蒸发式冷凝器传热传质特性数值模拟与实验研究
发布时间：2018-09-19 18:50
【摘要】：目前我国正在经历快速的社会经济转型,快速发展的同时也伴随着能源的巨大消耗,节能节水已成为解决当今能源问题的重要途径,蒸发式冷凝器作为空调系统中的重要设备,其本身存在减少能耗、节约水资源效果明显的特点,基于以上原因,本文对蒸发式冷凝器进行研究分析与结构优化,采用水平布置蛇形盘管的蒸发式冷凝器,对机组性能进行深入研究分析,主要研究内容如下:根据计算流体动力学(Computational Fluid Dynamics)中关于气-液两相流的处理方法,采用混合模型(Mixture)多相流模型,为了准确分析数值模拟水平布置的蒸发式冷凝器腔内流场变化情况,建立了水平布置蒸发式冷凝器三维数学模型,并分析蒸发式冷凝器分别在气相和气-液两相时三种不同进风方式(单面进风、两面进风、侧面进风)对蒸发式冷凝器内部流场的影响,结果表明:单面进风远离进风口侧速度在整个区域较低,此处在拐角处形成涡流,不利于此区域的的换热,与单相进风相比,两面进风方式在气流长度方向上较为对称,能够减少管壁和壁面处漩涡的数量与强度,侧面进风整体气流较均匀,但进风口侧由于风速过大,造成液相分布不均,为此进行了结构优化,并进行实验研究。详细的介绍了水平布置蒸发式冷凝器制冷系统的实验装置,该实验装置主要为蒸发式冷凝器制冷系统模拟的验证提供实验依据,并为换热器的性能和结构优化进行实验研究。在实验中,研究不同进风方式和湿球温度对水平布置蒸发式冷凝器机组性能的影响,由实验结果分析出侧进风方式机组的冷凝温度更低,压缩机功率消耗更少,这跟模拟分析结果相吻合,随后针对实验和模拟的结果(液相分布不均的问题)对机组进行结构优化和性能分析,对水平布置的蛇形盘管安装不同方式的换热筋板,并测试了冷却水喷淋密度、室外空气干(湿)球温度、空气流速及换热面积等参数对水平布置蒸发式冷凝的强化传热性能及制冷系统的制冷性能的影响。本课题通过对水平布置蒸发式冷凝器进行数值模拟和实验研究,并进行有效的结构优化,丰富了蒸发式冷凝器的理论与应用研究体系,为进一步研究蒸发式冷凝器性能研究和结构优化提供了参考。
[Abstract]:At present, China is experiencing a rapid social and economic transformation, rapid development accompanied by huge energy consumption, energy saving and water saving has become an important way to solve the energy problem. As an important equipment in air conditioning system, evaporative condenser has its own characteristics of reducing energy consumption and saving water resources. In this paper, the evaporative condenser is analyzed and optimized, and the performance of the unit is analyzed by using the evaporative condenser with serpentine coils arranged horizontally. The main research contents are as follows: According to the treatment method of gas-liquid two-phase flow in Computational Fluid Dynamics, mixing is adopted. Mixture multiphase flow model. In order to accurately analyze and simulate the flow field in the chamber of evaporative condenser with horizontal arrangement, a three-dimensional mathematical model of evaporative condenser with horizontal arrangement was established. Three different air inlet modes (one-side air inlet, two-side air inlet and side air inlet) were analyzed when the evaporative condenser was in gas phase and gas-liquid phase respectively. The influence of wind on the flow field in the evaporative condenser is studied. The results show that the velocity at the inlet side of the single-side air inlet is lower than that at the inlet side in the whole region, and the vortex is formed at the corner, which is not conducive to the heat transfer in this region. The quantity and intensity of the air flow in the side air inlet are uniform, but the liquid phase distribution is uneven because of the excessive air velocity at the side of the air inlet. The structure optimization is carried out and the experimental study is carried out. The experimental device of the evaporative condenser refrigeration system with horizontal arrangement is introduced in detail. The experimental device is mainly the simulation experiment of the evaporative condenser refrigeration system. In the experiment, the influence of different air inlet modes and wet bulb temperatures on the performance of evaporative condenser units with horizontal arrangement is studied. The experimental results show that the side air inlet mode has lower condensing temperature and lower compressor power consumption, which is compared with the simulation. The analysis results are consistent. Then the structure optimization and performance analysis of the unit are carried out according to the experimental and simulation results (the problem of uneven liquid distribution). Different heat exchanger ribs are installed on the serpentine coils arranged horizontally. The spray density of cooling water, the dry (wet) bulb temperature of outdoor air, the air velocity and the heat exchange area are tested. The heat transfer enhancement and refrigeration performance of evaporative condenser with horizontal arrangement are studied by numerical simulation and experiment, and the effective structure optimization is carried out, which enriches the theoretical and applied research system of evaporative condenser and further studies the performance of evaporative condenser. It provides a reference for research and structural optimization.
【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】：TB657
本文编号：2251008
[Abstract]:At present, China is experiencing a rapid social and economic transformation, rapid development accompanied by huge energy consumption, energy saving and water saving has become an important way to solve the energy problem. As an important equipment in air conditioning system, evaporative condenser has its own characteristics of reducing energy consumption and saving water resources. In this paper, the evaporative condenser is analyzed and optimized, and the performance of the unit is analyzed by using the evaporative condenser with serpentine coils arranged horizontally. The main research contents are as follows: According to the treatment method of gas-liquid two-phase flow in Computational Fluid Dynamics, mixing is adopted. Mixture multiphase flow model. In order to accurately analyze and simulate the flow field in the chamber of evaporative condenser with horizontal arrangement, a three-dimensional mathematical model of evaporative condenser with horizontal arrangement was established. Three different air inlet modes (one-side air inlet, two-side air inlet and side air inlet) were analyzed when the evaporative condenser was in gas phase and gas-liquid phase respectively. The influence of wind on the flow field in the evaporative condenser is studied. The results show that the velocity at the inlet side of the single-side air inlet is lower than that at the inlet side in the whole region, and the vortex is formed at the corner, which is not conducive to the heat transfer in this region. The quantity and intensity of the air flow in the side air inlet are uniform, but the liquid phase distribution is uneven because of the excessive air velocity at the side of the air inlet. The structure optimization is carried out and the experimental study is carried out. The experimental device of the evaporative condenser refrigeration system with horizontal arrangement is introduced in detail. The experimental device is mainly the simulation experiment of the evaporative condenser refrigeration system. In the experiment, the influence of different air inlet modes and wet bulb temperatures on the performance of evaporative condenser units with horizontal arrangement is studied. The experimental results show that the side air inlet mode has lower condensing temperature and lower compressor power consumption, which is compared with the simulation. The analysis results are consistent. Then the structure optimization and performance analysis of the unit are carried out according to the experimental and simulation results (the problem of uneven liquid distribution). Different heat exchanger ribs are installed on the serpentine coils arranged horizontally. The spray density of cooling water, the dry (wet) bulb temperature of outdoor air, the air velocity and the heat exchange area are tested. The heat transfer enhancement and refrigeration performance of evaporative condenser with horizontal arrangement are studied by numerical simulation and experiment, and the effective structure optimization is carried out, which enriches the theoretical and applied research system of evaporative condenser and further studies the performance of evaporative condenser. It provides a reference for research and structural optimization.
【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】：TB657
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