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

Abstract

Because of their better chemical resistance and fouling characteristics, plastic heat exchangers are of increasing interest for lower temperature applications. However, their lower thermal performance compared to that of metal heat exchangers has prevented their widespread use and 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. In polypropylene-based PHFHEs, the overall heat-transfer coefficients achieved here, 647-1314 and 414-642 W m -2 K -1 for the water-water and ethanol-water systems, respectively, are comparable with accepted design values for metal shell-and-tube heat exchangers; further, for 20% 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 metal heat exchangers. Devices less than 30 cm (1 ft) long yielded efficiencies of up to 97.5%, up to 3.7 number of transfer units (NTU) and a height of a transfer unit (HTU) as low as 5 cm; the latter is 20 times less than the lower limit for shell-and-tube exchangers and 10 times less than the typical values for plate heat exchangers. PHFHEs achieve conductance/volume ratios 3-10 times higher 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 both thermal performance and economical grounds.

Recent research developments in polymer heat exchangers – A review

“…Zarkadas and Sirkar 74,75 reported polymeric hollow fibre heat exchangers (PHFHE) for low temperature (up to 150-200•C) and low pressure applications (test rig as shown in Figure 19). Polypropylene (PP), polyetheretherketone (PEEK) and asymmetric polyethersulfone (PES) hollow fibres have been used to manufacture heat exchangers.…”

“…The authors concluded that PHFHE could offer comparable heat transfer performance with reduced weight and cost compared with metal heat exchangers. Figure 19 Experimental testing rig for heat transfer measurement of PHFHE 74 An olefin/paraffin distillation system using hollow fibre structured packings (HFSP) (as shown in Figure 20) was proposed by Yang et al 76 . Several commercially available hollow fibres, such as PP, polysulfone and PVDF were conceptually demonstrated.…”

Measuring Selected Parameters of Polypropylene Fibre Heat Exchangers

“…A separate group of plastic heat exchangers are heat exchangers in which the heat exchange surface is made of polypropylene fibres (capillaries) [12] and [13].…”

The energy–water nexus: Water use trends in sustainable energy and opportunities for materials research and development

“…Although most nonmetallic materials lack the high thermal conductivity of traditional metal options, they open up the possibility of alternate confi gurations such as polymeric hollow-fi ber systems with heat-transfer coeffi cients that rival those of traditional heat exchangers. 41 As with the other materials innovations discussed in this section, the possibility of using nonmetallic heat exchangers in power generation is still in the early stages, and a sustained and focused R&D effort will be needed.…”