Report#1

First Experiment of CHE 317, 2nd Semester 1435/36H

Date of Submission: 3 of March 2015

STUDENT NAME ID NUMBERFAISAL BIN MADHI 431106213

ABDURRAHMAN ALSULAIMAN

HAMMED ALHAMDAN 432100465

Energy Transport Operations (CHE 317)

Dr. Malik Alahmad

Chemical Engineering Department

Supervised by:

Dr. Mohamed Gaily

* Tasks:-

NAMES TASKS

FAISAL AWADHBIN MADHI

Introduction-SummaryTheory

ObjectivesProcedure

CalculationsResults

DiscussionReferences

ABDURRAHMANALSULIMAN

Recommendation

Conclusion

HAMMED ALHAMDAN

Appendices

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* TABLE OF CONTENTS:-

Summary3Introduction4Objectives5Theory5

Procedures6Results7

Calculation8Discution9Conclusion10

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Recomendation11Refrences11

Appendices12-13-14

* Summary:

Thermal conductivity is the property of a material to conduct heat. The objective from this experiment to measurement of the thermal conductivity of metals -Aluminum-Stain Steel- (k) and to Measurement of the resistance of metals (R). To find them we will use lows which in page 3.

.This experiment took 30 minutes because we have seventh reading , every reading took 5 minute and in the calculations we are depend on the Seventh reading. So, after 30 minute (the finally reading) we got onT1, T2, T3, T4, Tin and Tout. T1 and T2 for Stain

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Steel, T3 and T4 for Aluminum. In the procedure we explained how we did this experiment. In the result we have that helps us in calculations. First one for the measurement of the temperatures of stain steel and aluminum and the second one for the measurement of the lengths and diameters of stain steel and aluminum. After we did calculations we found the values of K and R for stain steel and aluminum. The thermal conductivity for stain steel is

11.84 W

m∗k and for aluminum is 140.14W

m∗k . The

resistance for stain steel is 4.30 WK and for aluminum

is 0.727WK . There is a small different between

theoretical values and the values that we found aftercalculation. There is inverse relation between thermal conductivity and temperature.

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* Introduction:-

Thermal conductivity: is the property of a material to conduct heat. It is evaluated primarily in terms of Fourier's Law for heat conduction.(1)

Heat transfer occurs at a higher rate across materials of high thermal conductivity than across materials of low thermal conductivity. Correspondingly materials of high thermal conductivity are widely used in heat sink applications and materials of low thermal conductivity are used as thermal insulation. Thermal conductivity of materials is temperature dependent. The reciprocal of thermal conductivity is called thermal resistivity. Gases have quite low values of thermal conductivity, liquids intermediate values, and solid very high values. (1)

The thermal conductivity of homogeneous solids variesquite widely, as may be seen for some typical values.The metallic solids of Aluminum and aluminum have very high thermal conductivities, while some insulating nonmetallic materials such as rock wool and corkboard have very low conductivities. (1) Heat or energy is conducted through solids by two mechanisms. In the first, which applies primarily to metallic solids, heat, like electricity, is conductedby free electrons which move through the metal lattice. In the second mechanism, present in all solids, heat is conducted by the transmission of energy of vibration between adjacent atoms. (2)

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Thermal conductivities of insulating materials such as rock wool approach that of air since the insulating materials contain large amounts of air trapped in void spaces. Superinsulation to insulate cryogenic materials such as liquid hydrogen is composed of multiple layers of highly reflective materials separated by evacuated insulating spacers. Values of thermal conductivity are considerably lowerthan for air alone. Ice has a thermal conductivity much greater than water. Hence, the thermal conductivities of frozen foods such as lean beef and salmon are much higher than for unfrozen foods. (3)

A high value for thermal conductivity indicates that the material is a good heat conductor, and a low value indicates that the material is a poor heat conductor or insulator. The variation of the thermal conductivity of various solids, liquids, and gases with temperature (2).

Determination of thermal conductivity of:

Gases: in gases the mechanism of thermal conduction is relative simple. The molecules are in continuous random motion, colliding with one another and exchanging energy and momentum (4).

Liquids: the physical mechanism of conduction of energy in liquids is somewhat similar to that of gases where higher energy molecules collide with lower energy molecules. (4)

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Solids: the thermal conductivity of homogenous solidsvaries quite widely, the metallic solid of copper andaluminum have very high thermal conductivity while some insulating nonmetallic materials such as rock wool and corkboard have very low conductivity.(4)

* Objectives:-

1- Measurement of the thermal conductivity of metals (Aluminum-Stain Steel).

2- Measurement of the resistance of metals.

*Theory:-

qA

=−k dtdx

(1)

Where:

K: Thermal conductivity [W/m*K]

q: The amount of heat flow rate (W).

A: Area (m2). A=π4D2

ΔT = (T2 - T1). (0C or K)

∆x= a distance between point 1 – 2 [m].

q=m∗cp∗∆Twater(2)

q : The amount of heat flow rate (W) [W].

cp: specific heat of water [kJ/kg.K].

m : mass flow rate.

∆Twater= ( Tout – Tin ).

R=∆xkA

(3)

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R: resistance of the martial {K/W}.

K: Thermal conductivity [W/m*K].

∆x: A distance between points 1 – 2 [m].

A: Area (m2).

*Procedure: -

An aluminum and stainless steel specimen was put together in the apparatus. All four thermocouples were in place and the apparatus was covered with the insulating jacket. The cooling water supply was turned on and the heater was switched to full power. The flow rate of cooling water was set to about 45.4 mL/min using the flow meter. After the apparatus reached steady-state, the specimen and cooling water temperatures was monitored to confirm that steady conditions have been achieved. Once at steady-state, the collection of the cooling water in the container provided was timed. After that the specimen temperatures (T1 to T4), and the cooling water temperatures (Tin, Tout) were recorded every five minutes and we did this experiment for 30 minutes.

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Figure 1: cushions thermal Conductivity.

* Results:-

Given Data:-

* Metals are:-

1) Aluminum (Al). 2) Stain Steel (S.S).

* Water flow rate (V) = 45.4mlmin

Table 1) Data of Diameters & Lengths for Metals :

Metal Diameter (mm) Length ∆x (mm)

Stain Steel (S.S)

25 25

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Figure 2: temperature measurement

Figure 3: Aluminum, Stain Steelexperiment

Figure 4: The parts inside the device

Aluminum (Al) 25 50

Table 2) Data of temperature from the Lab:-

Time(min)

Tw in

(0C )Tw out

(0C )T1 ( S.S

)

(0C )

T2 ( S.S

)

(0C )

T3 ( Al )

(0C )T4 ( Al )

(0C )

0 21.3 22.6 34.4 57.6 79.7 83.8

5 21.4 23.2 37.2 64.3 89.7 94.6

10 21.8 23.8 39.3 69.1 96.5 101.7

15 22.1 24.2 41.1 72.7 101.9 107.3

20 22.3 24.7 42.6 76.2 106.6 112.2

25 22.5 25.1 44 79.3 111 110.8

30 22.7 25.4 45.2 81.9 114.9 121.1

*Calculations-:* Calculate Tave:-

Tave=

Tin+Tout2

=22.7+25.4

2=24.050C

* The physical properties at T= 24.050C

from the book (4).

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Cp=4.18257 kJ

kg.K (Table A.2-5)

ρ=997.2985 Kgm3( Table A.2-3)

Area =(π4)(D

2¿=(π4

¿ (25∗10−3 )2=¿4.909*10-4 m2*

The area is for both Al and S.S since the have the

same diameter. *Calculating the thermal conductivity using the data

in tables at (t=30min):

.m=vxρ=45.460x106

∗97.2985=7.55x10−4kgs

q=mcp (Tout−T¿) = 7.55x10−4∗4.18257∗(25.4−22.7)=8.53∗10−3Kw=8.53w

And from equation-(2) we get :k=

q×LA×∆T

K (stainless-steel)=11.84 W

m.K

k (Aluminum) =140.14 Wm.K

*Calculating the resistances for the metals using

the data above: From equation (3)-:11

R=ΔxkA

R Stain Steel =4.30K

W

R Aluminum=0.727 K

W

Discussion -:*

*The Given data in this experiment:1 -Flow rate of water (ml/min)

2 -Tin, Tout of water (0C)

3-T1, T2,T3,and T4 of stain steel and aluminum and respectively (0C )

4 -Height, length, and diameter of aluminum and stainsteel (mm)

So ,in this experiment at Time = 30 min , we got : Tin(water) = 22.7 0C , Tout (water) = 25.4 0C , Tave=

24.05 0C After that we did the calculations to find the thermal conductivity (k) for stain steel and aluminum

and we found that:12

k Stain Steel = 11.84 W

m.K

k Aluminum = 140.14 Wm.K The value of the thermal conductivity of the aluminum

in the table (A.3-16) at T= 0 0C is 202 Wm.K

The value of the thermal conductivity of the stain

steel in the table (A.3-16) at T= 0 0C is 13.8 Wm.K

-By comparing the result between our experiment and the tables in the text book (4). We will see there is a relative between thermal conductivity and temperature and there is a small different between the theoretical values and the experimental values. The thermal conductivity inversely proportional with

temperature.

*Conclusion:-The objective from thermal conductivity experiment todetermine the thermal conductivity and the resistance

for stain steel and aluminum :ResistanceThermal

conductivityMetal

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(KW)(W

m∗K)

140.1411.84Stain Steel(S.S)

0.7274.30Aluminum (Al)

*Recommendation:--Different degree of the water temperature inter to

the device affects the accuracy of the accounts.-because the device is old version some our readings

not exact.

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-Prepare experience by teaching assistants before the

arrival of the students and thank him.-close the area between our experimental and other

device.-Reduce the number of students to perform the

experiment.-We want to see a new devices or machines that

describes what is happen inside a big companies like

SABIC ,ARAMCO, etc.

*Reference-:1 )http://en.wikipedia.org/wiki/Thermal_conductivity

2)https://ajutarut.files.wordpress.com/2013/07/e0b89ae0b897e0b897e0b8b5e0b988-4-steady-state-heat-transfer.pdf

3 )http://www.scribd.com/doc/134705447/Handbook-of-

Chemical-Processing-Equipment#scribd

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4 )Geankoplis, C. J., Transport Processes and Separation Process Principles. 4th ed. Published by Prentice Hall, 2003. P.P 239-240-960-961-987

*Appendices-:

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