RESULTS:
HEATERBRASS SAMPLE REGIONCOOLER
x (mm)01020304050607080
x (m)00.010.020.030.040.050.060.070.08
Test # (W) (C)T2(C)T3 (C)T4 (C)T5 (C)T6 (C)T7 (C)T8 (C)T9
(C)
A1040.644.345.535.0146.133.432.331.932.2
B2068.276.579.044.4146.238.534.033.333.2
C3099.8108.2111.555.4146.246.636.935.334.8
1. Plot the temperature profile along the entire length. This
should reveal three distinct sections of straight lines
(corresponding to the heater, brass sample, and cooler) having a
slope of approximately T/x.
2. Convert the measured temperatures to degrees Kelvin by the
following formula:T(K) = T(C) + 273.15T(K) = 40.6 + 273.15 = 313.75
K.
Test # (W)T1(K)T2(K)T3 (K)T4 (K)T5 (K)T6 (K)T7 (K)T8 (K)T9
(K)
A10313.75317.45318.65308.15419.25306.55305.45305.05305.35
B20341.35349.65352.15317.55419.35311.65307.15306.45306.35
C30372.95381.35384.65328.55419.35319.75310.05308.45307.95
3. Calculate the cross-sectional area (A) of the circular
cylinder by using the equation:A = /4dA = /4 x (0.025) = 4.91x10^-4
m
4. The brass sample region is the region interest. Ignore all
other temperature measurements except T4, T5, and T6 and calculate
the thermal conductivity of the brass. This is the slope of the
straight line in the brass sample region alone (plotted in 1),
given by the equation:k = (/A) x (x/T)units [W/m.K]
Test A, = 10Wk = (10/4.91x10^-4) x (0.05-0.03)/( 308.15-306.55)
= 254.58 W/m.K
Test B, = 20Wk = (20/4.91x10^-4) x (0.05-0.03)/( 317.55-311.65)
= 138.08 W/m.K
Test C, = 30W k = (30/4.91x10^-4) x (0.05-0.03)/( 328.55-319.75)
= 138.86W/m.K
5. Find published values of brass in books or on the internet.
Compare the value you obtained with these values. Which type of
brass does your results best compare with (e.g. yellow brass, red
brass etc.)? Discuss any source or error in your measured results.
Students should comment on how changing the average temperature
affects the thermal conductivity.MetalTemperature-t-(oF)Thermal
Conductivity-k-(Btu/(hroF ft))
Admiralty Brass6864
Copper Brass6864
Red Brass6892
Cartridge brass (UNS C26000)6869.4
Yellow Brass6867
This data is obtained from the internet source (
http://www.engineeringtoolbox.com). Moreover, the best types of
brass is Red Brass because it has the highest thermal conductivity.
This is because the higher thermal conductivity, the higher the
amount of heat that can be conducted by the material. Indeed, the
value of thermal conductivity of brass in room condition
(293K-299K) obtained from internet is 109 W/m.K. From the
experiment, for the range of temperature between (328.55K-319.75K)
the thermal conductivity values are 138.86W/m.K. During this
experiment there might be some errors occur that lead to
discrepancies between the experimental and theoretical data. The
errors might be because of insufficient time to allow for a steady
state to be achieved. Despite, to avoid this student should take
the reading of the stopwatch properly.
