Theoretical Prediction of Longitudinal Heat Conduction Effects on the Efficiency of the Heat Wheel Used for Ventilation in Powerhouse Building “Kjørbo” in Norway

The present study investigates effects of longitudinal heat conduction (LHC) on the heat recovery effectiveness of the heat wheel in the Powerhouse building “Kjørbo”. The effects LHC which are usually ignored in the heat wheel design play a relatively significant role in the heat wheel with high temperature efficiency and short depth in flow direction. The correlation developed by Shah, Kays and London is applied to predict the temperature efficiency and to investigate the impacts of the LHC. Good agreements have been observed between the theoretical predictions obtained from the correlation and experimental data collected from the field test at “Kjørbo”. The influence of the depth of the heat wheel, the airflow rates on the LHC and temperature efficiency were analysed. It was found that the heat wheel has difficulty to achieve a high temperature efficiency (85%) due to the effects of LHC. There is an optimal depth design for heat wheel in the flow direction to recovery maximum thermal energy with low pressure loss with considering the LHC effects. The present study provides preliminary analysis to optimize the heat wheel design and operation with the LHC being taken into account.