om he163 230-0210-he

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EXPERIMENTAL MANUAL

MODEL: HE163

SOLUTION ENGINEERING SDN. BHD.

NO.3, JALAN TPK 2/4, TAMAN PERINDUSTRIAN KINRARA,

47100 PUCHONG, SELANGOR DARUL EHSAN, MALAYSIA.

TEL: 603-80758000 FAX: 603-80755784

E-MAIL: [email protected]: www.solution.com.my

SOLTEQ EQUIPMENT FOR ENGINEERING EDUCATION

230-0210-HE

FILM & DROPWISECONDENSATION

UNIT

FILM & DROPWISE

CONDENSATION

UNIT

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SOLTEQFILM & DROPWISE CONDENSATION UNIT (Model: HE 163)

i

Table of Contents

Page

Table of Contents............................................................................................................................... i

List of Figures.iii

1.0 INTRODUCTION.................................................................................................................. 1

2.0 GENERAL DESCRIPTION.................................................................................................. 22.1 Unit Assembly22.2 Experimental Capabilities..22.3 Specifications32.4 Overall Dimensions42.5 General Requirements4

3.0 INSTALLATION AND COMMISSIONING........................................................................... 53.1 Temperature Sensors .................................................................................................... 53.2 Heating Element ............................................................................................................. 53.3 Cooling Water Supply .................................................................................................... 53.4 Cooling Water Drain ....................................................................................................... 53.5 Commissioning Procedures ........................................................................................... 5

4.0 SUMMARY OF THEORY..................................................................................................... 64.1 Mechanism of Condensation .......................................................................................... 64.2 Film-Condensation coefficient for vertical surfaces ........................................................ 7

5.0 GENERAL OPERATING PROCEDURES ......................................................................... 115.1 Electrical Connection .................................................................................................. 11

5.2 Temperature Selection ................................................................................................ 11 5.3 Heater Setting ............................................................................................................. 11 5.4 Cooling Water Control .................................................................................................. 116.0 EXPERIMENTAL PROCEDURE ....................................................................................... 12

6.1 General Start Up Procedures ....................................................................................... 126.2 General Shut Down Procedures ................................................................................... 12

6.3 Experiment 1: DEMONSTRATION OF FILMWISE & DROPWISECONDENSATIION ........................................................................................................ 136.4 Experiment 2: THE FILMWISE HEAT FLUX & SURACE HEAT TRANSFER

COEFFICIENT DETERMINATION AT CONSTANT PRESSURE ................................. 146.5 Experiment 3: THE DROPWISE HEAT FLUX & SURACE HEAT TRANSFER

COEFFICIENT DETERMINATION AT CONSTANT PRESSURE ................................. 156.6 Experiment 4: THE EFFECT OF AIR INSIDE CHAMBER ........................................... 16

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ii

7.0 EQUIPMENT MAINTENANCE .......................................................................................... 177.1 Heater .......................................................................................................................... 177.2 Condenser ................................................................................................................... 17

8.0 SAFETY PRECAUTIONS .................................................................................................. 18

8.1 Warning ........................................................................................................................ 188.2 Cautions ....................................................................................................................... 18

APPENDIX A Experimental Data Sheet

APPENDIX B Typical Experimental Result

APPENDIX C Sample Calculat ion

APPENDIX D Filmwise and Dropwise condensat ion

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iii

List of Figures

Page

Figure 1 Unit Construction for Film & Dropwise Condensation Unit 2

(Model: HE 163)

Figure 2 Film condensation on a vertical plate: a) increase in film thickness with 7Position, b) balance on element of condensate.

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1

1.0 INTRODUCTION

The use of steam both for power production to convey heat has a long history and itsuse in these fields is likely to continue into the foreseeable future.

In all applications, the steam must be condensed as it transfers heat to a coolingmedium which could be cold water in a condenser of generating station, hot water in aheating calorifier, sugar solution in a sugar refinery and etc. During condensation veryhigh heat fluxes are possible and provided that the heat can be quickly transferredfrom the condensing surface into the cooling medium, the heat exchangers can becompact and effective.

Steam may condense onto a surface in two distinct modes, known as the Filmwise andthe Dropwise condensation. For the same temperature difference between the steamand the surface, dropwise condensation is several times more effective than filmwise,

and for this reason the former is desirable although in practical plants, it seldom occursfor prolonged periods.

The SOLTEQ

Film & Dropwise Condensation Unit (Model: HE163) is designed to helpstudent to understand several key aspects in condensation topic, in particular theprocess of filmwise and dropwise condensation. It allows students to visualize bothphenomena and perform a few experiments to demonstrate both concepts.

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2

2.0 GENERAL DESCRIPTION

2.1 Unit Assembly

Figure 1:Unit Construction for Film & Dropwise Condensation Unit (Model: HE 163)

1. Pressure Relief Valve 6. Separator

2. Indicators 7. Dropwise Condenser

3. Flowmeter 8. Filmwise Condenser

4. Discharge Valve 9. Coiled-Heater

5. Pressure Transmitter 10. Vacuum Ejector

1

2

3

6

5

7

9

4

8

10

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2.2 Experiment Capabilities

Visual observation of filmwise and dropwise condensation, as well asnucleate boiling.

Determination of heat flux and heat transfer coefficients in both filmwise

and dropwise condensation at different operating pressures. Investigation on the relationship between saturation pressure and

temperature for water up to 100 C.

Study on the effect of air on heat transfer coefficient in the chamber.

2.3 Specifications

2.3.1 Steam Chamber

Borosilicate Glass cylinder with flanged ends and coverso

Outer Diameter : 105 mmo Height : 400 mmo Thickness : 5 mm

2.3.2 Condensers

Two water-cooled condensers fabricated from copper and brass.o Diameter : 12.7 mmo Length : 120 mmo Material :

Gold plated (dropwise condenser) Natural finish (filmwise condenser)

* Each condenser is fitted with 3 thermocouples to measure the meansurface temperature and 2 temperature sensors to measure the inletand outlet water temperatures.

2.3.3 Heating Element

Coiled Heater with thermal protectiono Power : 3.0 kW

o

Control : Triac control between 0.4 to 3.0 kW

2.3.4 Air Extraction System

Air cooler, separator, and water jet vacuum pump.

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2.3.5 Instrumentations

Temperature sensors at all important points.

Pressure sensor to measure the chamber pressure.

Flowmeters to measure the water flow rate through the

condensers:o Dropwise condenser : 0.4 4.0 LPMo Filmwise condenser : 0.1 1.0 LPM

2.3.6 Safety Features

Pressure switch to turn off the heater when chamber pressure

exceeds 1.50 Abs Bar.

Pressure relief valve to discharge at 1.50 Abs Bar.

2.4 Overall Dimensions

Height : 800 mmWidth : 900 mmDepth : 600 mm

2.5 General Requirements

Electrical : 230VAC/50Hz/25 AmpWater : Continuous water supply (Min 10LPM @ 2-3 Bar)

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3.0 INSTALLATION AND COMMISSIONING

Ensure that the main switch is switch off. Place the Film & Dropwise Condensation Uniton a bench.

3.1 Temperature SensorsFive temperature sensors are installed and each lead has a label. There arealso 6 thermocouple wires installed. Ensure that all thermocouples and thelead are in good condition.

3.2 Cooling Water SupplyThe Film & Dropwise Condensation Unit requires a source of clean andconstant temperature (cold) water with flow approximately 4 - 5 LPM at 2 to 3bar supply. The Film & Dropwise Condensation Unit comes with water inlet

valves to control the water flow rates. Connect the water supply to the cold-water inlet.

3.3 Cooling Water DrainThe Film & Dropwise Condensation Unit comes with two drain tubes; one forthe condenser and one for the vacuum ejector. They should be securedproperly so that it will not fall out during the experiment.

3.4 Commissioning ProceduresPush the reset button of the Earth Leakage Circuit Breaker (ELCB) inside thecontrol panel after the main power supply is switched on. The ELCB should bekicked off, indicating that the ELCB is functioning properly. If not, have atrained wireman to inspect the trainer for any electrical leakage. The ELCBshould be tested at least once a month. Switch on the main switch and checkthe indicators. They should display the measurements of all respectiveinstruments. Fill the boiler chamber with distilled water from the bottom valveuntil the water level is sufficient to fully cover the heater element. Switch on theheater and observe the boiling. Then, slowly open the cooling water of bothfilm and dropwise condensers. The flow indicators should display therespective flow rates. Switch off the heater, the unit is ready for use.

Note: Never operate the heater whenever the water level falls below theheater element as this will permanently damage the heater.

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4.0 SUMMARY OF THEORY

4.1 Mechanism o f Condensation

Condensation of a vapor to a liquid and vaporization of a liquid to a vapor bothinvolve a change of phase of a fluid with large heat-transfer coefficients.Condensation occurs when a saturated vapor such as steam comes in contactwith a solid whose surface temperature is below the saturation temperature, toform a liquid such as water.

Normally, when a vapor condenses on a surface such as a vertical orhorizontal tube or other surface, a film of condensate is formed on the surfaceand flows over the surface by the action of gravity. It is this film of liquidbetween the surface and the vapor that forms the main resistance to heat-transfer. This is called filmwise condensation.

Another type of condensation, dropwise condensation, can occur, where smalldrops are formed on the surface. These drops grow and coalesce, and theliquid flows from the surface. During this condensation, large areas of tube aredevoid of any liquid and are exposed directly to the vapor. Very high rates ofheat-transfer occur on these bare areas. The average heat transfer coefficientfor dropwise condensation is five to 10 times larger than the filmwisecoefficients.

Dropwise condensation can be promoted by making the surface non-wetting(via coating). However, dropwise condensation is difficult to maintain inindustrial applications due to oxidation, fouling and degradation of coating, andeventually film condensation occurs. Therefore, condenser designs are oftenbased on the assumption of filmwise condensation.

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4.2 Film-Condensation coefficients for vertical surfaces

Film-type condensation on a vertical wall or tube can be analyzed analyticallyby assuming laminar flow of the condensate film down the wall. The filmthickness is zero at the top of the wall or tube and increases in thickness as it

flows downward because of condensation. Nusselt assumed that the heat-transfer from the condensing vapor at Tsat, through this liquid film, and to thewall at Tw

was by conduction. Equating this heat-transfer by conduction to thatfrom condensation of the vapor, a final expression can be obtained for theaverage heat-transfer coefficient over the whole surfaces.

InFigure 2 (a), vapor at Tsatis condensing on a wall whose temperature is Tw.The condensate is flowing downward in laminar flow. Assuming unit thickness,

the mass of the element with liquid density

inFigure 2 (b)is (-y) (dx1)

.

The downward force on this element is the gravitational force minus the

buoyancy force, or (-y)(dx)(

-) g, where is the density of the saturated

vapor. This force is balanced by the viscous-shear force at the plane y of

(dv/dy) (dx1). Equating these forces;

( )( )( ) ( )dxdy

dgdxy ll

=

(4.2-1)

Integrating and using the boundary condition that = 0at y = 0;

( )( )2/2yyg l

= (4.2-2)

Figure 2: Film condensation on a vertical plate: a) increase in film thickness with position, b)balance on element of condensate.

The mass flow rate of film condensate at any point xfor unit depth is;

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( )( )

==

0

2

02/ dyyy

gdym

l

lll (4.2-3)

Integrating;

( )

l

ll gm

3

3

= (4.2-4)

At the wall, for area (dx1)m2

, the rate of heat transfer is as follows if a lineartemperature distribution is assumed in the liquid between the wall and thevapor;

( )

wsatl

y

lx

TTdxk

dy

dTdxkq

==

=0

1 (4.2-5)

In a dxdistance, the rate of heat transfer is qx

. Also, in this dxdistance, theincrease in mass from condensation is dm. Using Eq. (4.2-4);

( ) ( )

l

ll

l

ll dggddm

23

3

=

= (4.2-6)

Making a heat balance for dxdistance, the mass flow rate dmtimes the latentheat h fgmust equal the qx

from Eq. (4.2-5):

( )

wsatl

l

llfg

TTdxk

dgh

=

=

2

(4.2-7)

Integrating, with = 0at s = 0and= at x = x;

( )( )

4/1

4

=

llfg

wsatll

gh

TTxk (4.2-8)

Using the local heat-transfer coefficient hx

at x, a heat balance gives;

( )( ) ( )

wsatlwsatx

TTdxkTTdxh

= 11 (4.2-9)

This gives

lx

kh = (4.2-10)

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Combining Eqs. (4.2-8) and (4.2-10);

( )

( )

4/13

4

=

wsatl

lfgll

x

TTx

kghh

(4.8-17)

By integrating over the total length L, the average value of h is obtained asfollows;

=== L

Lxx hdxhL

h0 3

41 (4.2-11)

( )

( )

4/13

943.0

=

wsatl

lfgll

TTL

kghh

(4.2-12)

However, for laminar flow, experimental data are about 20% above Eq. (4.2-12). Hence, the final recommended expression for vertical surfaces in laminarflow is shown as Eq. (4.2-13):

( ) 4/13

13.1

==

Tk

Lgh

k

hLN

ll

fgll

l

Nu

(4.2-13)

where

is the density of liquid in kg/m3andthat of the vapor, g is 9.8066

m/s2, Lis the vertical height of the surface or tube in m, lis the viscosity of

liquid in Pas, k

is the liquid thermal conductivity in W/mK, T = Tsat-Twin K,

and h fgis the latent heat of condensation in J/kg at Tsat. All physical propertiesof the liquid except h fgare evaluated at the film temperature Tf= (Tsat+ Tw

)/2.For long vertical surfaces the flow at the bottom can be turbulent. TheReynolds number is defined as;

llD

mN

==

44Re

(vertical tube, diameter D) (4.2-14)

llW

mN

==

44Re

(vertical plate, width W) (4.2-15)

where mis the total kg mass/s of condensate at tube or plate bottom and =

m/Dor m/W. The NReshould be below 1800 for Eq. (4.2-13) to hold. The

reader should note that some references define NReas /. Then this NRe

should be below 450.

For turbulent flow for NRe

>1800;

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( ) 4.0Re

3/1

2

32

0077.0 NLg

k

hLN

l

l

l

Nu

==

(4.2-16)

Solution of this equation is by trial and error, since a value of NRe

must first be

assumed in order to calculate h.

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5.0 GENERAL OPERATING PROCEDURES

5.1 Temperature ReadingTo read a particular temperature, use the temperature selector knob to select

the desired reading. The knob indicates temperature T1 to T4. Tsurfof filmwiseand Tsurf

of dropwise are indicated by individual digital displays.

5.2 Cooling Water Flow ReadingTo read a particular flow, use the flow selector knob to select the desiredreading (FT1 or FT2).

5.3 Heater SettingTo turn on the heater, turn the heater switch to ON position. The powersupply to the heater is controlled by turning the potentiometer clockwise toincrease the value or anticlockwise to reduce the value. Use both coarse and

fine regulators to obtain the desired heating power.

5.4 Cooling Water ControlThe cooling water flowrate can be controlled by simply turning the valveclockwise to reduce flow rate or turning the valve anti-clockwise to increaseflow rate.

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6.0 EXPERIMENTAL PROCEDURE

6.1 General Start-up Procedures

1. Ensure that the main switch is in the off position.

2.

Turn the power regulator knobs fully anti-clockwise to set the power tominimum.

3. Check to ensure that valves V1 to V6 are closed.4. Fill the chamber with distilled water until the water level stays between the

heater and baffle plates. Always make sure that the heater is fullyimmersed in the water throughout the experiment. Water could be filledinto the chamber through the drain valve with the vent valve, V4 opened.Then close the vent valve, V4.

5. Adjust the water flow rate to the condenser by controlling the control valveaccording to the experimental procedure.

6. Turn on the main switch and the heater switch. Set the heater power by

rotating the power regulator clockwise to increase the heating power.7. Observe the water temperature reading; it should increase when the water

starts to heat-up.8. Heat up the water to boiling point until the pressure reaches 1.02 1.10

bar. Immediately open valve V1 and follow by valve V5 for 1 minute tovacuum out the air inside the condenser. Then close both valves V1 andV5.

9. Let the system to stabilize. Then take all relevant measurements forexperimental purposes. Make adjustment if required.

6.2 General Shut-down Procedures

1. Turn the voltage control knob to 0 Volt position by turning the knob fullyanti-clockwise. Keep the cooling water flowing for at least 5 minutesthrough the condensers to cold them down.

2. Switch off the main switch and power supply. Then, unplug the powersupply cable.

3. Close the water supply and disconnect the cooling water connection tubesif necessary. Otherwise, leave the connection tubes for next experiment.

4. Discharge the water inside the chamber using the discharge valve.

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6.3 Experiment 1: DEMONSTRATION OF FILMWISE AND DROPWISECONDENSATION

Objective:

To demonstrate the filmwise and dropwise condensation

Procedures:

1. Follow the basic procedure as written in section 6.1. Make sure that theequipment is connected to the service unit.

Assignment:

Describe the characteristics of filmwise and dropwise condensation and how itmay affect the efficiency of the condensers.

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6.4 Experiment 2: THE FILMWISE HEAT FLUX AND SURFACE HEATTRANSFER COEFFICIENT DETERMINATION AT CONSTANT PRESSURE

Objective:

To determine the filmwise heat flux and surface heat transfer coefficient atconstant pressure

Procedures:

1. Circulate cooling water through the filmwise condenser starting with aminimum value of 0.1 LPM.

2. Adjust the heater power to obtain the desired pressure at 1.01 bar.3. When the condition is stabilized, record the steam (Tsat) & surface

temperature (Tsurf

), Tin (T1) & Tout (T2), and flowrate.

Assignment:

1.

Plot Heat Flux vs. Temperature Difference (Tsat - Tsurf2. Plot a Surface Heat Transfer Coefficient vs. Temperature Difference (T

).sat -

TsurfNote: Power is calculated using the heat removed from the cooling water(

).

).

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6.5 Experiment 3: THE DROPWISE HEAT FLUX AND SURFACE HEATTRANSFER COEFFICIENT DETERMINATION AT CONSTANT PRESSURE

Objective:

To determine the dropwise heat flux and surface heat transfer coefficient atconstant pressure

Procedures:

1. Circulate cooling water through the dropwise condenser starting with aminimum value of 0.4 LPM.

2. Adjust the heater power to obtain the desired pressure at 1.01 bar.3. When the condition is stabilized, record the steam ((Tsat) & surface

temperature (Tsurf


Assignment:

1.

Plot Heat Flux vs. Temperature Difference (Tsat - Tsurf2. Plot Surface Heat Transfer Coefficient vs. Temperature Difference (T

).sat -

Tsurf3. Plot Heat Flux vs. Temperature Difference (T

).

sat - Tsurf) for filmwise anddropwise condensation in a single graph. Plot also Surface Heat TransferCoefficient vs. Temperature Difference (Tsat -Tsurf

) for filmwise anddropwise condensation in a single graph. Compare and discuss the heattransfer coefficients between filmwise and dropwise condensation.

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6.6 Experiment 4: THE EFFECT OF AIR INSIDE CHAMBER

Objective:To demonstrate the effect of air on heat transfer coefficient of condensation.

Procedures:

1. Circulate cooling water through the filmwise condenser at the highestflowrate until the pressure is reduced to below 1 bar.

2. Open the discharge valve and let an amount of air to enter the chamber.Note: Increase of 0.01 bar indicates 1% of air is injected.

4. Regulate the water flow rate to the condenser starting with a minimumvalue of 0.4 LPM.

5. Adjust the heater power to obtain the desired pressure at 1.01 bar.6. When the condition is stabilized, record the steam (Tsat) & surface

temperature (Tsurf

7.

Repeat step 1-6 for dropwise condensation.


Assignment:

1. Plot Surface Heat Transfer Coefficient vs. Temperature Difference (Tsat -Tsurf

2. Plot Surface Heat Transfer Coefficient vs. Temperature Difference (T

) with the presence of air, for filmwise and dropwise condensationrespectively.

sat -Tsurf

3. Describe the phenomena theoretically.

) with the presence of air and without presence of air in a single graph,for filmwise and dropwise condensation respectively. Compare anddiscuss the effect of air on heat transfer coefficients.

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7.0 EQUIPMENT MAINTENANCE

7.1 HeaterCool down the equipment before draining the water inside the glass vessel so

that the heater will not be overheated when there is no water inside the vessel.

7.2 CondenserMake sure tap water used is free from any contamination to prevent blockageinside the condenser.

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8.0 SAFETY PRECAUTION

8.1 Warning

High voltages exist and are accessible in the control panel. Return the unit toyour supplier for any servicing.

8.2 Cautions

1. Never splash water to the control panel. This will cause body injury anddamage to the equipment.

2. Never use your bare hand to test the AC Power Supply. It may causehazardous injury.

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APPENDIX AEXPERIMENTAL DATA SHEET

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EXPERIMENT 2:THE FILMWISE HEAT FLUX AND SURFACE HEAT TRANSFERCOEFFICIENT DETERMINATION AT CONSTANT PRESSURE

Flow rate(LPM) Power(W) Tin(degC) Tout(degC) Tsat(degC) Tsurf(degC) Tsat - Tsurf(degC) Tm(degC) (W/m2 U(W/m) 2.K)

qx = Heater Power (W)Tsat = Saturation Temperature (K)Tsurf = Surface Temperature (K) = Heat Flux (W/m2)

U = Heat Transfer Coefficient (W/m2.K)

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EXPERIMENT 3:THE DROPWISE HEAT FLUX AND SURFACE HEAT TRANSFERCOEFFICIENT DETERMINATION AT CONSTANT PRESSURE

Flow rate(LPM) Power(W) Tin(degC) Tout(degC) Tsat(degC) Tsurf(degC) Tsat - Tsurf(degC) Tm(degC) (W/m2 U(W/m) 2.K)

qx = Heater Power (W)Tsat = Saturation Temperature (K)Tsurf = Surface Temperature (K) = Heat Flux (W/m2)

U = Heat Transfer Coefficient (W/m2.K)

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EXPERIMENT 4:THE EFFECT OF AIR INSIDE CHAMBER

Flow rate(LPM)

FOR FILMWISE CONDENSER:

Power(W)

Tin(degC)

Tout(degC)

Tsat(degC)

Tsurf(degC)

Tsat - Tsurf(degC)

Tm(degC)

(W/m2U

(W/m) 2.K)

qx = Heater Power (W)Tsat = Saturation Temperature (K)Tsurf = Surface Temperature (K)

= Heat Flux (W/m2)U = Heat Transfer Coefficient (W/m2

.K)

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EXPERIMENT 4:THE EFFECT OF AIR INSIDE CHAMBER

Flow rate(LPM)

FOR DROPWISE CONDENSER:

Power(W)

Tin(degC)

Tout(degC)

Tsat(degC)

Tsurf(degC)

Tsat - Tsurf(degC)

Tm(degC)

(W/m2U

(W/m) 2.K)

qx = Heater Power (W)Tsat = Saturation Temperature (K)Tsurf = Surface Temperature (K)

= Heat Flux (W/m2)U = Heat Transfer Coefficient (W/m2

.K)

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APPENDIX BTYPICAL EXPERIMENTAL RESULT

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EXPERIMENT 1: DEMONSTRATION OF FILMWISE AND DROPWISE CONDENSATION

Objective:To demonstrate the filmwise and dropwise condensation

Typical Experimental Result:Not Applicable due to the experiment is just a demonstration and no data taking is involved.

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EXPERIMENT 2: THE FILMWISE HEAT FLUX AND SURFACE HEAT TRANSFERCOEFFICIENT DETERMINATION AT CONSTANT PRESSURE

Objective:To determine the filmwise heat flux and surface heat transfer coefficient at constant pressure

Typical Experimental Result:

Flow rate(LPM)

Power(W)

Tin(degC)

Tout(degC)

Tsat(degC)

Tsurf(degC)

Tsat - Tsurf(degC)

Tm(degC)

(W/m2U

(W/m) 2.K)

0.10 188 32.5 59.4 106.3 81.4 24.9 59.3 46491 784

0.20 237 32.4 49.4 106.4 77.6 28.8 65.1 58762 902

0.30 241 32.5 44.0 106.3 73.1 33.2 67.9 59627 878

0.40 279 33.2 43.2 106.2 67.7 38.5 67.9 69132 1018

0.50 279 33.9 41.9 106.1 64.3 41.8 68.1 69132 1015

0.60 268 33.8 40.2 106.3 63.6 42.7 69.3 66367 958

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EXPERIMENT 3: THE DROPWISE HEAT FLUX AND SURFACE HEAT TRANSFERCOEFFICIENT DETERMINATION AT CONSTANT PRESSURE

Objective:To determine the dropwise heat flux and surface heat transfer coefficient at constant pressure


Flow rate(LPM)

Power(W)

Tin(degC)

Tout(degC)

Tsat(degC)

Tsurf(degC)

Tsat - Tsurf(degC)

Tm(degC)

(W/m2U

(W/m) 2.K)

0.40 321 32.1 43.6 106.4 84.3 22.1 68.4 79502 1163

0.80 491 32.3 41.1 106.2 76.8 29.4 69.4 121673 1753

1.20 578 32.2 39.1 106.1 74.5 31.6 70.4 143104 2033

1.60 659 32.1 38.0 106.2 73.1 33.1 71.1 163152 2294

2.00 670 32.3 37.1 106.4 72.2 34.2 71.7 165918 2315

2.40 703 32.4 36.6 106.3 71.2 35.1 71.8 174213 2427

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EXPERIMENT 4: THE EFFECT OF AIR INSIDE CHAMBER

Objective:To demonstrate the drop of heat transfer coefficient when 1% air is injected.


Filmwise Condensation

Flow rate(LPM)

Power(W)

Tin(degC)

Tout(degC)

Tsat(degC)

Tsurf(degC)

Tsat - Tsurf(degC)

Tm(degC)

(W/m2U

(W/m) 2.K)

0.10 248 34.0 50.4 106.3 73.1 33.2 63.7 61436 964

0.20 275 33.8 46.8 106.4 71.5 34.9 65.9 68125 1034

0.30 294 33.8 44.8 106.4 66.8 39.6 66.9 72832 1088

0.40 305 33.5 42.3 106.4 62.1 44.3 68.4 75557 1105

0.50 308 33.4 41.4 106.3 61.4 44.9 68.8 76300 11090.60 324 33.6 40.3 106.3 60.5 45.8 69.3 80264 1158

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Dropwise Condensation

Flow rate(LPM)

Power(W)

Tin(degC)

Tout(degC)

Tsat(degC)

Tsurf(degC)

Tsat - Tsurf(degC)

Tm(degC)

(W/m2U

(W/m) 2.K)

0.40 320 32.4 36.8 106.3 61.3 45.0 71.7 79273 1106

0.80 424 32.4 35.4 106.4 57.5 48.9 72.5 105036 1449

1.20 470 32.4 34.9 106.4 56.2 50.2 72.7 116432 1601

1.60 493 32.5 34.7 106.4 55.1 51.3 72.8 122129 1678

2.00 456 32.5 34.6 106.3 54.8 51.5 72.7 112963 1553

2.40 478 32.5 33.8 106.3 53.6 52.7 73.1 118413 1619

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APPENDIX CSAMPLE CALCULATION

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Result Analysis:

1. Heat remove from the condensation,

Formula Used:

2. Log mean temperature difference,

3. Heat flux,

4. Heat transfer coefficient,

Where Diameter of the condenser, d = 0.0127m

Length of the condenser, L = 0.098m

Specific heat capacity of water,C= 4.186kJ/kg.K

EXPERIMENT 2: THE FILMWISE HEAT FLUX AND SURFACE HEAT TRANSFER

COEFFICIENT DETERMINATION AT CONSTANT PRESSURE

Flow rate(LPM)

Power(W)

Tin(degC)

Tout(degC)

Tsat(degC)

Tsurf(degC)

Tsat - Tsurf(degC)

Tm(degC)

(W/m2U

(W/m) 2.K)

0.10 188 32.5 59.4 106.3 81.4 24.9 59.3 46491 784

0.20 237 32.4 49.4 106.4 77.6 28.8 65.1 58762 902

0.30 241 32.5 44.0 106.3 73.1 33.2 67.9 59627 878

0.40 279 33.2 43.2 106.2 67.7 38.5 67.9 69132 1018

0.50 279 33.9 41.9 106.1 64.3 41.8 68.1 69132 1015

0.60 268 33.8 40.2 106.3 63.6 42.7 69.3 66367 958

Referring to the partial immerged data (1stdata)

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Volumetric flow rate, Q

Q = 0.10 LPM

=

= 1.667g/s

Power,qx

qx =

1 2

1

2

ln

( ) ( )

( )ln

( )

(106.3 32.5) (106.3 59.4)

(106.3 32.5)ln(106.3 59.4)

t tTm

t

t

Tsat Tin Tsat Tout

Tsat Tin

Tsat Tout

=

=

=

= 1.667g/s x4.186kJ/kg.Kx (59.4 32.5)C

= 187.7W

Log mean temperature difference,Tm

= 59.3 C

Flow direction

Tout

Tin

Tsat Tsat

Tmid

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Heat flux,

2

2

4 187.7

3.142(0.0127)3.142 0.0127 0.098

4

xq

ddL

=

+

=

+

= 46492.3W/m

46492.3

59.3

UTm

=

=

2

Heat transfer coefficient,U

= 784W/m2.K

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APPENDIX DFILMWISE AND DROPWISE CONDENSATION

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Figure D1:Filmwise condensation

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