Week 1- Mixing Tee

To simulate the flow of air through mixing tee and to understand the effect of length of pipe and momentum ratio of velocity of mixing of air by using two different types of pipe short tee pipe and long tee pipe

in industrial process mixing is performed to allow heat and mass transfer to occur between one or more streams components or phases.we can always see in modern industries such example.

hot air flowing in the main pipe is mixed with cold air flowing through a tee . the standard devation of temp is computed to quantity the degree of mixing the velocity and temp fields are also computed the effects of the mesh size ,turbulance model on result were examined.

hot inlet temp=36 degree C

cold inlet temp=19 degree C

we have 2 case 

1=short tee with hot inlet velocity 3m/s.

    momentum ratio of 2,4.

2=long tee with hot inlet velocity 3m/s.

    momentum ratio of 2,4.

momentum ratio is defined as the ratio of velocity at the cold inlet to the velocity at the hot inlet

so........

veelocity at cold inlet=6 m/s

for second one

velocity at cold inlet =12 m/s

CASE MODEL

CASE -1 SHORT TEE

FOR INLET VELOCITY 3 m/s , MOMENTUM RATIO OF 2

MESH SIZE IS 0.002 m

mesh element metric that identifies the quality of mesh was employed and it can be seen that the elemets of the lowest quality are minimal here most of elements have quality range 0.7-1.hence the mesh is of acceptable quality.

MESH

RESIDUAL

STANDARD DEVEATION

AREA WEIGHT AVERAGE TEMPERATURE 

CONTOUR

TEMPERATURE

VELOCITY

FOR 

INITIAL VELOCITY 3 m/s AND MOMENTUM RATIO OF 4

MESH SIZE IS 0.002 m (IT REMAIN SAME AS ABOVE CASE)

RESIDUAL PLOT

STANDARD DEVEATION

TEMPERATURE PLOT

CONTOUR

TEMPERATURE

VELOCITY

CASE 2 - LONG TEE

FOR INLET VELOCITY OF 3 m/s AND MOMENTUM RATIO OF 2

MESH SIZE 0.002 m

mesh element metric that identifies the quality of mesh was employed and it can be seen that the elemets of the lowest quality are minimal here most of elements have quality range 0.7-1.hence the mesh is of acceptable quality.

MESH

RESIDUAL

STANDARD DEVEATION

AREA WEIGHT TEMPERATURE

AREA WEIGHTED VELOCITY

CONTOUR

TEMPERATURE

VELOCITY

FOR

INLET VELOCITY OF 3 m/s AND MOMENTUM RATIO OF 4

MESH SIZE IS 0.002 m (IT REMAIN SAME AS ABOVE CASE)

RESIDUAL

STANDARD DEVEATION

AREA WEIGHT TEMP

AREA WEIGHT VELOCITY

CONTOUR

TEMPERATURE

VELOCITY

CONCLUSION:

* As seen in the case 1a and case 1b the temperature at the outlet drops down significantly due to high velocity of cold air from the inlet this is possible due to the turbulent mixing at the tee joint between hot air because of the high velocity of cold air . which is not possible in case of low velocity cold air.

*the temperature contour at the outlet for short tee cases shows that some of the high temperature flows sips through without properly mixing with the flow whereas in the temp contour of long tee case the high temp flow throughly mixes with the rest of the flow.

*we can say that we should use long tee and high velocity inlet for application.