7/26/2019 Assignment 1 April 2016

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CONFIDENTIAL ASSIGNMENT 1 1 EH/APRIL 2016/CHE463

(Answer ALL questions individually and submit by 3/5/2016, 5pm)

QUESTION 1(!1, "!1)

a) A youn# en#ineer is as$ed to determine t%e rate o& %eat loss &rom a &urna'e wall perunit area and t%e temperature at t%e inter&a'e %e wall is 'onstru'ted &rom an innerlayer o& 05 'm t%i'$ steel ($ * +0 /m-.) and an outer layer o& 10 'm ir'onium bri'$($ * 25 /.) as s%own in &i#ure 1 %e inner sur&a'e temperature is 00 . and t%eoutside sur&a'e temperature is +60 . tate two (2) o& your assumptions

i#ure 1 urna'e all(10 mar$s)

b) ompare t%e %eat loss &rom an insulated and an uninsulated 'opper pipe under t%e&ollowin# 'ondition %e pipe ( $ * +00 /m-.) %as an internal diameter o& 10 'm and aneternal diameter o& 12 'm aturated steam &lows inside t%e pipe at 1104 and t%e %eattrans&er 'oe&&i'ient is estimated to be 10,000 /m2-. %e pipe is lo'ated in a spa'e at304 and t%e %eat trans&er 'oe&&i'ient on its outer sur&a'e is estimated to be 15 /m2-.%e insulation available to redu'e %eat losses is 5 'm t%i'$ and its 'ondu'tivity is020 /m-.

Figure 2 C!!er !i!e

" H#$ Ci!%# U&i'er(i%i Te$&)gi MARA CONFIDENTIAL

7/26/2019 Assignment 1 April 2016

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CONFIDENTIAL ASSIGNMENT 1 2 EH/APRIL 2016/CHE463

(10 mar$s)

QUESTION 2*CO1+ PO1,

A &lat plate wit% 15 m lon# and 155 m/s o& air velo'ity is to be maintained at 04 in t%e airw%en &ree stream temperature is 104 etermine t%e widt% o& &lat plate at w%i'% air must&low over t%e plate so t%at t%e rate o& ener#y dissipitation &rom t%e plate is 35 $ onsidert%e 'riti'al 7eynolds number, 7e'r* 5 10

5

8se 9 3/12/1 PrRe664.0L

k

LhNu == &or laminar &low

[ ] 3/18.0 Pr836Re036.0 ==L

k

LhNu &or turbulent &low

a$e t%e &ollowin# air properties at 5049

703.0Pr10029.2

3.100702813.00877.1

5

3

=

=

=

==

sm

kgx

Ckg

Jc

Cm

Wk

m

kgp

(11 mar$s)

END OF QUESTION PAPER

" H#$ Ci!%# U&i'er(i%i Te$&)gi MARA CONFIDENTIAL