机房空调中不同型式下不同夹角对翅片管蒸发器性能影响的研究

发布时间：2018-07-03 03:09

本文选题：机房空调 + 正、反V型翅片管蒸发器　；参考：《南京师范大学》2017年硕士论文

【摘要】：随着IT行业在全球的迅速发展,数据中心的高能耗已经成为一个不可忽视的问题。对机房空调而言,换热器作为热量交换的一个非常重要的组件,其效率的高低直接影响到制冷系统的性能。因此,节省能源的有效途径之一就是加强换热器的合理设计和运行管理。本文主要采用商业软件FLUENT对机房空调中不同角度的正、反V型翅片管蒸发器进行数值模拟,得到了两种型式的翅片管蒸发器三种角度下(32.5° ,39° ,45.5° )外部空间的温度场、速度场和迎面风速云图,以及空气侧换热量、努塞尔数和空气侧的压降,而且从迎面风速不均匀度等方面分析了造成这种差异的原因。本文采用了焓差试验台对模拟结果进行验证。此外,本文还对不同风量和不同相对湿度的反V型翅片管蒸发器空气侧的特性进行比较,比较了三种角度在风量百分比为100%、90%、80%、70%四种工况下的换热性能,以及不同相对湿度对换热性能的影响,包括相对湿度分别为45%、50%、55%和60%的四类情况。对比分析了各种工况下的制冷量和能效比,并且从蒸发温度、压缩机的吸、排气温度和吸、排气压力以及冷凝温度等方面分析造成这种差异的原因。就所进行的各项研究,得到了如下的结论:(1)随着翅片管换热器夹角的增大,换热器空间内部的流场越来越均匀,换热面的速度分层现象也有一定的减少,高温区和低温区的区域都有所减小。空气侧努塞尔数和压降均呈现上升的趋势,且正V型式下的努塞尔数普遍低于反V型式,压降普遍高于反V型式。(2)换热器迎面速度分布呈现出相似的变化趋势,位于风机垂直正下方位置迎面风速都是最大,并以此为中心逐渐向外递减,在换热器边缘位置达到最小。反V型蒸发器夹角为32.5°、39°和45.5°对应的迎面风速不均匀度分别为0.86、0.62 和 0.56。(3)随着风量百分比的降低,三种夹角蒸发器系统的制冷量都会减小,而能效比都呈上升趋势。且不论风量百分比如何变化,夹角为39°和45.5°时,其制冷量和能效比都远高于夹角为32.5°的蒸发器,并且在风量百分比为80%和70%时,这种差异更加明显,与制冷量最高的角度相比,制冷量分别下降了5.7%和6%,能效比分别下降了 3.5%和6.7%。当风量百分比为70%时,夹角为45.5°的蒸发器系统的制冷量比夹角为39°的蒸发器系统的制冷量提高了 3.4%,能效比增加了 3%。(4)随着相对湿度的增加,三种角度蒸发器的制冷量和能效比整体上呈增加趋势。当风量百分比为80%时,夹角为32.5°的蒸发器在相对湿度从55%增加到60%时,制冷量和能效比增长速度较其他各类情况都很大。本文对机房空调中不同型式不同角度的正、反V型翅片管蒸发器进行数值模拟和实验研究,得到了上面的一些结论,具有一定的工程实用价值以及学术意义,为机房空调中的蒸发器设计与优化提供一定理论依据。
[Abstract]:With the rapid development of IT industry in the world, the high energy consumption of data center has become a problem that can not be ignored. As a very important component of heat exchange, the efficiency of heat exchanger directly affects the performance of refrigeration system. Therefore, one of the effective ways to save energy is to strengthen the rational design and operation management of heat exchanger. In this paper, the commercial software fluent is used to numerically simulate the positive and inverse V-shaped finned tube evaporators in the air conditioning room. The temperature field in the outer space (32.5 掳/ 39 掳/ 45.5 掳) is obtained for two types of finned tube evaporators (32.5 掳/ 39 掳/ 45.5 掳). The velocity field and face wind speed cloud map, as well as the heat transfer on the air side, the Nusselle number and the pressure drop on the air side are analyzed, and the reasons for the difference are analyzed from the aspects of the inhomogeneity of the face wind speed. In this paper, the enthalpy difference test bench is used to verify the simulation results. In addition, the characteristics of the air side of the reverse Vfinned tube evaporator with different air volume and relative humidity are compared, and the heat transfer performance of three different angles is compared under the four working conditions of 100% air volume, 80% air volume and 70% air volume. And the influence of different relative humidity on heat transfer performance, including four kinds of cases where the relative humidity is 4550% and 60%, respectively. The refrigerating capacity and energy efficiency ratio under various working conditions are compared and analyzed, and the reasons for the difference are analyzed from the aspects of evaporation temperature, compressor suction, exhaust temperature and suction, exhaust pressure and condensing temperature, etc. The conclusions are as follows: (1) with the increase of the angle of finned tube heat exchanger, the flow field in the heat exchanger space becomes more and more uniform, and the velocity stratification of the heat exchanger surface is reduced to a certain extent. The region of high temperature region and low temperature region are decreased. Both the Nussel number and the pressure drop on the air side show an upward trend, and the Nusselle number in the positive V-type is generally lower than that in the anti-V-type, and the pressure drop is generally higher than that in the anti-V-type. (2) the distribution of the head-on velocity of the heat exchanger shows a similar trend. The wind speed is the largest in the vertical and lower position of the fan, and gradually decreases outwards at the center, and reaches the minimum in the edge position of the heat exchanger. The windward wind unevenness corresponding to the angle of 32.5 掳/ 39 掳and 45.5 掳for the reverse V-type evaporator is 0.86 掳0.62 and 0.56 respectively. (3) with the decrease of the air volume percentage, the cooling capacity of the three kinds of angle evaporator systems will decrease and the energy efficiency ratio will increase. Regardless of the percentage of air flow, the refrigerating capacity and the energy efficiency ratio of the evaporator are much higher than those of the evaporator with the angle of 32.5 掳at the angles of 39 掳and 45.5 掳, and the difference is more obvious when the percentage of air volume is 80% and 70%, compared with the angle with the highest refrigerating capacity. The refrigerating capacity decreased by 5.7% and 6% respectively, and the energy efficiency ratio decreased by 3.5% and 6.7%, respectively. When the air volume percentage is 70, the refrigerating capacity of evaporator system with an angle of 45.5 掳is increased by 3.4% and the energy efficiency ratio is increased by 3% than that of evaporator system with an angle of 39 掳. (4) with the increase of relative humidity, The refrigerating capacity and energy efficiency ratio of the three angle evaporators are increasing as a whole. When the air volume percentage is 80 and the evaporator with an angle of 32.5 掳increases from 55% to 60 g relative humidity, the increase rate of cooling capacity and energy efficiency ratio is larger than that of other conditions. In this paper, the numerical simulation and experimental study on the positive and inverse Vfinned tube evaporators of different types and different angles in the air conditioning system of the engine room are carried out, and some conclusions above are obtained, which are of certain engineering practical value and academic significance. It provides some theoretical basis for the design and optimization of evaporator in the air conditioner of engine room.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU831.4

【参考文献】