THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
Table of Contents
1.0
Title..................................................................... Title........................................................................................................................................... ........................................................................ .. 1
2.0
Abstract Abstract. ..................................................................................................................................... ..................................................................................................................................... 3
List of Symbols ........................................................................................................................................ ....................................................................................................................................... 4 ....................................................................................................................................... ........................................................................ .. 5 List of figure .................................................................
3.0
.................................................................................................. 6 Introduction And Applications ...................................................................................................
4.0
................................................................................................................................... 7 Objectives. ...................................................................................................................................
5.0
....................................................................................................................................... ........................................................................ .. 8 Theory .................................................................
6.0
.................................................................................................... 12 Experimental Procedures .....................................................................................................
6.1 Apparatus/Experimental Setup ........................................................... ............................................................................................... .................................... 12 6.2 Procedure ............................................................................................... .................................................................................................................................... ..................................... 15
7.0
............................................................................................................... ................................................ 16 Data and calculations ...............................................................
7.2 Sample calculations: .................................................................... ................................................................................................................... ............................................... 16 7.2 Data: .............................................................................................................................. ............................................................................................................................................ .............. 19
8.0
.............................................................................................................................. ...................................................................... ... 20 Discussion ...........................................................
9.0
................................................................................................................................ .......................................................... 20 Conclusion ......................................................................
10.0
............................................................................................................................... 21 References References ................................................................................................................................
11.0
Appendices Appendices ........................................... .................................................................. ............................................. ............................................ ............................ ...... 22
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
2.0Abstract We knew that the air properties is changes based on what types of process that we running it. Each types of process which is the simple heating, steam humudification, simple cooling and dehudification have their own result and reason why it is occur like that. With that data and result we can study throughout about the air-conditioning. But still an error must be avoided in order to get the precise data.
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
List of Symbols A
Area over which force (F) acts (m2)
E
Elastic modulus (GPa)
F
Force (N)
( )
Initial dimension in direction i (mm)
T
Specimen thickness (m)
Rate of chart displacement (mm/min)
Rate of sample displacement (mm/min)
w
Specimen width (m)
Displacement of chart (mm)
Displacement of sample (mm)
Strain
=0
Predicted strain at zero stress
Normal strain in direction i
E
Error in the predicted elastic modulus (GPa)
F
Error in the force (N)
Change in dimension in direction i (mm)
t
Error in the specimen thickness (m)
w
Error in the width (m)
=0
Error in the predicted strain at zero stress
Error in the predicted intercept of stress-stain data (MPa)
Error in the stress (MPa)
Predicted intercept of stress-strain data (MPa)
Engineering stress (MPa)
Yield point (MPa)
Ultimate strength (MPa)
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
List of figure Figure 1: Air-Conditioner(Home or office usage).................................................................................... 6 Figure 2: Heating coil mechanism ........................................................................................................... 9 Figure 3: Schematic diagram for condensation process ......................................................................... 9 Figure 4: Shematic diagram for humidifying section ............................................................................ 10 Figure 5: The flow of air through insulator and mixing section ............................................................ 11 Figure 6: Computer Linked Air Conditioning Laboratory Unit ( P.A. Hilton) ......................................... 12 Figure 7: Computerized Data Display System ...................................................................................... 13 Figure 8: Control Panel.......................................................................................................................... 13 Figure 9: System Schematic Diagram.................................................................................................... 14
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
3.0
Introduction And Applications
Air conditioning system is a process of treating the air to establish and maintain required standard of the occupants in the conditioned space. Air conditioning system consists of a group of equipment connected in series to control the environmental parameters. It is a direct application of the refrigeration cycle. The properties of air can be altered by experiencing certain thermodynamics process. The most basic of processes involved in an air conditioning system are simple heating, steam humidification, simple cooling and dehumidification. Air-conditioning is useful to maintain the surrounding environment of temperature and ambient to satisfy the the temperature of human comfort, which is between 20°C to 25°C. Conventional air-condition is use to cool and to heat the surrounding environment, but in some country, air-condition may use both heating and cooling, with or without humidifing air. Also the industrial usage of air-condition is to reduce temperature of thermal produce machine. Nowadays, we can see the the usage of the air-conditioning is increasing day by day wheather is on house or at the office. It shows to us that most people desire a good surrounding for their comfortable life. For that, air conditioning is a solution for that and it is important for us to study how it works. Theoretically, analysis of air conditioning processes is required for maintaining proper temperature and humidity in living space such as residential, commercial, and industrial facilities.
Figure 1: Air-Conditioner(Home or office usage)
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
4.0 Objectives The purpose of this experiment is to: 1. To study and understand the changes in air properties as it is treated in a basic airconditioning unit system. 2. To develop knowledge of refrigeration cycle and air conditioning system. 3. To experiencing the air conditioning system in practical. 4. to experiencing the usage of Computer Linked Air Conditioning Laboratory Unit ( P.A. Hilton)
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
5.0 Theory The type of air conditioning process :
simple heating (raising the temperature)
simple cooling (lowering the temperature)
humidifying (adding moisture)
dehumidifying (removing moisture)
Air conditioning process are modeled as steady flow processes with general mass and energy balance.
Mass balance
dry air ∑ ̇ ∑ ̇ wet air ∑ ̇ ∑ ̇ or ∑ ̇ ∑ ̇
Energy Balance
̇ ̇ ∑ ̇ = ̇ ̇ ̇ ∑
Simple Heating and Cooling
- value of
is constant
- sensible heating by means of a electric resistance heater, a hot water coil, heat pump and etc. - In simple heating, specific humidity remained constant but the relative humidity decreases - In simple cooling, the cooling coil is in place. Therefore the humidity remained constant but the relative humidity increases.
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
Figure 2: Heating coil mechanism
Dry air
: ma1 = ma2 = ma
Water/ Vapour
: ma 1 = ma 2 = 2
1
: Qin + mah1= ma h2
Energy
Qin= ma(h2 - h1)
Cooling with Dehumidification
- When the relative humidity is too high, some moisture is removed from the air to dehumidify it. - When the air is cooled below its dew point temperature, condensation will start to form. - Water vapor is removed from the cooled air and the relative humidity is lowered.
Figure 3: Schematic diagram for condensation process
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
Dry air
: ma1 = ma2 = ma
Water/ Vapour
: ma 1 = ma 2 + mw mw = ma( 1 - 2)
Energy
:
mhin= Qout +
mhout
Qout = m (h1 - h2) - mwhw
Heating with Humidification
- Low relative humidity fom simple (sensible) heating can be eliminated by humidifying the air. - The air is passed through a heating section and then through a humidifying section.
Figure 4: Shematic diagram for humidifying section
Dry air
: ma1 = ma2 = ma
Water/ Vapour
: ma 2 + mw = ma 3 mw = ma( 3 - 1)
Energy
: mah2 + mwhw = mah3 mwhw = ma(h3 - h2)
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
Adiabatic Mixing of Airstreams
- Air-Conditioning appilcation may require mixing of airstreams. - The turn air is mixed with a small fraction of fresh outside air before it is routed into the living space. - When hot humid air is mixed with cold air the result may be fog. - The mixing point is below the saturation line, and the moisture in the air condensates as
small droplets floating in the air. - If the mixing point is below the saturation line, water is condensated as droplets and fog is created.
Figure 5: The flow of air through insulator and mixing section
Dry air mass balance :
ma1 + ma2 = ma3
Water mass balance
:
ma11 + ma22 = ma33
Energy balance
:
ma1h1 + ma2h2 = ma3h3
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
6.0 Experimental Procedures 6.1 Apparatus/Experimental Setup
Computer Linked Air Conditioning Laboratory Unit ( P.A. Hilton)
Control Cooling
Panel
Area
Fan
Stop Container
Watch Figure 6: Computer Linked Air Conditioning Laboratory Unit ( P.A. Hilton)
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
Computer Display
Printer
CPU
Figure 7: Computerized Data Display System
Figure 8: Control Panel
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
Figure 9: System Schematic Diagram
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
6.2 Procedure
Start the unit by having the suction fan running and the screen displaying the master menu. Programme 1 shows the process data displayed on a schematic layout of the system. programme 2 displays the properties of the treated air on the psychrometric chart. There are for condition for this experiment. 1) No Process- the data and psychrometric chart are
print to read the initial
properties of the air as it enters the air-conditioning unit. 2) Sensible heating a) 1kW pre-heater is switch on and allow 5 minute. The data and psychrometric chart are print. b) Then, 05kW re-heater is switch on and allow 5 minute. The data and psychrometric chart are print c) For this process, the temperature rise of the air is calculate at the exit. 3) Steam humidification – all water heater is switch on to boil the water. When steam is produces, only 3 kW if heat is switch to maintain the steam and allow 5 minute. The data and psychrometric chart are print. Then the amount of steam introduced, the change in relative humidity and corresponding rise of temperature are calculate. 4) Colling and Dehumidification- the compressor of the refrigeration system is switch on. The air is cool until 18 oCto 20oC (stable temperature), allow 5 minute when the temperature is stable. The heat rate and amount of moisture removed from the air are calculate. During experiment the time and the rate of condensation (100ml) are measure from the beginning of the cooling process (stable temperature). Compare with analysis
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
7.0
Data and calculations
7.2 Sample calculations: 1. SENSIBLE HEATING
Pre-heater Tdry out = 37.4 °C
Twet out = 26.8 °C
Tdry in = 27.6 °C
Twet in = 23.1 °C
Temperature rises at the exit =
∆ Tdry
= Tdry out - Tdry in
= 37.4 °C - 27.6 °C = 9.8 °C
∆ Twet =
Twet out - T wet in
= 26.8 °C - 23.1 °C = 3.7 °C
Re-heater Temperature rises at the exit =
∆ Tdry
= Tdry out - Tdry in
= 48.7 °C - 27.1 °C = 21.6 °C
∆ Twet =
Twet out - Twet in
= 29.0 °C - 22.4 °C
= 6.6 °C
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
2. STEAM HUMIDIFACTION
Ma = 0.0533 kg/s From the Psychrometric chart
Ø1
= 67 %
ω 1
= 0.016 kg v/kga
Ø2
= 96 % ω1
= 0.030 kg v/kga
Amount of steam induced mw
= ma (ω2- ω1) = 0.0533 (0.030 - 0.016 ) = 7.462 x 10 -4 kg/s
Change in relative humidity Ư
= Ø2- Ø1 = 96 % - 67 % = 29 %
Temperature rises at the exit ∆Tdry = 37.2°C – 27.6°C = 9.6 °C ∆Twet = 36.3°C – 23.3°C = 13.0 °C
3. COOLING AND DEHUMIDIFICATION
Ma = 0.2079 kg/s From the Psychrometric chart
Ø1
= 62 %
ω 1
= 0.009 kg v/kga
h1
= 35.8 kJ/kg
Ø2
= 96 % ω1
h2
= 0.0155 kg v/kga
=69.0 kJ/kg
Amount of steam induced mw
= ma (ω2- ω1) = 0.2079 (0.0155 - 0.009 ) = 1.35135 x 10 -3 kg/s
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
Change in relative humidity Ư
= Ø2- Ø1 = 96 % - 62 % = 34 %
Temperature rises at the exit ∆Tdry = 29.2°C – 13.1°C = 16.1 °C ∆Twet = 23.3°C – 13.0°C = 10.3 °C Amount of heat transfer
hw= hf @ T8 = 14.1 from table A-4, therefore h w= ? hf (kJ/kG)
Temperature(°C)
42.022
10
hw
14.1
62.982
15
=
hw= 59.2092 kJ/kg Qout = ma (h2 – h1 )- mwhw = 0.2079 (69.0 -35.8 )- 7.462 x 10 -4 (59.2092 ) = 6.858 kJ/s
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
7.2 Data: Experiment NO PROCESS
SENSIBLE HEATING
STEAM HUMIDIFICATION
COOLING AND DEHUMIDIFICATION
Reading T1 (TAd) (oC) T2 (TAw) o ( C) T3 (TBd) o ( C) T4 (TBw) (oC) T5 (TCd) o ( C) T6 (TCw) o ( C) T7 (TDd) (oC) T8 (TDw) o ( C) T9 (T1) o ( C) T10 (T2) o ( C) T11 (T3) (oC) T12 (T4) o ( C) Qp (W) Qr (W) Qb (W) Pevap (P1) (kN/m2) Pcond (P3) (kN/m2) ma (g/s) mr (g/s) TIME (s) DRAIN WATER(ml)
27.5
27.6
27.1
27.6
28.9
27.2
23.1
23.1
22.4
23.3
23.3
23.3
28.2
42.3
44.6
36.5
29.2
29.3
24.1
30.0
30.3
37.8
24.4
24.1
27.6
39.4
44.0
36.4
13.4
12.5
22.9
27.0
27.9
36.9
13.1
12.2
27.5
37.4
48.7
36.3
14.1
13.1
23.3
26.8
29.0
37.2
14.1
13.0
-
-
-
6.0
6.4
-
-
-
69.0
78.7
-
-
-
42.4
43.1
-
-
-
2.7
2.7
-
1019.9
1005.5
-
-
-
0
534.7
-
-
-
-
2806.2
-
-
-
-
168.1
169.8
-
-
-
1043.5
1067.9
205.6
199.0
53.3
207.9
120.0
-
-
-
10.4
10.0
-
-
-
5 minutes
21 minutes
-
-
-
100
100
55.3
Table 1: Data recorded
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
8.0
Discussion
This part of report is individually hand written. The result of each member is attached with this report.
9.0
Conclusion
This part of report is individually hand written. The result of each member is attached with this report.
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
10.0 References
Webside:
1) http://en.wikipedia.org/wiki/HVAC [Accessed 27/09/14] 2) http://www.brighthubengineering.com/hvac/125581-design-principles-and-majorsystem-components-for-hvac/ [Accessed 27/09/14]
Books:
3) Yunus A. Cengel , AfshinJ. Ghajar,2007, Heat and Mass Transfer (fundamentals and applications),Fourth edition in SI units,McGrawHill,Singapore 4) Yunus A. Cengel, Michael A. Boles,2006, Thermodynamics: An Engineering Approach 5th Edition, McGraw Hill. 5) Yunus A. Vengeland Micheal A. Boles, Thermodynamics An Engineering Approach,7th edition in SI units, 2011 , The McGraw-Hill Companies. .
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
11.0 Appendices
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THERMODYNAMICS II ANALYSIS OF AIR-CONDITIONING EMD5M5A
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