Experimental study of convective heat transfer in a ventilated rectangular cavity

Abstract

This work presents the design, construction, and evaluation of a rectangular ventilated cavity. The cavity has a heated wall, a fixed air inlet port, and an air outlet port that can change in four different configurations: C-1, the outlet gap is on the upper side of the left wall; C-2, the outlet is on left of the top wall; C-3, the outlet is in the middle of the top wall; and C-4, the outlet is on right of the top wall of the cavity. The experimental tests were carried out with a heating power of 200 and 400 W. The measured indoor air temperatures in nine points, the wall surface temperatures, and heat flows are reported for validation of computer codes. Then, the numerical modeling for the ventilated cavity was done with an in-house code based on the finite volume method to show the relevance of the experimental data. From experimental result for a heating power of 400 W, the configuration C-4 presented the smallest air temperature increment of 3.3°C and the lower average indoor air temperature. In addition, configuration C-4 was more efficient to remove heat than the other configurations, with a maximum percentage of heat removed being 4.75%, 4.32%, and 2.11% more than configurations C-1, C-2, and C-3, respectively. From the validation, the maximum error was 9.9% and 11.5% for the test of 400 and 200 W, respectively. In general, most comparison points had an error smaller than 5%. From both comparisons, it can be concluded that numerical results have an acceptable quantitative approximation.

CFD Analysis of Different Ventilation Strategies for a Room with a Heated Wall

“…The fact that Configuration (II) offers the highest flow rate among three proposed configurations, as seen in Figures 5-7 and 9, agrees well with the experiments by Macias-Melo et al [27] and Vaquez-Ruiz et al [28]. They reported that for a room with a heated wall, the highest airflow rate is obtained when the opening or the roof vertical solar chimney is right on top of the heated wall.…”

“…The problem of the natural ventilation of a room with a wall heated by solar radiation has also been considered in many previous studies. With a simple opening at the top of the room with one vertical wall heated, Marcias-Melo et al [27] showed that the most efficient case for removing heat was when the opening was on the top of the heated wall. To enhance the ventilation rate, Vazquez-Ruiz et al [28] added a solar chimney to the top of the room.…”

Factors affecting the performance of ventilation cavities in highly insulated assemblies

“…It seems that increase of the exterior thermal resistance (R value) may improve cavity conditions in HI structures, but finding an optimal ventilation rate is challenging. The results of Macias-Melo et al (2018), Langmans et al (2016, Viljanen et al (2020) and Jensen et al (2020) suggest that exterior insulation may reduce the ventilation rate of cavity in summer, because it partially prevents the warming of the cavity by solar irradiation. Earlier studies aimed at improving the hygrothermal conditions in the cavities of HI walls have not been found.…”

Thermal performance analysis of a naturally ventilated system using PMV models for different roof inclinations in composite climatic conditions

“…Subudhi et al [33] concluded from their study that natural ventilation depends on the position and size of the openings. Xamán et al [34], Macias-Melo et al [35], Serrano-Arellano et al [36] and Xamán et al [37] too established that ventilation, and hence, thermal comfort is dependent on the position of the opening. Moosavi et al [38] did a comprehensive review of earlier studies done for different design considerations in a building to obtain an optimum and effective ventilation and suggested the outlet opening size as the most influential parameter affecting the behaviors of the ventilation pattern along with the indoor thermal condition.…”