Double-skin façades (DSFs) can moderate heat transfer and airflow between the outdoor environment and the building interior; however, their performance in hot-arid climates is highly dependent on cavity geometry, ventilation arrangement, and the interaction between the airflow and any active cooling surfaces. The objective of this study is to establish, under a single idealised extreme hot-arid design point, how sealed, ventilated and actively cooled double-skin façade cavities differ in their predicted temperature, velocity and turbulent kinetic energy fields, and which arrangements merit controlled follow-up study. The four configurations are treated as an idealised comparative case study rather than as validated building-performance predictions. This exploratory study uses computational fluid dynamics (CFD) to compare the aerothermal behaviour of four DSF cavity configurations under prescribed external air and outer-wall temperatures of 50 °C, an inner-wall temperature of 24 °C, and an external inlet velocity of 3.06 m/s. The configurations comprise a sealed 0.4 m cavity (M1), a wind-driven ventilated 0.4 m cavity (M2), the same ventilated cavity with six 25 mm cooling pipes at 10 °C (M3), and a concept-stage lateral-flow arrangement combining a 0.10 m cavity, a 0.025 m slit and four 80 mm cooling pipes at 10 °C (M4). The simulations employ the standard k-ε turbulence model with fixed thermal boundary conditions. Along the reported sampling lines, M1 exhibited a nearly uniform air temperature of approximately 45.7 °C, whereas M2 remained close to the imposed 50 °C external-air temperature. M3 produced lower temperatures in the immediate vicinity of the cooling pipes, but most of the sampled profile remained near ambient conditions. M4 exhibited a broader spanwise temperature range of approximately 26.9–50 °C, with local pipe-adjacent air temperatures approaching 24 °C and cooler regions developing along parts of the lateral flow path. The findings provide preliminary concept-screening evidence and support further controlled parametric analysis, higher-fidelity modelling, and experimental validation.
The thermal performance of double‐skin façades (DSFs) is strongly affected by the design of shading devices integrated within the cavity. While previous studies have mainly focused on blind angle and position, the influence of blind slat size remains insufficiently explored, particularly under hot climate conditions. In this study, a two‐dimensional computational fluid dynamics (CFD) model, validated against experimental data, is developed to investigate airflow patterns, temperature distribution, and heat transfer within the DSF cavity. Five blind sizes ranging from 40 mm to 240 mm are analysed. The results show that increasing blind size enhances solar radiation absorption, leading to higher cavity air temperatures, with peak values reaching approximately 315.8 K. However, larger blinds significantly reduce the inner glass temperature and decrease heat transfer towards the indoor environment due to improved shading performance. In addition, the airflow structure is modified, with noticeable changes in velocity distribution and natural ventilation behaviour within the cavity. Overall, the findings highlight that blind size is a key design parameter that can improve the thermal behaviour of DSF systems and reduce heat gains in buildings located in hot climates.
Maha Fguiri, Ali Fguiri, M. Jeday et al.· Bauphysik· 0 citations
This study analyzes the thermal behavior and airflow characteristics within a confined balcony space under typical hot and humid climatic conditions in Ho Chi Minh City. A computational fluid dynamics (CFD) model was developed and numerically assessed through mesh-independence and convergence analyses, incorporating an external air domain to ensure realistic boundary conditions. The Taguchi method, combined with analysis of variance (ANOVA), was employed to evaluate the influence of four key factors: number of outdoor units, installation position, ventilation opening ratio, and ambient wind velocity. The results indicate that the number of outdoor units is the dominant factor affecting the average balcony temperature, contributing the largest variation. Ambient wind velocity has a moderate influence, while installation position and ventilation opening ratio exhibit relatively minor effects. The consistency between Taguchi and ANOVA analyses confirms the reliability of the findings. Based on the signal-to-noise (S/N) ratio analysis using the “smaller-thebetter” criterion, the optimal configuration was identified as A1-B2-C1-D1. A verification simulation showed that the model converged and achieved an average temperature of 304.24 K, significantly lower than in the initial simulation cases. The findings highlight the importance of controlling internal heat sources and optimizing airflow pathways to improve thermal conditions in confined balcony spaces. This study provides practical insights into the design and installation of airconditioning systems in urban residential buildings.
Hung-Son Dang, Thi-Anh-Tuyet Nguyen, H. Lai· 2026 11th International Conf...· 0 citations
To address uneven temperature and relative humidity distributions, localized heat accumulation, and insufficient air velocity in an enclosed stacked-cage laying hen house, a three-dimensional computational fluid dynamics (CFD) model of the laying hen house was developed using field-measured structural and environmental data, and a porous-media model was established for the cage zone. Model validation showed that the normalized mean square error (NMSE) values for temperature, relative humidity, and air velocity were all below 0.25, confirming the reliability of the CFD model. Through visualization analysis of the contour maps, the problems of uneven airflow distribution in the original ventilation system and significant heat accumulation at the fan end were identified. On this basis, numerical simulations were conducted for six air-inlet configurations by varying two key parameters: air-inlet spacing and air-inlet number. The simulation results showed that, compared with the original model, the configuration with an air-inlet spacing of 1.14 m and a total of 32 air inlets on the two gable walls improved the uniformity of temperature, air velocity, and relative humidity by 18.00%, 10.54%, and 18.38%, respectively, while reducing the mean effective temperature index (ETI) in the cage zone by 0.5 °C. This configuration effectively alleviated localized heat accumulation and improved air-velocity uniformity. These findings provide a theoretical basis and technical support for the structural optimization and environmental regulation of enclosed stacked-cage laying hen houses.
Natural evaporative water coolers provide refrigerant-free, ultra-low-energy water cooling for hot–dry climates, yet computational fluid dynamics (CFD) studies of such systems at full device scale are absent from the literature. This paper develops a three-dimensional CFD model of a complete natural evaporative water cooler in OpenFOAM and validates it season-wise against the authors' experimental campaign at the Taguchi-optimised operating point of each season. The water side resolves the entire 76.2 m helical copper coil (inner diameter 4.5 mm, 80.85 turns) with a structured butterfly O-grid mesh of 155,200 hexahedral cells generated by a purpose-built sweep algorithm; the wetted evaporative pad is represented by an external film boundary condition referenced to the ambient wet-bulb temperature. A companion air-side model treats the pad–coil assembly as a Darcy–Forchheimer porous zone inside the cooler housing. The film coefficient was calibrated once, at the summer optimum only (h = 41 W/m²·K); the same value was reused unchanged for the winter simulation — making winter a genuine blind prediction — while the monsoon value (h = 28 W/m²·K) was estimated a priori from the resistance network for the reduced sprinkle rate and humid air. The model reproduces the measured seasonal temperature drops of 9.7, 5.4 and 5.6 °C with deviations of −0.5%, −1.6% and −1.2% for summer, monsoon and winter respectively, and cooling effectiveness within 2 percentage points of experiment in all seasons. The calibrated wetted-pad conductance is 1.9 times the dry-pad analytical estimate, quantifying the contribution of direct film evaporation, and the resolved Dean vortices (De ≈ 340) explain the weak experimental sensitivity to coil water velocity in summer.
M. Trivedi, Diptesh R. Patel· International journal of com...· 0 citations
: The complex interplay of heat transfer mechanisms, namely conduction, natural convection, and radiation, within hollow block roofs exposed to solar irradiation gives rise to an inherently nonlinear thermal exchange problem. A key yet insufficiently explored question is the extent to which this nonlinearity governs the macroscopic thermal behavior of roofing systems. In this study, a computational investigation is conducted on two roof configurations incorporating five hollow block geometries representative of common construction practices in hot climatic regions. The objective is to identify the optimal design capable of minimizing heat losses and thereby enhancing the overall thermal performance of buildings. The outer roof surfaces are subjected to terrestrial solar radiation and convective exchange with the outdoor environment, whereas the inner surfaces interact with indoor ambient conditions. The governing partial differential equations and associated boundary conditions are discretized using the finite volume method in conjunction with the SIMPLE algorithm. Particular attention is devoted to examining the effects of solar radiation intensity, solid wall thermal conductivity, and cavity aspect ratio on fluid flow characteristics and heat transfer across the roof structures. The results highlight the critical importance of incorporating solar radiation effects into roof design.
Ayoube Baalla, M. Najjaoui, T. Ait-Taleb et al.· Fluid Dynamics & Materia...· 0 citations
Increasing heat transfer in double-pipe heat exchangers (DPHEs) is an interesting topic due to challenges that still remain to be solved, especially when working under low-to-moderate flow rate regimes where poor mixing and thermal boundary layers reduce the effectiveness of convection. Despite numerous studies conducted on the basis of metal-foam and insert-type enhancement methods, existing research mostly covers completely-filled or simplified partially-filled cases. The present work numerically investigates thermo-hydraulic performance of a countercurrent DPHE using various structured metal-foam inserts installed in the annulus region. In particular, a three-dimensional CFD model of the studied geometry was successfully validated with previously reported experimental data with deviations not exceeding ±5 % for the average Nusselt number and ±7 % for the friction factor. In simulations, hot water flows inside the inner pipe at temperature 75 °C and 3 L/min, whereas cold water enters the annulus at temperature 30 °C with flow rates of 1 to 9 L/min, equivalent to Reynolds numbers of 205-1845. In total, nine geometries were considered including a smooth basecase, fully filled foam geometry, circular ring foam baffles, continuous three-strips foam geometry, as well as five interrupted three-strips foams with 5, 7, 9, 11, and 13 interruptions, respectively. For all cases, copper foam with porosity 0.9 and pores density 40 PPI was used, while water thermophysical properties were assumed constant. It was found that inserting structured metal-foam increases heat transfer due to mixing effect and repeated disruption/regeneration of thermal boundary layer. As compared with the smooth base case, the fully filled metal-foam geometry showed the largest improvement in heat transfer performance by providing up to 15 times higher values of the average Nusselt number. Nevertheless, the interrupted strips foam designs demonstrated the best thermo-hydraulic characteristics in terms of trade-off between enhanced heat transfer and increased pressure drop penalty. In particular, the interrupted foams led to approximately 1.5-3 times higher friction factor than the smooth geometry, while performance evaluation factor PEF equaled approximately 2.8. Therefore, it can be concluded that interrupting structured metal-foam inserts could be considered promising passive enhancement approach for low-to-moderate Reynolds number DPHEs.
Inas Faiz Kadhim, A. J. J. Al-jassani, H. Al-Bugharbee· Mathematical Models in Engin...· 0 citations
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