شبیه‌سازی سه‌بعدی جریان گاز هلیم در چاه‌گرمایی‌آلومینیومی با میکروکانال‌های مستطیلی در رژیم جریان لغزشی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه کاشان*مکانیک

2 دانشگاه شهاب دانش

چکیده

در کار حاضر، برای اولین بار، جریان گاز هلیم در یک چاه گرمایی آلومینیومی با میکروکانال‌های مستطیلی شکل، با لحاظ کردن انتقال حرارت توأمان در بخش سیال و جامد و در نظر گرفتن شرط مرزی سرعت لغزشی و پرش دمایی، مورد بررسی عددی قرار گرفته است. در این پژوهش جریان گاز در محدوده عدد نادسن بین0/006 و 0/048 و با اعمال شار حرارتی 500 وات بر مترمربع به کف چاه درنظر گرفته شده است. معادلات حاکم بر جریان با استفاده از طرح بالا دست مرتبه دوم گسسته‌سازی شده و به کمک الگوریتم کاپلد در نرمافزار تجاری انسیس-فلوئنت حل شده‌اند. نتایج نشان می‌دهد با افزایش نسبت فشار ورودی به خروجی عدد نادسن ورودی و محلی کاهش می‌یابد. همچنین با افزایش عدد نادسن ورودی عدد پوازی محلی کاهش می‌یابد. اضافه براین، با افزایش عدد نادسن ورودی )کاهش نسبت فشار( عدد ناسلت متوسط ابتدا کاهش و سپس افزایش می‌یابد؛ در این خصوص با افزایش عدد نادسن از 0/006 به 0/024عدد ناسلت متوسط 54/40 %کاهش و با افزایش عدد نادسن از 0/024 به 0/048 عدد ناسلت متوسط 5/42 %افزایش می‌یابد. با افزایش عدد نادسن مقاومت حرارتی پیوسته افزایش می‌یابد به طوری‌که با افزایش عدد نادسن از 0/006 به 0/048 مقاومت حرارتی 966/34 %افزایش می‌یابد. همچنین با افزایش عدد نادسن ورودی، اثرات لغزش جریان افزوده شده و ضرایب لغزش و پرش دما افزایش می‌یابد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Three-Dimensional Simulation of Helium Gas Flow in an Aluminum Heat Sink with Rectangular Microchannel in Slip Flow Regime

نویسندگان [English]

  • Ahmad Reza Rahmati 1
  • Mojtaba Sepehrnia 2
1 ِDepartment of mechanical Eng, Univ. of Kashan
2 Department of Mechanical Engineering, Shahabdanesh University, Qom, Iran
چکیده [English]

In the present work, for the first time, gas flow with considering slip velocity and temperature jump boundary condition is studied in a heat sink consisting of rectangular fins and microchannels with calculating conjugated heat transfer. In this paper, helium gas flow with Knudsen number between 0.048 to 0.06 has been studied. Heat flux applied to the bottom of the aluminum heat sink is 500W/m2. The governing equation for fluid flow has been discretized using second-order upwind method and solved with using the Coupled algorithm in Ansys-Fluent commercial software. Results show that inlet and local Knudsen numbers decrease with increasing pressure ratio and also local Poiseuille number decreases with increasing inlet Knudsen number. Also, with increasing inlet Knudsen number (reduction of pressure ratio), first the average Nusselt number decreases and then increases. In this case, the average Nusselt number decreases about 54.4% with increasing Knudsen number from 0.006 to 0.024 and the average Nusselt number increases with increasing Knudsen number from 0.024 to 0.048. With increasing Knudsen number, thermal resistance increases continuously. The results show that with increasing inlet Knudsen number, slip and temperature jump coefficients increase.

کلیدواژه‌ها [English]

  • Heat sink
  • Microchannel
  • Nusselt number
  • Knudsen number
  • Slip flow

مراجع

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نشریه مهندسی مکانیک امیرکبیر
دوره 52، شماره 2
اردیبهشت 1399
صفحه 477-492

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