Polymeric Hollow Fiber Heat Exchangers: An Alternative for Lower Temperature Applications

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• 作者：Dimitrios M. Zarkadas and Kamalesh K. Sirkar
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2004
• 出版时间：December 8, 2004
• 年：2004
• 卷：43
• 期：25
• 页码：8093 - 8106
• 全文大小：377K
• 年卷期：v.43,no.25(December 8, 2004)
• ISSN：1520-5045

文摘

Because of their better chemical resistance and fouling characteristics, plastic heat exchangersare of increasing interest for lower temperature applications. However, their lower thermalperformance compared to that of metal heat exchangers has prevented their widespread useand acceptance. To overcome this constraint, polymeric hollow fiber heat exchangers (PHFHEs)are proposed as a new type of heat exchanger for lower temperature/pressure applications. Inpolypropylene-based PHFHEs, the overall heat-transfer coefficients achieved here, 647-1314and 414-642 W m^-2 K^-1 for the water-water and ethanol-water systems, respectively, arecomparable with accepted design values for metal shell-and-tube heat exchangers; further, for20% of our water-water runs, it was higher than any value reported for plastic heat exchangers.The extremely large surface area/volume ratio of PHFHEs makes them more efficient than metalheat exchangers. Devices less than 30 cm (1 ft) long yielded efficiencies of up to 97.5%, up to 3.7number of transfer units (NTU) and a height of a transfer unit (HTU) as low as 5 cm; the latteris 20 times less than the lower limit for shell-and-tube exchangers and 10 times less than thetypical values for plate heat exchangers. PHFHEs achieve conductance/volume ratios 3-10 timeshigher than shell-and-tube devices accompanied by low-pressure drops, as low as 1 kPa/NTU,compared to 30 kPa/NTU for metal heat exchangers. Considering the much lower cost, weight,and elimination of metal contamination, PHFHEs can substitute metal heat exchangers on boththermal performance and economical grounds.