When social practices produce space and create passive cooling systems in hot arid region

Practice social of people is the key to produce space and give a possibility to maintain thermal comfort and energy efficiency. The main objective of this research is to adapt the traditional strategies in the architecture actual, to achieved a thermal comfort and improve on reducing cooling load through the using of vernacular gait. Today, it is necessary to practice these systems in the current or conventional architecture of household. The study is especially for arid cities namely the region of Saoura, in the hot and dry climatic zone in Algeria, considered for this study. Two main factors is considered such as design and urban where taken into account in order to select the appropriate and specific passive cooling strategy. The results show that the passive cooling strategy of courtyard would be appropriate for arid regions, however a high thermal mass would be suitable for construction. In conclusion, this work made it possible to choose a suitable passive cooling strategy for all types of construction in hot and dry climates. Finally, this paper puts forward a set of recommendations to improve the passive design of future buildings in hot and arid climates.

Improving Energy Efficiency by Utilizing Wetted Cellulose Pads in Passive Cooling Systems

The effectiveness of using wetted cellulose pads on improving the performance of two conventional passive cooling systems has been evaluated. First, an experimental design was developed to determine the impact of using a wetted cellulose pad on the temperature and velocity of the airflow. A cellulose pad (7090 model) with a cross-sectional area of 0.5 × 0.5 m2 and three different thicknesses of 10, 15, and 30 cm were selected and tested. The results indicated that using wetted cellulose pads with thicknesses ranging from 10–30 cm decreased the outlet airflow temperature from 11.3 to 13.7 °C on average. For free airflow at velocity 3.5 m/s, the outlet airflow velocity from the wetted cellulose pad decreased to 0.9, 0.7 and 0.6 m/s, respectively, for cellulose pads with thicknesses of 10, 15, and 30 cm. By applying experimental results on a psychrometric chart, the humidity ratio of outlet airflow was obtained between 40–70%. The study established airflow velocity as the critical parameter in passive cooling systems. With the novel concept of combining wetted cellulose pads for passive cooling systems (i.e., wind catchers and induced ventilation), there is good potential to reduce the energy requirements for thermal comfort in buildings in regions with a hot and arid climate.

Performance Analysis of Photovoltaic Module with Different Passive Cooling Methods

This paper analyses the difference in terms of performance of passive cooling systems for photovoltaic (PV) modules. The objective of this paper is to identify which passive cooling systems offers the best results in reducing the operating temperature and improving the generation of output power. The performance of photovoltaic (PV) module will gradually decrease as the operating temperature increases. The energy from the sun’s photons are not enough to knock out the electrons from the atom to generate more electricity. That being the case, two passive cooling systems is developed which is the cotton wick structures with water and aluminium fins were attached to the back side of the photovoltaic (PV) module. The cotton wick structures with water utilises the capillary action of the water to extract excess heat from the module while the aluminium fins act as a heat sink that can remove heat from module to the adjacent air. Results showed that the cooling systems managed to enhance the output power by an average of 3.94% for the module with cotton wick structures with water while an average of 2.67% increment for the module under aluminium fin mounted as the cooling system.

Thermal Cycling in Converter IGBT Modules with Different Cooling Systems in Pitch- and Active Stall-Controlled Tidal Turbines

This paper compares active and passive cooling systems in tidal turbine power electronic converters. The comparison is based on the lifetime of the IGBT (insulated gate bipolar transistor) power modules, calculated from the accumulated fatigue due to thermal cycling. The lifetime analysis accounts for the influence of site conditions, namely turbulence and surface waves. Results indicate that active cooling results in a significant improvement in IGBT lifetime over passive cooling. However, since passive cooling systems are inherently more reliable than active systems, passive systems can present a better solution overall, provided adequate lifetime values are achieved. On another note, the influence of pitch control and active speed stall control on the IGBT lifetime was also investigated. It is shown that the IGBT modules in pitch-controlled turbines are likely to have longer lifetimes than their counterparts in active stall-controlled turbines for the same power rating. Overall, it is demonstrated that passive cooling systems can provide adequate cooling in tidal turbine converters to last longer than the typical lifetime of tidal turbines (>25 years), both for pitch-controlled and active speed stall-controlled turbines.

STUDY ON THERMAL CHARACTERISTICS OF U-SHAPED HEAT PIPE

The latest accident in Japan's nuclear power station became a valuable experience to start engaging passive cooling systems (PCS) more aggressively to improve safety aspects in nuclear power reactors being studied in Indonesia. This investigation is related to the U-shaped heat pipe (UHP) research as PCS of water in the cooling tank (CT). The objective of this research is to study the thermal characteristics of UHP as PCS in the CT. The experiment on small-scale UHP and simulation with RELAP5 code has been conducted to understand the performance of UHP. The experiment results of the small-scale UHP model will be used as a basic understanding of simulating and designing a UHP with big scaling. The study result showed the highest thermal performance of UHP was obtained when it operated on the higher temperature of heat load and higher air cooling velocity. The more UHPs inserted into the cooling pool, the more heat that can be discharged into the environment. This result also shows promising use of UHP for CT PCS. The use of UHP as PCS can enhance the safety aspect of the nuclear reactor, especially in station blackout event.

SISTEM SUBGROUND PASSIVE COOLING PADA GEREJA DI CIBUNUT, KUNINGAN, JAWA BARAT

Subground passive cooling is a passive cooling technique that is carried out by flowing cold air in the ground into the room. The Pasio Christi Church in Cibunut, Kuningan, West Java was founded in 1965. Then the church implemented a passive cooling subground system through renovations carried out on May 11, 2018. This passive cooling system is usually carried out in areas with subtropical to cold climates, however Cibunut who has a tropical climate tries to implement this system. In fact, there is concern if the system is implemented in the tropics, such as humidity entering the system, causing fungal problems that can have an impact on health. . Therefore this research describes the application of the subground passive cooling system in tropical climates with the following steps: (i) data collection in the form of literature studies, (ii) identification of the subground passive cooling system of Cibunut Church, (iii) elaboration of theory regarding subground passive cooling, (iv) analysis of the application of subground passive cooling of the Cibunut church with the results of theoretical elaboration. This research is expected to be able to contribute in science, especially regarding the application of subground passive cooling systems in tropical climates.Abstrak: Subground passive cooling merupakan teknik pendinginan pasif yang dilakukan dengan mengalirkan udara dingin dalam tanah ke dalam ruangan. Gereja Pasio Christi di Cibunut, Kuningan, Jawa Barat didirikan sejak 1965. Lalu gereja ini menerapkan sistem subground passive cooling melalui renovasi yang dilakukan pada 11 Mei 2018. Sistem pendinginan pasif ini biasanya dilakukan pada wilayah dengan iklim subtropis hingga iklim dingin, namun demikian Cibunut yang beriklim tropis mencoba untuk menerapkan sistem ini. Padahal ada kekawatiran jika sistem ini diterapkan di wilayah tropis, seperti kelembaban yang masuk dalam sistem sehingga muncul permasalahan jamur yang dapat berdampak pada kesehatan. Oleh karena itu pada penelitian ini mendiskripsikan mengenai penerapan sistem subground passive cooling pada wilayah beriklim tropis dengan langkah-langkah sebagai berikut : (i) pengumpulan data dalam bentuk studi literatur, (ii) identifikasi sistem subground passive cooling Gereja Cibunut, (iii) elaborasi teori mengenai subground passive cooling, (iv) analisis penerapan subground passive cooling gereja Cibunut dengan hasil elaborasi teori. Dari penelitian ini diharapkan mampu memberikan sumbangsih dalam keilmuan terutama mengenai penerapan sistem subground passive cooling pada wilayah beriklim tropis.

Influence of the chamber inclination angle and heat-generating element location on thermal convection of power-law medium in a chamber

Purpose This paper aims to study the mathematical modeling of passive cooling systems for electronic devices. Improving heat transfer is facilitated by the correct choice of the working fluid and the geometric configuration of the engineering cavity; therefore, this work is devoted to the analysis of the influence of the position of the heat-generating element and the tilted angle of the electronic cabinet on the thermal convection of a non-Newtonian fluid. Design/methodology/approach The area of interest is a square cavity with two cold vertical walls, while the horizontal boundaries are adiabatic. An element of constant volumetric heat generation is placed on the lower wall of the chamber. The problem is described by Navier–Stokes partial differential equations using dimensionless stream function and vorticity. The numerical solution is based on the developed computational code using the finite difference technique and a uniform rectangular grid. Findings The key conclusions of this work are the results of a detailed analysis of streamlines and isotherms, the average Nusselt number and profiles of the average heater temperature. It was found that more intensive cooling of the heat-generating element occurs when the cavity is filled with a pseudoplastic fluid (n < 1) and not inclined (α = 0). The Rayleigh number of Ra = 105 and the thermal conductivity ratio of k = 100 are characterized by the most positive effect. Originality/value The originality of the research lies in both the study of thermal convection in a square chamber filled with power-law fluid under the influence of a volumetric heat production element and the analysis of the influence of geometric and thermophysical parameters characterizing the considered process.

Atrium Impact on a School-Building: Thermal Performance in a Hot Climate

The process of climate change has increased the planet’s mean temperature. An example of this are the 44.3 °C registered in July in the cities of Córdoba and Seville (Spain). In this scenario, the educational centers in Andalusia, mostly built during the 20th century, are unable to reach the thermal comfort inside the classrooms throughout the year, without resorting to mechanical air conditioning procedures. This study simultaneously monitors indoors, outdoors and transitional spaces of a case study to verify the effectiveness of the passive cooling systems and the Atrium thermal effect of the building. Our results demonstrate that temperatures inside classrooms are influenced by the orientation and their air circulation (atrium or outdoor) and as expected, the higher temperature in the building are registered in the classrooms in the last floor.