Heat & Mass Transfer Lab
Experiment 1
Objectives:
To measure the temperature distribution for a steady-state conduction of energy through a
uniform plane wall and demonstrate the effect of a change in heat flow.
Apparatus Description:
• Heat Transfer Base Unit (TD1002)
• Computer Compatible Linear Heat Conduction Accessory TD1002a.
The Apparatus is setup as shown in the following figure. Attach the TD1002a Linear Heat
Conduction Experiment module with the TD1002 Heat transfer experiment Base unit. To make
the composite wall, clamp the stainless steel, brass and Aluminium intermediate section.
Introduction:
Provided that the heated, intermediate and cooled sections are clamped tightly together,
so that the two end faces are in good thermal contact, and create a composite wall by
clamping the Stainless-steel section (intermediate section) between two Brass sections
(heated and cooled sections).
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Heat & Mass Transfer Lab
Conduction: This refers to the way heat moves through a solid substance from one particle
to another. It happens when two objects of differing temperatures are in direct contact. Until both
objects attain the same temperature, heat energy is conveyed from the one that is warmer to the
one that is cooler. As an illustration, when we come into contact with a hot frying pan, heat moves
from the pan to your hand.
Convection: This refers to the movement of heat in fluids (both liquids and gases) due to the
bulk fluid motion. When the fluid is heated, it loses density and ascends, while the cooler, denser
fluid descends. This establishes a convection current, which circulates heat within the fluid. an
instance of convection is the heating of water in a pot; the hot water at the bottom rises, and the
cooler water moves down to replace it, creating a circular motion.
Radiation: This involves the transfer of heat via electromagnetic waves, with a focus on
infrared radiation. Radiation, in contrast to conduction and convection, does not need a medium
to propagate; a vacuum can allow it to happen. Every object radiates and takes in radiant energy.
As an illustration, the warmth you experience from the sun results from radiation, with the sun's
energy traversing space and heating the Earth.
Procedure:
• First of all, we ensured that the wall is clean and free of defects that could affect heat
conduction.
• Then we measured the length of the wall.
• Next, we placed thermocouples or temperature sensors at equal intervals along the length
(15 mm = 0.015 m) of the wall.
• Then, we turned on the heat source and set it to a specific power level & recorded the
power input.
• Then we allowed the system to reach steady state. This is achieved when the temperature
readings at all points on the wall remain constant over time.
• We recorded the temperature readings from all thermocouples when steady state
achieved.
• Then we repeated the process for (40w, 49.7w, 60.7w and 69.9w) power levels to observe
the effect of heat flow on temperature distribution. • We observed that how the
temperature gradient changes with increased heat flow.
Department of Mechanical Engineering, Air University A&AC Kamra 2
Heat & Mass Transfer Lab
Observation & Calculations
Distance between each thermocouple = 15 mm = 0.015 m
Sr No. Heater Power (W) T1 (C) T2 (C) T3 (C) T4 (C) T5 (C) T6 (C) T7 (C)
1. 40 54.5 50 40.5 39.6 38.7 34.8 31.2
2. 49.7 58.6 53.7 43.4 42.3 41.3 37 33
3. 60.7 66.8 60.7 47.8 46.5 45.3 40.1 35.2
4. 69.9 74.1 67 52.3 50.7 49.2 43.2 37.6
Results Analysis & Discussion:
From the data, we observe a clear trend:
1. Effect of Heater Power on Temperature Distribution:
• With the heater power rising from 40 W to 69.9 W, the temperatures at all measured points
(T1–T7) rise as well.
• The first sensor (T1), nearest to the heat source, consistently shows the highest
temperature, whereas the last sensor (T7) shows the lowest.
• This corroborates that thermal energy moves from the heated surface to the cooler end,
thereby creating a temperature gradient.
2. Temperature Gradient and Heat Conduction:
• The temperature decrease over the plane wall shows a declining trend from T1 to T7,
illustrating steady-state one-dimensional heat conduction.
• Near the heat source, the temperature difference between adjacent points is more
pronounced (T1–T3), and it diminishes as heat disperses further away.
• This is consistent with Fourier’s Law of Conduction, which asserts that the heat flux is
proportional to the temperature gradient.
3. Effect of Increasing Heat Flow:
When comparing various power levels:
• With 40 W, the temperature decreases from T1 to T7 by 23.3 K (a reduction from 54.5 K
to 31.2 K).
• With a power of 69.9 W, the temperature drop rises to 36.5 K (from 74.1 K to 37.6 K).
Department of Mechanical Engineering, Air University A&AC Kamra 3
Heat & Mass Transfer Lab
• This suggests that a greater heat input leads to a steeper temperature gradient, signifying
a larger thermal driving force for conduction.
4. Thermal Resistance and Uniformity:
• The relatively smooth temperature variations at the points indicate that the material has
uniform thermal conductivity.
• Any departures from a perfect linear temperature profile may result from contact
resistances, flaws in the material, or losses of heat to the environment.
Graph:
Plot a graph of temperature against distance along the bar and draw the best straight line through
the points.
100
90
80
70
60
50
40
30
20
10
0
1 2 3 4 5 6 7 8
Distance
Department of Mechanical Engineering, Air University A&AC Kamra 4
