Week 1- Mixing Tee

AIM

To set up steady-state simulations to compare the mixing effectiveness when hot inlet temperature is 36⁰C & the Cold inlet is at 19⁰C.

1. Case 1
   • Short mixing tee with a hot inlet velocity of 3m/s.
   • Momentum ratio of 2, 4.
2. Case 2
   • Long mixing tee with a hot inlet velocity of 3m/s.
   • Momentum ratio of 2, 4.

Introduction

Mixing Tees utilizes a specifically engineered internal geometry to efficiently mix two fluid or gase streams into one combined stream and obtain the desired result.

Applications

Air conditioners

Nuclear Power plants

Waste water treatment

Procedure

Pre-processing

Geometry is imported into the space claim

Firstly the geometry is updated from the solid model using volume extract to fluid path

Then the initial conditions and conditions are provided in the fluent where standard deviation and area weighted average of temperature is found usind iterative convergence.

Solving

Case:1(default mesh =1.0219e-002m)

Short tee (k `epsilon`)

Cold inlet Velocity - 6m/s

Post processing

Short Mixing tee(k`omega`)

Cold inlet velocity at 6m/s

Short Mixing tee(k`epsi`)

Cold inlet velocity at 12m/s

Case:2(default mesh = 1.3853e-002m)

Geometry

mesh

Long mixing tee(k`epsi`)

Cold Inlet velocity at 6m/s

Temperature across the plane

Velocity across the plane

Temperature across the axis

Velocity across the axis

Long mixing tee(k`epsi`)

Cold Inlet velocity at 12m/s

	Momentum ratio	Elements	Iterations to converge(approx)	Average Outlet temperature(approx)
Short tee	2	12613	325	30.25
	4	12613	173	27.5
Long tee	2	15549	373	30.3
	4	15549	190	27.5

Grid Independence test

Grid size=0.005

Grid size=0.004

Grid size=0.003

Grid independence table

Mesh size(m)	Area weighted Average temperature (c)	Standard deviation of temperature
5e-3	30.250	1.6286124
4e-3	30.353	1.615835
3e-3	30.351	1.628464

Inference

Since the standard deviation of K`epsi`is lower than k`omega` I proceeded the further cases using Kepsilon for better results and convergence.

The length of the mixing tee didn't affect the outlet as can be seen from the different momentum ratios.

As the velocity of the cold inlet increased the outlet temperature decreased significantly, therefore the momentum had a crucial role in effective temperature reduction.

Conclusion

Thus the set up steady-state simulations to compare the mixing effectiveness when hot inlet temperature is 36⁰C & the Cold inlet is at 19⁰C has simulated and proved.