蒸发式空冷器热质传递实验及计算模拟研究

Experimental and numerically investigation of heat and mass transfer in evaporative cooler

为分析空冷器传热传质性能,搭建工业用8排圆管管束中型蒸发冷却实验台对其进行实验和模拟研究。分别利用Poppe和Merkel类似假设建立控制方程对空冷器热质传递性能进行模拟。为保证模拟精度,依据实验数据拟合了蒸发空冷器传热传质经验公式。采用分段计算法在Matlab平台编写模拟计算求解程序。Poppe法和Merkel法模拟计算所得管内工质出口温度、空气出口焓值和喷淋水温与实验对比一致性较好,均可用于空冷器不同工况下换热性能预测。管束30分段已满足计算精度要求,模拟所得各参数分布可为空冷器进一步分析提供依据。相比Merkel法,Poppe法计算所得的空气出口焓值及喷淋水温误差更小,但需要更长的计算时间。

A medium size industrial evaporative cooler with 8 rows tube bundles was established for the analysis of its heat and mass transfer performance.By employing assumptions similar to Poppe and Merkel,the control equations were derived to investigate the performance of evaporative cooler numerically.To ensure simulation accuracy,the empirical formulas for the water film heat transfer coefficient and air-water mass transfer coefficient were obtained from experimental data.Then the simulation code was programed while piecewise calculation was applied.The results show that both Poppe and Merkel methods can predict outlet working substance temperature,air outlet enthalpy and deluge water temperature accurately,and can be used to predict the performance of evaporative cooler in different operated conditions.The simulation results indicate that 30 segments can meet the calculation accuracy requirement.The distribution of parameters obtained from simulation results can provide basis for further analysis of evaporative cooler.Compared with Merkel method,Poppe method can predict air outlet enthalpy and deluge water temperature more accurately,but takes more calculation time.