Exp 7 Complete

8/11/2019 Exp 7 Complete

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ABSTRACT

The primary objective of this experiment is to carry out the thermodynamic

processes on air and also to analyze the processes characteristics (experimental

results) using the psychometric chart. Five thermodynamics processes were tested in

this experiment, which includes cooling, heating, humidification of air, cooling and

dehumidification of air and lastly, heating and humidification of air. Through the

results, and analysis using the psychometric chart, we are to calculate the energy

reuired for air cooling, air heating, cooling and removal of water from air, heating

and addition of water into air.

The experiment was carried out using the !ilton "ir #onditioning $nit.

#alculating the enthalpy change and power of varies thermodynamic process over the

air conditioning unit validated the result. %ith prior assumption, the calculated

enthalpy change and power was smaller than the enthalpy change in there invalidating

the assumption. &t was mathematically difficult to calculate and get an accurate

reading from psychometric chart because of the nature of transient system. Therefore,

the enthalpy change and power were inconclusive.

'ased on the result, enthalpy change for heating and humidification in the air

process is highest compared to other process. n the other hand, power for the

heating and humidification process was the highest among other process.

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TABLE OF CONTENTS

Contents Page

"bstract i

ist of Tables iii

ist of Figures iii

*omenclature iv

+. &ntroduction +

-. Theory and %oring /uations 0

0. 1aterial and 1ethods 2

3. 4esult and 5iscussion +

6. #onclusion and 4ecommendation +6

7. 4eferences +7

"ppendix " +2

"ppendix ' -3

"ppendix # -8

"ppendix 5 -9

"ppendix / 0

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LIST OF TABLES

Table Title Page

"+ %et bulb and dry bulb temperature readings taen from +2

the experiment

"- /xperimental 5ata for the %hole :rocess +9

"0 #ooling process values from psychometric chart -

"3 !eating process values from psychometric chart -

"6 ;apor humidification in air from psychometric chart-+

"7 #ooling and water dehumidification from air process -+

values from psychometric chart

"2 !eating and water humidification in air --

"8 /nergy and power results --

LIST OF FIGURES

Figure Title Page

#+ :sychometric #hart < =.&. unit -8

5+ 5ry>bulb temperature -9

5- 5ew>point temperature -9

50 4elative humidity -9

/+ !ilton "ir>conditioning $nit 0

iii


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NOMENCLATURE

" cross sectional area

d diameter

u internal energy

d heat transfer

dw wor

: power

m mass flow rate

"i inlet air area

"o outlet air area

Twb wet bulb temperature

Tdb dry bulb temperature

hinitial enthalpy for inlet air

hfinal enthalpy for outlet air

?! enthalpy change

ha absolute humidity

hr relative humidity

;! humid volume

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1. INTRO!UCTION

This report discusses the various thermodynamics processes on air experiment

and to analyze the experimental results by using the psychometric chart. The five

processes that were being carried out were cooling, heating, humidification, cooling

and dehumidification of air and heating and humidification of air. The data reuired

was obtained from the computer, which was provided in the Food and :rocess

laboratory connected to the !ilton "ir>#onditioning $nit. The energy involved and

the power reuired in each process was then calculated using the psychometric chart.

:sychometric chart has been used to the study of the psychometric process.

n a psychometric chart (or humidity chart) several properties of a gas>vapor mixture

are cross>plotted, providing a concise complication of large uantity of physical

property data.

The enthalpy, ! can be read directly from the psychometric chart with

reference to the dry bulb and wet bulb temperature obtained. The dew point and the

relative humidity can determined from the chart as well.

The remainder of the report provides detailed analysis of the Theory and

%oring euations for this experiment. The specific procedure is outlined in 1aterial

and 1ethod section. :resentation of the findings and detailed discussion of the result

can be found in 4esult and 5iscussion section. &n a nutshell, summary of the report

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and recommendation are integrated into the #onclusion and 4ecommendation

section.

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". T#EOR$ AN! %OR&ING E'UATIONS

:sychometric is the study of energy and the water vapor in the air when the

thermodynamic go through process such as cooling, heating, humidification of the air,

cooling and dehumidification of air and also heating and dehumidification in air. "ll

these process can be presented and defined by using the psychometric chart.

:sychometric chart is based on the @ibbs phase rule, which states that specifying a

certain number of the intensive variables of a system automatically fixes the value of

the remaining intensive variables. The process can be traced and well monitored. &t is

well presented and defined by using psychometric chart, Figure #+.

The different properties of humid air at + atm that appear on the psychometric

chart are defined and described as followsA

5ry>bulb temperature, TdbA

&t is the air temperature as measured by a standard thermometer that has no

water on its surface. &t indicates the intensity of the sensible heat content of

the substance. &t does not signify anything about the latent heat content.

Temperature of the air is actually referred as the dry>bulb temperature.

%et>bulb temperature,TwbA

&t is a temperature associated with the moisture content of the air. The uantity

is best defined in terms of how it is measured. " wic (water>soaed cloth

which is wrapped around the bulb of a thermometer) evaporates water into the

flowing air. "s heat transfer from the bulb accompanies the evaporation, the

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bulb temperature will drop at a certain value and remains there. The final

temperature reading is the wet>bulb temperature of the air flowing past the

wic.

"bsolute humidity (moisture content), haA

&t is the ratio of mass of vapor to mass of dry air. &t is the ordinate of the chart.

4elative humidity, hrA

&t is a measure of how saturated the air is with the water. &n other words,

relative humidity is the ratio of the actual mass of water vapor in the air to the

mass of water vapor that would saturate the air at the same temperature. &f the

air is holding all the moisture it can for a specific set of conditions, then it is

said to be saturated, +B hr. The amount of moisture the air can hold

increases as the dry>bulb temperature of the air increase. %hen relative

humidity of the air is referred, it is important to define the dry>bulb

temperature of the air that being referred. #urve on the chart correspond to

specified values of hr(+B, 9B, 8B, etc.).

!umid volume, ;!A

&t is the volume occupied by + g of dry air plus the water vapor that

accompanies it.

5ew point, TdpA

&t is a temperature at which humid air becomes saturated if it is cooled at

constant pressure. &f moist air is cooled, it cannot hold the same amount of

moisture. "t some point, the moisture will condense out of the air onto any

nearby surface. 5ew point is reached as the dry>bulb temperature is reduced

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and the specific humidity is held constant. n the chart, dew point is read

along the saturation line (+B hr).

=pecific enthalpy of saturated airA

The diagonal scale above the saturation curve on the chart shows the enthalpy

of a unit mass of dry air plus the water vapor it contains at saturation. To

obtain the enthalpy, constant wet>bulb temperature line is determined from the

saturation curve at the desired temperature to the enthalpy scale.

/nthalpy deviationA

The remaining curves on the chart are almost vertical and convex to the left,

with labeled values of>.6, >.+, >.-, and so on. /nthalpy deviation is added

to the value of specific enthalpy.

The heated refrigerant vapor that is drawn into the compressor is subjected to

higher pressure. "s a result of being pressurized, the temperature of the vapor

increases. The refrigerant then passes into the condenser where enough heat is

removed and the hot vapor changes bac to a hot liuid refrigerant, which is still

under pressure. The liuid refrigerant then flow to the expansion valve. "s the liuid

passes through the valve, pressure is reduced immediately. The pressure decrease

lowers the temperature of the liuid even more and it is ready to absorb heat.

&n the air>cooling process, the refrigerant vapor is passed through a fan>cooled

coil. The air blown over the coil is cooler than the refrigerant vapor. Thus the vapor

gives off heat to the air through the coils wall. The air is then blown to the outdoors

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and the heat is dissipated in the atmosphere. &n the condensing process, the air pics

up heat from the refrigerant. &n both instances, a coil is the heat transfer surface.

The following are woring euations that had been used in the experimentA

From the First aw of Thermodynamics,

C D /nthalpy change, ?h

D ?hfinal> ?hinitial EEEEE (0)

The power is defined asA

: D .m

x ..............................................................................(3)

#hanges in the humidity of air

D (absolute humidity of air at state of cooling and dehumidification

of air process) (absolute humidity of air at final state of cooling

process)

#hanges in the humidity volume of the water

D (humid volume of water at initial state of cooling G

dehumidification of air process) (humid volume of water at final

state of cooling G dehumidification)

&n this experiment, the assumptions made are as listed belowA

The inlet and outlet ducts were round pipes.

The processes were steady>flow process and the mass flow rate of dry air

remained constant during the process.

5ry air and the water vapor were ideal gases.

The inetic and potential energy changes were negligible.

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(. MATERIALS AN! MET#O!S

@enerally, air conditioner is operating using the vapor>compression refrigeration

cycle. 'asically, an air>conditioning system consists of four parts which includes A

i. :reheaters A Four electrical heaters used to heat the air entering the air>condition

ii. 'oilerA &t is used to supply steam for humidifier. &t is made of stainless steel

container and three electrical heaters dipped into the water

iii. #ooling #oil A &t is used to cool the air with or without dehumidification

iv. 4otating vane anemometer A &t is used to measure air flow rate in feet per minute

v. 4eheaters A Four electrical heaters after the cooling coil which reheats the cooled

air before delivery to the space, if reuired

vi. #ompressor>#ondenser unit A To complete the refrigeration cycle

vii. Fan A For air circulation

viii. Thermocouples and thermometers ) For measuring dry and wet bulb

temperatures

The specific procedures for the experiment are as followA>

A* Cooling +ro,ess

+. Fan and compressor of the !ilton air>conditioning is switched on.

-. The air velocity is determined by adjusting rotation of the fan.

0. The air velocity then, is measured and recorded.

3. "ir>cooling process continued until the stability of the system was reached.

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6. The wet>bulb temperature and dry>bulb temperature for the entering air and

leaving air were recorded.

7. The heat transfers enthalpy and power for the air>cooling process was

calculated.

B* #eating +ro,ess

+. The fan was switched on and the velocity of air was measure and recorded.

-. Then, electrical heaterswere switched on and it was left that way until the

stable

condition was reached by the system.

0. Temperature readings of the wet>bulb and the dry>bulb for both inlet air and

outlet air were recorded.

3. Finally, the enthalpy and energy for the heating process was calculated.

C* -a+or u/i0ii,ation in air

+. The fan was switched on. The velocity of air was measured and recorded.

-. Then, electrical heaters (The lower heater, upper heater and water heater) were

switched on to heat the water in tan until mist was observed on the glass in the

euipment.

0. Temperature readings of the wet>bulb and the dry>bulb for both inlet air and

outlet air were recorded.

3. The amount of humidity in air was calculated.

6. Finally, the enthalpy, sensible heat and latent heat for the vapor humidification

7. :rocess in air ware also calculated.

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!* Cooling +ro,ess an0 2ater 0eu/i0ii,ation ro/ air


-. Then, the compressor was switched on and the cooling process was carried on

until the water evaporation from the air occurs.

0. Temperature readings of the web>bulb and dry>bulb for both inlet air and outlet

air were recorded when the evaporation occur.

3. Cuantity of the wasted water was calculated.

6. Finally, the energy of the whole process was calculated

E* #eating +ro,ess an0 2ater u/i0ii,ation in air


-. The lower heater (-%) was switched on to boil the water.

0. The first and second pre heaters (+%) were switched on to dry the water.

3. Temperature readings of the web>bulb and dry>bulb for inlet air, air after

sprayer, air after heater and outlet air were recorded.

6. Finally, the energy of the whole process was calculated.

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3. RESULTS AN! !ISCUSSION

a* Cooling Pro,ess

From Table "0, the increase in wet bulb and dry bulb temperature of the outlet

air before cooling process compared to that of the inlet air was due to the unwanted

external heat supply to the system from surrounding namely the heat from the

compressor which gives rise to the initial enthalpy change of .8 H I g 5" that can be

determined from the psychometric chart. There was a great decrease in both wet bulb

and dry bulb temperature of the outlet air after the cooling process had been carried out

and it gave a final stage enthalpy change of >2.2 H I g. Therefore the total enthalpy

change of the cooling process was >8.6 H I g.

The negative sign showed that the process was exothermic reaction. /xothermic

reaction is a reaction that releases heat or energy to the surroundings. Therefore, the final

enthalpy was less than the initial enthalpy. The power of cooling was calculated to be

>+.620 %. The negative sign means that the wor was done on the system by the

surroundings.

The relative humidity of air increased during the cooling process even if the

specific humidity remained constant. This was due to the humidity was the ratio of the

moisture content to the moisture capacity of the air at the same temperature. The dew

point temperature decreased to --.8 o # at the final outlet.

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4b* #eating Pro,ess

&n heating process, there was no moisture added or removed from the air and the

amount of moisture in the air was constant. From Table "3, the enthalpy increased after

the heating process which had a change of -2.+ H I g. The positive sign showed that

the process was endothermic reaction and the energy was absorbed into the process from

the surrounding. Therefore, the initial enthalpy was less than the final enthalpy. The

power of heating was calculated to be 3.98- %. The positive sign means that the wor

was done by the system. From Table -, the relative humidity decreased during heating

process. The relative humidity at the final was -. B.

4,* -a+or #u/i0ii,ation in Air Pro,ess.

From the Table "6, the enthalpy change was -6.6 HIg because energy was

needed to add moisture into the air. The positive sign showed that heat transfer from the

surrounding to the system. The power that was supplied by the !ilton>air conditioning

was 3.22 %. The dew point temperature for outlet air at final stage is higher than other

in the table 0 which means that vapor humidification in air becomes saturated if it is

cooled at constant pressure only at 0+.+o#.

40* Cooling an0 %ater !eu/i0ii,ation Pro,ess.

For cooling and dehumidification, the sensible heat is transferred out of the air

due to the drop of temperature and the latent heat is removed as water dehumidification

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too place when the air reaches the final temperature. &n this process the liuid

temperature is low enoughJ the air is cooled below its dew point, --.6o# and caused

some of the water vapor in it to condense. The uantity of water disposal is -6 ml. Then,

the enthalpy for this process is>+3.9HIg and it was exothermic reaction because of the

negative sign. The power of this process is >-.20+ % and the negative sign shows that

the wor is done by the system. &n this process, the changes in the humidity of air are

>.-8 g !-Ig 5". The negative sign in the answer of changes in the humidity of

air shows that the moisture content is reduced in the dehumidification process. Thus,

there is water disposal from the air in the form of liuid.

4e* #eating an0 #u/i0ii,ation in Air Pro,ess.

5uring heating and water humidification in air process, notice on the table "2

that when the air and water mixture move to higher relative humidity, the dry bulb

temperature rises. For instance, the outlet would move to a state of 23.6 B relative

humidity. !owever, this value is not constant for all the humidification process because

relative humidity of air different everyday.

For heating and humidification in air process, the enthalpy change is 39.7 HIg.

The positive sign showed that more energy reuired releasing the vapor from the air.

:ower needed is 8.980 %. Thus the surrounding was moist in the experiment, since a

lots of power was reuired to vaporize the water.

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For spraying temperature, the enthalpy change is -3.6HIg and power is 3.302

%. !owever, the experiment data is different from the theoretical data because the wet

bulb temperature decreased with a small amount. This is due to the inconsistency of

temperature, the movement of student around created a mild wind (moving air) that

affected the measurement.

Finally for heating temperature, the enthalpy change is -6.+ HIg and the power

is 3.637 %. &n heating, energy is needed to brea the bond of water to vapor and mix

into the air. Therefore, the enthalpy is positive.

The problems encountered in the experiment

&nconsistent of temperature

The body temperature of the student was also a factor affects temperature. The

movement of student created mild wind (moving air) that could affect the measurement

of temperature. The sensitive thermometer in the air>conditioning unit could detect even

a very small change in the surrounding. 'esides that, the transmission resistance of the

computer cable will also cause inaccuracy of the data.

&nconsistent of mass flow rateA

The movement of student created a mild wind (moving air) inside the laboratory room

even though the experiment was conducted inside a laboratory.The transmission

resistance of the computer also contributed to the inconsistency.

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The precaution step involved in this experiment

+. &n order to reduce the instability of data cause by air flow from surrounding, the

experiment was carried out inside a closed laboratory room.

-. The body temperature is one of the factors that cause the inconsistent of the

temperature. %e are avoided to stand in front of the fan chamber.

0. The amount of water collected in the cooling and dehumidification process is

measured by cylinder. The water was poured carefully in order to avoid spillage.

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5. CONCLUSION AN! RECOMEN!ATIONS

&n conclusion, the heating and humidification in air process attained the highest

change of enthalpy which is 39.7 HIg with the power of 8.980 % . The second

highest enthalpy change was heating process with an enthalpy change of -2.+ HIg and

the third highest enthalpy change was changes of vapor humidification in air process as

-6.6 HIg. &n addition, cooling had an enthalpy change of >8.6 HIg, while cooling

and dehumidification with >+3.9 HIg enthalpy change. Furthermore, the spraying

temperature had -3.6 HIg enthalpy change and for the heating temperature, it had

-6.+ HIg change of enthalpy.

For future experiments, no one is supposed stand or sit near or in front of the air

inlet and air outlet area to ensure that the velocity of inlet air and outlet air are stable. %e

also must wait until the temperature of inlet air and outlet air is stable before the data to

be taen. "fter finish one process, we must wait for 6 minutes to ensure the temperature

of the system is stable before continue with the following process. &n process of cooling

and dehumidification in air, we must wait until all of water has finished dripping before

reading of amount of water dripped is taen. 'esides that, no people should stand in

front of the air inlet and air outlet area to prevent any disruption on the air flow that will

cause inaccuracy in the data obtained.

+6


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6. REFERENCES

+. 4ichard /. =onntag, #laus 'orgnae. (+998).Introduction to

Engineering Thermodynamics. (-nd/dition) *ew Hersey A Hohn %iley G =ons,

&nc.

-. 4ichard 1. Felder, 4onald %. 4ousseau. (-). Elementary Principles of

Chemical Processes(0rd /dition). *ew Hersey A Hohn %iley G =ons, &nc.

0. ;. :aul ang. (+993). :rinciples of "ir>conditioning. *ew Kor A 5elmar

:ublishers &nc.

3. Kunus ". #engel, 1ichael ". 'oles. (-7). Thermodynamics < "n /ngineering

"pproach (6th/dition). *ew Kor A 1c@raw>!ill :ublications.

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APPEN!ICES

"::/*5&L "

Ra2 !ata

Table A1) %et bulb an0 0r7 bulb te/+erature rea0ings ta8en ro/ te e9+eri/ent.

:rocess &nlet "ir Temperature

Ti ( o # )

utlet "ir

Temperature

Te ( o # )

#hange of

Temperature

Tchange (o # )

%et bulb 5ry bulb %et bulb 5ry bulb %et bulb 5ry bulb

". #ooling 'efore -3.- 0+.+ -3.3 0+.0 >.3 >.0

"fter -3.9 0+.9 --.9 -0.0 0.- 2.7

'. !eating 'efore -6.0 0+.8 -6.0 -2.3 .- 0.

"fter -6.9 0-. 0+.7 66. >6.9 >--.8

#. ;apor

!umidification in

"ir

'efore -6.6 0-. -7.- 0-.9 >.7 >+.-

"fter -7.+ 0-.2 0+.8 03.6 >2.7 >-.3

5. #ooling and

%ater

5ehumidification

'efore -6.9 0-.6 -7.3 00.0 >.6 >.7

"fter -7. 0-.8 --.8 -0.7 0.3 8.9

/. !eating and

!umidification in

"ir

'efore -7.+ 0-.9 -7.+ 0+.- >.0 .3

"fter -7.7 0+.6 06.7 3.+ >++. >+7.+=praying

temperature "fter 0+.6 07.+ *" *" *" *"

!eating

Temperature "fter 06.7 3.+ *" *" *" *"

*" D *ot applicable

+2


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Table A") E9+eri/ental !ata or te %ole Pro,ess.

:rocess

&nlet

Temperature Tin

(o#)

utlet

Temperature

Tout(o#)

Temperature

#hanges

(o#)

"ir F

4ate,

(gIs%eb

'ulb

5ry

'ulb

%eb

'ulb

5ry

'ulb

%eb

'ulb

5ry

'ulb

+8


23/36

")#ooling

&nitial-3.- 0+.+ -3.3 0+.0 .- .-

+86

Final-6.- 0+.9 --. --.8 >0.- >9.+

+80

')!eating

&nitial

-6.0 0+.8 -6.0 -2.3 >3.3

+86

Final

-6.9 0-. 0+.7 66. 6.2 -0.+8+

#)#hanges of

!umidification in the

"ir

&nitial

-6.6 0-. -7.- 0-.9 .2 .9+82

Final

-7.+ 0-.2 0+.8 03.6 6.6 +.8+83

5)#ooling and

5ehumidification

&nitial

-6.9 0-.6 -7.3 00.0 .6 .8

+86

Final

-7. 0-.8 --.8 -0.7 >0.- >9.-

+80

/)5ehumidification of

"ir

&nitial

-7.+ 0-.9 -7.+ 0+.- >+.2+83

Final-7.- 0-.9 0-.8 3-.3 7.7 9.6

+8+

Table A() Cooling +ro,ess :alues ro/ +s7,o/etri, ,art.

#ooling :rocess %et

'ulb

Tweto

#

5ry

'ulb Tdry

o

#

/nthalpy

! (H I g

5")

"bsolute

!umidity

% ( g

!- I g

5" )

4elative

humidity

hr (B)

5ew

:oint

Tdew (o

#)

'efore &nlet "ir -3.- 0+.+ 2-.2 .+7-+ 67.9 -+.7

utlet "ir -3.3 0+.0 20.6 .-+6 62.+ -+.8

"fter &nlet "ir -3.9 0+.9 26.7 .+2 62. --.0

+9


24/36

utlet "ir --.9 -0.0 72.9 .+232 97.2 --.8

Table A3) #eating +ro,ess :alues ro/ +s7,o/etri, ,art.

!eating :rocess %et

'ulb

Tweto#

5ry

'ulb Tdry

o #

/nthalpy

! (H I g

5")

"bsolute

!umidity

% ( g

!- I g

5" )

4elative

humidity

hr (B)

5ew

:oint

Tdew (o#)

'efore &nlet "ir -6.0 0+.8 22.0 .+22+ 69.7 -0.

utlet "ir -6.0 -2.3 22.6 .+962 83.7 -3.7

"fter &nlet "ir -6.9 0-. 29.9 .+873 7-. -0.8utlet "ir 0+.7 66. +2.- .+993 -. -3.9

Table A5) -a+or u/i0ii,ation in air ro/ +s7,o/etri, ,art.

;apour

!umidification

:rocess

%et

'ulb

Tweto#

5ry

'ulb Tdry

o #

/nthalpy

! (H I g

5")

"bsolute

!umidity

% ( g

!- I g

5" )

4elative

humidity

hr (B)

5ew

:oint

Tdew (o#)

'efore &nlet "ir -6.6 0-. 28.+ .+297 69.8 -0.-

utlet "ir -7.- 0-.9 8+.- .+828 69.0 -0.9

"fter &nlet "ir -7.+ 0-.2 8.2 .+879 69.2 -0.8

utlet "ir 0+.8 03.6 +9.0 .-9+- 8-.8 0+.+

Table A6) Cooling an0 2ater 0eu/i0ii,ation ro/ air +ro,ess :alues ro/

+s7,o/etri, ,art.

#ooling and %ater %et 5ry /nthalpy "bsolute 4elative 5ew

-


25/36

5ehumidification

:rocess

'ulb

Tweto#

'ulb Tdry

o #

! (H I g

5")

!umidity

% ( g

!- I g

5" )

humidity

hr (B)

:oint

Tdew (o#)

'efore &nlet "ir -6.9 0-.6 29.9 .+830 69.7 -0.7

utlet "ir -7.3 00.0 8-. .+896 68.6 -3.+

"fter &nlet "ir -7. 0-.8 8.0 .+832 68.2 -0.2

utlet "ir --.8 -0.7 72.6 .+2+9 90.6 --.6

Table A;) #eating an0 2ater u/i0ii,ation in air.

!eating and

!umidification

:rocess

%et

'ulb

Tweto#

5ry

'ulb Tdry

o #

/nthalpy

! (H I g

5")

"bsolute

!umidity

% ( g

!- I g

5" )

4elative

humidity

hr (B)

5ew

:oint

Tdew (o#)

'efore &nlet "ir -7.+ 0-.9 8.2 .+87 68.8 -0.8

utlet "ir -7.+ 0+.- 8.8 .+90- 72.+ -3.3

"fter &nlet "ir -7.7 0+.6 80. .-2 78.6 -6.

;apour

=pray

0+.6 07.+ +2.7 .-227 2-.3 0.0

utlet "ir 06.7 3.+ +0-.2 .069 23.6 03.2

Table A8.6 >+.67-

!eating -2.+ 3.98-;apor !umidification in "ir -6.6 3.22

#ooling and

5ehumidification

>+3.9 >-.20+

!eating and !umidification

in "ir

39.7 8.980

-+


26/36

=praying Temperature -3.6 3.302

!eating temperature -6.+ 3.637

--


27/36

APPEN!I= B

Cal,ulation

("ll the enthalpies are obtained from psychometric chart)

Cal,ulation or ,ooling +ro,ess>

Flow rate D +86 gIs

?h initial = 20.6 HIg < 2-.2 HIg

D .8 HIg

?h final D 72.9 HIg < 26.7 HIg

D > 2.2 HIg

/nthalpy change, ?! D ?h final >?h initial

D >2.2 HIg < .8 HIg

D > 8.6 HIg

:ower, % D m ?!

D +86 gIs x ( >8.6 HIg ) x +gI+g

D >+.620 %

Cal,ulation or eating +ro,ess>

Flow rate D +8+.6 gIs

?h initial D 22.6 HIg < 22.0 HIg

D .- HIg

?hfinal D +2.- HIg < 29.9 HIg

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D -2.0 HIg

/nthalpy change, ?! D ?h final > ?h initial

D -2.0 HIg < .- HIg

D -2.+ HIg

:ower, % D m ?!

D +8+.6 gIs x -2.+ HIg x +gI+g

D 3.98- %

Cal,ulation or :a+or u/i0ii,ation in air>

Flow rate D +83.7 gIs

?h initial D 8+.- HIg < 28.+ HIg

D 0.+ HIg

?h final D +9.0 HIg < 8.2 HIg

D -8.7 HIg


D -8.7 HIg < 0.+ HIg

D -6.6 HIg

:ower, % D m ?!

D +83.7 gIs x -6.6 HIg x +gI+g

D 3.22 %

-3


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Cal,ulation or ,ooling +ro,ess an0 0eu/i0ii,ation o air +ro,ess>

Flow rate D +80.0 gIs

?h initial D 8-. HIg < 29.9 HIg

D -.+ HIg

?h final D 72.6 HIg < 8.0 HIg

D >+-.8 HIg


D >+-.8 HIg < ( >-.+ HIg)

D>+3.9 HIg

:ower, % D m ?!

D +80.0 gIs x (>+3.9 HIg) x +gI+g)

D >-.20+ %

Cuantity of water disposedA -6ml

#hanges in the humidity of airA

("bsolute humidity of air at final state of cooling and dehumidification of air process) kg,+232., !-Ig 5"

D >.-8g !-Ig 5"

Cal,ulation or eating an0 u/i0ii,ation in air +ro,ess>

Flow rate D +8+.+ gIs

?h initial D 8.8 H I g < 8.2 H I g

-6


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D .+ H I g

?h final D +0-.2 H I g < 80. H I g

D 39.2 H I g


D 39.2 H I g < .+ H I g

D 39.7 H I g

:ower, % D m ?!

D+8+.+ gIs x 39.7 H I g x +gI +g

D 8.980 %

For s+ra7ing te/+erature>


D +2.7 H I g < 80. H I g

D -3.6 H I g

:ower, % D m ?!

D +8+.+ gIs x -3.6 H I g x +gI+g

D 3.302 %

For eating +ro,ess>


D +0-.2 HIg < +2.7 HIg

D -6.+ HIg

:ower, % D m ?!

D +8+.+ gIs x -6.+ HIg x +gI+g

D 3.637 %

-7


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APPEN!I= C

Figure C1) Ps7,o/etri, ,art

-2


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APPEN!I= !

Figure 5+A 5ry bulb temperature.

Figure 5-A 5ew point temperature.

Figure 50A 4elative humidity

-8


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0+


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Documents

Exp 7 Complete