ABSTRACT Numerical models are central to the design of phase‐change material (PCM) thermal systems, yet their credibility is more often asserted than demonstrated. Although reviews of PCM materials and applications are abundant, comparatively little attention has been given to how modeling assumptions, parameter choices, and validation practices determine predictive reliability. This review examines numerical models of solid–liquidphase change from three perspectives: benchmarking, parameter sensitivity, and application‐oriented model selection. Enthalpy‐based, enthalpy–porosity, effective heat‐capacity, simplified conduction, sharp‐interface, reduced‐order, and data‐driven approaches are assessed in terms of physical fidelity, computational cost, treatment of natural convection, interface representation, parameter sensitivity, and validation evidence. Particular attention is given to the mushy‐zone constant, which can alter melting time, flow structure, and phase‐front position while leaving temperature predictions apparently acceptable. Representative benchmarks involving cavity melting, cylindrical tubes and capsules, optical imaging, and X‐ray computed tomography are used to clarify adequate validation evidence and explain why temperature‐only comparison is insufficient. Application‐specific validation requirements and modeling risks are synthesized for building envelopes, battery and electronics thermal management, latent‐heat thermal‐energy‐storage units, solar systems, and reduced‐order or AI‐based frameworks. The analysis shows that no model is universally optimal: credible PCM simulation requires matching model complexity to the dominant physics, available validation observables, and intended engineering decision. Research priorities include standardized open benchmark data sets, systematic reporting of parameter sensitivity, uncertainty‐aware calibration, and hybrid physics–data‐driven models.
ABSTRACT Paraffin wax (PW) is a commonly used phase‐change material (PCM) for latent heat energy storage; however, its thermal conductivity is lower (0.21 W/[m·K]), making it an alternative to choose nanoenhanced PCM. In this study, activated carbon (AC) nanoflakes derived from the waste biomass (synthesized from the dead leaves of Kigelia africana ) were treated chemically with reduced graphene oxide (rGO) nanosheets to derive a hybrid nanocomposite in a 50:50 binary mixture and dispersed in PW with concentrations of 0.1 and 0.3 wt% through a probe sonication process to attain a homogeneous mixture. The synthesized hybrid composites are characterized through X‐ray diffraction and field‐emission scanning electron microscopy. The thermal characteristics of the prepared samples, thermal behavior during phase change, thermal conductivity, and thermal stability of the composite are measured using differential scanning calorimetry, a TEMPOS thermal properties analyzer, and thermogravimetric analysis (TGA), respectively. Results showed that the composite nanoadditive PW is superior to single nanoplatelets (rGO). The thermal conductivity of the PW is improved from 0.25 to 0.49 W/(m·K) with rGO–AC and 0.41 W/(m·K) with rGO using 0.3 wt%, with a relative improvement of 96% and 64%, respectively, compared with the PW. It is also found that the composite nanoparticle in PW retained more latent heat than neat PW: at 0.1 wt%, the thermal energy storage efficiency is 105.4% with rGO–AC, indicating no measurable loss of latent heat within the measurement uncertainty, compared with 92.6% with rGO. TGA showed that both additives improved the thermal stability of the wax. With 0.1 wt% rGO–AC, the onset decomposition temperature increased by and the temperature of maximum mass‐loss rate by . The improved performance of the hybrid is attributed to the AC nanoflakes anchored within the rGO sheets, which limit sheet restacking and enhance their dispersion in the wax. The results show that a low loading of a hybrid rGO–AC additive, derived in part from waste biomass, can markedly improve heat transfer in PW while retaining its heat‐storage capacity.
ABSTRACT Solar stills provide a simple, low‐cost, and sustainable solution for freshwater production in arid and water‐scarce regions. However, their widespread adoption remains constrained by low freshwater productivity. The present study numerically investigates the effect of film cooling on the thermal performance and freshwater productivity of a conventional solar still. A transient two‐dimensional finite‐difference model is developed to solve the coupled energy equations governing the system components, providing high‐fidelity spatial and temporal representations of the temperature field and the freshwater productivity. The numerical model is validated against experimental data available in the literature. The results show that the glass‐cover cooling technique increases the maximum water‐to‐glass temperature difference from 8.31°C to 18.15°C. In addition, the daily freshwater productivity increases from 2.69 to 3.20 kg.m −1 .day −1 , representing an improvement of 18.95%. The average energy efficiency also increases from 24.24% to 29.18%. Furthermore, a parametric analysis identifies an optimal cooling‐water film thickness of 5 mm and a volumetric flow rate of 0.1 L.s −1 .
ABSTRACT The rapid advancement of modern electronics resulted in intensified thermal management challenges, and positioned microchannel heat sinks (MCHSs) as a promising technology to dissipate high heat fluxes in next generation electronics. This review critically examines recent developments in passive thermo‐hydraulic enhancement of MCHSs, with emphasis on three major approaches: channel geometry modification, internal flow modifying structures, and working fluid enhancement. The reviewed studies are synthesized according to their underlying heat transfer mechanisms, including secondary flow generation, boundary layer redevelopment, vortex‐induced mixing, wake interaction, recirculation, and increased effective heat transfer area. Particular emphasis is placed on the balance between heat transfer enhancement and hydraulic losses, as an increase in Nusselt number alone does not necessarily indicate better thermo‐hydraulic performance. The review considers integrated and hybrid enhancement configurations, as the combined use of different flow disturbing elements provided improved heat transfer with properly designed interaction. Excessive flow blockage resulted in a pressure drop penalty and reduces the overall benefit. Nanofluids and hybrid nanofluids are also discussed, considering their potential to enhance thermal performance as well as practical concerns such as stability, increased viscosity, particle sedimentation, and higher pumping requirements. In addition, emerging AI/ML approaches are reviewed across performance prediction, deep learning, physics‐informed modelling, surrogate‐assisted optimization, reinforcement learning, and CFD–ML frameworks. The analysis indicates that AI/ML can accelerate design exploration and optimization within defined parameter domains, but limitations associated with dataset quality, extrapolation, uncertainty, and independent validation remain. Finally, key research gaps involving experimental validation, manufacturability, multi‐parameter optimization, transient thermal behavior, uncertainty quantification, and intelligent thermal control are identified. The review provides an integrated perspective for developing high performance and practically viable MCHSs for next‐generation electronics cooling.
ABSTRACT This study explores recent advances in cord‐based wick systems that regulate water depth in distillers, a key parameter influencing desalination performance. Maintaining a shallow water layer generally improves output, and cord wick technology minimizes thermal losses by selectively absorbing only the saline water that evaporates. Several design modifications—including reflectors, air‐circulation fans, and baffles integrated with phase change materials (PCMs)—have substantially increased the efficacy of cord‐wick distillers. For instance, a configuration combining cords, mirrors, a fan, and baffles achieved a 264% rise in freshwater yield. Beyond productivity gains, these improvements also provide ecological benefits, including an estimated annual reduction of approximately 28.71 tons of CO 2 emissions, as well as water purification costs ranging from USD 0.01 to 0.0185 per liter. These findings support continued efforts to maximize desalination efficiency through cord wick‐based approaches in solar distillation systems. Our work demonstrates a strong commitment to advancing the United Nations Sustainable Development Goals (SDGs), particularly SDG 6: Clean Water and Sanitation.
