laporan praktikum raihan

LAPORAN PRAKTIKUM

Remote Laboratory

Disipasi Kalor Hot Wire

LABORATORIUM FISIKA DASAR

UPP IPD

UNIVERSITAS INDONESIA

2013

Nama : Raihan Alisha NabilaNPM : 1306437126Fakultas/Prodi : Teknik / Sipil Int’lJudul modul : Disipasi Kalor Hot WireNomor modul : KR01Tanggal praktikum : 3 Oktober 2013

KR01 – Heat Dissipation Hot Wire

Experiment ObjectivesUsing hotwire as the air velocity censor

Equipments• hotwire)

• Fan

• Voltmeter and Ampere meter

• Adjustable power supply

• Camcorder

• Unit PC DAQ and automatic control devices

Theory Normal single hotwire probe is a type of the most widely used as censors to provide information about the flow velocity in the axial direction only. This type of probe consists of a short metal wire which united the two fine steel wire. Each probe tip is connected to a voltage source. Electric energy flows in the probe will have dissipation by wire becoming heat energy. The amount of electrical energy that is dissipated is proportional to the voltage, the electric current flowing in the probe and duration of electric current to flow.

P = v i Δ t .........( 1 )

When the probe is exhaled by the air then it will change the value of the resistance wire that alter the amount of electric current flow. The faster the air flow then the changes of the resistance value and also greater and the electrical current flow also changed.

Heat transfer amount received by the probe revealed overheat ratio defined as:

Overheat Ratio = RwRa

Rw = wire resistance at the operating temperature (air blows). Ra = wire resistance at room temperature.

Hot wire probe must be calibrated to determine the equation that states the relationship between voltage wire (wire voltage, E) with a reference velocity (reference velocity, U) after equation is obtained, then the information velocity in each experiment can be evaluated using the equations. Equation is obtained in the form of linear equations or polynomial equations.

The experiment is to measure the voltage wire at a room temperature and when energized air produced by the speed of the fan. Airflow velocity by the fan will be varied through the power supplied to the fan that is 70, 110, 150 and 190 of the maximum 230 m / s.

Experiment Procedure1. This rLab experiment can be

done by click the rLab button in the bottom site.

2. Activate the web cam (clic the video icon in the rLab website).

3. Add the air flow with the 0 m/s velocity, with clicking the option drop down in the icon “atur kecepatan aliran”.

4. Turn on the fan by clicking the radio button in the icon “menghidupkan power supply kipas”.

5. Measure the voltage and the electrical flow in the hot wire by clicking the “ukur” icon.

6. Repeat the second steps until the fourth for the velocity of 70 , 110 , 150 , 190 and 230 m/s.

Tasks & Evaluation 1. Graph represents the relation between the voltage hotwire and the

times for every velocity of the air flows as shown below:

The voltage when V= 0 m/s

TimeAir

VelocityV-HW I-HW

1 0 2.112 54.02 0 2.112 54.03 0 2.112 53.94 0 2.112 53.95 0 2.112 53.96 0 2.112 53.97 0 2.112 53.98 0 2.112 53.99 0 2.112 54.0

10 0 2.112 54.1

1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

2.5


V-HW

Second

Volta

ge


TimeVelocity

of airV-HW I-HW

1 70 2.067 55.52 70 2.067 55.03 70 2.067 54.44 70 2.066 54.25 70 2.066 54.66 70 2.065 55.37 70 2.066 55.48 70 2.066 54.89 70 2.068 54.3

10 70 2.067 54.3

1 2 3 4 5 6 7 8 9 102,062

2,064

2,066

2,068

2,070


V-HW

Second

Volta

ge


TimeAir

velocityV-HW I-HW

1 110 2.051 54.72 110 2.052 55.43 110 2.052 55.84 110 2.051 55.25 110 2.050 54.66 110 2.051 54.47 110 2.050 54.98 110 2.051 55.69 110 2.050 55.7

10 110 2.050 55.0

1 2 3 4 5 6 7 8 9 102,049

2,050

2,051

2,052

2,053


V-HW

Second

Volta

ge


TimeAir

VelocityV-HW I-HW

1 150 2.042 56.12 150 2.043 55.53 150 2.042 54.84 150 2.043 54.55 150 2.044 54.96 150 2.043 55.77 150 2.042 56.08 150 2.043 55.49 150 2.043 54.7

10 150 2.043 54.5

1 2 3 4 5 6 7 8 9 102,041

2,042

2,043

2,044

2,045


V-HW

Second

Volta

ge


TimeAir

velocityV-HW I-HW

1 190 2.043 56.02 190 2.039 55.33 190 2.039 54.74 190 2.039 54.75 190 2.040 55.46 190 2.039 56.17 190 2.039 55.78 190 2.038 54.89 190 2.038 54.6

10 190 2.038 55.1

1 2 3 4 5 6 7 8 9 102.035

2.036

2.037

2.038

2.039

2.04

2.041

2.042

2.043

2.044


V-HW

Second

Volta

ge


TimeAir

velocityV-HW I-HW

1 230 2.036 55.42 230 2.036 56.13 230 2.036 56.04 230 2.035 55.25 230 2.036 54.76 230 2.035 54.87 230 2.035 55.58 230 2.036 56.29 230 2.037 55.9

10 230 2.037 55.1

1 2 3 4 5 6 7 8 9 102.034

2.0345

2.035

2.0355

2.036

2.0365

2.037

2.0375


V-HW

Second

Volta

ge

The average value of each voltage can be seen below:

at V= 0 m/s V= 2.112+2.112+2.112+2.112+2.112+2.112+2.112+2.112+2.112+2.112

10V= 2.112 volt

at V= 70 m/s V=

2.067+2.067+2.067+2.066+2.066+2.065+2.066+2.066+2.068+2.06710

V= 2.067 volt

at V= 110 m/s V=

2.051+2.052+2.052+2.051+2.050+2.051+2.050+2.051+2.050+2.05010

V= 2.051 volt at V= 150 m/s

V= 2.042+2.043+2.042+2.043+2.044+2.043+2.042+2.043+2.043+2.043

10

V= 2.043 volt

at V= 190 m/s V=

2.039+2.039+2.039+2.039+2.040+2.039+2.039+2.038+2.038+2.03810

V= 2.039 volt

at V= 230 m/s

V= 2.036+2.036+2.036+2.035+2.036+2.035+2.035+2.036+2.037+2.037

10V= 2.036 volt

2. Graph that shown the relation between the voltage of hotwire and the velocity of the air flow:

0 70 110 150 190 2301.98

2

2.02

2.04

2.06

2.08

2.1

2.12 2.112

2.067

2.0512.043 2.039 2.036

Graph of relation between the voltage of Hot Wire and the air velocity

Air Velocity

Hot

Wire

Vol

tage

3. The equation of air flow as the function from the hotwire voltage can be measured by the least square method:

a =

∑Xi2∑Yi−∑Xi∑(XiYi)N ∑Xi2−(∑ Xi)2

= (128500∗12.35 )−(750∗1532.44)

(6∗128500 )−562500

= 2.099

b = N∑(XiYi)−∑Xi∑YiN ∑ Xi2−(∑Xi)2

= (6∗1532.44 )− (750∗12.35 )

(6∗128500 )−562500

= -0.000325

( b is a gradient of (m), so the value of m = -0.000325)

y² Δ = 1

N−2 (∑Yi ²∑Xi2 (∑Yi )2−2∑Xi∑Yi∑ (XiYi )+N (∑XiYi )2

N ∑Xi2−(∑Xi )2 )=

16−2

(25.147 (128500∗152.5225 )−(2∗750∗12.35∗1532.44 )+6∗2348372.3536(6∗128500 )−562500 )

= 159.835

i Xi Yi Xi² Yi² XiYi

1 0 2.112 0 4.461 0

2 70 2.067 4900 4.272 144.69

3 110 2.051 12100 4.207 225.61

4 150 2.043 22500 4.174 306.45

5 190 2.039 36100 4.158 387.41

6 230 2.036 52900 4.145 468.28

∑ 750 12.35 128500 25.417 1532.44

bΔ = y Δ √ N

N ∑Xi2−(∑ Xi)2

= 12.643 √ 6(6∗128500 )−562500

= 0.0678

b = m = 0.0678Δ Δ

y = mx+a

y = -0.000325x + 2.099

So the equation of air velocity as the function from hotwire voltage is y = -0.000325x + 2.099

4. Based on the experiments and the data obtained, it can be used as a hot wire air flow velocity sensor by using wire as a sensor. How it works with each end connected to a source hotwire voltage electrical energy that can flow in the hotwire. Electrical energy will be dissipated by a heat hotwire. The heat sensor in order to maintain a constant temperature in order to calculate the wind speed.

5. Analysis

• Experiment Analysis

Heat Dissipation on Hot Wire experiment was performed 6 times experimenting with different flow velocity is 0 m / s , 70 m / s , 110 m / s , 150 m / s , 190 m / s , 230m / s . When the fan is not turned on , a large current and voltage has not affected the speed of the fan. When the fan starts up, the fan speed was set in accordance with the variations given. When the fan is turned on, the speed of the wind affects the electrical current and the voltage flowing. Electric currents become larger, comparable to the speed of the fan is given. While the voltage becomes smaller, inversely proportional to the wind speed generated fan. This is caused by the air that is blown by the fan causing resistance in the wire which in turn affects the voltage and current. This is done to see how the influence of time on the voltage on the hot wire at a

certain speed and how the effect of time on the average voltage. Tension in the wire will produce electricity that will be in the dissipation of heat energy by a wire so that the wire will be hot. The heat will be used to maintain a constant temperature sensor in order to calculate the wind speed in the experiment.

While the wind speed changes depending on the value of the sensor resistance. In addition, this experiment can also be used to analyze the relationship between the speed of the air flow of electric current. When air is blow, the wire resistance value will change so that change the value of the electric current flowing. The faster the air flow, then change the value of the electric current flowing turns and the resistance value becomes larger.

• Result Analysis

Results of this experiment is the voltage, time and speed the flow of wind interconnected. When the flow velocity is 0 m \ s it will generate a voltage and current of an average of 2.112 volts. When the flow velocity of 70 m \ s going to get the voltage and current of the variety which when it will get an average of a voltage of 2.067 volts and when the flow velocity of 110 m \ s will get the average voltage of 2.051 volts, for the flow velocity of 150 m \ s will get the average voltage of 2.043 volts, for a flow velocity of 190 m \ s going to get an average voltage of 2.039 volts, and last for a speed of 230 m \ s will generate average voltage of 2.036 volts.

• Graphic Analysis

Voltage versus time graph shows the relationship between the voltage and the time given on the wind speed varies according to the experimental procedure. On this graph, time serves as a voltage variable X and Y is defined as a variable indicates that the wind speed is given by the fan anyway, so the longer the wind blows the heat energy becomes smaller. So the value of the voltage will be smaller due to the addition of time there. This decrease occurs because of heat dissipation that occurs on hotwire a certain wind speed. In the second graph angina velocity relationship with voltage, students got also a negative comparison between the voltage and speed of the wind flow. Almost the same

as the relationship of time, this graph shows that the greater the wind velocity, it will be diminishing the power supply voltage.

• Conclusion

Conclusion that we can make is:

1) The graph shows that the smaller the value of the voltage at the wind speed increases. This is due to the greater angina given, then gradiant temperature probe which passes the greater was also causing greater heat loss

2) Wire the hot wire can only be used to estimate large / small wind, not to determine its value, namely by looking at the voltage and current changes that occur in the wire hot wire.

3) Wind Speed happens inversely proportional to the voltage (V) and inversely proportional to the electric current (I)

4) The resulting equation of the graph of air flow velocity to the voltage that is y = -0.000325x + 2.099

Reference• Giancoli, D.C.; Physics for Scientists & Engeeners, Third Edition,

Prentice Hall, NJ, 2000.

• Halliday, Resnick, Walker; Fundamentals of Physics, 7th Edition, Extended Edition, John Wiley & Sons, Inc., NJ, 2005.

Attachment

Time

Air Velocit

y V-HW I-HW1 0 2.112 542 0 2.112 543 0 2.112 53.94 0 2.112 53.95 0 2.112 53.96 0 2.112 53.97 0 2.112 53.9

8 0 2.112 53.99 0 2.112 54

10 0 2.112 54.11 70 2.067 55.52 70 2.067 553 70 2.067 54.44 70 2.066 54.25 70 2.066 54.66 70 2.065 55.37 70 2.066 55.48 70 2.066 54.89 70 2.068 54.3

10 70 2.067 54.31 110 2.051 54.72 110 2.052 55.43 110 2.052 55.84 110 2.051 55.25 110 2.05 54.66 110 2.051 54.47 110 2.05 54.98 110 2.051 55.69 110 2.05 55.7

10 110 2.05 551 150 2.042 56.12 150 2.043 55.53 150 2.042 54.84 150 2.043 54.55 150 2.044 54.96 150 2.043 55.77 150 2.042 568 150 2.043 55.49 150 2.043 54.7

10 150 2.043 54.5

1 190 2.043 562 190 2.039 55.33 190 2.039 54.74 190 2.039 54.75 190 2.04 55.46 190 2.039 56.17 190 2.039 55.78 190 2.038 54.89 190 2.038 54.6

10 190 2.038 55.11 230 2.036 55.42 230 2.036 56.13 230 2.036 564 230 2.035 55.25 230 2.036 54.76 230 2.035 54.87 230 2.035 55.58 230 2.036 56.29 230 2.037 55.9

10 230 2.037 55.1

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