Review of polymer compact heat exchangers, with special emphasis on a polymer film unit

Abstract

This paper comprises of a general review on polymer compact heat exchangers (PCHEs). The first part outlines the types of polymers used and their respective characteristics. The second part presents the relative merits and the current PCHEs available in process industries. Following this, the recent advances in the field are addressed and finally, their future applications are discussed. In this paper, the types of polymers that can be used, as an alternative material of construction to metals in heat exchangers have been listed out. The relative merits of using polymers over metals are shown through a quantitative comparison, between PVDF and Hastelloy heat exchangers. When incorporating the same tube dimensions, thickness and fluid film coefficients, significant cost savings can be achieved using the PVDF exchanger. The descriptions of the three main categories of polymer compact heat exchangers currently available in industry are then provided to some detail. Following this, the polymer film compact heat exchanger (PFCHE) design is introduced to address the disadvantages of both metallic and present polymer heat exchangers. Notable design aspects of the unit are the use of thin (100 μm) polymer films to address the thermal conductivity deficiency and the adoption of laminar flows to deal with high-pressure drops. In addition, the presence of corrugations on the films promotes better fluid mixing, which increases the thermal performance of the unit. Due to its excellent thermal, chemical and mechanical stability, PEEK (poly ether ether ketone) is adopted in the PFCHE design. The benefits of the PFCHE design aspects (thin films, corrugations, narrow channels and developing laminar flow) are then highlighted. The paper concludes with a listing of the potential applications for the PFCHE in the process industries, based on the incentive provided by available polymer exchanger designs, particularly those incorporating thin polymer films.