energy balance untuk teknik kimia

7/24/2019 Energy Balance Untuk Teknik Kimia

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E N E R G Y

A N D

E N E R G

Y

B A L A

N C E

T

I M P E N G

A J A R

P E N G A

N T A R

I L M U

K E T E K N

I K A N



INTRODUCTION

Energy is expensive….

Efective use o ener! is i"#ort$nt t$s% or c&e"ic$' enineers(Topics of this chapter

Ener! )$'$nce

Ener! $n* ener! tr$nser

+or"s o ener! , Kinetic - Potenti$' - Intern$' Ener!

Ener! tr$nser , .e$t $n* /or%

Usin t$)'es o t&er"o*!n$"ic *$t$

Mec&$nic$' ener! )$'$nces



TYPICAL PROBLEM0

Power requirement for a pump Pure mechanical energy

balance Heat / Wor calculation for a !esire! change

"emoval of heat from reactor

#ombustion problem

"equirement of energies for each apparatus



1(2 +ORM0 O+ ENERGY3 T.E +IR0T LA/ O+ T.ERMODYNAMIC0$orms of energy Kinetic ener! , *ue to t&e "otion o t&e s!ste"

Potenti$' ener! , *ue to t&e #osition o t&e s!ste"

Intern$' ener! , *ue to t&e "otion o intern$' "o'ecu'es U , ro" t&er"o*!n$"ic c$'cu'$tion

$orms of energy transfer .e$t 456 , ener! 7o8 *ue to te"#er$ture *iference /or% 4/6 , ener! 7o8 *ue to t&e *rivin orce ot&er t&$n

te"#er$ture *iference 4orce9 tor:ue9 vo't$e9 ;6

c

K g

mv E

2

2

=

h g

g m E

c

p =



ENERGY BALANCE ON CLO0ED 0Y0TEM0

%alance equation

&$inal 'ystem Energy( ) &*nitial 'ystem Energy(

+ &,et Energy Transfer(

*nitial 'ystem Energy

$inal 'ystem Energy

,et Energy Transfer

ki pii E E U ++

kf pf f E E U ++

W Q +

W Q E E U k p +=∆+∆+∆

The -rst law ofThe -rst law of

thermo!ynamicsthermo!ynamics

for close!for close!

systemssystems



IMPORTANT POINT0

!epen!s on composition state temperature of the

system. ,early in!epen!ent of pressure for i!eal gasesliqui!s soli!s.

0 + 1 2!iabatic process

*f there are no moving parts W + 1

Potential energy change !ue to the changes in height



1(< ENERGY BALANCE0 ONOPEN 0Y0TEM0 AT 0TEADY 0TATE

$low wor an! shaft wor

+'o8 8or% , 8or% *one on s!ste" )! t&e 7ui* itse' $t t&e in'et $n*t&e out'et

0&$t 8or% , 8or% *one on t&e s!ste" )! $ "ovin #$rt 8it&in t&e

s!ste"

f s W W W +=

ProcessUnit

)/(

)/(

2

3

m N P

smV

in

in

)/(

)/(

2

3

m N P

smV

out

out

out out inin f V P V P W −=



0PECI+IC PROPERTIE0

'peci-c properties

4Pro#ert!6 - 4A"ount 4M$ss9 Mo'e nu")er9;66

=o'u"e 9 ener!9 ; E>tensive #ro#erties

0#eci?c vo'u"e9 s#eci?c ener!9 ; Intensive #ro#ert!

E>$"#'e6

=o'u"e , e>tensive #ro#ert! *e#en*s on s!ste" si@e

0#eci?c =o'u"e , intensive #ro#ert! in*e#en*ent o s!ste" si@e

),...(),( 3 kJ U cmV Extensive properties

),.../(ˆ),/(ˆ 3mol kJ U mol cmV Intensive properties



ENT.ALPY

*t is convenient to !e-ne the following property for the

calculation of energy balance for 3owing systems. Ent&$'#!

0#eci?c Ent&$'#!

PV U H +≡

V P U H

ˆˆˆ +≡



T.E 0TEADY0TATE OPEN 0Y0TEM ENERGYBALANCE

W Q E E U k p +=∆+∆+∆

f s W W W +=

out out out ininin f V P mV P mW ˆˆ −=

c

K g

mv E

2

2

∆=∆

h g

g m E

c

K ∆=∆

U mU ˆ∆=∆V P U H ˆˆˆ +≡

sk p W Q E E H +=∆+∆+∆



1( TABLE0 O+ T.ERMODYNAMIC DATA H ' 4… Thermo!ynamic function

Tables of Thermo!ynamic 5ata

T$)u'$tion o v$'ues o t&er"o*!n$"ic unctions 4U9 .9 =9((6 $t v$riouscon*ition 4T $n* P6

It is i"#ossi)'e to %no8 t&e $)so'ute v$'ues o U 9 . or #rocess"$teri$'s On'! c&$nes $re i"#ort$nt 4 ∆U9 ∆.9;6

Reerence st$te

C&oose $ T $n* P $s $ reerence st$te $n* "e$sure c&$nes o U $n*. ro" t&is reerence st$te t$)u'$tion



0TEAM TABLE0

#ompilation of physical properties of water



1( ENERGY BALANCE PROCEDURE0

'olve material balance 6et all the 3ow rate of streams

5etermine the speci-c enthalpies of each streamcomponents

Usin t$)u'$te* *$t$

C$'cu'$tion

#onstruct energy balance equation an! solve it. sk p W Q E E H +=∆+∆+∆



1(1 MEC.ANICAL ENERGY BALANCE0

#hemical equipment &"eactor 5istillation columnEvaporator Heat exchanger…(

.e$t 7o89 intern$' ener! c&$nes 4ent&$'#! c&$ne6 $re"ost i"#ort$nt

0&$t 8or%9 %inetic ener!9 #otenti$' ener! c&$nes $re

ne'ii)'e

7echanical equipment &Pump "eservoir PipesWells Tans Waste 5ischarge…(

.e$t 7o89 intern$' ener! c&$nes $re ne'ii)'e

0&$t 8or%9 %inetic ener!9 #otenti$' ener! c&$nes $re "osti"#ort$nt

Q H ≈∆

sk p W Q E E H +=∆+∆+∆

W E E k p =∆+∆



MEC.ANICAL ENERGY BALANCE0

W Q E E U k p +=∆+∆+∆

mW mQU z g

g

g

v P s

cc

/)/ˆ(2

2

=−∆+∆+

∆

+

∆

ρ

mW F z

g

g

g

v P s

cc

/

2

2

=+∆+∆

+∆

ρ

02

2

=∆+∆

+∆

z g

g

g

v P

cc ρ

ρ /1ˆˆ == out in V V

)lossfriction( /ˆ mQU F −∆=

0,0 == sW F

Bernoulli Equation

Important equation for the calculationOf equipments consist of pipes, tanks and pumps



EAMPLE



EERCI0E

R = 8!"##$% &'()"'mol)"



TA0K

energy balance untuk teknik kimia

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