فهرس المقالات Thermal resistance

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  1 - Numerical Investigation of Forced Convection Heat Transfer for Different Models of PPFHS Heatsinks
  Soheil Sadrabadi Haghighi hamidreza goshayeshi Iman Zahmatkesh
  10.30486/admt.2022.1957347.1348
  In his research article, several models of heatsink were optimally designed in fin length, width and height along with pin placement which consists of 4 pin fin heatsink models heatsink (including square with different pin angles, circular, truncated cone, and cone pin أکثر

  In his research article, several models of heatsink were optimally designed in fin length, width and height along with pin placement which consists of 4 pin fin heatsink models heatsink (including square with different pin angles, circular, truncated cone, and cone pin heatsinks and one model of the plate-fin heatsink (PFHS)) in order to achieve better thermal performance as well as less energy consumption and were numerically investigated under high air velocity and heat fluxes. Different parameters such as peak temperature, Nusselt number, heat resistance, pressure drop, and energy consumption were compared. The results show that the square PPFHS with the pin angle of 45 degrees has the highest thermal performance compared to the rest of the models while also having the highest pressure drop and energy consumption between the models consuming more than 255 and 358 percent more energy in order to have the same air velocity in the pathway, while the truncated and the fully formed cone model despite having 25% and 30% less thermal performance, have the least pressure drop between the pin models of the heatsinks and therefore consume the least energy out of the PPFHS. تفاصيل المقالة
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  2 - مروری بر پارامترهای مؤثر بر ضریب کارایی در خنک کن های ترموالکتریک
  نادر رهبر سعید کامرانی فر
  سیستم‌های ترموالکتریک دارای مزایای فراوانی از جمله سازگاری با محیط‌زیست، بدون سروصدا بودن و قابلیت اطمینان بالا هستند. با توجه به کاهش روز افزون منابع سوخت‌های فسیلی و آلایندگی ناشی از آن‌ها استفاده از سیستم‌های ترموالکتریک به دو صورت خنک‌کن و ژنراتور رو به افزایش است. أکثر

  سیستم‌های ترموالکتریک دارای مزایای فراوانی از جمله سازگاری با محیط‌زیست، بدون سروصدا بودن و قابلیت اطمینان بالا هستند. با توجه به کاهش روز افزون منابع سوخت‌های فسیلی و آلایندگی ناشی از آن‌ها استفاده از سیستم‌های ترموالکتریک به دو صورت خنک‌کن و ژنراتور رو به افزایش است. اما یکی از مهم‌ترین معایب خنک‌کن‌های ترموالکتریک پایین بودن ضریب کارایی آن‌ها است. امروزه محققان تمرکز خاصی بر ضریب عملکرد ترموالکتریک داشته و در تلاش هستند که آن را بهبود بخشند. جهت آشنایی بیشتر با پارامترهای مؤثر بر ضریب عملکرد در این مقاله به مرور آن‌ها پرداخته شده است. بدین منظور ابتدا تأثیر مقاومت تماسی الکتریکی و گرمایی بررسی شده است که در ماژول‌های ترموالکتریک کوچک، با نادیده گرفتن آن به نتایج مطلوبی نخواهیم رسید. همچنین با کاهش مقاومت تماسی الکتریکی می‌توان مقدار ضریب کارایی را 50 تا 60 درصد افزایش داد. سپس رابطه ضریب عملکرد با طول ترموالمنت، اختلاف دما و جریان الکتریکی آورده شده است و در نهایت به بررسی ماژول‌های چندمرحله‌ای بر ضریب عملکرد پرداخته شده است که در نتیجه افزایش مراحل، ضریب عملکرد نیز افزایش یافته است. تفاصيل المقالة
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  3 - Effect of Polypropylene Fibers on Strength and Thermal Resistance of Concrete
  Jamal Ahmadi Hossein Aghajanloo
  In this paper, the effect of Polypropylene Fibers added to concrete on strength and thermal resistance of high strength concrete has been investigated. Therefore, five tests have been carried out to reach this goal which it includes; effect of weight percent of polyprop أکثر

  In this paper, the effect of Polypropylene Fibers added to concrete on strength and thermal resistance of high strength concrete has been investigated. Therefore, five tests have been carried out to reach this goal which it includes; effect of weight percent of polypropylene fibers on mechanical properties of concrete, effect of fiber’s length on the strength of high strength concrete, effect of fiber’s volume on the thermal stability of high strength concrete, examine the phenomenon of spalling concrete high resistance against heating, determine the changing of compressive strength of high strength concrete in different temperatures. The results present that the compressive strength has declined with the percentage of fiber concrete after 0.7 kg/m3 . Moreover, in all cases the tensile strength and concrete’s bending strength will be increased by fiber content. تفاصيل المقالة
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  4 - A Review on the Photovoltaic Panels: Applications, ‎Modeling and Economic Evaluation with Focusing on ‎the Phase Change Material Cooling Method
  Seyyed Masoud Seyyedi
  A photovoltaic (PV) panel consists of several photovoltaic cells designed to convert solar radiation into electrical energy. Cooling of PV cells is an important task to increase PV panel efficiency, improve output power and optimize performance parameters. There are var أکثر

  A photovoltaic (PV) panel consists of several photovoltaic cells designed to convert solar radiation into electrical energy. Cooling of PV cells is an important task to increase PV panel efficiency, improve output power and optimize performance parameters. There are various methods for PV cooling. Phase change materials (PCMs) can be used to cool PV panels. The integrated system is called PV-PCM system. This paper provides an overview of the history, applications, mathematical modeling and economic evaluation for PV-PCM systems. The focus of this study is on the cooling of the PV cells using PCMs. Furthermore, the other types of PV systems (hybrid systems) are investigated. The effects of main parameters on the performance of PV or PV-PCM systems are investigated, too. Mathematical modeling including thermal and electrical models are presented. Finally, the advantages and disadvantages of PV-PCM system and its future overview are discussed. The results discover that the PV panel temperature up to 20 °C and electrical efficiency up to 5% can be reduced by PCM.. The results discover that the PV panel temperature up to 20 °C and electrical efficiency up to 5% can be reduced by PCM. تفاصيل المقالة