Polymeric Hollow Fibers Heat Exchanger with a Cross-winding Structure

audiovizuální tvorba

en

Nowadays, the using of polymeric heat exchangers becomes widespread. One type of polymeric heat exchanger is a polymeric hollow fiber heat exchanger (PHFHE). This heat exchanger consists of plastic microchannels as the heat transfer surface. A diameter of microchannels is smaller than 1 mm. The heat exchanger consists of hundreds of such fibers, which leads to a huge heat transfer area comparing with the size of the whole heat exchanger (high compactness). Polymers are not good conductor of heat generally. Used fibers have a very thin wall (about 0.1 mm), the thermal resistance of the fiber wall is not significant then. Therefore, such heat exchangers have thermal performance comparable to metal heat exchangers. Moreover, plastic heat exchangers have a number of advantages in comparison with metal heat exchangers such as a low weight, resistance to corrosion and impurities. Another important factor is that the production of PHFHE requires significantly less energy than production of metal heat exchangers, therefore, the production of PHFHE have less impact on the environment. The theory of heat transfer inside the polymeric hollow fiber is well described in the literature. However, the description of the heat transfer on the outer surface of fibers is more complex and nowadays is poorly described in literature. This work is devoted to the study of the heat transfer process in a shell-and-tube type of PHFHE developed at the HeatLab, FME, Brno University of Technology. The heat exchanger is manufactured by the cross-winding of polypropylene hollow fibers with a diameter of 0.8 mm. During these tests, water was used as a working fluid for both heat exchanger sides, in the fibers and in the shell. The paper presents the results of the PHFHE experimental investigation and their comparison with computing simulation realized in ANSYS CFX.

Nowadays, the using of polymeric heat exchangers becomes widespread. One type of polymeric heat exchanger is a polymeric hollow fiber heat exchanger (PHFHE). This heat exchanger consists of plastic microchannels as the heat transfer surface. A diameter of microchannels is smaller than 1 mm. The heat exchanger consists of hundreds of such fibers, which leads to a huge heat transfer area comparing with the size of the whole heat exchanger (high compactness). Polymers are not good conductor of heat generally. Used fibers have a very thin wall (about 0.1 mm), the thermal resistance of the fiber wall is not significant then. Therefore, such heat exchangers have thermal performance comparable to metal heat exchangers. Moreover, plastic heat exchangers have a number of advantages in comparison with metal heat exchangers such as a low weight, resistance to corrosion and impurities. Another important factor is that the production of PHFHE requires significantly less energy than production of metal heat exchangers, therefore, the production of PHFHE have less impact on the environment. The theory of heat transfer inside the polymeric hollow fiber is well described in the literature. However, the description of the heat transfer on the outer surface of fibers is more complex and nowadays is poorly described in literature. This work is devoted to the study of the heat transfer process in a shell-and-tube type of PHFHE developed at the HeatLab, FME, Brno University of Technology. The heat exchanger is manufactured by the cross-winding of polypropylene hollow fibers with a diameter of 0.8 mm. During these tests, water was used as a working fluid for both heat exchanger sides, in the fibers and in the shell. The paper presents the results of the PHFHE experimental investigation and their comparison with computing simulation realized in ANSYS CFX.

Heat transfer; polymer hollow fiber; heat exchanger; condensation

12.06.2018