Toward zero-carbon HVAC for temperate regions: Cooling using Thermoelectric Heat Exchanger: An Experimental Study

As buildings contribute up to 40% of greenhouse gas emissions, exploring eco-friendly and sustainable HVAC and heat recovery solutions is vital. This experimental study presents a novel integration for passive wind towers that use thermoelectric heat exchangers to cool or heat fresh air as it enters a room. The proposed method utilises thermoelectric modules (TEM) also known as Peltier devices or thermoelectric coolers (TECs) to regulate the surface temperature of heat pipes within a wind tower. The TECs are capable of cooling as well as heating based on the current polarity. This paper focuses on investigating the cooling potential of this system through a range of experimental and CFD analyses. The primary experimental setup consisted of heat pipe(s), TEC module, heatsink and fans for heat dissipation. Water-filled aluminium heat pipes allow effective and consistent temperature distribution across their length (1m). Preliminary results show a reduction of pipe surface temperatures by up to 11.8ºC using 40.8W of power at natural convection (indoor). Despite the rated voltage of 12V, experimental results showed 7.5V of input voltage delivers an optimal temperature drop (10.1ºC) to power consumption (13.5W) ratio. Convection tests showed reduced temperature drop with higher wind velocities, however, an addition of a volume control damper (at 30° opening) before the heat pipes was proposed as a solution to restore optimum cooling. The CFD model of a wind tower mounted on top of a closed room having two rows of heat pipes was used for simulations. A total of 35 heat pipes were modelled to reflect steady state temperatures from the experimental data, which showed temperature reductions below the pipes of 0.9ºC with no damper and 3.5ºC with damper at 1m/s supply wind velocity and of 3.7ºC with no damper and 6.6ºC with damper at 0.5m/s supply wind velocity. The preliminary results showed a viable opportunity for a solar-powered thermoelectric heat exchanger system on passive wind towers. The proposed TEC-based cooling offers a low-maintenance, sustainable and environmentally friendly solution to meet the heating and cooling demands of buildings in temperate regions. Further design optimisation and improvements are recommended to maximise the cooling performance whilst ensuring ventilation requirements.