Assignment for Lab Report - Air recirculation through a duct-room system

You need to attend the laboratory class that you are enrolled. Not attending the laboratory class will lead to a zero mark.

In the laboratory class, complete Test A and Test B.

Do the following analysis and write a minimum 2500-word report.

(1) In the report you need to explain how the values, including the heat flow rates and heat losses, are calculated. The formulae and theory must be given. Only showing the results is not satisfactory.

(2) In test A, calculate the heat loss between T2 and T4 and the heat loss between T4 and T5 (see Figure 1 for the positions of T1 - T5). Discuss how these heat losses are affected by temperature T2.

(3) By assuming zero heat loss between T1 and T2, find out the power supplied by the preheater. Discuss if there is any difference between the power in Test A and that in Test B, and what is the possible reason for the difference.

(4) In test B, calculate the heat loss between T5 and T1, and heat loss between T4 and T5. Discuss how these heat losses are affected by the temperature T2.

(5) Compare the temperatures in Test A with their counterparts in Test B and analyze the reason for the difference.

(6) Discuss the possible reasons that lead to errors in the measurement.

Note:

You need to use the theory about thermal and fluid engineering, thermodynamics and fluid mechanics to complete the assignment and write the report. This report tests students' ability to solve simple problem using what they have learnt.

Appendix A is a working table that can be used to record the experimental data. Appendix B lists some formulae (not all) for air flow in a duct.

Test A

In test A, air enters the duct through inlet louvre and exit through the outlet louvre. The system is not a recirculated system. Before the air enters the room, it is heated by the preheater.
- Inlet Louver fully open; outlet louvre fully open, recycle louvre fully close.
- Set the fan speed to 50%. In the following steps, keep the fan speed constant.

- Set the preheat control to manual 40%. Wait until the temperatures are stabilized. Record the temperatures and the flow velocities.
- Increase the preheat control to manual 60% and record the temperatures and the flow velocities after the temperatures stabilize.

Test B

In test B, the air flows through a recirculation duct.

Close the Inlet Louvre and outlet Louvre, open Recycle Louvre fully. The system becomes an air recirculation system. Set the preheat control to manual 40%. Wait until the temperatures are stabilized. Record the temperatures and flow velocities.

Attachment:- thermal report.rar