Performance analysis of a thermoelectric generator applied to wet flue gas waste heat recovery

Abstract

Thermoelectric generation technology, which is used to recover the waste heat of wet flue gas, is studied by establishing a mathematical model to analyze the generation characteristics of wet and dry flue gas. The effects of flue gas parameters are analyzed and discussed. The results show that differently from dry flue gas, when condensation occurs in wet flue gas, it not only releases a large amount of latent heat, but also increases the heat transfer coefficient between the flue gas and the module, and an increase in module area creates an inflection point in the output power curve for wet flue gas. Moreover, the maximum output power of wet flue gas is significantly larger than that of dry flue gas. The maximum output power and corresponding module area are clearly observed to increase as the gas flux increases, but the extreme value of generating efficiency decreases slightly. Specifically, as flue gas temperature increases, the maximum output power increases, whereas the optimal module area required remains unchanged beyond a certain temperature. In addition, an increase in the flue gas temperature has a greater impact on the performance of sensible heat. When the water vapor content decreases to a certain value, the maximum output power can be obtained without condensation. Therefore, there exists a critical water vapor content that can directly determine whether the latent heat of condensation can be recovered. This critical value increases as the flue gas temperature increases. Furthermore, increasing the flux ratio of cooling water and flue gas can also effectively reduce this critical value.