Experimental Investigation of Cylindrical Topology-Based Exhaust Thermoelectric Generator for Potential Marine Application

Abstract

Abstract. Waste heat recovery systems harness thermal energy that would otherwise be lost to the surroundings, converting it into useful power without additional fuel consumption. In marine vessels, nearly 50% of the total fuel energy supplied to onboard diesel power plants is wasted, with engine exhaust being the primary contributor. While the energy potential in exhaust gases is significant, the relatively low exhaust temperatures limit the effectiveness of conventional waste heat recovery systems. Thermoelectric waste heat recovery presents a promising solution for such applications, offering a compact and maintenance-free design. However, its widespread adoption is hindered by relatively low conversion efficiency and high material costs. Despite advancements in thermoelectric materials, optimizing the thermal design of exhaust heat exchangers remains a key challenge. Rectangular heat exchangers are often favored for these applications because maintaining effective thermal contact is more challenging on curved surfaces typical of cylindrical designs. This study presents the performance evaluation of a novel, scalable, cylindrical thermoelectric generator (TEG) designed to overcome some of these challenges. The proposed design enables seamless installation of a flat thermoelectric module (TEM) on a curved surface while preserving cylindrical flow, leading to enhanced thermal uniformity and improved overall efficiency of the TEG system. The performance evaluation of the test rig was carried out on a 3.5 kW diesel engine operating at a constant rpm under varying engine loads (no load, 25%, 50%, 75%, and 90%). The optimized three-row cylindrical TEG with 12 thermoelectric modules achieved a maximum matched power output of 18.7 W at 42.1 V with an efficiency of 2%. The findings underscore the potential of cylindrical TEG systems as a viable replacement for exhaust gas coolers on marine platforms, offering a sustainable and efficient approach to waste heat recovery.