67243 cooling and heating load calculation chapter-2

কারিগরি রিক্ষাঅরিদপ্তরিিতত্ত্বাবিারে পরিচারিত
ফেসবুক িাইভক্লারিস্বাগত
OnlineTVET.com
Facebook.com/onlinetvet

ÒwØZxq- Aa¨vqÕÕ
4_©-ce©,†iwdªRv‡ikbGÛ
Gqvi KwÛkwbs †UK‡bvjwR
PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.
welq †KvW t 67243

Avey†gvnv¤§` AvwZKzj¨v
BÝUªv±i(†UK&) Avi Gwm
XvKvcwj‡UKwbK BÝwUwUDU,‡ZRMuvI,XvKv-
1208
atiqullahrac@gmail.com
রিক্ষক পরিরচরত

G.O: 2. Understand the “Concept
of Psychometric Chart.”
mvB‡µv‡gwUªKPvU©
m¤ú‡K©aviYv

S.O: 2.1 Draw and Explain the
Psychrometric Chart
S.O: 2.2 Draw and Explain
Comfort Chart.
S.O: 2.3 Describe Effective
Temperature.

S.O: 2.4 Explain the Following
Psychrometric Processes,
Sensible Heating,
Sensible Cooling,
Humidification,
De-Humidification,
Cooling and De-Humidification,
Heating and Humidification
S.O: 2.5 Solve Problems on
Psychrometric Processes and
Comfort Chart.PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

‡h Pv‡U©i gva¨‡g evZvm Ges evZv‡m Aew¯’Z
Rjxqev®ú mswgkÖ‡Y wewfbœ ¸bvejxi msL¨vg~jK
gvb
†hgb-
1।WªvBevj¦ZvcgvÎv(DryBulbTemperature/DBT)
2।I‡qUevj¦ZvcgvÎv(Wet Bulb Temperature/WBT)
3।wkwkivs¼(Dew Point Temperature/DPT)
S.O: 2.1 Draw and Explain the Psychrometric Chart
mvB‡µv‡gwUªKPvU© GieY©bv I AsKb

4। Gb_vjcx(Enthalpy),
5।†¯úwmwdK wnDwgwWwU(Specific
Humidity),
6।wi‡jwUfwnDwgwWwUevAv‡cwÿKAv`ª©Zv
(Relative Humidity/RH %)I
7। †¯úwmwdK fwjDg(SpecificVolume)
ev Avt AvqZb BZ¨vw` wbY©q Kiv nq,
Zv‡KB mvB‡µ‡gwUªKPvU©e‡j|PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

weÁv‡bi †h kvLvq ï®‹ evZvm (Dry air) Ges
cvwbi ev‡®úi wgkÖY m¤ú‡K© Av‡jvPbv Kiv nq,
Zv‡K mvB‡µv‡gwUª(Psychrometry)e‡j|
A_ev evZv‡mi I Rjxq ev‡®úi wewfbœ êwkó¨
m¤ú‡K© Rvbv‡KmvB‡µv‡gwUªe‡j|
Avi †h êwkó¨ m¤ú‡K© Rvbv hvq Zv‡K
mvB‡µv‡gwUªK êwkó¨ e‡j|
mvB‡µv‡gwUª(Psychrometry)

G QvovI cÖ‡KŠkj weÁv‡bi †h kvLvq
Av`ª© evZvm, ï®‹ evZvm, Rjxq ev‡®úi
wgkÖY Ges wewfbœ k‡Z©¨i Aax‡b
ï®‹ evZvm (Dry air) Ges Rjxq ev‡®úi wgkª‡Yi
AvPiY m¤ú‡K© Abykxjb I Av‡jvPbv Kiv nq Zv‡K
mvB‡µv‡gwUª(Psychrometry)e‡j|

ï®‹ evZvm (Dry Air/da)t
Abv`ª© ev Rjxq KYvgy³ evZvm‡K ï®‹ evZvm (Dry
Air/da) e‡j|
weï×ï®‹ evZvm KZK¸‡jv M¨v‡miwgkÖY| G‡`i g‡a¨
Aw·‡Rb (O2) I bvB‡Uªv‡RbB (N2) cÖavb|
GUv QvovI Kve©b WªvB-A·vBW (CO2),
Rjxqev®ú(H2O) Ges KZ¸‡jv wbw®Œq M¨vm
†hgb- wnwjqvg(He), wbqb(Ne), wµcUb(Kr),
†Rbb(Xe), †iWb(Rn) Ges AvM©b(Ar)
BZ¨vw`wgwkÖZAe¯’vqAv‡Q|

evZv‡mi wewfbœ Dcv`v‡bi nvi wb¤œiƒct
1.bvB‡Uªv‡Rb(N2) 78%
2.Aw·‡Rb (O2) 21%
3.Rjxqev®ú,Kve©bWªvB-A·vBWIAb¨vb¨ 1%
‡gvUt100%
evZv‡miAvbweKIRb=28.966Ges
M¨vmaªæeK=Ra =0.28wK‡jvRyj/‡KwR†Kjwfb|

Av`ª© evZvm (Moist air)t
GUv ï®‹evZvm (da)Ges Rjxq ev‡®úiwgkÖY|
evZv‡m cvwbi ev‡®úi cwigvb wbf©i K‡i, evZv‡mi
ZvcgvÎvi(Temp.) Ges cig Pv‡ci(AP) Dci|
m¤ú„³evZvm (Saturated air)t
GUv ï®‹ evZvm Ges Rjxqev‡®úi wgkÖY,
hLb evZv‡mi g‡a¨ m‡e©v”P cwigvb Rjxq ev®ú aviY K‡i|
Rjxq ev®ú mvaviYZ A`„k¨ M¨v‡mi g‡Zv AwZ DËß
ev‡®úi AvKv‡i N‡U|

hLb m¤ú„³evZvm‡KkxZj Kiv nqZLb Rjxqev®ú
Nbxf‚Z n‡Z ïiæ K‡i Ges Rjxq ev®ú Kzqvkvi
AvKv‡i `„k¨gvbnq|
m¤ú„³Zvi gvÎv(Degree of Saturation)t
GKK f‡ii ï®‹ evZv‡m Aew¯’Z Rjxq ev‡®úi
cÖK…Z fi GesPvc I Zv‡c GKB cwigvb
m¤ú„³evZv‡m Rjxq ev‡®úi f‡ii
AbycvZ‡KB m¤ú„³Zvi gvÎv (Degree of
Saturation) e‡j|

Av`ª©Zv(Humidity)t
GK †KwR (1kg) ï®‹ evZv‡m we`¨gvb Rjxq ev‡®úi fi‡K
Av`ª©Zv (Humidity) e‡j|
†Kv‡bv ¯’v‡bi evZv‡m KZUzKz Rjxq ev®ú Av‡Q A_©vr
evZv‡m KZLvwb ï®‹ ev †fRv Av`ª©Zv Øviv Zv wb‡`©k Kiv
nq|
G‡K gm/kg of dry air ev ms‡ÿ‡c gm/kg of da Øviv
cÖKvk Kiv nq|
G‡K Avevi †¯úwmwdK wnDwgwWwU (Specific
humidity) ev wnDwgwWwUAbycvZ (Humidity
ratio)ejv nq|PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

cig Av`ª©Zv(Absolute humidity)t
GKK AvqZ‡bi evZv‡m†hcwigvbRjxq ev®ú _v‡K,
Zv‡K cig Av`ª©Zv (Absolute humidity)e‡j|
A_ev GK NbwgUvi (1m3) evZv‡m we`¨gvb Rjxq
ev‡®úi fi‡Kcig Av`ª©Zv e‡j|
G‡Kgm/m3 of dry air Øviv cÖKvkKiv nq|
G‡Kgrains/m3 ØvivI cÖKvk Kiv nq|
MvwYwZKfv‡e, GK †KwR Rjxq ev®ú = 15430 ‡MÖBb
(gr)
A_ev †KwR/NbwgUvi (kg/m3)PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

Av‡cwÿK Av`ª©Zv (Relative humidity)t
‡Kv‡bv wbw`ó ZvcgvÎvq wbw`ó AvqZ‡bi evZv‡m
†h
cwigvb Rjxq ev®ú _v‡K Ges H ZvcgvÎvq H
AvqZ‡bi evZvm‡K m¤ú„³ Ki‡Z †h cwigvb Rjxq
ev‡®úicÖ‡qvRbnq,
GB `ywUi AbycvZ‡K Zzjbxq ev Av‡cwÿK Av`ª©Zv
(Relative humidity ev RH%) e‡j|
GUv†KRH%ØvivcÖKvk Kivnq|PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

∴ Av‡cwÿK Av`ª©Zv, (RH)
=
cixÿYxq evZv‡m Rjxq ev‡®úi cwigvb
GKB AvqZ‡bievZvm‡Km¤ú„³Ki‡Z cÖ‡qvRbxq Rjxqev‡®úicwigvb
×100%
‡hgb- 30%, 40%, 60%, 85% BZ¨vw`|
RH % =
Rjxq ev‡®úi cwigvb/m3 †Kv‡bv Av`ª© evZv‡m
GKB ZvcgvÎvIPv‡c m¤ú„³ evZv‡m Rjxq ev‡®úi cwigvb/m3
=
mv
ms
GLv‡b AvqZ‡bi GKK e¨eüZ
GLv‡b, mv= Rjxqev‡®úi cwigvb NbwgUvi (m3)
ms = m¤ú„³evZv‡mRjxqev‡®úicwigvbNbwgUvi(m3)
RH = Av‡cwÿK Av`ª©Zv (Relative humidity)

WªvB evj¦ ZvcgvÎv(Dry bulb temperature/DBT)t
mvaviY _v‡g©vwgUv‡i evZv‡mi †h ZvcgvÎv
(Temp.) cvIqv hvq, Zv‡K WªvB evj¦ ZvcgvÎv
(Dry bulb temperature/DBT)e‡j|
GUv‡K DBT ZvcgvÎv e‡j Ges td ev tdb Øviv
cÖKvk Kivnq|
I‡qUevj¦ZvcgvÎv(Wet bulb temperature/WBT)t
_v‡g©vwgUv‡iievj¦wfRvKvcow`‡qRov‡bvAe¯’vq
(270 wgUvi/wgwbU †e‡M evZv‡m Nywi‡q)
evZv‡miZvcgvÎvi(Temperature)

‡hgvb cvIqvhvq, Zv‡K I‡qUevj¦ZvcgvÎv(Wet
bulb temperature/WBT)e‡j|
I‡qU evj¦ ZvcgvÎv WªvB evj¦ ZvcgvÎv A‡cÿv Kg nq|
KviY, wfRv Kvco ‡_‡K cvwb ev®úvwqZ nIqvi d‡j
evj¦VvÛvnq Ges
GB KvRevZv‡miAv`ª©ZviDci wbf©ikxj|
G‡K WBTØviv cÖKvk Kivnq|

I‡qUevj¦wW‡cÖkb(Wet bulb depression/WBD)t
‡h †Kv‡bv we›`y‡Z WªvB evj¦ Ges I‡qU evj¦
ZvcgvÎvi cv_©K¨‡K I‡qU evj¦ wW‡cÖkb e‡j|
I‡qU evj¦ ZvcgvÎv (WBT) evZv‡mi Av‡cwÿK
Av`ª©Zv(Relativehumidity)Dciwbf©ikxj|
WªvBevj¦GesI‡qUevj¦ZvcgvÎvicv_©K¨hZ†ewkn‡e
evZv‡miAv`ª©ZvZZKgn‡e|
AviDfqZvcgvÎvicv_©K¨hZKgn‡eevZv‡mi
Av`ª©ZvZZ†ewkn‡e|PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

100% m¤ú„³ evZv‡mi I‡qU evj¦ ZvcgvÎv, WªvB
evj¦ ZvcgvÎv Ges wkwkiv¼ (Dew Point
Temperature/DPT)mgvb n‡e|
GKB WªvBevj¦ZvcgvÎvq ï®‹evZv‡mi†P‡qwfRv
evZv‡mi I‡qU evj¦ ZvcgvÎv AwaK n‡e|
100% Av`ª©Zv Qvov WªvB evj¦ ZvcgvÎv
I‡qU evj¦ ZvcgvÎv n‡Z †ewk n‡e|

wkwkiv¼ (Dew Point Temperature/DPT)
‡h ZvcgvÎvq evZv‡mi Rjxq KYv wkwk‡i
(Dew) cwiYZ nq, Zv‡KB wkwkiv¼ (Dew
Point Temperature/DPT)e‡j|
‡h ZvcgvÎvq GKwU wbw`ó AvqZ‡bi evZvm Zvi
wfZ‡ii Rjxq ev®ú w`‡q m¤ú„³ nqA_ev
‡h ZvcgvÎvq evZv‡mi Rjxq ev®ú Nbxf‚Z n‡q
wkwk‡icwiYZ nq,Zv‡KI wkwkiv¼e‡j|

wWD c‡q›UwW‡cÖkb(Dew Point
Deperssion)t
evZv‡mi WªvB evj¦ ZvcgvÎv Ges wWDc‡q›U
ZvcgvÎvi cv_©K¨‡K wWD c‡q›U wW‡cÖkb e‡j|
w¯øsmvB‡µvwgUvi t
‡hwgUv‡iimvnv‡h¨ evZv‡miWªvBevj¦ZvcgvÎv
GesI‡qU evj¦ZvcgvÎvigvbGK‡Î cvIqvhvq
Zv‡KB w¯øs mvB‡µvwgUvi e‡j| G‡Z `ywU
_v‡g©vwgUvi cvkvcvwk GKB †cø‡Ui Ici

evZv‡mi7wU (mvZwU)êwkó¨ wb‡q †hPvU©ˆZix Kiv
nq,
Zv‡KmvB‡µv‡gwUªKPvU©(Psychrometric Chart)
e‡j|
Ab¨fv‡e, †hPv‡U©i gva¨‡gevZv‡mi †h†Kv‡bv
2wU êwkóëv ¸vY¸‡Yi mvnv‡hÄci 5wU êwkó¨
Rvbv hvq,Zv‡K mvB‡µv‡gwUªKPvU©
(Psychrometric Chart)e‡j|
2.1 Explain the Psychrometric Chart
mvB‡µv‡gwUªK PvU© Gi eY©bv

cÖ‡Z¨KwU jvBb wfbœ wfbœfv‡e wfbœ&
wfbœ êwkóÏ êwk‡óï gvbwb‡`©k K‡i|
evZv‡mi Ae¯’v we¯ÍvwiZfv‡e Rvbvi Rb¨
mvB‡µv‡gwUªK PvU© eënvi Kiv nq|
we‡klZ Gqvi KwÛkwbs (Air Conditioning
/AC)wWRvB‡biRb¨GUvAZ¨šÍcÖ‡qvRbxq|
G PvU© †_‡K evZv‡mi wewfbœ Ae¯’v
AwZmn‡RB†eiKivhvq|PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

‡hgb-
1| evZv‡mi WªvB evj¦ I I‡qU evj¦ ZvcgvÎv Rvbv
_vK‡jPvU©†_‡KAv‡cwÿKAv`ª©ZvRvbvhvq|
2| WªvB evj¦ ZvcgvÎv I Av‡cwÿK Av`ª©Zv
Rvbv_vK‡jI‡qUevj¦ZvcgvÎvRvbvhvq|
3| I‡qU evj¦ ZvcgvÎv I Av`ª©Zv Rvbv
_vK‡j WªvBevj¦ ZvcgvÎv Rvbv hvq|

4| I‡qU evj¦ ZvcgvÎv I WªvB evj¦ ZvcgvÎv
Rvbv_vK‡jwkwkiv¼(DPT)Rvbvhvq|
5|WªvBevj¦IAv‡cwÿKAv`ª©ZvRvbv_vK‡j
wkwkiv¼Rvbvhvq|
6| WªvB evj¦ I Av‡cwÿK Av`ª©Zv (Relative
humidity RH%) Rvbv _vK‡j evZv‡m ev‡®úi
cwigvbRvbvhvq|

Abyiƒ‡c,
WªvBevj¦ZvcgvÎvI wWD c‡q›U,
I‡qU evj¦ZvcgvÎvI Av‡cwÿKAv`ª©Zv,
I‡qU evj¦wWD c‡q›U ZvcgvÎv,
WªvBevj¦ I I‡qU evj¦ZvcgvÎvGes
†Kejwkwkiv¼Rvbv_vK‡jevZv‡mAew¯’Z
ev®ú`vbvi(Grains of moisture)
cwigvbRvbvhvq|

mvB‡µv‡gwUªK Pv‡U© A¨vewmmv
(Abcissa)WªvB evj¦ ZvcgvÎv Ges
AiwW‡bU (Ordinate) †¯úwmwdK
wnDwgwWwU (Specific humidity)
wb‡`©k K‡i|
m¨vPz‡ikb Kvf© wewfbœ WªvB evj¦
ZvcgvÎv 100% Avt Av`ª©Zv wb‡`©k K‡i|
GUv I‡qU evj¦ Ges wWD c‡q›U ZvcgvÎv

PSYCHROMETRIC CHART

S.O: 2.1 Draw and Explain the Psychrometric Chart
mvB‡µv‡gwUªKPvU©Gi eY©bvI AsKb

Kg‡dvU©(Comfort)KwÛkbA_©n‡jvAvivgcÖ`Ae¯’v
evZv‡miwb¤œwjwLZAe¯’vqAwaKvskgvbyl
¯^v”Q›`¨ AbyfeK‡i, ‡hgb-
1|ZvcgvÎv(Temperature) 65-78wW.dv‡ibnvBU
2|Av`ª©Zv(Humidity) 50%
3|evZv‡miMwZ/‡eM(AirVelocity)2-15dzUcÖwZ
wgwb‡U

mZivsgvby‡likix‡iiRb¨Avivg-`vqKAe¯’v
ZvcgvÎv(Temperature);
Av`©ªZv(Humidity),
evZv‡miMwZ/‡eM(AirVelocity),
weï×Zv I k‡ãiKvw•LZ wbqš¿Y Gi Dci wbf©ikxj|
Kg‡dvU© Pv‡U©i†h wbw`ó¨GjvKvq I Ae¯’vq AvivgcÖ`
nq,
Zv‡KB Kg‡dvU© †Rvb (Comfort zone) e‡j|
kxZIMÖx®§Kv‡jiRb¨IGKg‡dvU©†RvbHPv‡U©‡`Lv‡bvPresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

Kg‡dvU©PvU©WªvBevj¦ZvcgvÎvi(DBT)ms¯ú‡k©
I‡qUevj¦ZvcgvÎvi(WBT)GKwUb·vwe‡kl,
hviDci Av‡cwÿKAv`ª©ZvGes B‡dKwUf
ZvcgvÎvijvBb ¯’vcb Kiv nq|
kxZKv‡j Kg‡dvU©†Rv‡biB‡dKwUfZvcgvÎv
63 n‡Z 71 wWMÖxdv. ev17.22 n‡Z 21.66℃|
MÖx®§KvjxbKg‡dvU©†Rv‡bi B‡dKwUf
ZvcgvÎv
66wWMÖxdv.n‡Z75wWMÖxdv.ev18.88n‡ZPresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

B‡dKwUfZvcgvÎvWªvBevj¦ZvcgvÎv(DBT)
I‡qUevj¦ZvcgvÎv(WBT)GesevZv‡miMwZi¯^iƒc,
hvMigevVvÛvimg-Abyf‚wZ‡KmsMÖnevcÖ¯‘Z
K‡i|
Kg‡dvU©†RvbKg‡dvU©Pv‡U©iGgbGKwU
†ÿÎdj,
†hLv‡b Kvco cwiavb Ges Kvh©ve¯’vq
AvbygvwbK mg-Avivg cvIqv hvq|PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

Elements of the answer ‐ Fresh Air (as opposed
to stale)
→ Good Level of Oxygen (O2)
→ Sufficient Air Exchange with Outside
‐ Not too Hot and not too Cold
→ Control of Temperature
‐ Not too Dry and not too Humidity

→ Control of Relative Humidity
‐ Good Amount of Light,
but no Excess and no Glare.
→ Enough Light,
Preferably Diffuse
‐ Human Dimension to the Context.
→ Appropriate Geometric
Dimensions,
Pleasing Shapes

Kg‡dvU© PvU© Comfort Chart

Kg‡dvU© PvU AsKb I eY©bv

B‡dKwUf/ Kvh©Kwi ZvcgvÎv t Bnv GKwU m~PK
(Index)wn‡m‡ewe‡ePbvKiv nq,
hvgvby‡likix‡iiDcievZv‡miZvcgvÎv(Temperature)
Av‡cwÿKAv`ª©Zv(Relative Humidity RH%)Ges
evZv‡mi†eM(AirVelocity)mw¤§wjZwµqvd‡ji
AbyeÜ¯’vcbK‡i|

B‡dKwUf ZvcgvÎvi msL¨vm~PK gvb w¯’i
A_©vr (5 †_‡K 8 wgUvi/wgwbU)
hvm¤ú„³ evZv‡mi ZvcgvÎvi mgvbA_©vr
†Kvbwbw`óAe¯’vq†hcwigvbDòZv(Temperature)ev
kxZjZviAbyf‚wZDrcbœnqB‡dKwUfZvcgvÎvI
HGKBcwigvYAbyf‚wZDrcbœK‡i|

PsychrometricProcesses(mvB‡µv‡gwUªK
cÖ‡mm)
mgynwb¤œiæc:
1. ‡mbwmejwnwUs(Sensible Heating)
c×wZ
2. ‡mbwmejKzwjs(Sensible Cooling) c×wZ
3. wnDwgwWwd‡Kkb(Humidification)PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,M# 01711-056403

5. Kzwjs GÛ wW-wnDwgwWwd‡Kkb
c×wZ
Cooling and De-Humidification
6. wnwUs GÛ wnDwgwWwd‡Kkb
c×wZ
Heating and Humidification
7. wnDwgwWwd‡Kkb evB w÷g Bb‡RKkbPresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

8. A¨vwWqv‡ewUK †KwgK¨vj wW-
wnDwgwWwd‡Kkbc×wZ
Adiabatic Chemical De-Humidification
9. A¨vwWqv‡ewUK wgwK&ªs Ae Gqvi w÷g
c×wZ
Adiabatic Mixing of Air Steam
10.KywjsGÛwnDwgwWwd‡KkbevBIqvUviBb‡RKkb
c×wZ

‡mwÝej wnwUs cÖ×wZ t Av‡cwÿK Av`©ªZv (RH %)
ev †¯úwmwdK wnDwgwWwUi †Kvb cwieZ©b bv
NwU‡q evZvm‡K DËß/Mig (Hot) Kivi c×wZB nj
‡mwÝej wnwUs cÖ×wZ
‡mwÝej wnwUs cÖ×wZ Gi †ÿ‡Î ev®ú A_ev Mig
cvwb wnwUs K‡q‡ji wfZiw`‡q AwZµg Kiv‡bv nq|
wnwUs K‡qj B‡jKwUªK †iwRU¨vÝ K‡qj n‡Z cv‡i|
Av`©ª evZv‡mi ‡mwÝej wnwUs ‡h-‡Kvb ZvcgvÎvq
Kiv †h‡Z cv‡i|

‡mwÝejKzwjs c×wZt Av‡cwÿK Av`©ªZv
RELATIVE HUMIDITYev RH %ev
†¯úwmwdK wnDwgwWwUi †Kvb cwieZ©b bv
NwU‡q
evZvm(Air) ‡K kxZj/ VvÛv(Cold) Kivi
c×wZB nj ‡mwÝejKzwjs (Sensible
Cooling) c×wZ|PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

wnDwgwWwd‡Kkb ev Av`ª©KiY t WªvB evj¦
ZvcgvÎvi(DBT) cwieZ©b bv NwU‡q
Rjxq ev®úhy³ ev †hvRb, m¤ú„³(+) Add.
Kivi c×wZB nj wnDwgwWwd‡Kkb
(Humidification) ev Av`ª©KiY|

wW-wnDwgwWwd‡Kkb ev Abv`ª©KiY t
WªvBevj¦ZvcgvÎvi(DBT)cwieZ©bbvNwU‡q
Rjxqev®úAcmviYevwe‡qvM(-)Kivic×wZBn‡jv
wW-wnDwgwWwd‡Kkb(De-Humidification)ev
Abv`ª©KiY
wW-wnDwgwWwd‡Kkb cÖwµqvq Rjxq
ev®ú
AcmviY(Moisture Rejected) Kiv nq|

Kzwjs Ges wW-wnDwgwWwd‡Kkb(Cooling and de-
humidification)t
G c×wZ mvaviYZt MÖx®§Kvjxb kxZvZc wbqš¿‡bi
†ÿ‡Î evZvm‡K VvÛv Ges Abv`ª© Kivi Rb¨ e¨envi Kiv
nq|
Kzwjs K‡q‡ji Dci w`‡q A_ev VvÛv cvwbi
†®úÖi ga¨w`‡qevZvmAwZµvšÍnq|
G c×wZ‡Z evZv‡mi WªvB evj¦ ZvcgvÎv(DBT)
Ges †®úwmwdK wnDwgwWwU n«vm cvq|PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

wnwUs GÛ wnDwgwWwd‡Kkb (Heating and
Humidification)t
G c×wZ mvaviYZt kxZKvjxb kxZvZc wbqš¿‡bi(Winter
AC) †ÿ‡Î evZvm‡K Mig (Hot) Ges Av`ª© (Humidity)
Kivi Rb¨ e¨envi Kiv nq|
wnwUs K‡q‡ji Dci w`‡q A_ev Mig cvwbi †®úÖi ga¨
w`‡qevZvmAwZµvšÍ nq|
G c×wZ‡Z evZv‡mi WªvB evj¦ ZvcgvÎv(DBT) Ges
†®úwmwdKwnDwgwWwUe„w×cvq|PresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

mgm¨vejx

awi,
ï®‹evZv‡mi Rb¨ (Dry air)
Pa = AvswkK Pvc(Partial pressure)
Va = AvqZb(Volume)
Ta = cig ZvcgvÎv (Absolute Temperature)
ma = fi (ï®‹ evZvm),
Ra = M¨vm aªæeK,
mvB‡µv‡gwUªK wi‡jkbmtAv`ª©ZviAbycvZ

GeswfRvevAv`ª©evZv‡miRb¨-
Pv = AvswkKPvc (Partial pressure),
Vv =AvqZb(Volume),
Tv = cig ZvcgvÎv,
mv = fi(ev®ú),
Rv =M¨vmaªæeK,
awi, ï®‹evZvmGes Rjxqev®ú cvi‡d±ev Av`k©
M¨v‡mig‡ZvAvPiY K‡i|

ï®‹ evZv‡mi (Dry air) ‡ÿ‡Î,
Pa Va = ma Ra Ta ……………….(1)
GesRjxqev‡®úi †ÿ‡Î,
Pv Vv = mv Rv Tv ……………….(2)
G QvovVa = Vv GesTa = Tv = Td
GLv‡bTd = WªvB evj¦ ZvcgvÎv (DBT)
mgxKiY (1) I (2) bs mgxKiY n‡Z cvB,
Pv
Pa
=
mvRv
ma RaPresentedBy :A.M.AtiqullahINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

cÖ‡qvRbxqm~Îvejxt
1. 𝐏 𝐯 = Rjxqev‡®úiAvswkKPvc(Partial pressure)
2.Avt Av`ª©Zv, ∅ =
𝐏 𝐯
𝐏 𝐬
3.‡¯úwmwdKwnDwgwWwU, W = 0.622×
𝐏 𝐯
𝐏 𝐛−𝐏𝐯
4.wi‡jwUfwnDwgwWwU,(RH%) =
𝐏𝐯
𝐏 𝐬
S.O:2.5 Solve problems on Psychrometric
Processes and Comfort Chart.

5. ‡fcvi †WbwmwU(Pv)=
𝛚( 𝐏 𝐛−𝐏𝐯)
𝐑 𝐚 𝐓 𝐚
6.‡mbwmejwnU d¨v±i,SHF = 𝐒𝐞𝐧𝐬𝐢𝐛𝐥𝐞 𝐇𝐞𝐚𝐭
𝐓𝐨𝐭𝐚𝐥 𝐇𝐞𝐚𝐭
= 𝐒𝐇
𝐒𝐇+𝐋𝐇
=
𝐇 𝐀−𝐇 𝟏
𝐇 𝟐−𝐇 𝟏
7. PV = mRT or PV = nRT.
8.
𝐏 𝐯
𝐏 𝐚
= 𝐦 𝐯 𝐑 𝐯
𝐦 𝐚 𝐑 𝐚

‡`qv Av‡Q, td = 28℃,Pb =760mmofHg,Ges
𝛚 =0.016kg/kgda
awi,ev‡®úi AvswkK Pvc= 𝐏𝐯
AvgivRvwb,Av`ª©ZviAbycvZ, 𝛚 = 0.622×
𝐏 𝐯
𝐏 𝐛−𝐏𝐯
0.016 = 0.622×
𝐏 𝐯
𝟕𝟔𝟎−𝐏𝐯
2|28℃WªvBevj¦ZvcgvÎvGes760mmofHgPv‡cevqygÛjxqevZv‡mi
Av`ª©ZviAbycvZ(Humidityratio)0.016kg/kgda|wbY©qKi‡Z
n‡e-1|Rjxqev‡®úiAvswkKPvc,2|wkwkiv¼,3|Av‡cwÿKAv`ª©Zv(RH%),
4|†¯úwmwdKGb_vjwcGes5|†fcvi†WbwmwU|

2.16 - 0.622𝐏 𝐯 =0.622 𝐏𝐯
∴ 𝐏 𝐯 = 19.06 mm of Hg
= 19.06 × 0.133 KN/m2
∴ 𝐏 𝐯 = 2.535 KN/m2
[ ∵ 1mm of Hg = 0.133 KN/m2 ]
∴Rjxqev‡®úiAvswkKPvc, 𝐏 𝐯 = 2.535 KN/m2
DËi|

2| wkwkiv¼ (Dew point temperature)
†h‡nZz Rjxq ev‡®úi AvswkK Pvc (𝐏𝐯 ) Gi mswkøó
wWDc‡q›UZvcgvÎvBm¤ú„³ZvcgvÎv,
GLb w÷g†Uwej (Strem table) †_‡K
2.535 KN/m2 (0.02535 bar) Ges
mswkøó (Corresponding)
myZivswkwkiv¼tdp = 21.11℃

3| Av‡cwÿK Av`ª©Zv t
GLb w÷g†Uwej (Strem table) †_‡K
28℃ WªvB evj¦ ZvcgvÎvi mswkøó Rjxq ev‡®úi m¤ú„³ Pvc,
Pb = 0.03778 bar
= 3.778 KN/m2
∴ Av‡cwÿK Av`ª©Zv = ∅ =
𝐏 𝐯
𝐏 𝐬
=
𝟐.𝟓𝟑𝟓
𝟑.𝟕𝟕𝟖
= 0.67 %
∅ = 0.67 % Answer.

4| †¯úwmwdKGb_vjwc t
awi, H = †¯úwmwdK Gb_vjwc KJ/Kg da
Ldp = 21.11℃ = wWDc‡q›U ZvcgvÎvi mswkøó
cvwbi ev®úxfe‡bi myßZvc
=2451.75 KJ/Kg [ Steam Table n‡Z ]
Avgiv Rvwb,
H = 1.022td + 𝛚(Ldp + 2.3tdp )
=1.022 ×28 + 0.016(2451.75 + 2.3 ×21.11)
H =28.62 + 40 = 68.62 KJ/Kg da Answer

5| †fcvi †WbwmwU(Pv) t
Avgiv Rvwb,
Pv =
𝛚( 𝐏 𝐛−𝐏𝐯)
𝐑 𝐚 𝐓 𝐚
=
𝟎.𝟎𝟏𝟔× 𝟕𝟔𝟎 −𝟏𝟗.𝟎𝟔 ×𝟎.𝟏𝟑𝟑
𝟎.𝟐𝟖𝟕 × 𝟐𝟕𝟑+𝟐𝟖 𝐊
=
𝟏.𝟓𝟕𝟔𝟕𝟐𝟎𝟑𝟐
𝟖𝟔.𝟑𝟖𝟕
∴ Pv =0.018 Kg/m3 da. Answer

এই পাঠ সম্পরকি ত ফতামারদি
ফকাে প্রশ্ন আরেরক?

67
THANKS!
Any questions?
You can find me at
atiqullahrac@mail.com
PresentedBy :A.M.ATIQULLAH,INSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE, Dhaka-1208

Aa¨vq-2qGi cÖkœvejx t
1. msMv wjL t- K) ‡mwÝej wnwUs cÖ×wZ L) ‡mwÝej Kzwjs cÖ×wZ M)
wnDwgwWwd‡Kkb ev Av`ª©KiY N) wW-wnDwgwWwd‡Kkb ev Abv`ª©KiY O)
KzwjsGeswW-wnDwgwWwd‡Kkb P)wnwUsGÛwnDwgwWwd‡Kkb |
2.mvB‡µv‡gwUªKPvU©ej‡ZKxeySvq?DnvAsKbK‡i†`LvI?
3.Kg‡dvU©PvUKx?DnvAsKbK‡i†`LvI?
4.B‡dKwUfevKvh©KwiZvcgvÎvej‡ZKxeySvq?
5. Psychrometric processes(mvB‡µv‡gwUªKcÖ‡mm)¸‡jv†jL?

01 FEBRUARY'2020Presented By : A.M.Atiqullah INSTRUCTOR(Tech)RACD.P.I
69

এই ক্লাসটি পূেিায় ফদখরত রভরিট করিা
onlinetvet.com
Presented By : A.M.Atiqullah,INSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE, Dhaka-1208.

Presented By : A.M.Atiqullah,INSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE, Dhaka-1208.

2.1 Find the U factor of a) Brick wall without plaster. b) Brick wall with
plaster on one side. c) Brick wall with plaster on both side.
2.2 Find out U value from the chart of hollow tiles, cylindrical blocks,
concrete blocks, etc, of different insulation thickness and K factors.
2.3 Find out the U factors from the chart of common cold storage walls, roofs
and floors at different insulation thickness and K factors
2.4 Solve Problems on relating U factors for common wall of commercial
building and cold storage.

1.Basic Refrigeration and Air conditioning - P. N. Ananthanarayanan
2.Principal of Refrigeration - Roy J. Dossat
3.A text book of Refrigeration and Air-conditioning - R. S Khurmi & J K Gupta
4.A course in Refrigeration and air conditioning - S. C. Arora & S Domkundwar
5.Modern refrigeration and airconditioning for engineers - Prof. P S Desai
6.Refrigeration and air conditioning - C P Arora
7.Refrigeration and air conditioning - Ahmadul Ameen

Comfort Zone(SHL+THL)
PresentedBy :A.M.AtiqullahhINSTRUCTOR(Tech)RACDHAKA POLYTECHNIC INSTITUTE,Tejgaon,Dhaka.

Aa¨vq-2 (AsK)

QUESTION ?
Presented By : A.M.Atiqullah INSTRUCTOR(Tech) RAC DHAKA POLYTECHNIC INSTITUTE,TEJGAON I/A Dhaka-1208

67243 cooling and heating load calculation chapter-2

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