相变材料蓄放热机理及其基站冷却的能效研究

发布时间：2018-05-21 00:45

本文选题：相变储能技术 + 通信基站　；参考：《湖南大学》2014年博士论文

【摘要】：电子行业和通信技术的快速发展使得通信基站的数量日益剧增,通信基站全天候不间断的通信要求,使通信网络的能耗迅速增长,其中空调部分能耗占基站总能耗的46%,降低基站内制冷系统的能耗成为研究热点。基站空调系统的节能主要集中于引入可再生能源,太阳能、风能、地热能等可再生能源的利用成为重点研究对象,然而太阳辐射和室外环境温度周期性变化,且基站内夜间的冷负荷远远小于白天的冷负荷,可再生能源的利用存在严重的供需不平衡。相变储能技术可通过相变材料的相变过程储存或释放能量,解决可再生能源在利用时的空间和时间不匹配的问题,延长可再生能源的利用时间,减少通信基站内空调的运行时间,降低基站能耗。本文主要研究相变材料蓄放热机理及其基站冷却的能效,研发通信基站用被动式储能技术即相变墙体和主动式储能技术即相变储能空气处理机组,分别模拟仿真两种技术在我国五个气候区域内的全年运行工况；以投资回收期和节能率分别评价相变墙体和相变储能空气处理机组在不同气候区域内通信基站制冷系统节能中的适应性。针对被动式相变储能技术在通信基站围护结构中的应用,建立相变换热过程的移动热源法模型,进行相变材料一维蓄放热过程的无量纲解析。相变传热过程的换热量与传热温差和材料的导热系数的0.5次方呈正比,与相变传热时间的0.5次方呈反比,即q=f(|Ste|0.5,(κl/κs)0.5,Fo-0.5)。与实验测试数据和已公开发表的模型求解结果对比,准确性较高。当|Ste|/(κl/κs)1时,增大材料的导热系数比增大传热温差更有利于加快固-液相界面的移动,提高相变换热量；反之,增大传热温差可有效提高相变换热量。建立相变材料的凝固放热和融化吸热过程的实验研究,对比验证上述模型。分析相变换热过程的热阻和液相材料自然对流现象对换热热流和相变时间的影响,引入传热增强系数,量化液相材料流动对融化过程的增强效果,简化了自然对流现象相变问题的求解。液相材料的自然对流分别增强竖直和水平方向传热系数12%和33%,同一传热方向上,相同边界条件下融化过程的热流大于凝固过程的热流。液相材料的流动扩大了融化过程中相变温度的范围,延长了相变过程时间,对凝固过程中的相变温度范围没有影响。根据上述的模拟计算结果,系统研究被动式相变储能技术在通信基站中的应用方式,将相变材料板应用于通信基站墙体,综合考虑室外自然冷源利用率、PCM板利用率和空调性能系数等影响因素，，以投资回收期评价相变墙体的经济可行性，对相变材料板和相变材料温度的选择进行优化。各地应用相变墙体的投资回收期由短到长为：昆明、郑州、沈阳、长沙、广州，随相变温度的升高而减小，当PCM板相变温度大于室外环境空气平均温度加5oC时，投资回收期基本不变。为提高相变墙体的换热效果，设计开发相变储能空气处理机组实现主动式相变储能技术在通信基站中的应用。基于相变换热过程的理论数值和实验结果，对比通信基站传统空调，分析相变储能空气处理机组各工况的能效比、运行时间和节能率，探讨室外气象参数对节能率的影响，指导主动式相变储能技术在通信基站中的节能应用。考虑机组的蓄放能过程，提出新能效比(EER′)评价机组的运行性能，克服了传统能效比在该机组中应用的局限性。室外空气温度越低，相变储能空气处理机组EER′值越大，其在我国五个城市内全年平均EER′为14.04W/W。相变储能空气处理机组在昆明地区通信基站内的全年平均节能率达到67%，在我国五个城市的平均节能率为50%。
[Abstract]:The rapid development of electronic industry and communication technology makes the number of communication base stations increasing increasingly. The energy consumption of communication network is increasing rapidly. The energy consumption of air conditioning part of the base station is 46% of the total energy consumption of the base station, and the energy consumption of the refrigeration system in the base station has become a hot spot. The use of renewable energy, solar energy, wind energy, geothermal energy and other renewable energy should be focused on. However, the solar radiation and outdoor environment temperature change periodically, and the cold load at night in the base station is far less than the cold load in the daytime. The utilization of renewable energy has serious imbalance of supply and demand. Phase change energy storage technology It can store or release energy through phase change phase change of phase change material, solve the problem of space and time mismatch of renewable energy, prolong the utilization time of renewable energy, reduce the running time of air conditioning in the communication base station, and reduce the energy consumption of base station.
This paper mainly studies the heat storage and release mechanism of phase change materials and the energy efficiency of the base station cooling, and develops the passive storage technology of the communication base station, that is, phase change wall and active energy storage technology, that is, phase change energy storage air processing unit, and simulated the operating conditions of two technologies in five climate regions of China respectively. The adaptability of phase change wall and phase change energy storage air treatment unit in the energy saving of communication base station in different climate regions is evaluated respectively. In view of the application of passive phase change energy storage technology in the enclosure structure of communication base station, a moving heat source model of phase change heat transfer process is established, and the one dimension heat storage and heat release process of phase change materials is carried out. Dimensional analysis. The heat transfer and heat transfer temperature difference of the heat transfer process is proportional to the 0.5 square of the thermal conductivity of the material, and is inversely proportional to the 0.5 square of the heat transfer time. That is, q=f (|Ste|0.5, (kappa l/ kappa s) 0.5, Fo-0.5). Compared with the experimental data and the published model solution results, the accuracy is higher. When |Ste|/ (kappa l/ kappa s) 1, increase the material The thermal conductivity of the material is better than the increase of the heat transfer temperature difference, which is beneficial to speed up the movement of the solid liquid interface and improve the heat transfer of the phase change. On the contrary, the increase of heat transfer temperature difference can effectively improve the heat transfer of the phase change.
The experimental research on the solidification and exothermic process of phase change materials is established. The effects of thermal resistance and natural convection on heat exchange and phase change time in the phase change heat transfer process are analyzed. The enhancement coefficient of heat transfer is introduced to quantify the enhancement effect of liquid material flow on the melting process, and the natural pair is simplified. The natural convection of the liquid phase material increases the vertical and horizontal heat transfer coefficients 12% and 33% respectively. In the same heat transfer direction, the heat flow in the melting process is larger than the heat flow in the solidification process. The flow of liquid phase materials expands the range of phase transition temperature during the melting process and prolongs the phase transition time. It has no effect on the temperature range of phase change during solidification.
According to the simulation results mentioned above, the application mode of passive phase change energy storage technology in communication base station is systematically studied. Phase change material board is applied to the wall of communication base station. The factors such as utilization ratio of outdoor natural cold source, utilization ratio of PCM board and performance coefficient of air conditioning are taken into consideration, and the economic feasibility of phase change wall is evaluated by investment recovery period. The selection of phase change material plate and phase change material temperature selection is optimized. The investment recovery period of phase change wall is from short to long: Kunming, Zhengzhou, Shenyang, Changsha and Guangzhou decrease with the increase of phase transition temperature. When the phase transition temperature of PCM plate is higher than that of outdoor environment, the investment recovery period is basically unchanged.
In order to improve the heat transfer effect of the phase change wall, a phase change energy storage air treatment unit is designed and developed to realize the application of active phase change energy storage technology in the communication base station. Based on the theoretical and experimental results of the phase change heat transfer process, the energy efficiency ratio, running time and the operation time of the phase change energy storage air treatment unit are analyzed. The effect of outdoor meteorological parameters on energy saving rate is discussed, and the energy saving application of active phase change energy storage technology in the communication base station is guided. Considering the storage energy process of the unit, the new energy efficiency ratio (EER ') is proposed to evaluate the operating performance of the unit, and the limitation of the application of the traditional energy efficiency ratio in the unit is overcome. The lower the outdoor air temperature is, the phase transition is lower. The greater the EER 'value of the energy storage unit, the average annual energy saving rate of the average annual EER' is 67% in the Kunming communication base station in the five cities of China, and the average energy saving rate in the five cities of our country is 50%.
【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU83

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