Optimizing waste heat recovery in a dual-fuel diesel engine through thermoelectric generation and heat pipe integration

Thermoelectric generation (TEG) is a solid-state technique that efficiently captures waste heat from the exhaust of internal combustion engines. Heat pipes are passive energy recovery devices that work with minimum temperature decrease, making them very efficient. TEGs and heat pipes are distinguished by their absence of mechanical components and noiseless performance, relying solely on thermal energy for operation. This research examines the practicality of combining a device for thermoelectric generation with a heat pipe (TEG–heat pipe system) to capture and utilize wasted heat from a stationary diesel engine that operates in dual-fuel mode. The engine uses waste cooking oil methyl ester as a pilot fuel and introduces biogas (0.75 kg/h) as an induction fuel. The performance of the system was evaluated by conducting experiments at different engine loads, specifically 1, 2, and 3 kW. The experiments aimed to analyze the impact of integrating a heat pipe into the system. The findings suggest that incorporating a heat pipe with the thermoelectric generator (TEG) greatly increased the temperature difference between the modules. However, the amount of heat supplied to the modules reduced as the heat exchanger lengthened. In summary, the integration of TEG–heat pipe has shown the ability to produce additional electrical power from engine exhaust, hence enhancing energy efficiency.