An integrated approach for the design and development of polymer composites to replace metallic tubes in heat exchanger applications

Heat transfer tubes are essential components in heat exchangers and many other equipment used in process industries, power generation and air conditioning systems. These tubes are conventionally manufactured from a variety of high thermally conductive metals like copper, aluminum, nickel alloys and stainless steels. These metallic tubes frequently suffer from failure due to corrosion and erosion especially in harsh environments. Moreover, metallic tubes are characterized by high costs associated with material, manufacturing and maintenance. This is the motivation for the development of non-metallic composite materials for heat exchanger applications and is the major goal of the proposed project. Polymers are attractive materials for the construction of heat exchangers but have one essential negative character, which is their low thermal conductivity. Traditionally polymers have only been known as excellent thermal insulating parts. However, things have changed recently. The usage of highly conductive fillers (such as graphite, silicon carbide, boron nitride) is now offering new dimensions in heat conduction applications such as heat exchangers. These conductive particles have to create a network of conductive paths within the polymer matrix and have to be inert to heat transfer fluids in order to avoid negative effects like corrosion, and fouling. The shape, orientation, volume and size of filling inclusions in the polymer matrix have strong impact on the thermal conductivity of the composite materials. The proposed project is focused on an integrated approach where polymer-based composites will be designed, developed and tested for enhanced thermal performance with a potential to replace metals used for heat exchanger tubes. As a first step, various heat exchanger design alternatives will be modeled and analyzed in terms of effectiveness using in-house developed codes and commercially available software to set the target thermal and structural properties, which will lead to the feasibility of replacing metallic tubes with polymer composite tubes. Based on the target thermal and structural properties, various combinations of polymer matrices and thermally conductive fillers will be identified through computational design tools that will lead to the final composite designs. This will be followed by an experimental stage where some designed composites with predicted matrix and filler attributes will be developed and tested for validation of the computational codes. A performance evaluation of the polymer composite will be conducted where lab-scale heat exchanger(s) will be built using commercially available polymer composite tubes and a detailed modeling and analysis will be performed to evaluate the potential of replacing metallic tubes with polymer composites in heat exchanger applications pertaining to power and process industries. Detailed guidelines will be devised for material selection and synthesis of polymer composites used for heat exchanger tubes with enhanced thermal performance based on proposed integrated approach.