Advanced Flow Modelling CFD Group

Assignment-3

Objectives

Objectives of this assignment are:

1. Numerically simulate and analyse the heat transfer in a simple rectangular duct (aspect ratio 2) given in Figure 1.
3. Numerically explore how this heat exchanger performance can be improved
4. Develop competency in using FLUENT with conjugate heat transfer
5. Develop analysis skills across analytical and numerical methods of assessing heat exchanger performance

System to be modelled

The hot working fluid passes through the inner duct and cold fluid passes through the outer duct.

Figure 1: Schematic of the rectangular duct with dimensions.

The fluid flow properties for the hot and the cold fluid
Hot fluid mass flow rate 1 kg/s
Cold fluid mass flow rate 1 kg/s
Hot fluid temperature 150°C
Cold fluid temperature 30°C
Absolute pressure for hot fluid 101325 Pa
Absolute pressure for cold fluid 101325 Pa

Procedure and discussion points:

1. Create the computational geometry in DesignModeler/ Solidwroks/any CAD software with the mentioned dimensions. The aspect ratio of the rectangular duct is 2.

2. Build an appropriate mesh for the model and perform a grid refinement study.

3. Using the converged grid, check the iterative convergence.

4. Aluminium rectangular duct, Parallel flow with ½ hot and ½ cold

5. Aluminium rectangular duct, Parallel flow with ½ hot and ½ cold

6. Aluminium rectangular duct, Counter flow with ½ hot and ½ cold

7. Aluminium square duct, Counter flow with ½ hot and ½ cold

8. Draw the temperature contour at the cold outlet, hot outlet, and whole domain for all cases and discuss your results.

9. Plot the temperature profile along a selected line from inlet to outlet for all cases and discuss.

10. Plot the pressure contour and calculate the pressure drop at outlet of the domain.

11. Calculate the heat transfer coefficients.

12. Calculate the Nusselt number from the following correlation and discuss;

Nu_D = 0.023 Re_D^4/5 P_rⁿ

13. Connect your results with the existing literature.