Nanostructured Deposition of Structurally Strong Heat Exchangers for Energy Harvesting

Abstract

The world is moving towards renewable energy and energy harvesting methods to face challenges such as global warming and environmental pollution. Thermo electric generators are devices which are used to harvest heat energy and convert it into usable electric energy. To maximise the performance of thermo electric generators efficient heat transfer devices should be used to maximise the thermal gradient across thermo electric generator module. Electrodeposition is a low-energy manufacturing process which can be used to make components using copper which has a very high thermal conductivity. Electrodeposition can produce high strength, lightweight copper components with complex internal geometries, which can be difficult to manufacture using conventional manufacturing methods. It is a layer-by-layer manufacturing process in which nanostructured components can be produced without having to use powder particles, which can be toxic and hazardous. Additives can be added to basic electrolytic solutions to improve the properties of electrodeposited materials.In this research, the above advantages of electrodeposition are exploited to manufacture strong and lightweight heat exchangers with increased heat transfer capability to maximise the energy harvesting of thermo electric generators. To achieve the above task, a 100L industrial scale tank was commissioned and used to manufacture nanostructured heat exchanger tubes with increased strength and hardness to use in heat transfer applications. Structural and thermal simulations were performed to identify the design requirements for the heat exchanger tubes. Tensile testing and nanoindentation tests were performed to determine the strength and the hardness of the material manufactured in the 100L tank. During the electrodeposition process, Thiourea was used as an additive to increase the hardness of electrodeposited copper. A method to determine, monitor and maintain the appropriate thiourea concentration in the electrolyte solution is introduced in this research. By controlling the thiourea concentration in the electrolytic solution the hardness of the product manufactured can be controlled.An innovative design of a lightweight heat exchanger tube with improved heat transfer performance is proposed. It is found that the introduced design which has turbulators integrated to the periphery of the tube has a 24% increase in heat transfer compared to the straight tubes. The use of thiourea as an additive in copper electrodeposition in a 100L tank can produce nanoengineered copper with a 98% increase in proof stress, and a 100% increase in the ultimate tensile strength compared to the normal copper. These high strength copper can be used to manufacture thin lightweight tubes without compromising their pressure-withstanding capabilities. Therefore, this work has shown the potential of electrolytic additive manufacturing to manufacture strong and lightweight heat exchangers with increased heat transfer capabilities

Date of Award	Apr 2024
Original language	English
Awarding Institution	Coventry University
Sponsors	Lloyd’s Register Foundation
Supervisor	Olivier haas (Supervisor), Rong Lan (Supervisor), David Parfitt (Supervisor) & Nigel Jennett (Supervisor)