1. Stewart Gillies The University of Queensland
MEASUREMENT OF AIRFLOW THROUGH REGULATORS AND REAL TIME INTEGRATED MONITORING
Stewart Gillies
The University of Queensland
North American / Ninth U.S. Mine Ventilation
Symposium, June 2002, Kingston Canada

2. Outline of Presentation
Introduction
Theory of Regulators
Field Tests of Regulators
UQEM Real Time Mine Ventilation System
Trials of the UQEM System
Conclusions
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

3. THEORY OF MINE REGULATORS
An artificial resistance (in the form of shock loss) or a large thin plate installed in a fluid conduit with an orifice.
When a difference in pressure exists between the two sides fluid flows as shown.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

4. Mathematical Modelling of Regulators
Irregularity in shape and symmetry and their positioning in roughly square or rectangular airways,
Construction of the opening - louvres, sliding door, window or curtain or placement of drop boards, and
Uncontrolled air leakage.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

5. C-Section (Drop Board Type) Regulator
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

6. An Example of Louvre Regulator
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

7. Derivation of Regulator Equation
Bernoulli’s equation can be applied to both sides of the orifice to calculate the velocity and hence the airflow quantity.
A correction must be made for the contraction of the jet at the vena contracta.
Velocity at the orifice is obtained with the following equation:
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

8. Derivation of Regulator Equation (cont.)
Airflow quantity through regulator is as follows.
where Cc is the coefficient of contraction (Ac/Ar)
Ar is orifice opening area
N is the ratio of the orifice and airway cross
sectional area, (Ar/A)
Ps is the differential pressure across regulator
 is air density
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

9. FIELD TESTS OF REGULATORS
To verify airflow behaviour through a drop board regulator.
Airflow quantity and pressure drop across the regulator were measured.
Airflow quantity through the regulators can also be calculated in theory from pressure measurements.
Results compared with measured values and the reasons for significant differences investigated.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

10. Comparison of measured and predicted Q
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

11. Reasons for the differences in Quantities
Error during measurement:
Small cross-sectional area
No-symmetrical condition and shape
Leakage occurs due to gaps or holes between boards, regulator frame and the airway walls.
Airflow quantity can be expressed as follows to account for leakage.
where Ql is the leakage quantity
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

12. Airflow Paths in Regulator
Regulators can be treated as a set of two parallel airways namely:
Regulator opening and
Leakage paths
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

13. Resistance of Regulator
The total resistance of regulator (Rt) can be modelled to consist of the regulator opening resistance (Ro) and the leakage path resistance (Rl).
The regulator opening resistance (Ro) can be calculated from the derived formula
Where A is the airway cross sectional area.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

14. Resistance of Regulator
When the regulator is in a fully closed condition, the air flows through the leakage path only with resistance Rl which can be empirically derived.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

15. Measured and Predicted Airflow Quantity
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

16. Regulator Resistance vs Opening Area
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

17. UQEM Regulator Characteristic Curves
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

18. Plan of UQ Experimental Mine Showing locations of doors and sensors
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

19. VENTSIM – Real Time Simulations
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

20. VENTSIM - Remote Station Database Interface
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

21. VENTSIM - Airway Edit Interface
Input of Remote Station Number
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

22. TRIALS OF THE UQEM SYSTEM
Trial Scenarios:
The inclined shaft door was open, and the regulator in 116’ level set on fully open.
The inclined shaft door was open, and the regulator was set 1/5 open with 12 boards
The inclined shaft door was open, and the regulator set on fully closed.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

23. Schematic of UQEM Ventilation System
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

24. Accuracy of Trial Results
Ventsim monitoring system predicts changes with reasonable accuracy although some differences in quantities were larger than 10%.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

25. Constraints of the System – Transition Time
The transient period in UQEM is short and therefore is not of great significance in interpreting the network system. However, in large-scale mines, the period can be up to 10 minutes or more.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

26. Updating of Ventilation Simulation Models
The trial demonstrated the importance and necessity of updating simulation models after changes.
The three scenarios were examined for how the network reacted to the input of a real time fixed quantity in terms of maintenance of model accuracy without a change to the regulator/door R value
Based on air quantity observations it is not necessary to make adjustment to the regulator/door R in the model as % error is no more than 5%.
However when comparing the predicted pressure drops across regulators, significant need for adjustment was found.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

27. North American / Ninth US Mine Ventilation Symposium
CONCLUSIONS
Efforts to mathematically model some operating mine regulators have been described.
Theoretical calculations to predict airflow quantity through regulators based on measured pressure drop are inadequate due to leakage, geometry etc.
It is necessary to quantify the resistance of the leakage path based on regulator opening area and then recalculate the total resistance of the regulators.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada

28. North American / Ninth US Mine Ventilation Symposium
CONCLUSIONS Cont.
An investigation was undertaken as to whether the Real Time Airflow Monitoring system can accurately detect changes in a ventilation network and identify constraints.
The system was able to detect changes and to predict the changes accurately.
Limitations caused by transient period delays have been examined.
It is important to update the simulation models based on real time data.
North American / Ninth US Mine Ventilation Symposium
June 2002, Kingston Canada