Solar Passive Technology Research Articles

Optimizing the Marangoni effect towards enhanced salt rejection in thermal passive desalination

Amid escalating water scarcity and rising energy prices, the scientific community strives to propose innovative and efficient water treatment solutions. In this context, solar passive technologies have attracted much attention. Furthermore, recent studies have experimentally revealed that the Marangoni effect, when leveraged in well-designed passive devices, may be a promising pathway towards long-term stable performance. This study presents a comprehensive numerical exploration of applying the Marangoni effect to mitigate salt accumulation, a challenge in long-term system operation. Through an extensive sensitivity analysis, we evaluate the solute molar outflow induced by the Marangoni effect, as different parameters vary. Specifically, the Marangoni effect induces enhanced mass transport, outperforming pure diffusive flow by over three orders of magnitude, under nighttime isothermal conditions. Furthermore, we provide a semi-empirical equation describing accurately the mass transfer versus the Marangoni number. Hence, nighttime brine discharge simulations show rapid salt reduction from the evaporator, reaching seawater-like salinity levels within two hours, setting stage for optimal daytime performance. To the best of our knowledge, this discharge time is the lowest reported in the literature under equivalent conditions. In conclusion we believe that the still poorly explored Marangoni effect may offer a durable mean of providing freshwater, particularly in emergencies.

Building Façade Retrofit with Solar Passive Technologies: A Literature Review

Worldwide, buildings have been presented as one of the main energy consumers and, for that matter, there is an increased tendency to invest in policies and measures that promote more efficient buildings. Among the chosen strategies, the need to promote the use of passive solutions and retrofit the existing building stock is often pointed out. Portuguese building stock has proven to be obsolete in terms of thermal comfort, which can directly affect the energy demand for climatization purposes. Considering the great solar availability in the country, when compared to other European locations, building retrofit with solar passive technologies can be a suitable solution. This paper aims to review studies on the application of solar passive technologies to retrofit façades in the Mediterranean climate context, with a special focus on Portugal. Four retrofit passive solar technologies were reviewed, namely glazing, sun shading, sunspaces and Trombe wall technologies.

Trombe wall for a residential building in Sichuan-Tibet alpine valley – A case study

Trombe wall (also called T-Wall) as a reliable renewable energy system has attracted increasing attention from both academics and engineers under the current energy crisis. This study then focused on a Tibetan dwelling retrofitting in the Sichuan-Tibet Alpine Valley, adopting T-wall as a passive heating solution. We investigated a classic T-wall in the target building based on field measurement, orthogonal experiment, and numerical simulation methods. It was known that the maximum average indoor temperature of the master room can reach 18.87 °C in the coldest month (January) of the Sichuan-Tibet Alpine Valley. Six key influencing factors were analyzed accordingly, including the south T-wall-to-wall ratio, inlet/outlet height, glazing inclination angle, storage wall thickness, storage wall material and cavity gap. Among those analyzed factors, it was obtained that the highly significant factors are the south T-wall-to-wall ratio and glazing inclination angle. The larger the proportion of the south T-wall-to-wall ratio, the better the indoor temperature is. The best glazing inclination angle was obtained as 100 for the target residential building under the local conditions. Solar passive technology as a cost-effective solution can improve the indoor thermal environment of the Tibetan dwellings in the Qinghai-Tibet Plateau. The total annual energy consumption of the Tibetan dwelling using the optimal combination can be reduced by about 72% compared to that of the existing Tibetan houses. The research outcomes can provide a practical guide on the future design of passive solar technologies.

Influence Of Passive Techniques on Thermal Performance of Building in Moderate Zone

Solar passive technologies need to be integrated in Building Designs. This helps not only save energy but also decreases stress and strains in building due to thermal disturbances. The main objective is to achieve comfort for utility for life cycle of the building. Passive techniques are main remedies to increase the building comfort hours without any use of artificial resources. This paper shows the thermal performance of building by simulating different passive techniques before constructing a new building and examines the possible changes that can have influence on comfort inside. A project of proposed building in moderate zone in India at latitude 16.69N and Longitude 74.23E is further examined for manifestations in real time using appropriate simulation tools. The study finalizes that for project under moderate zone, maximum discomfort hours are in summer. Applying the passive techniques to decrease the discomfort hours will finally increase the thermal performance of the building. For Moderate zone, implementation of passive techniques with changes in building material, orientations, air exchanges etc. decrease the discomforts to 9.4% which is 823 hours in a year.