Abstract

Thermoelectric cogeneration offers an opportunity to recover waste heat from a variety of combustion systems. Computationally efficient simulations of practical systems that allow optimization and illustrate the impact of key material and system parameters are necessary. This work compares differences in thermoelectric material conversion efficiency and system-level power generation by simulating three combustion systems: a water heater, an automotive exhaust system, and an industrial furnace. A more detailed simulation for a 15 kW tankless, methane-fueled water heater further explores the potential for small-scale, stationary cogeneration. The simulation uses the finite volume method and links convective flow in a compact heat exchanger and conduction through the system to determine thermoelectric power generation. For a single water heater pipe, 126 W of electrical power can be generated, and a typical system could yield 370 W. While varying thermoelectric material parameters such as thermal conductivity can improve thermoelectric output by over 50%, system components like thermal interface materials can severely limit power output. The impact of thermal interface resistance on power generation efficiency is established for all three combustion systems. The analysis demonstrates the impact system parameters have on the feasibility of thermoelectric waste heat recovery in combustion systems.