Retrofit Optimization of Raised-Floor Plenum Thermal Performance for Energy-Efficient and Sustainable Operation of Non-Standard Campus Data Centers

Optimization Analysis of Thermal Distribution in a Confined Balcony Space Under Air-Conditioning Outdoor Unit Operation Using Taguchi-Based CFD Simulation

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.

Numerical validation of spatial temperature distribution in Decker’s experiment using FDS program for fully opened configuration

This paper presents a comprehensive numerical validation and performance analysis of fire-induced thermal environments in a large scale garage using Decker’s experimental data as a benchmark. Numerical simulations were performed using Fire Dynamic Simulator (FDS) to evaluate the longitudinal temperature distributions for different Heat Release Rate (HRR) from 200 kW to 4 MW for the thermostat at X = 14.3 m. The model shows a high level of accuracy with the average relative error for the peak temperatures being less than 7.1%. The study also presents the transient behavior of smoke and heat beyond validation. In the 4 MW scenario, the ceiling temperature reached 806 °C, which is a serious threat to the structural stability. Results also indicate a significant disparity between the smoke production and the exhaust capacity; the garage was totally smoke-logged within 60 s, thus effectively depleting the Available Safe Egress Time (ASET). These results highlight the importance of the combination of passive fire protection, such as thermal insulation, with optimized mechanical ventilation systems to achieve both the structural integrity and life safety during high intensity fire events.

Comparative CFD Analysis of Double-Skin Façade Cavities Under Extreme Hot-Arid Conditions

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.

Thermofluid Design and Performance Evaluation of a Natural Draft Air-Cooled Condenser Towards Annual Performance Modeling of Concentrated Solar Power Plants

This paper presents the sizing and performance evaluation of a natural draft air-cooled condenser, with a nominal heat rejection rate of 75 MWth, for implementation at a concentrated solar power plant in the Northern Cape province of South Africa. Initial sizing and optimization of the tower geometry is done with the aid of a one-dimensional thermofluid model at design point conditions. A high-density Latin hypercube sampling-based parametric sweep was conducted that covers the geometric design envelope, which is defined via the tower and heat exchanger heights, and the tower base and outlet diameters. Following this, the performance of the best-performing tower geometry is verified via detailed three-dimensional computational fluid dynamics (CFD), and the geometry adjusted slightly to achieve the desired heat rejection rate. This process includes refinement and validation of the CFD model compared to previous work, with the heat rejection rate matching the previous results within 0.1%, as well as performing grid convergence studies to ensure mesh independence. The refinements include a more direct coupling with the solver continuity equation, improving the accuracy of the heat exchanger integration via porous media, and a decrease in computational overhead to reduce the time required for parametric studies. The best-performing geometry implemented in the CFD model features a tower height of 80 m, base diameter of 58 m, outlet diameter of 40.15 m, heat exchanger height of 11.25 m and heat exchanger width of 3.551 m, with the model predicting a conservative heat rejection rate of 76 MWth at the design point. Finally, a methodology is presented to evaluate the performance of the system over the full range of ambient conditions encountered during an annual operating cycle. The methodology will be applied in further work to develop a reduced-order surrogate model for application in annual performance studies.

Experimental analysis of earth air heat exchanger for space cooling: A clean energy approach

In response to the rising energy demands and increasing reliance on air conditioning due to extreme heat in India, this study attempts to investigate the thermal performance and sustainability of a horizontally configured Earth Air Heat Exchanger (EAHE) system. Thermal modeling was developed using MATLAB R2024b and has been experimentally validated for a 4 ft. × 4 ft. × 4 ft. room. This setup was installed in Dadri, India and experimentally tested for 3 days under varying air flow velocities. The system demonstrated significant cooling potential, with temperature drop of up to 7.3°C between the inlet and outlet air of EAHE. The correlation coefficient ( r  = 0.84 to 0.89) and root mean square percent deviation (<4%) between the theoretical and experimental values confirms the reliability of the model. The validated theoretical model was then applied to a realistic sized room of 12 ft × 12 ft × 12 ft, showing an average reduction of 480 W in cooling load of room which corresponded to a seasonal energy saving of 468 kWh. The Energy Payback Time (EPBT) of EAHE was calculated to be 4.42 years and a potential carbon mitigation of 43.5 ton over 50 years and a carbon credit value of $435. This study highlights the potential of EAHE as a sustainable, low energy solution for passive cooling in India, resulting in reduced electricity consumption and carbon emissions which is aligned with UN goals namely, SDG 7, SDG 11, SDG12, and SDG 13.

Numerical Investigation of Airflow Temperature and Velocity Distribution in a Cleanroom