افزایش بازدهی دسته لوله دایروی پره‌دار با تغییر شکل و تغییر پارامترهای هندسی در جریان آشفته

پایان, سمیرا; ایمانی, فائزه; حسینی, مجتبی

افزایش بازدهی دسته لوله دایروی پره‌دار با تغییر شکل و تغییر پارامترهای هندسی در جریان آشفته

نوع مقاله : مقاله پژوهشی

نویسندگان

¹ عضو هیئت علمی دانشگاه

² سیستان و بلوچستان

چکیده

در این مقاله، افزایش بازدهی دسته لوله‌های فشرده پره‌دار با سطح مقطع دایروی، استفاده‌شده در مبدل‌های پوسته و لوله، بررسی می‌شود. به این منظور ابتدا تغییر سطح مقطع یک ردیف از دسته لوله بدون پره با لوله بیضوی در جریان آشفته مطالعه می‌شود و تأثیر قطر و گام طولی روی بهترین عملکرد دسته لوله بررسی می‌گردد. پس از محاسبه بهترین حالت از نظر عملکرد، تأثیر اعمال پره بر بازدهی دسته لوله تغییر شکل داده‌شده بررسی می‌شود. از روش SST- k-ω برای حل جریان در این حالات استفاده می‌شود. نتایج نشان می‌دهد که با تغییر شکل ردیف پنجم از دسته لوله‌ها با قطر 02/0 متر از دایروی به بیضوی، افزایش کارایی حدود 21% است، با کاهش قطر لوله‌ها تا 015/0 متر و با افزایش قطر تا 024/0 متر و ثابت نگه‌داشتن گام طولی، به ترتیب تغییر شکل ردیف چهارم افزایش کارایی تا حدود 31% و ردیف ششم افزایش کارایی حدود 6% را به همراه دارند. در قطر 02/0 متر، کاهش گام طولی و افزایش آن به ترتیب 35% و 18% افزایش بازدهی را نتیجه می‌دهد. سپس میتوان گفت که افزایش کارایی هم به قطر لوله و هم به گام طولی بستگی دارد، اما تغییرات قطر تأثیر بیشتری روی انتخاب بهترین ردیف دارد. همچنین، دسته لوله با ترکیبی از لوله‌های بیضوی و دایروی بازدهی را تا 11% و 12% به ترتیب برای قطر 02/0 و 024/0 متر افزایش می‌دهد.

کلیدواژه‌ها

20.1001.1.23223278.1398.8.1.8.9

عنوان مقاله [English]

The Increase of Efficiency of Bundle of a Circular Finned-tubes with Change of Shape and Geometrical Parameters in Turbulent Flow

نویسندگان [English]

samira Payan ¹
faeze Imani ²
mojtaba Hosseini ²

¹ sistan o baloochestan

² sistan o baloochestan

چکیده [English]

In this paper, the increase of efficiency of a compact bundle of finned tubes with circular cross-section used in Shell and Tube heat exchanger are studied. For this purpose, first we study the change of cross-section of one of the rows of without fin tube bundle with an elliptical tube in turbulent flow and investigate the effect of diameter and longitudinal pitch length on the performance of the bundle. Next, we investigate the effect of fins on the performance the bundle. The SST k-ω method is used for turbulence. In tubes with a diameter of 0.02 m, the efficiency increase is about 21%, when altering the fifth row. By reducing the diameter of the pipes to 0.015 m, while longitudinal step length is kept unchanged, it can be seen that the fourth row has more efficiency than the rest (about 31% with an increase in diameter of up to 0.024 m) the alternation of the sixth row boosts performance by about 6%. By decreasing and increasing longitudinal step length, the efficiency is increased by 35%, and 18%, respectively in diameter 0.02m. As a result, it can be said that increase of efficiency depends on both pipe diameter and longitudinal step length, But diameter changes has greater impact on choosing the best row. Also, mixed circular and elliptical tube bundles with circular fins increase efficiency 11% and 12% with diameter of 0.02m and 0.024m, respectively, in comparison to full circular finned-tubes bundle

کلیدواژه‌ها [English]

Bundle of Tubes
Shape Change of Rows of Tubes
Efficiency

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