Mixing flow T-Joint

Challenge-1

A comparative steady-state analysis of a mixing T pipe (as shown in fig 1) is done.

Fig.1: T joint with hot and cold fluid (mixing) flow.

Three cases are analyzed as per the description below:

Case-1: Short length pipe with hot inlet air (x-axis) inlet velocity of 3m/s and cold air (y-axis) inlet velocity of 6m/s. The temperature and velocity distribution of the case is as follows:

Case 2: Long length pipe with hot inlet air (x-axis) inlet velocity of 3m/s and cold air (y-axis) inlet velocity of 6m/s. The temperature and velocity distribution of the case is as follows:

Case 3: Short length pipe with hot inlet air (x-axis) inlet velocity of 3m/s and cold air (y-axis) inlet velocity of 12m/s. The temperature and velocity distribution of the case is as follows:

The table of comparison is as follows:

	Cell Count (tetrahedral)	Average outlet temperature (deg. Celsius)	No. of iterations for convergence
Case-1	105912	20	147
Case-2	140609	20.05	between 175 to 200
Case-3	105912	17.5	between 200 to 250

The residual plots for all three cases are shown below:

Case:1

Case 2:

Case 3:

Conclusion:

From the above analysis, it was observed that using a longer length pipe (case 2), an increase in the overage outlet temperature was 0.05 deg-cel, which is 0.25% higher when compared to case 1. But on the other side by increasing the cold air inlet velocity (case 3), we can see a significant drop of 2.5 deg-cel in output air.

Thus it can be concluded that increasing the cold air velocity is a better option to increase the effectiveness of the given T joint.