Fluid flow and heat transfer characteristics

مقدم أطروحة جامعية

Hilal, Kifah Hamid

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم الهندسة الكهروميكانيكية

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2004

الملخص الإنجليزي

Forced convective heat transfer in a vertical channel symmetrically heated with a constant heat flux, and packed with saturated porous media, : has been investigated theoretically and experimentally in the present work..

The packed channel was made with spherical glass particle of three different diameter (1, 3, 10 mm) respectively; in a range (0.0416 < d < 0.416) where (d) is the ratio of particle diameter to inner channel radius.

The water flow in the packed channel is assumed to be hydrodynamic -ally fully developed and the effects of inertia, porosities and Brinkman friction are taken into account in the momentum equation .The Four momentum equation physical models have been used, defined as the general model (DFBM), Brinkman model (DBM), general without Brinkman model (DFM) and Dare model (DM) in this study.

The initial variable values and boundary conditions are similar for both theoretical and experimental investigation.

The results are obtained for 470 < Re (Reynolds number) < 1694, 10< Red (particle Reynolds number) < 350 and 2.1 kw / m2 < q>v (heat flux) < 7.4 kw / m2.Radial velocity distribution which obtained from solving the four model momentum equation show that the velocity at channel core have approximately the same value and its begin to increase into the maximum value at the channel wall in (DFM) model, and at (0.5, 1.47, 4.57) percent of radius from channel wall for (Dp = 1, 3, 10 mm) in (DBM) and (DFBM) models, while it remain constant at (DM) models.

The channeling phenomena enhanced heat transfer rate in (DFBM) and (DBM) when compared to prediction of the popular (DM) model.

Decreasing particle diameter will increased the channeling phenomena and pressure drop through the packed bed.

The numerical result also the effect of increasing Reynolds number, which tends to increase fire drop, heat transfer and thermal entry length, while Increasing lisle Reynolds number will increase drag coefficient and decrease action factor.

The experimental setup, using a copper tube as a packed bed assembly with (48 mm) inside diameter and (1150 mm) heated length with a constant heat flux boundary condition.

The test section was vertically oriented with water flowing against gravity and packed with glass spheres (1, 3, 10 mm) diameter respectively.

The results show an increase in local Nusselt number when Reynolds number and heat flux increase, the heat transfer rate increase as the particle diameter increase at the range of (1 ~ 3 mm) and decrease with increasing particle diameter at the range (3 - 10 mm).

The friction factor decrease with increases the particle diameter and particle Reynolds number.

Many empirical relations, who obtained experimentally, are in good agreement with the numerical correlation.

The following correlation are presented the analogy between friction factor and heat transfer coefficient : St pr 2 / 3 = 0.0212 (F) 0.32639 d = 0.04166, E = 0.356 St Pr 2 / 3 = 0.0223 (F) 0.325941 d = 0.125, E = 0.382 St Pr 2 / 3 = 0.0126 (F) 0.478248 d = 0.4166, E = 0.462

التخصصات الرئيسية

هندسة الميكاترونكس

الموضوعات

• ديناميكا الموائع

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-305875