تحلیل عددی رفتار هیدرودینامیک اختلاط سه فازی پوسته برنج، شن و هوا در بستر سیال حبابی با رفتار دانه‌ای ذرات

علوم کاربردی و محاسباتی در مکانیک

مقاله 5، دوره 34، شماره 2 - شماره پیاپی 28، مرداد 1401، صفحه 61-86   

نوع مقاله: مقاله پژوهشی

شناسه دیجیتال (DOI): 10.22067/jacsm.2022.71387.1041

نویسندگان

رضا کریمی احمدی؛ حمیدرضا نظیف^*

دانشکده فنی و مهندسی دانشگاه بین المللی امام خمینی، قزوین، ایران.

چکیده

زیست‌توده به عنوان یک منبع انرژی تجدید‌پذیر در سراسر جهان از اهمیت زیادی برخوردار است. نقش اختلاط و جدایش ذرات زیست‌توده و ماده بستر در فرآیند گازی‌سازی بستر سیال بسیار حائز اهمیت است. هر چه میزان اختلاط این ذرات به خوبی انجام شود، کیفیت گازهای سنتز شده خروجی از فرآیند گازی‌سازی زیست توده افزایش می‌یابد. این پژوهش با استفاده از ابزار دینامیک سیالات محاسباتی به روش حجم محدود با رویکرد جریان چند فازی اویلرین به بررسی فرآیند اختلاط سه فازی پوسته برنج (زیست‌توده)، شن (ماده بستر) و هوا در بستر سیال حبابی می‌پردازد. تاثیر ضریب برخورد بین ذرات و شرایط مرزی دیوار برای فاز جامد در فرآیند اختلاط زیست‌توده و ماده بستر مطالعه شده است. در این پژوهش، تاثیر لغزش آزاد، لغزش جزئی و بدون لغزش برای ذرات در برخورد با دیوار بررسی شده است. در شرایط لغزش جزیی، سرعت ذرات پوسته برنج و شن در مقایسه با دو حالت دیگر بیشتر می‌باشد، لذا هر چه سرعت ذرات در بستر افزایش یابد، اختلاط و توزیع یکنواخت ذرات در بستر افزایش می‌یابد. بررسی افت فشار در بستر سیال نشان می‌دهد، در شرایط لغزش آزاد، افت فشار به ترتیب 09/8 درصد و 2/14درصد نسبت به دو حالت لغزش جزیی و لغزش کلی کمتر می‌باشد. همچنین سه نوع پوسته برنج با ضرایب برخورد متفاوت مطالعه شده است. در نتیجه این مطالعه، با کاهش ضریب برخورد بین ذرات، سرعت ذرات پوسته برنج و شن حدود 9 درصد افزایش یافته و افت فشار حدود 22 درصد کاهش می‌یابد.

کلیدواژه‌ها

بستر سیال حبابی؛ رویکرد اویلرین؛ هیدرودینامیک؛ زیست‌توده؛ اختلاط ماده بستر و زیست‌توده؛ ضریب برخورد؛ ضریب برخورد آیینه‌ای؛ شرط مرزی دیوار برای فاز جامد

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