Precautions and Conclusion

Precautions:

• Wait for some time for system to attain steady condition.
• Make sure that both the heating elements are on.
• Power supply to the heating element should be switched off as soon as relay cuts it off.
• The band switch should be rotated slowly.
• The selector switch should not be in middle position when the power supply is on.
• Source temperature should not be set more than 150 ^o C for both the fins.

Conclusion:

• Actual heat transfer is more than theoretical value because area exposed to conduction is more due to manufacturing limitations.

• Central fin gets more heated because of its less interaction with air.

• Temperature drop across Aluminium fin is less than brass fin because of its thermal conductivity.

• Value of h is always greater than 5 in natural convection and it can not go beyond 1.

• A fin can not be designed for 100% efficiency.

• Aluminium fins conduct more heat than brass fins at same temperature difference.

• Efficiency of brass fin is 77.7%.

• Efficiency of Aluminium fin is 87.5%.

• Thermal resistance of brass is more than Aluminium.