مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

طراحی شبکه مبدل‌های حرارتی با درنظرگرفتن اُفت فشار و تعیین مسیر بهینه جریان‌ها در داخل لوله یا پوسته

نوع مقاله : پژوهشی اصیل

نویسندگان
گروه مهندسی شیمی، دانشکده فنی مهندسی، واحد اهر، دانشگاه آزاد اسلامی، اهر، ایران
چکیده
در این تحقیق روش ساده و مفید برای پیداکردن مسیر مناسب جریان‌های سرد و گرم در داخل مبدل‌های حرارتی لوله- پوسته در مسایل طراحی شبکه مبدل‌های حرارتی (HENs) با درنظرگرفتن اُفت فشار جریان‌ها ارایه شده است. در حالت کلی، طراحی شبکه مبدل‌های حرارتی به‌کمک برنامه‌ریزی ریاضی منجر به بروز مشکلاتی می‌شود که به‌وسیله مدل‌های برنامه­ریزی اعداد صحیح مخلوط غیرخطی. (MINLP) پاسخ داده می‌شود. بهینه‌سازی چنین فرمولاسیون‌هایی به‌دلیل وجود متغیرهای پیوسته و گسسته باعث ایجاد مشکلاتی در همگرایی می‌شود. در این تحقیق به‌جای حل همزمان متغیرهای گسسته و پیوسته، از الگوریتم ژنتیک برای پیداکردن بهینه ساختار شبکه مبدل‌های حرارتی (متغیرهای گسسته) استفاده شده است. برای پیداکردن مقادیر بهینه متغیرهای پیوسته شبکه، با دسته‌بندی این نوع از متغیرها به دو گروه و استفاده از فرمولاسیون برنامه‌ریزی شبه‌خطی (QLP) به‌جای مدل برنامه‌ریزی غیرخطی (NLP)، از پیچیدگی حل مدل NLP نیز تا حدود زیادی کاسته شده است. مقادیر بهینه متغیرهای پیوسته و گسسته با توجه به یک تابع هدف مشترک که رسیدن به حداقل هزینه سالیانه شبکه مبدلی است، به دست می‌آیند. مقایسه روش پیشنهادی با مراجع نشان می‌دهد که این روش توانایی کاهش هزینه پمپاژ جریان‌ها تا حدود ۰/۷۶% را دارد.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Synthesis of Heat Exchanger Networks with Considering Pressure Drop and Finding Optimized Streams Path Inside Tube and Shell

نویسندگان English

V. Sadri
H. Soltani
Chemical Engineering Department, Engineering Faculty, Ahar Branch, Islamic Azad University, Ahar, Iran
چکیده English

In this research, taking into account the pressure drop of the streams, a simple and useful method is presented for finding the proper path of hot and cold streams inside shell-tube heat exchangers in the synthesis of heat exchangers networks (HENs). Generally, the HENs synthesis by mathematical programming leads to the problems which are answered by Mixed Integer Non Linear Programming (MINLP) methods. Optimization of such formulations results convergence difficulties due to the existence of both continuous and integer variables. In this study, instead of solving simultaneously integer and continuous variables, the genetic algorithm was used to find optimal HEN structure (integer variables). To find optimal values for continuous variables of the network, by categorizing this type of variables into two groups and using Quasi Linear Programming (QLP) instead of the nonlinear programming model (NLP), the complexity of the NLP model solution is also greatly reduced. The optimal values of continuous and integer variables are obtained with respect to a common objective function that reaches the minimum annual cost of the HEN. The comparison of the proposed method with the references shows that this method has the ability to reduce the cost of pumping flows to about 0.76%.

کلیدواژه‌ها English

Shell-Tube Heat Exchanger Network Synthesis
Pressure drop
genetic algorithm
Quasi-Linear Programming (QLP)
Optimized Streams Path within Exchangers
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