TAILIEUCHUNG - Heat Transfer Handbook part 140

Heat Transfer Handbook part 140. The Heat Transfer Handbook provides succinct hard data, formulas, and specifications for the critical aspects of heat transfer, offering a reliable, hands-on resource for solving day-to-day issues across a variety of applications. | COLUMNS AND OTHER CONTACTORS 1389 important in vaporizing systems where the droplets can grow in size quite substantially throughout the column. Generally heat transfer per unit of droplet surface area decreases as the droplet grows. Another positive factor is that the wake behind the droplet can be stripped away at each tray. The net result of both of these aspects is that the heat transfer can be increasedsubstantially comparedto a corresponding spray column. Packed Columns Another approach to improving on spray column performance is to use packed-bed arrangements. In this configuration the main contacting zone as shown in the spray column diagr mi would be filled with objects of petentlally any shape. Itrnh packed beds and laf nk d towert aan hc sonyasted to spray columns is sevaral ways. Ce atalyly the cost is higher than the latter for either of these options. The spray column can yield higher peeSormance than that orr cohmuis with urten s sue . flee report by Kunesh 1993 . However there are situations when backmixing can seriously degrade performance of spray columns. Also if a vapor is introduced into a thick layer of liquid u i h as might be the caee orr a ppaay column a 1x 111 pedume drop through the liquid might be encountered. This would increase the power required for moving the vapor. In both of these cases packedcolumns or other devices with internals might offer beneficial performance improvements. Usually packings are used when a hquid ii in oontact whh a gao ov vEtoor. Ii is desiredto have as much liquidsurface in contact with the vapor or gas as possible. As the liquid flows over the packings essentially wetting the t i the area in contact between the two fluids is related to the area of the packing. Packings can also be used in liquid-iiquid iystems to ostlrt m sumovtng toe waee fomm 110 yifpessed ilqaia and increasing the heat transfer. Although a simple configuration can be imaginedwhere packedspheres are used in fact this is not a .

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