Mixing efficiency

Aim: To determine the heat transfer in T- pipe and study the mixing efficiency in the tee joint at the outlet by varying the momentum ratio at (velocity at cold inlet / velocity at hot inlet) and length of the pipe

Step-up

Step 1	Cad model is imported into space claim
	Inside Tee-volume is extracted
Step 2	Meshing is done element size take 1e-3
	Name of the section is provided
Step 3	In setup: setting up physics-steady, pressure-based absolute is selected. setting up physics: energy and viscous (k-omega-SST/K-epsilon Realizable)
	setting up physics-zones- Boundary-Inlet_x ,Inlet_y velocity and temperature are provided
	Solving –Definitions-New-Surface reports-area-weighted-average and standard deviation is chosen
	Solving-Initialization-t zero is selected and run-calculation is done graphs are noted
Step 4	Result: contour plots of temperature and velocity is obtained

Step1:

Step2:

Step3:

Models-viscous

Zones-Boundaries

Case1: Short mixing tee with a hot inlet velocity of 3m/s and momentum ratio of 2

K-epsilon model:

Temperature and velocity simulation (epsilon)

K-omega model:

Temperature and velocity simulation (omega)

From this two models we can conclude that simulation of temperature and velocity are well captured in k-omega model at the walls but it takes larger cycle to converge

Case 1

1. Short Tee inlet hot velocity 3m/s along x axis, momentum ratio 2

Plots

Summary:

Temperature	30.5 Outlet temperature
Convergence	300-350cycles
Std-dev of temp	2-2.5
cells	578312

Temperature and Velocity Simulation

2. Short Tee inlet hot velocity 3m/s along x axis, momentum ratio 4

Plots

Summary:

Temperature	27.5 Outlet temperature
Convergence	225-275 cycles
Std-dev of temp	2-2.5
cells	578312

Temperature and Velocity Simulation

Case2

1. Inlet velocity 3m/s hot along x axis and momentum ratio is 2m/s

Summary:

Temperature	30.5Outlet temperature
Convergence	300-350
Std-dev of temp	1-2
cells	768454

Temperature and velocity simulation

2.Inlet velocity 3m/s hot along x axis and momentum ratio is 4m/s

Summary:

Temperature	27.5 Outlet temperature
Convergence	225-275 cycles
Std-dev of temp	1-2
cells	768454

Temperature and Velocity Simulation

Case Type	Cell Count	Averageoutlet Temperature	IterationFor convergence
Short Tee Momentum ratio 2	578312	30.5C	300-350cycle
Short Tee Momentum ratio 4	578312	27.5C	225-275 cycle
Long Tee Momentum ratio 2	768454	30.5C	300-350 cycle
Long Tee Momentum ratio 4	768454	27.5C	225-275cycle

Conclusion:

• When we campare bertween shorter tee and longer tee w.r.t momentum ratio(2,4)we get identical results (length of the pipe doesn't affect) .Higher the momentum ratio higher will be the mixing efficiencyand it requires low number of cycles to converge
• Overall shorter tee can be used instead of longer tee ,so that material cost can be reduced and optimum efficiency of mixing can be obtained