冷却塔全年热湿交换特性及适宜条件研究

发布时间：2018-06-13 17:44

本文选题：冷却塔 + 全年热湿交换特性　；参考：《北京工业大学》2014年硕士论文

【摘要】：冷却塔作为空调系统的重要冷却设备之一，近些年被越来越多的应用于建筑物非夏季工况（非额定工况）条件下的系统中。但是，由于冷却塔的热湿交换特性受很多因素的影响，导致冷却塔厂家所提供给用户的产品样本中，冷却塔热工性能曲线只是以夏季工况为依据，一般只针对湿球温度较高时，很少有厂家能够提供冷却塔在非夏季工况的热工性能曲线。然而，室外气象参数的变化直接影响冷却塔的热湿交换能力。随着季节和室外空气湿球温度、进口水温、水气比等因素的变化，冷却塔的运行工况将偏离其额定工况条件，也即冷却塔热湿交换能力将随其运行条件而改变。但关于这个问题目前没有引起大家足够的重视和注意，即使在非夏季工况运行冷却塔，人们也仍然习惯地沿用产品技术样本给出的技术参数进行相关评价，致使冷却塔的综合运行效率偏低或达不到预期的冷却效果。为了把握非额定工况运行条件下（特别是过渡季节、冬季），影响冷却塔高效运行的因素及其适宜的运行条件，本研究提出了冷却塔非额定工况下的的评价指标，并选取了冷却塔的四变量模型作为分析模型，且通过Matlab编程对模型的计算值与实测值进行了比较，计算结果表明两者的相对误差小于5%，验证了模型的有效性。基于四变量模型，本文对冷却塔的全年热湿交换特性进行了分析研究，研究结果表明：室外湿球温度变化直接影响冷却塔出力，且冷却塔变水量调节较变风量调节更具节能效果。另外，以南京地区为例，基于冷却塔变水量运行条件，分析了夏季负荷高峰期（7、8月份）冷却塔运行适宜的水气比为μ=0.5~1（μ=W/G0，W=0.67W0~1.33W0）；夏季负荷平谷期（6、9月份）适宜的水气比为μ=0.3~1（μ=W/G0，W=0.4W0~1.33W0）；过渡季节、冬季冷却塔运行适宜的水气比为μ=0.5~0.76（μ=W/G0，W=0.67W0~W0）。基于以上研究，本文进一步分析了冷却塔应用于常规空调系统的适宜条件，计算分析结果表明：对于常规空调系统，在夏季运行过程中，冷却塔应优先进行变水量调节，更利于提高系统能源利用效率，且7、8月份冷却塔运行适宜的水气比为μ=0.5~1；6、9月份适宜的水气比为μ=0.3~1；而在过渡季节及冬季，针对冷却塔应用于免费供冷系统时，切换温度为室外湿球温度小于9℃，水气比为μ=0.5~0.76，且南京地区在冬季和过渡季节3月、11月时，，开启冷却塔免费供冷系统更具节能效果。利用该研究思路进一步对我国31个省会城市适宜应用冷却塔免费供冷系统的时间进行了分析，分析结果可为冷却塔免费供冷系统的设计及运行提供参考依据。另外，针对南京地区某住宅建筑小区土壤源热泵系统出现的热堆积问题为分析对象，课题组提出了冷却塔过渡季节土壤补偿蓄冷新方法，并分析了此系统中冷却塔全年运行的适宜条件，其结果表明：南京地区6、9月份、冷却塔、适宜的水气比为μ=0.3~1；过渡季节（3月、11月、10月下），冷却塔适宜的水气比为μ=0.5~0.76。研究结果表明：采用冷却塔过渡季节土壤补偿蓄冷方法，土壤热堆积问题可得到有效抑制，研究结果可为冷却塔全年高效节能运行与系统优化设计提供参考依据。
[Abstract]:As one of the important cooling equipment of the air conditioning system, the cooling tower has been more and more applied to the system under non rated operating conditions in recent years. However, the heat and wet exchange characteristics of the cooling tower are influenced by many factors, which lead to the thermal properties of the cooling tower in the cooling tower manufacturers. The energy curve is only based on the summer working condition. In general, only when the temperature of the wet bulb is high, few manufacturers can provide the thermal performance curve of the cooling tower in the non summer conditions. However, the change of outdoor meteorological parameters directly affects the heat and humidity exchange capacity of the cooling tower. The operating conditions of the cooling tower will deviate from its rated operating conditions, that is, the heat and humidity exchange capacity of the cooling tower will change with its operating conditions. However, there is no enough attention and attention to this problem at present. Even in the non summer operation of cooling tower, people are still used to use the product technology samples. The relative evaluation of technical parameters leads to the low efficiency of the cooling tower and the failure of the expected cooling effect.
In order to grasp the factors affecting the efficient operation of the cooling tower and its suitable operating conditions under the operating conditions of the non rated operating conditions (especially in the transition season, winter), the evaluation index of the cooling tower under the non rated operating conditions is put forward, and the four variable model of the cooling tower is selected as the analysis model, and the calculation of the model is calculated by Matlab programming. The comparison between the measured value and the measured value shows that the relative error of the two is less than 5%, and the validity of the model is verified. Based on the four variable model, the heat and humidity exchange characteristics of the cooling tower are analyzed and studied. The results show that the temperature change of the outdoor wet bulb directly affects the output of the cooling tower, and the variable water regulation of the cooling tower is more than that of the cooling tower. In addition, taking Nanjing area as an example, based on the operating conditions of variable water quantity in the cooling tower, the optimum water and gas ratio of the cooling tower in summer load peak (7,8 month) was analyzed. The appropriate water and gas ratio of summer load in Pinggu period (6,9 month) was mu =0.3~1 (W=0.67W0~1.33W0), and the appropriate water and gas ratio of summer load in the summer period (6,9 month) was mu =0.3~1 (W=0.4W0~1.33W0). In the transitional season, the suitable water / gas ratio for cooling tower operation in winter is =0.5~0.76 (=W/G0, W=0.67W0~W0).
Based on the above research, this paper further analyzes the suitable conditions for the cooling tower to be used in the conventional air conditioning system. The calculation and analysis results show that, for the conventional air conditioning system, the cooling tower should give priority to the variable water regulation during the summer operation, which is more conducive to improving the energy efficiency of the system, and the appropriate water and gas ratio in the cooling tower of the 7,8 month. For =0.5~1, the appropriate water and gas ratio is =0.3~1 in the month of 6,9, while in the transition season and winter, when the cooling tower should be used for free cooling system, the temperature of the cooling tower is less than 9 C, the ratio of water to gas is =0.5~0.76, and the free cooling system of the cooling tower is more efficient in the winter and transition season in Nanjing and in November. This study further analyzes the time of the cooling tower free cooling system suitable for the 31 provincial capital cities in China. The analysis results can provide reference for the design and operation of the cooling tower free cooling system. In addition, the heat accumulation problem of the soil source heat pump system in a small residential building area in Nanjing area is solved. For the analysis object, a new method of soil compensation and cooling in the transition season of cooling tower is put forward, and the suitable conditions for the whole year operation of the cooling tower in this system are analyzed. The results show that the suitable water and gas ratio is mu =0.3~1 in the 6,9 month of Nanjing and the appropriate water and gas ratio, and the appropriate water and gas ratio of the cooling tower is =0.5~0. in the transition season (March, November, and the month). 76. the results of the study show that the problem of soil thermal accumulation can be effectively suppressed by the method of soil compensation and cooling in the transition season of cooling tower. The results can provide reference for the efficient and energy-saving operation of the cooling tower and the system optimization design for the whole year.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU831

【参考文献】