A Novel Heat Recovery Device for Passive Ventilation Systems

The purpose of this study was to assess the performance of a novel heat recovery device for integration with a passive ventilation system. Current heat recovery devices are not suitable for integration with passive ventilation systems due to the high pressure drop experienced by airstreams across the devices. This would result in low ventilation supply rates required for good indoor air quality. The device could be also reconfigured to dehumidify an incoming airstream, lowering the relative humidity of the air. These modifications would improve the air quality and reduce energy demand on mechanical ventilation systems.
The novel heat recovery device was designed and constructed using 3D printing techniques and tested experimentally using different inlet conditions for two counter-current airstreams. Numerical analysis using Computational Fluid Dynamics (CFD) calculated solutions for air velocity, gauge air pressure, air temperature and relative humidity before and after the heat recovery device using the same geometry as the printed prototype. The experimental testing of prototypes of the heat recovery device validated these characteristics.
The results from the experiments and CFD analysis showed that the novel design of the heat recovery device achieved the three primary objectives of the project. The pressure drop measured across the heat recovery device was between 10.02-10.31Pa, significantly lower 150Pa experienced in standard devices. The resultant air velocity suggested that an air supply rate of 140.86 litres per second was possible, high enough to provide ventilation to a room with 17 occupants. The device was capable of increasing the temperature of the incoming airstream by up to 0.68°C when the temperature of the outgoing airstream was 40°C. Finally, the relative humidity of an incoming airstream with 100% relative humidity was reduced by up to 67.01%, at regeneration temperatures between 25-40°C, significantly lower than current temperatures of 120°C.