ENERGY RECOVERY FROM DOMESTIC HOT WASTEWATER USING A HEAT PIPE-INTEGRATED THERMOELECTRIC GENERATOR

In this study, an experimental investigation was conducted to evaluate energy recovery from domestic waste hot water using heat pipes and thermoelectric generators. The system, designed to simulate real conditions, sourced hot water from a thermostatic water bath and included six thermoelectric elements. Experiments were performed at water bath temperatures of 30-50°C and mass flow rates of 3, 4, and 5 g/s. Heat pipes were integrated on the cold sides of the thermoelectric elements to remove heat and assess the impact on electrical power output and generator efficiency. The performance of the heat pipes in dissipating heat and their effect on the system is discussed, as well as the impact of cooling the condenser sections of the heat pipes by natural and forced convection. As the water bath temperature increased, the temperature difference across the thermoelectric elements grew, leading to higher power generation. Similarly, increasing the mass flow rate transferred more energy to the system, further enhancing power output. However, efficiency decreased because the increase in electrical power was smaller than the corresponding rise in energy input. The maximum electrical power of 0.043 W was obtained with fan-assisted heat pipe cooling at 50°C and 5 g/s, while the highest efficiency of 2.2% occurred at the same temperature with 3 g/s. Overall, the results demonstrate the significant potential of domestic waste hot water for energy recovery using thermoelectric generators.