Effects of geometrical parameters on the thermohydraulic characteristics of periodic cross-corrugated channels

Abstract

Ventilation air heat recovery used in building energy conservation involves simultaneous heat and moisture/ mass transfer and is characterized with small temperature and moisture partial pressure differences. It is critical to consider the trade-offs between heat and mass transfer effectiveness and pressure loss. This study is the exploration of using numerical heat transfer analysis for this purpose. Simulations are performed to study the geometric effect on thermohydraulic characteristics of a periodic cross-corrugated channel for the Re range of 200-3000. The effect of Apex angle and aspect ratio on heat transfer, pressure drop and thermohydraulic performance in the corrugated channel is investigated. To accurately predict the transitional flow in the topology, a model performance evaluation is conducted in two steps through the cross comparisons between predictions and related correlations (or experiment results). Of the seven turbulence models selected, the Reynolds stress model fits the correlation and experiment the best and thus is employed for comparative study. The results show that the Apex angle strongly influence the heat transfer and pressure loss in a triangular cross-section corrugated channel. For the purpose of heat transfer enhancement, cross-corrugated triangular channels at the 90° and 120° Apex angles are recommended. The aspect ratio has a relatively greater impact on flow frictional loss, compared to its effect on the heat transfer for the studied cases. For this flow regime, the cross-corrugated triangular duct with the Apex angle of 150° is shown to be the optimum choice over all the studied channels. The JF factor is enhanced by 4.1-7.0 times that in a triangular channel with Apex angle of 90°.