To demonstrate the relationship between power input and surface temperature in forced convection.

1. Experiment # 4
Objective:
To demonstrate the relationship between power input and surface temperature in forced
convection.
Apparatus:
Fig4.1 (Free & Forced convection heat exchanger)
Procedure:
 Place the fan assembly on the top of the duct.
 Place the finned heat exchanger into the duct.
 Set the heater power control to 50 watts (clockwise). Allow sufficient time to achieve
steady state conditions before noting the heated plate temperature (𝑇 𝐻) and the ambient
temperature (𝑇𝐴).
 Set the fan speed control to give a reading of 0.5m/s on the thermal anemometer, allow
sufficient time to achieve steady state conditions. Recored heated plate temperature (𝑇 𝐻)
and ambient temperature (𝑇𝐴).
 Repeat this procedure by setting the fan speed control to give 1.0m/s and 1.5m/s.

2.  Plot a graph of air velocity against temperature (𝑇 𝐻-𝑇𝐴).
Observation:
Sr #
Air
velocity
(m/s)
Plate
Temperature
𝑻 𝑯
(℃)
Air
Temperature 𝑻 𝑨
(℃)
𝑻 𝑯-𝑻 𝑨
1 0 73 24 49
2 0.5 66 24 42
3 1 56 24 32
4 1.5 47 24 23
Graph:
Result:
The graph shows that the increase in the velocity of air the temperature difference is decrease
and the heat transfer through the fin is very high in force convection.