Kalın cidarlı borularda eşzamanlı gelişen laminer akışta geçici rejim birleşik ısı transferi
Transient conjugated heat transfer in simultaneously developing laminar flow in thick walled pipes
Yazar: SELÇUK DARICI
Danışman: PROF.DR. ŞEFİK BİLİR
Selçuk Üniversitesi / Fen Bilimleri Enstitüsü / Makine Mühendisliği Ana Bilim Dalı
Derece: Doktora, 2004
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
ÖZET Doktora Tezi KALIN CİDARLI BORULARDA EŞ ZAMANLI GELİŞEN LAMİNER AKIŞTA, GEÇİCİ REJİM BİRLEŞİK ISI TRANSFERİ Selçuk DARICI Selçuk Üniversitesi Fen Bilimleri Enstitüsü M a ki ıı a Mühendisliği Anabilim Dalı Danışman : Prof. Dr. Şefik BİLİR 2004, 178 Sayfa Jüri : Prof. Dr. Şefik BİLİR Doç. Dr. Mahmut MAT Yrd. Doç. Dr. Rafet YAPICI Yrd. Doç. Dr. Suna KARGICI Yrd. Doç. Dr. Faruk KÖSE Bu çalışmada, borularda laminer akış eş zamanlı gelişme bölgesi geçici rejim birleşik ısı transferi, iki boyutlu cidar ve eksenel akışkan iletimi dikkate alınarak incelenmiştir. Problem, kalın cidarlı, başlangıçta eşit sıcaklıktaki yarı sonsuz bir boruda, sürekli, hidrodinamik ve ısıl olarak gelişmekte olan akış için, çevre akışkanı sıcaklığındaki ani değişme şartı ile ele alınmış ve akış alanı ile ısı transferi sayısal olarak incelenmiştir. Boyutsuz süreklilik, Navier-Stokes ve enerji denklemleri sonlu kontrol hacim yöntemi ile ayrıklaştırılarak SIMPLE algoritması ile çözülmüştür. Akışkan tarafı diferansiyel denkleminin ayrıklaştırılması bir kesin çözüm profili kullanılmıştır. Sonlu fark denklemlerinin çözümünde, kaydırılmış grid düzeni kullanılmıştır. Problemin analizi için yeni bir bilgisayar programı geliştirilmiştir.solution of the finite difference equations, staggered grid arrangament is used. A new computer program is developed for the analysis of the problem. A parametric study is done to analyse the effects of six defining parameters on heat transfer characteristics namely, the Peclet number, the Prandtl number, the Biot number, the ratio of wall thickness to inside radius of the tube, ratio of wall to fluid thermal conductivities, and ratio of wall to fluid thermal diffusitivies. In order to understand the effects of velocity profile on heat transfer characteristics, solutions are obtained for three different velocity profiles. These are hydrodynamically fully developed flow (Poiseuille flow), simultaneously developing flow and slug (uniform) flow. The results arc compared with the literature. The results arc found to be significantly dependent on the parameter values. The Peclet and the Prandtl numbers are effective for the flow field, while the wall thickness the ratio and the Peclet number are more effective parameters for heat transfer characteristics. Key Words : Laminar flow heat transfer in pipes, conjugated heat transfer, transient heat transfer, simultaneously developing flow, numerical solution. IV

Abstract:
ABSTRACT Phd Thesis TRANSIENT CONJUGATED HEAT TRANSFER IN SIMULTANEOUSLY DEVELOPING LAMINAR FLOW IN THICK WALLED PIPES Selçuk DARICI Selçuk University Graduate School of Natural and Applied Sciences Department of Mechanical Engineering Supervisor : Prof. Dr. Şefik BİLİR 2004, 178 Pages Jury : Prof. Dr. Şefik BİLİR Assoc. Prof. Dr. Mahmut MAT Assist. Prof. Dr. Rafet YAPICI Assist. Prof. Dr. Suna KARGICI Assist. Prof. Dr. Faruk KÖSE Transient conjugated heat transfer in simultaneously developing laminar flow is analysed involving two-dimensional wall and fluid axial conduction. A thick walled /semi-infinite circular pipe which is considered initially isothermal and the problem is handled for steady, hydrodynamically and thermaly developing flow with a sudden change in the ambient temperature. The flow field and heat transfer are numerically investigated. Nondimensional continuity, Navier-Stokes and energy equations are discretized by using finite control volume method and solved with SIMPLE algorithm. Differential equation at the fluid side is discretized by using an exact profile. In the msolution of the finite difference equations, staggered grid arrangament is used. A new computer program is developed for the analysis of the problem. A parametric study is done to analyse the effects of six defining parameters on heat transfer characteristics namely, the Peclet number, the Prandtl number, the Biot number, the ratio of wall thickness to inside radius of the tube, ratio of wall to fluid thermal conductivities, and ratio of wall to fluid thermal diffusitivies. In order to understand the effects of velocity profile on heat transfer characteristics, solutions are obtained for three different velocity profiles. These are hydrodynamically fully developed flow (Poiseuille flow), simultaneously developing flow and slug (uniform) flow. The results arc compared with the literature. The results arc found to be significantly dependent on the parameter values. The Peclet and the Prandtl numbers are effective for the flow field, while the wall thickness the ratio and the Peclet number are more effective parameters for heat transfer characteristics. Key Words : Laminar flow heat transfer in pipes, conjugated heat transfer, transient heat transfer, simultaneously developing flow, numerical solution. IV