A comparison between HIGHFLUX and plain tubes, boiling pentane in a horizontal kettle reboiler

An experimental study has been undertaken into the enhancement obtained in the heat-transfer coefficients when HIGHFLUX tubes are used in preference to plain tubes while boiling pentane. The study involved two experimental facilities, a single-tube pool boiler and a 241 tube, 17 row by 17 column, thin slice kettle reboiler. The pool boiling results show that the HIGHFLUX tubes produce heat-transfer coefficients that are up to five times larger than their plain tube counterparts. In flow boiling the enhancement is 3-6 times. In both cases, HIGHFLUX tube performance is shown to deteriorate when small degrees of subcooling are present in the liquid. The deterioration still leaves the HIGHFLUX tubes with a significantly higher heat-transfer coefficient than the plain tubes. Existing flow boiling design methodologies are shown to produce performance characteristics that HIGHFLUX tubes do not follow. © 2002 Elsevier Science Ltd. All rights reserved.