CFD ANALYSIS OF MIXING EFFICIENCY OF A MIXING TEE USING ANSYS FLUENT
OBJECTIVE
To setup steady state simulations to compare the mixing effectiveness of a mixing tee for three different cases
CASE: 1
CONDITIONS:
- short mixing tee
- hot air temperature=30°C
- cold air temperature=10°C
- momentum ratio =2
- hot air velocity =3m/s
- momentum ratio= cold air velocity/hot air velocity
RESULTS OF CASE 1:
TEMPERATURE DISTRIBUTION DIAGRAM:
VELOCITY DISTRIBUTION DIAGRAM:
AVERAGE OUTLET TEMPERATURE PLOT:
STANDARD DEVIATION OF TEMPERATURE PLOT:
OBSERVATIONS:
- The average standard deviation of outlet temperature is 2.3°C.
- The average outlet temperature is 23.5°C.
- Less Mixing effectiveness compared to case 2 and 3.
CASE: 2
CONDITIONS:
- Long mixing tee
- hot air temperature=30°C
- cold air temperature=10°C
- momentum ratio =2
- hot air velocity =3m/s
- momentum ratio= cold air velocity/hot air velocity
RESULTS OF CASE 2:
TEMPERATURE DISTRIBUTION DIAGRAM:
VELOCITY DISTRIBUTION DIAGRAM:
AVERAGE OUTLET TEMPERATURE PLOT:
STANDARD DEVIATION OF TEMPERATURE PLOT:
OBSERVATIONS:
- The average standard deviation of outlet temperature is 3.2°C.
- The average outlet temperature is 23.3°C.
- Slightly better Mixing effectiveness compared to case 1.
- Comparing with case 1, we can conclude that the mixing efficiency is not increasing by increasing the length of the tee.
- A varation in outlet temperature occurs due to higher standard deviation of temperature.
CASE: 3
CONDITIONS:
- short mixing tee
- hot air temperature=30°C
- cold air temperature=10°C
- momentum ratio =4
- hot air velocity =3m/s
- momentum ratio= cold air velocity/hot air velocity
RESULTS OF CASE 3:
TEMPERATURE DISTRIBUTION DIAGRAM:
VELOCITY DISTRIBUTION DIAGRAM:
AVERAGE OUTLET TEMPERATURE PLOT:
STANDARD DEVIATION OF TEMPERATURE PLOT:
OBSERVATIONS:
- The average standard deviation of outlet temperature is 2°C.
- The average outlet temperature is 20.2°C.
- Better Mixing effectiveness compared to case 1 and case2.
- Comparing with case 1 and case 2, we can conclude that the mixing efficiency is increasing by increasing the velocity of the cold inlet.
- Less varations in outlet temperature.
COMPARISON TABLE:
CONCLUSION:
- The mixing efficiency increases with increase in the velocity of cold inlet.
- Mixing efficiency can be slightly improved by increasing the length of the tee.
- Case 3 has better mixing efficiency than case 1 and case 2 because of the higher velocity of the cold inlet.
- Case 2 can provide better mixing efficiency if we increase the cold inlet velocity.