Ministry of Higher Education and Scientific Research
University of Babylon /College of Material s Engineering
Dept. of Eng. of Polymers and Petrochemical Industries
First month Examination (2016-2017)
Sub.: heat transfer Date:12/ 12/2016
Stage: Third NOTE: Answer Three Questions Time:1.5Hrs.
Q1) A double-pane window consists of two 3-mm thick layers of glass separated by a 12-mm wide stagnant air space. For specified indoors and outdoors temperatures, determine the rate of heat loss through the window and the inner surface temperature of the window? K glass= 0.78 W/m.°C and K air= 0.026 W/m.°C? figure(1)
Q2)Show that the critical thickness of insulation of a circular pipe given by
r0=k/h
Q3) A 3.0-cm-thick plate has heat generated uniformly at the rate of 5×105W/m3
. One side of the plate is maintained at 200?C and the other side at 45?C. Calculate the temperature at the center of the plate fork=16 W/m•?C?
Q4) The figure below shows part of a set of radial aluminum fins(k=180W/m.K)that are to be fitted to a small air compressor .The device dissipates 1 Kw by convection to surrounding air which is at 20 0C .each fin is 100mm long ,30mm high and 5mm thick .The tip of each fin may be assumed to be adiabatic and heat transfer coefficient of h=15 W/m2.K acts over the remaining surfaces. Estimate the number of fins required to ensure the base temperature drop not exceed 120 0C? figure(2)
A=1.2mx2m
T?1=24 oC T?2=-5 oC
h2=25 W/m2?°C
h1=10 W/m2?°C
figure(1) figure(2)
Good luck
Head of the Department: Examiner:
Assist. Prof. Dr. Nizar .J.Hadi Mr.Qusai A.M
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
الرجوع الى لوحة التحكم
|