Leakage Testing

System Requirement:

  1. TO ENSURE DESIGNED AIRFLOW RATE.
  2. TO ENSURE DESIGNED AIR CONDITIONS.
Both the Above Conditions are not achieved; Whenever the SCOPE OF AIR LEAKAGE comes in system.
Area Of Air Leakage:
  1. Supply Air.
  2. Return Air.


If Air Leaks From Supply Air Hollow Profile:
Condition A: Return Air through hollow profile.
If Leakage takes place in Supply Air, it is lost in the open space above roof ceiling, resulting to;

  1. Delay In Achieving The Defined Temperature Of Work Space.
  2. Longer Operation Of Control Valve & Chilling Circuit.
Ultimately Causing;
  • Discomfort At Work Place.
  • Energy Loss due Longer Operations equipments.


Condition B : Return Air Through Open Space.
If Leakage takes place in Supply Air, it is lost in the open space above roof ceiling interns become “ Return Air Component and resulting to;

  1. Higher Work space temperature with respect to the Set temperature;
    • As the Return Air (Mixture Of Leaked Supply + Return From Workspace) temperature reduces to temperature lower then Workspace temperature, resulting in Closing Of Chilling Circuit and reduction in fan speed.
    • Discomfort At Workspace
  2. Set Point is changed to avoid discomfort at workspace.
    • Longer Operation Of Control Valve & Chilling Circuit.
    • Delay In Achieving The Defined Temperature Of Work Space.
Ultimately causing;
  • Discomfort at Work Place.
  • Energy Loss due to longer Operations of equipments.


If Air Leaks In Return Air Hollow Profile:
If Leakage takes place in Return Air, the air from the open space above roof ceiling is mixed with the air returning from Workspace, resulting to;
1. Increasing the return Air Temperature.

  • Increased return air temperature will be higher then the Set point, the controls will never be closed even the workspace has reached to the desired conditions.
  • Discomfort at workspace due lower temperature.
  • Longer Operation Of Control Valve & Chilling Circuit.
Ultimately causing;
  • Discomfort at Work Place.
  • Energy Loss due Longer Operations equipments.


Conclusion:
If air leakage takes place, irrespective of from Supply Air Hollo Profile OR Return Air Hollow Profile, but it only leads to a MAJOR IMPACT;

  1. ENERGY LOSS.
  2. Discomfort @ Work Place

And the Energy LOSS can be stipulated as

CASE STUDY :

  • SYSTEM CAPACITY : 50 TR
  • AIR QUANTITY : 25000 CFM.
  • AIR LEAKAGE RATE: 5% -(1250 CFM )
  • Electrical Load : 1.3 KW per TR
  • Operating Period : 10 Hrs / Day
Lost TR = Air Leakage Rate X 4.45 X (hrm – hadp) /12000
hrm = 30.3 btu/ lb( Enthalpy Of the room )
hadp =22.6 btu / lb ( Enthalpy Of Apparatus )



CASE - A : Air Leakage From SUPPLY AIR and Return Air Through Hollo Profile:
AIR LEAKAGE RATE : 5 %
LOSS OF TR = 1250 x 4.45 x (30.3 – 22.6) / 12000
                         = 3.6 TR (7.1 % OF SYSTEM CAPACITY)
Loss Of Electrical Energy = 3.6 X 1.3 = 4.68 KW
Means Energy Loss = 4.68 Unit / Hr
                                      = 4.68 X 10 / Day = 46.8 Units / Day
Loss Per Day @ Rs 4.15 / Unit.
Stipulated Loss = Rs 46.8 X 4.15 / Day
                              = Rs 194.22 / Day
                              = Rs 194.22 X 25 / Month
                              = Rs 4,855.5 / Month
                              = Rs 4,855.5 X 12 / Year
                              = Rs 58,266 / year
Loss Of Life Cycle – 10 Years = Rs 58,266 X 10 / Life cycle
                                                       = Rs 582,266 / Life Cycle

CASE - B: Air Leakage From SUPPLY AIR and Return Air Through Open Space:
Since the total operation time is prolonged due to Unbalanced System Temperature, it does not lead to the loss of 100% TR as calculated above ( 3.6 TR – 7.1% ) , as the return air ( mix of Return Air + Leakage From Supply Air ) becomes cooler and trips the systemed as the return air has reached to set point.
But, the system takes additional Burdon of Electrical load, the moment we reduce set point for each degree of temperature change (e.g 30 to 29deg cent.)
The loss can be 30% of the loss in above case.
Loss Of Life Cycle – 10 Years = Rs 582,266 X 0.30/ Life Cycle
                                                       = Rs 174,679 / Life Cycle

CASE – C: If Air Leaks In Return Air Hollo Profile:
In this case the ambient air leaks in the return air and system operations are prolonged.
Loss Of Life Cycle – 10 Years = Rs 174,679 / Life Cycle