of special velocity on the separation of liquid, the velocity of flow is analyzed, and the inlet velocity of 1.5m/s is considered as the appropriate flow rate. On the basis of numerical calculation and analysis of 13 different conical liquid-separating devices, it is considered that a taper separation device with cone angle below the central line of the fluid inlet has the best overall liquid separation effect. The effect of different cone height h on the fluid distribution is studied. The results show that the solution is the best at 35mm. The results of this paper are expected to provide a reference for improving the performance of dry shell-tube evaporator.
【學(xué)位授予單位】：南京師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB64

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 劉紅禹;王艷云;豐艷春;汪德濤;;單弓形和螺旋形折流板換熱器的數(shù)值模擬及性能分析[J];煉油技術(shù)與工程;2007年11期

2 洪文鵬;辛凱;;小尺度管殼式換熱器流動(dòng)和傳熱數(shù)值模擬[J];化工機(jī)械;2013年04期

3 KANNAN K.;RUDRAMOORTHY R.;;EXPERIMENTAL AND NUMERICAL ANALYSIS OF LAMINAR AND LOW TURBULENT FLOW DISTRIBUTIONS IN INLET DIVIDING HEADER OF SHELL AND TUBE HEAT EXCHANGER[J];Journal of Hydrodynamics;2010年04期

，

本文編號(hào)：1805936