周向平行细通道夹套的换热特性

Heat Transfer Characteristics of a Jacket with Circumferential Parallel Minichannels

提出一种周向平行细通道的夹套结构,采用数值方法对细通道夹套的换热特性进行研究,分析了流量、通道尺寸和数量对换热性能的影响,并与无细通道夹套进行比较.结果表明,研究范围内细通道夹套内筒壁面的平均温度和温度不平均系数分别比无细通道夹套平均低9.7 K和36.7%,且二者均随流量增大而减小;当通道高度一定时,通道宽度越小即通道数越多,内筒壁面平均温度越低,而温度不平均系数几乎不变;细通道夹套的通道数越多,同一横截面上流体温度分布越均匀,且流体温度不均匀系数随质量流量增大趋于定值;内细通道夹套的平均传热系数约为无细通道夹套的0.87~2.04倍;细通道夹套的通道数越多,传热系数越大;平均传热系数随质量流量增大而增大,当流量增加到一定程度时,其增加趋势变缓,通道数越多,变缓的趋势越明显.由模拟数据拟合出细通道夹套平均努塞尔数的关联式为Nu_(ave)=3.71696Re^(0.30341)(D_h/R_c)^(0.28574).

A novel jacket with circumferential parallel minichannels was proposed, and numerical simulation on the heat transfer characteristics of the jacket was carried out. The effects of mass flow rate, size and number of channels on the heat transfer were examined, which was compared with the jacket without minichannels. The results indicate that the average temperature and temperature inequalization coefficient of inner cylinder wall in the jacket with minichannels are 9.7 K and 36.7% lower on average than those of the jacked without minichannels in research scope, respectively, and both decrease with the increase of mass flow rate. Under a given height of minichannel, the smaller the width of minichannel, leading to more minichannels, the lower the average temperature of inner cylinder wall, but the temperature inequalization coefficient is almost constant. The more the minichannels of jacket, the more uniform the temperature on the same cross section, and the temperature inequalization coefficient reaches a constant value with the increase of mass flow rate. The average heat transfer coefficient of the jacket with minichannels is 0.87~2.04 times of that of the jacket without minichannels, which increases with the increase of number of minichannels. The coefficient rises with the increase of mass flow rate, but when the flow rate reaches a certain extent, the incremental rate of the coefficient is gentle, and the more the minichannels, the gentler the incremental rate. Based on the simulation data, the average Nusselt number can be expressed as Nu_（ave）=3.71696Re^（0.30341）（D_h/R_c）^（0.28574）.