Simulation study of a dual-cavity window with gravity-driven cooling mechanism

Utilization of high temperature cooling sources or natural energy sources can potentially contribute to improving energy efficiency in buildings. In this study, a dual-cavity window with gravity-driven cooling mechanism (GDC window) was proposed to integrate the low-grade cooling sources into the glazing system for improving the thermal performance of the window. The embedded pipes circulated with low-grade cooling water are the key component of GDC window, which can remove the absorbed solar heat and reduce the heat gain through the window. A numerical model based on CFD simulation was developed to analyze the flow characteristic and heat transfer within the GDC window. Model validation was conducted by comparing the simulation results with measurement data obtained from previous study. Numerical simulations were carried out to compare the thermal performance of GDC window with that of conventional blinds window. Sensitivity analysis was performed to evaluate the influence of some design parameters on the flow characteristic and thermal performance of GDC window. The simulated results show that compared with the blinds window, the GDC window reduces 57.4% and 40.4% of heat gain in summer for the low-grade cooling water of 18 °C and 25 °C, respectively. Reducing the flow resistance within the GDC window is significant for improving the heat removal performance of the embedded pipes. This study provides an alternative solution to integrate the low-grade cooling sources into the glazing system for enhancing the energy-efficiency and decreasing the building energy demand in cooling-dominated buildings.