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As a common means of building ventilation, monitor roofs have been employed to introduce indoor airflow via thermal buoyancy and/or wind. However, preventing rainwater from entering the room via the monitor roof has become an important practical issue. In this study, the effect of installing a rain shelter on the natural ventilation performance of a monitor roof was studied via computational fluid dynamics (CFD). The experimental monitor roof was 1.2 m in width and 1.2 m in height, with/without eave overhang. The results revealed that after rain shelter installation, a rain protection effect was achieved, and the ventilation rate increased because of flow structure conformity, with an overall average effectiveness of 1.02. The ventilation potential and the basic flow patterns corresponding to different design schemes were described in detail. Moreover, a correlation equation for the hybrid natural ventilation rate under the recommended design schemes was provided. HIGHLIGHTS: The natural ventilation performance of a monitor roof with a rain shelter was numerically investigated. The parameter effectiveness was considered to assess design alternatives. A rain protection effect was achieved, and the ventilation rate increased. Correlation equations of the induced natural ventilation rate were established. [ABSTRACT FROM AUTHOR]

A trend toward high power and relatively small package sizes in electronic components has resulted in a dramatic increase in the corresponding heating flux; thus, the enhancement of internal convection has been a focus of attention. In this study, to improve the thermal efficiency of the internal flow, the forced-convection heat transfer of concurrent flows of functional working fluids through the outer annulus/inner tube of a concentric double tube was investigated experimentally and compared to that of an identical double tube filled with water, for which limited information is available. The fluids in the outer annulus/inner tube were 0.5% Al2O3-water nanofluid/pure water, 1.0% Al2O3-water nanofluid/pure water, and 1.0% Al2O3-water nanofluid/4.63% phase-change nanofluid. The nominal values of the main parameters were as follows: heating power = 120 W, 160 W, and 200 W; Reynolds number = 800, 1300, and 1700; and concurrent flow ratio = 0.1, 0.29, 0.45, 1.0, 1.6, and 2.38. The results indicated that when the outer annulus and the inner tube were filled with a 1.0% Al2O3-water nanofluid and a 4.63% PCM emulsion/or water, respectively, a high total flow rate and high flow ratio could suppress the rise in the wall temperature and increase the average heat transfer coefficients. Although using a functional working fluid may enhance heat transfer, this gain is considerably smaller than the increase in the pressure drop, resulting in the figures of merit for nearly all the considered cases being lower than 1. [ABSTRACT FROM AUTHOR]

With growing concerns about building energy consumption, thermoelectric generators (TEGs) have attracted significant attention for their potential to generate clean, green, and sustainable power. This comprehensive review explores the applications of thermoelectric generators (TEGs) in building systems, focusing on recent advancements from 2013 to 2024. The study examines TEG integration in building envelopes, including façades, walls, windows, and roofs, as well as non-integrated applications for waste heat recovery and HVAC systems. Key findings highlight the potential of TEGs in energy harvesting and thermal management, with façade-integrated systems generating up to 100.0 mW/m² and hybrid LCPV/T-TEG systems achieving overall efficiencies of 57.03%. The review also identifies critical parameters affecting TEG performance, such as solar intensity, thermoelectric arm length, and PCM melting temperature. Despite promising results, challenges remain in improving overall system efficiency, cost-effectiveness, and scalability. Future research directions include developing more efficient thermoelectric materials, optimizing system designs for various climatic conditions, and exploring integration with smart building management systems. This review provides valuable insights for researchers and practitioners working towards more energy-efficient and sustainable building designs using TEG technology. [ABSTRACT FROM AUTHOR]

In energy storage, energy transfer and thermal management applications, phase change material (PCM) nanoemulsions are promising; however, supercooling has always been an important issue in the research and application of PCMs. When supercooling occurs, the efficiency of energy storage applications may possibly be reduced. In this study, n-octadecane and n-eicosane (as core materials), and nonionic surfactants (hydrophile-lipophile balance value = 8) were used to prepare n-octadecane and n-eicosane emulsions with a mass concentration of 1–9%. The effects of particle size and operation temperature on emulsion viscosity were investigated, and the relationships between supercooling and the PCM particle size, PCM concentration and process cooling rates were analyzed. The results showed that small PCM particles could form a 2nd freezing point far from the melting point, resulting in a large supercooling degree. As the process cooling rates increased, the supercooling became more pronounced. However, when the high-concentration emulsion was mainly composed of small particles and subjected to low cooling rates, the concentration effect was significant, thereby decreasing the supercooling effect. [ABSTRACT FROM AUTHOR]