مطالعه عددی جریان و انتقال حرارت در لوله گیرنده حفره‌ای یک برج خورشیدی با آشوبگرهای مختلف تحت شار حرارتی غیریکنواخت

نوع مقاله : مقاله پژوهشی

نویسندگان

• سیاوش زینل پور
• زهرا مهردوست

گروه مهندسی مکانیک، واحد اهواز، دانشگاه آزاد اسلامی، اهواز، ایران

10.22067/jacsm.2022.76201.1111

چکیده

در این مقاله، تأثیر استفاده از چهار نوع آشوبگر مختلف درون لوله گیرنده حفره‌ای برج خورشیدی به منظور بهبود انتقال حرارت و کاهش توزیع دمای غیر‌یکنواخت بررسی شده است. شبیه‌سازی عددی به صورت سه بعدی انجام شده و تأثیر شکل آشوبگرها، موقعیت قرارگیری درون لوله گیرنده، گام و ضخامت آشوبگر و همچنین تأثیر شار حرارتی غیریکنواخت بر عدد ناسلت، ضریب اصطکاک و دمای سطح لوله گیرنده بررسی شده است. جریان به صورت تراکم‌ناپذیر، پایا، آشفته و عدد رینولدز در محدوده 8000 تا 20000 در نظر گرفته شده است. نتایج شبیه‌سازی عددی برای چهار نوع آشوبگر نوار تابیده، نوار موج‌دار، نوار حلزونی و نوار پره‌دار نشان داد که آشوبگر نوار موج‌دار نسبت به سه نوع دیگر، دارای عدد ناسلت بالاتر و دمای متوسط کمتر روی سطح خارجی لوله گیرنده است. افزایش عدد ناسلت نوار موج‌دار نسبت به نوار پره‌دار، تابیده و حلزونی به ترتیب %8/1، %2 و %2/3 و نسبت به لوله گیرنده بدون آشوبگر %10 است. با افزایش ضخامت آشوبگر و کاهش گام، عدد ناسلت افزایش یافته و دمای متوسط سطح خارجی لوله گیرنده کاهش می‌یابد. بررسی موقعیت قرارگیری آشوبگر در سه حالت نزدیک به دیواره شار حرارتی غیریکنواخت، وسط لوله و نزدیک به دیواره عایق نشان داد که با افزایش فاصله آشوبگر از ناحیه اعمال شار حرارتی غیریکنواخت، اختلاط جریان سیال گرم و سیال سرد بهتر صورت می‌گیرد و توزیع دما یکنواخت‌‌تر می‌شود. بنابراین بهترین موقعیت برای قرار گرفتن آشوبگر، دورترین فاصله نسبت به دیواره شار حرارتی غیریکنواخت است.

کلیدواژه‌ها

• برج خورشیدی
• لوله گیرنده حفره‌ای
• شار حرارتی غیر یکنواخت
• آشوبگر
• انتقال حرارت

موضوعات

• انتقال حرارت

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عنوان مقاله [English]

Numerical Study of Flow and Heat Transfer in Cavity Receiver Tube of a Solar Power Tower with Different Inserts under Non-uniform Heat flux

نویسندگان [English]

• Siavash Zeynalpour
• Zahra Mehrdoost

Department of Mechanical Engineering,Ahvaz Branch, Islamic Azad University, Ahvaz, Iran

چکیده [English]

In this paper, the effect of using four different types of inserts in cavity receiver tube of solar power tower to improve heat transfer and reduce non-uniform temperature distribution is investigated. Numerical simulation is performed in three dimensions and the effect of inserts configurations, position inside receiver tube, pitch and thickness of insert and the effect of non-uniform heat fluxon the Nusselt number, friction factor and temperature of outer surface of receiver tube are investigated. The flow is incompressible, steadystate, turbulent and the Reynolds number is in the range of 8000 to 20000. Numerical simulation results for four types of inserts: twisted-tape, wavy-tape, helical-tape and louvered-tape show that wavy-tape compared to the other three types, has the higher Nusselt number and the lower average temperature of receiver tubesurface. The Nusselt number of the wavy-tape is increased by 1.8%, 2% and 3.2% relative to the louvered-tape, twisted-tape and helical-tape, respectively and 10% relative to the receiver tube without insert. By increasing the insert thickness and decreasing the insert pitch, the Nusselt number increases and average temperature of receiver tubesurface decreases. Investigating the insert position in three cases: close to the non-uniform heat flux wall, the middle of the tube and close to the insulation wall show that by increasing the distance of insert from non-uniform heat flux wall, the mixing of hot and cold fluids flow is better and the temperature distribution is more uniform.Therefore, the best position to place insert is the farthest distance from the non-uniform heat flux wall.

کلیدواژه‌ها [English]

• Solar power tower
• cavity receiver tube
• non-uniform heat flux
• insert
• heat transfer

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