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MECHANICAL CONTROLS
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1.Objectives : The objectives of thermalco trols are i! "he the
col# #iscomfort co #itio
$revail%a! to $reve t heat loss
b! to &tili'e heat (ai from s& a #i ter al so&rces
c! to com$e sate for a ) et heat loss *
b) heati ( +hich &ses some form ofe er()
ii! "he hot #iscomfort co #itio $revail% a! to $reve t heat (ai
b! to ma,imi'e heat loss
c! to remove a ) e,cess heat b) cooli (*
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iii! "he co #itio s var) #i&r all) bet+eehot a # col#
#iscomfort%
a! to eve o&t variatio b! 1. i the col# $hase a # -. the
hot$hase c! to com$e sate for both e,cess b) a
e,ibleheati ( / cooli ( s)stem
-.0e(ree of co trol :
The mecha ical co trols are $ositivel)ecessar) at e,treme co
#itio s* +he h&malife is at ris .
Mecha ical co trol is a o$tio al case +heit is 2&estio of
$erso al comfort.
Creatio of comfort i #oor co #itio s
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i!The societ) +e live a #ii!3i a cial mea s at o&r
#is$osal
4. Heati ( : Heati ( i b&il#i ( ca be $rovi#e# locall)
i.e. b) co versio of some form of e er() i toheat
The form of e er() ma) be at&ral li e+oo#* coal* co e or oil
etc.
It ma) also be $rocesse# form of e er() li e
(as* electricit) or atomic e er() etc. The $rocesse# e er() is
co verte# i to area#il) &seable form a # #istrib&te#
thro&(h a
et+or of $i$es or cables to the $oi ts of &se
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Ce tral Heati ( :
I case of ce tral heati ( the so&rce is e$t atthe ce tral
$oi t a # s&bse2&e tl) #istrib&te# b)some co ve)i (
me#i&m.
The co ve)i ( me#i&m ma) be +ater * oil orma) be steam
Ce tral heati ( s)stem co sists of three #isti cteleme ts% a!
the heat raisi ( $la t 5boiler or f&r ace! b! the
#istrib&tio et+or 5#&cti ( or $i$i (!
c! the heat emitter & its 5#i6&sers* ra#iators orco
vectors!
7.Si'e of i stallatio : si'e a # ca$acit) of heati ( i
stallatio
Rate of heat loss from the b&il#i (
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So i crease# i i s&latio re#&ces the heatloss rate.
8.9roblems associate# +ith heati ( : a! 0istrib&tio of
heat:
tem$erat&re (ra#ie t bet+ee areas ofco ce trate# heat
loss5e.(. +i #o+! a # 'o esof heat o&t$&t & its ma) be
so stee$ thatstro ( co vectio c&rre ts 5#ra&(hts! are(e
erate#* +hich e6ects comfort co #itio s. b! 0r) ess :
it is res<a t of heati ( +he cool air of me#i&m
h&mi#it) is heate# *
its relative h&mi#it) is #ecrease#
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E,% air at c 0;T a # 8O< RH* heate# to - c0;T+ill ca&se
the #ro$ of RH to #ro$ &$ to 17<
c! Co #e satio : ca be ca&se# i #irectl) the +arm i #oor air
+ill rea#il) ta e omoist&res from a ) available so&rce* li
e%
h&ma e,halatio * bath etc.So its RH i creases * co se2&e
tl) its #e+
$oi t tem$erat&re is also i crease#
=.>e tilatio : ve tilatio is ver) m&ch ecessar) tomai tai
a comfortable i #oor e viro me t
at&rall) I some cases the a#e2&ate amo& t of air
s&$$l) ca be e s&re# b) ee$i ( the #oors
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?.Mecha ical ve tilatio s)stem: I mecha ical co trol ve tilatio
the air is
move# b) motor #rive fa s. The) ma) bea! $ro$eller or a,ial o+
fa s
b! im$eller or ta (e tial o+ fa s
1.A e,ha&st s)stem / removes the &se# air a #lets the
fresh air to come i-.A $le &m s)stem % s&$$l) air i to the
s$ace a #force o&t the &se# air thro&(h (rills4.A bala
ce# s)stem / both s&$$lies a # removesair.
