空调系统冷却塔及冷冻水管网的运行特性实验分析研究

发布时间：2018-03-05 20:38

本文选题：运行特性　切入点：冷却塔　出处：《华南理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：空调系统节能运行是公共建筑节能减排的关键所在，，而冷冻水系统和冷却水系统的运行性能直接决定了空调系统的能耗。本文分别对冷却水系统中冷却塔和冷冻水系统管网的运行特性进行了理论分析及实验研究，为空调系统优化运行提供参考。冷却塔是冷却水系统中一个重要的设备，其运行性能将对冷凝器的换热有直接影响，从而对整个空调系统的运行效率产生影响。本文在充分考虑回流、蒸发损失、刘易斯数和实际填料特性数的基础上分别对机械通风横流塔和逆流塔建立数学模型，并对两种类型塔进行了测试验证。结果表明，横流塔出水温度相对误差低于3.5%；逆流塔出水温度相对误差低于2%，从而验证了理论模型是准确可靠的。分析了刘易斯数、特性数修正系数、飘水和回流对冷却塔运行的影响。结果表明，对于大温差的模拟研究需对刘易斯关系式进行修正，否则，模拟结果可能和实际结果相差较大，尤其是出塔空气干球温度和出塔空气相对湿度；实际特性数与标准工况值偏离越大，对冷却塔性能影响越大。分析结果表明填料特性数修正系数从1降到0.5，换热量减少达到23.5%；而从1降到0.1，换热量减少高达74.3%。冷却塔存在回流会影响冷却塔的冷却能力同时会影响周边人群舒适感。当回流率增加到50%时，出水温度升高2.7°C，换热量减少40.68%和舒适度指数变化1.92。冷冻水系统运行性能直接影响到整个系统的能耗和空调区域的舒适性。基于压差控制对冷冻水系统管网的静态和动态特性进行实验分析研究。结果表明，实验得到冷冻水系统压差特性和水泵能耗特性与理论所得的结论较吻合；旁通阀设定压差值和控制压差值的选择对主机功率的影响不大却对水泵功率影响显著，而且影响压差控制的稳定性和控制精度。当控制压差小于或者稍大于旁通阀设定压差值时，管网稳定性较好；而当控制压差大于旁通压差设定值且相差较大时，管网严重震荡；当控制压差接近旁通设定压差值时，实际压差接近控制压差，控制精度较高；而当控制压差偏离旁通阀设定压差值时，实际压差偏离控制压差，控制精度较差，且控制压差偏离旁通阀设定压差值越大，实际压差与控制压差偏差越大，控制精度越差。
[Abstract]:Energy saving operation of air conditioning system is the key to energy saving and emission reduction of public buildings. The operation performance of chilled water system and cooling water system directly determines the energy consumption of air conditioning system. In this paper, the operating characteristics of cooling tower and pipe network in cooling water system are analyzed theoretically and experimentally. Provides the reference for the air conditioning system optimization operation. The cooling tower is an important equipment in the cooling water system. Its operation performance will have a direct effect on the heat transfer of the condenser, thus has an impact on the operation efficiency of the whole air conditioning system. Based on the Lewis number and the actual packing characteristic number, the mathematical models of the mechanical ventilation crossflow tower and the countercurrent tower are established, and the two types of columns are tested and verified. The results show that, The relative error of outlet temperature of cross flow tower is lower than 3.5 and that of counterflow tower is less than 2. The theoretical model is proved to be accurate and reliable. The effects of Lewis number, characteristic number correction coefficient, floating water and reflux on the operation of cooling tower are analyzed. The simulated results may differ greatly from the actual results, especially the dry ball temperature and the relative humidity of the outlet air, and the deviation between the actual characteristics and the standard operating conditions is greater. The results show that the correction coefficient of packing characteristics decreases from 1 to 0.5, and the heat transfer decreases to 23.50.The heat exchange decreases up to 74.3% from 1 to 0.1. The cooling energy of cooling tower is affected by the existence of backflow in the cooling tower. The force also affects the comfort of the surrounding crowd. When the reflux rate increases to 50, The effluent temperature increased by 2.7 掳C, the heat exchange decreased by 40.68% and the comfort index changed by 1.92. The operation performance of the chilled water system directly affects the energy consumption of the whole system and the comfort of the air conditioning area. Based on the pressure difference control, the static and dynamic characteristics of the chilled water system pipe network are studied experimentally. The results show that, The experimental results show that the pressure difference characteristics and pump energy consumption characteristics of the chilled water system are in good agreement with the theoretical results, and that the selection of the pressure-difference value and the control pressure difference value of the bypass valve have little effect on the power of the main engine but have a significant effect on the power of the pump. When the control pressure difference is less than or slightly larger than the set pressure difference value of the bypass valve, the pipe network stability is better, but when the control pressure difference is greater than the set value of the bypass pressure difference and the difference is large, the pipe network is severely shaken. When the control pressure difference is close to the bypass pressure-difference value, the actual pressure difference approaches the control pressure difference, and the control accuracy is higher, but when the control pressure difference deviates from the preset pressure difference value of the bypass valve, the actual pressure difference deviates from the control pressure difference, and the control accuracy is poor. The greater the value of the pressure difference between the control pressure difference and the control pressure difference, the greater the deviation between the actual pressure difference and the control pressure difference, and the worse the control precision.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB657

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