Influence of design parameters of a polypropylene hollow-fibre heat exchanger on its thermal performance

Abstract

The article presents potential applications of fibres made of polypropylene in new types of heat exchangers. It describes the properties of polypropylene and the method of sealing fibres in the potting process. An analysis was carried out to calculate the thermal capacity and pressure loss of the exchanger. An experimental stand was used to examine the heat transport in a shell-and-tube exchanger in a counter-flow set-up. Measurements were carried out with several designs of this type of exchanger comprising transparent as well as porous fibres. The experiment confirmed that transparent fibres in an exchanger provide heat transfer that is 20 % better than that of the porous fibres. In the case of an exchanger comprising 1400 transparent fibres with an outer diameter of 0.275 mm. the overall heat-transfer coefficient k, at a flow rate of secondary water of 150 was found to be 603 W.m(-2).K-1. With the use of "whirlers" on the outer side of fibres, the k value elevated to 933 W.m(-2).K-1, and at a flow rate of 200 L.h(-1) the heat-transfer coefficient amounted to as much as 1191 W.m(-2).K-1.