Week 4 - CHT Analysis on Exhaust port

AIM :

Conjugate Heat Transfer analysis on Exhaust Port

OBJECTIVES:

1. Give a brief description of why and where a CHT analysis is used.
2. Maintain the y+ value according to the turbulence model and justify the results.
3. Calculate the wall/surface heat transfer coefficient on the internal solid surface & show the velocity & temperature contours in appropriate areas.
4. How would you verify if the HTC predictions from the simulations are right? On what factors does the accuracy of the prediction depend on?

why and where a CHT analysis is used

CHT allow us to simulate the heat energy exchange between solid and fluid volumes at their interfaces.

CHT is used in the following industries

• Internal Combustion enngines
• Electromobility
• Aftertreatement
• Pumps and compressor
• electronic circuit cooling
• the design of thermal protection system for space vehicles
• thermal insulation of nuclear reactor
• turbine blade cooling
• solar panel design.

Solution Procedure and set ups

• Geometry editing

MESHING

PHYSICS SETUP

RESULTS

k-EPSILON STANDARD TURBULENT MODEL

Heat transfer coefficent of wall 18.954 w/mm^2 .K

Surface Heat transfer coefficent 21.367 W/m^2 .K

wall Y plus =20.603 (FOR K-EPSILON WALL Y+ >11)

CASE 2 K-W STANDARD MODEL

RESULTS

Heat transfer coefficent of wall 18.984 w/mm^2 .K

Surface Heat transfer coefficent 21.3807 W/m^2 .K

wall Y plus = 0 (FOR K-OMEGA WALL Y+ <1)

How would you verify if the HTC predictions from the simulations are right?

Nu= hL/k

h=Nu*k/L

Nu=0.027Re^0.8 *Pr^0.33 (for Turbulent flow)

On what factors does the accuracy of the prediction depend on?

• no.of elements in the meshing
• refinement of meshing
• inflation layer at the inlets and outlets
• proper selection of turbulent model