NUMERICAL INVESTIGATION OF HEAT TRANSFER ON THE OUTER SURFACE OF POLYMERIC HOLLOW FIBERS

Polymeric hollow-fiber heat exchangers (PHFHEs) are heat exchangers that use polymeric microchannels as the heat-transfer surface. The main purpose of this work was to determine the optimal arrangement of polymeric hollow fibers in a PHFHE. The object of study was a bundle of parallel polymeric hollow fibers with an outer diameter of 0.8 mm. The heated working fluid flew inside the hollow fibers. The heat was transferred by a cooling medium from the outside of the hollow fibers. Heat-transfer coefficients on the outer surface of the hollow fibers were obtained using computer modelling. For the case of water cooling, a sharp heat-transfer-coefficient increase was observed as the angle alpha between the hollow-fiber position and the direction of the cooling-medium flow increased to 30 degrees; however, its further increase to 45 degrees had no significant effect. With the water cooling, the total heat-transfer coefficient of the PHFHE increased by 35 % and with the air cooling, it increased by 15 %. The angle of 30 degrees can he considered as the optimal angle for manufacturing such PHFHEs.