Thermoelectric Power Generation from Waste Heat of Natural Gas Water Heater

Waste heat is a viable source of recoverable energy in both industrial anddomestic scenario. One of the methods to convert waste heat to electrical power is byusing thermoelectriccells.In this paper, a power generation unit consist of 60 TECs was designed, fabricated and tested with the aim to recover the waste heat from domestic natural gas water heater. In the conceptual design, the waste heat from the flue is transferred to the hot water reservoir by using heat pipes (with fins). The cold water is entering to the power generation unit and serving as coolant for the TECs and thus at the same time, the cold water is preheated prior entering to the burner and this unit as a cogeneration system. In the experiment, the power generation unit was tested in a hot water bath at varying hot water temperature (50 °C -100 °C) and different cold water flow rates, ranging from 11 LPM to 33 LPM. With 60 TECs, the power generation unit has generated the electric power at the minimum of 3.9 W and a maximum 42.4 W under maximum flow rate, with the aforementioned range for hot water temperature and incoming cold water at 19.5 °C, which corresponds to typical scenario for hot water heating system.