Federal AviationAdministration
HEAT RELEASE RATE Updates
2014 June Materials MeetingSwitzerland
Materials Working Group
Michael Burns, FAA Tech Center
June, 2014
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
AGENDA
OSU
• Orifice Meter Discussion
(Static Pressure Taps)
CHAPTER HR UPDATE (HR2)
• Combined Supplement with Test method
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Heat Release Rate Test ApparatusJune 2014
• Protruding pressure taps (beyond the pipe inner wall) vs. surface pressure taps (flush with inner wall) may have a influence on pressure readings
• Could have an influence on total airflow
OSU:
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Supplemental material moved to Test Method as follows: Added BTU/ft2*sec units
Environmental Chamber – Added Radiation Door Assembly Figure
Radiation Source
• Power Supply Capacity – 12 kVA is sufficient
• Diamond-Shaped Mask Mounting – ½ inch diameter machine screw
(approximately 4 inches in length)
• Mask Position – Approximately 3 inches from the reflector plate
• Mask shaft-head or nut only on side facing specimen
(no threads extending towards specimen)
HR2: HEAT RELEASE TEST METHOD
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Thermopile Wiring
• Color coding differences - Chromel yellow/green; Alumel red/white
Upper Pilot Burner
• Caution Statement – Do not disturb burner position once set
• Flame Profile – To increase orange tip, reduce air from the mixture
Drill hole sizes added for:
• Upper Pilot Burner (#59 Drill)
• Air Distribution Plate (# 4 Drill)
• Second Stage Plate (# 28 Drill)
Drip Pan - Foil can be used to line the drip pan to facilitate cleaning after use
HR2: HEAT RELEASE TEST METHOD
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Heat Flux Gauge (HFG)
• Cooling Water Tubing – Rigid due to the high temperatures
• Cleaning – Gently wipe with soft, water-dampened sponge
• Caution Statement – Damage done to the coating during the cleaning process will affect the measurement accuracy of the sensor
Specimen Preparation
• Added recommended specimen foil wrapping technique
• Foil trimming – no scoring or incisions permitted
• Spring Plate Pressure – Recommended applying equal pressure to specimens of equal thickness by inserting the specimen retaining rod in the same holes for each specimen tested
HR2: HEAT RELEASE TEST METHOD
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Heat Flux Calibration Procedure (Corner)
• Caution Statement – Do not disturb burner position when rotating calibration fixture 90 degrees
• Added options for improving 4-corner uniformity:
Adjust power settings
Reposition globars - Hottest to coolest (bottom to top)
Move mask – Closer to or further from HFG
Move globars – Adjustment left or right
Reflector plate – Adjust slope (top and bottom)
Added Rounding, Accuracy and Units section
HR2: HEAT RELEASE TEST METHOD
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Calculation of Calibration Factor Kh – Added example assuming 60 mV baseline; 7 mV rise for each change in flow
HR2: HEAT RELEASE TEST METHOD
Kh = 0.5879∗ሺF1 − F0ሻሺV1 − V0ሻ kW/mV
If:
Baseline Flow
(SLPM)
High Flow
(SLPM) Baseline
(mV)
High Flow (mV) Δ Flow Δ mV Kh
1 2 60 67 1 7 0.0840 1 3 60 74 2 14 0.0840 1 4 60 81 3 21 0.0840
Then: Kh = (Kh (1 → 2) + Kh (1 → 3) + Kh (1 → 4)) / 3 kW/mV Average Kh = 0.0840 kW/mV Cv = 0.0% (< 5% therefore calibration is valid)
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Test Preparation
• Thermopile – Baseline mV observed daily as an indicator of developing problems
Variations in heat flux (heat flux gauge malfunction)
Defects in thermopile
Air leakage – Environmental chamber/lower plenum, exhaust stack or holding chamber door seal
Test Performance
• The use of an externally positioned mirror may assist in viewing upper pilot flames during testing
HR2: HEAT RELEASE TEST METHOD
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Heat Release Rate – Added example for calculating HRR (Peak HRR)
HR2: HEAT RELEASE TEST METHOD
Heat Release Rate = ሺTestmV − BaselinemVሻ ∗ ቀ Kh0.02323 m2ቁ kW/m2
ሺTestmV − BaselinemVሻ ∗ ቀ Kh0.02323 m2ቁ kW/m²
If: BaselinemV = 60 [Average thermopile millivolt reading at baseline (mV)] TestmV = 81 [Thermopile millivolt reading at any point during test (mV)] Kh = 0.0840 [Calibration factor (kW/mV)] Then: Heat Release Rate = ሺ81 − 60ሻ ∗ ቀ0.08400.02323ቁ kW/m² = ሺ21ሻ ∗ ሺ3.62ሻ kW/m² = 75.93 kW/m²
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Total Heat Release – Added example for calculating Total HR (2-Min. THR)
HR2: HEAT RELEASE TEST METHOD
σ ൫Test mV − Baseline mV൯ ∗ ൬ Kh0.02323 m2൰n−1t=0 x kW · min/m² If: n = 120 [Total number of data collection points in 2 minutes] x = 60 [Total number of data collection points in 1 minute] BaselinemV = 60 [Average thermopile millivolt reading at baseline (mV)] TestmV = 81 [Thermopile millivolt reading at any point during test (mV)] Kh = 0.0840 [Calibration factor (kW/mV)] Scan # Heat Release Rate T = 0 75.93 T = 1 75.93 . 75.93 . 75.93 . 75.93 T = 119 75.93 TOTAL 9111.0 Then: Total Heat Release (After 2 minutes) = (9111.0 / 60) kW · min/m² = 151.9 kW · min/m²
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Test Report
• Laboratory
• Fully identify the material tested
• Graphically report the heat release rate (kW/m2) as a function of time (in seconds) for each test
• Maximum heat release rate and time (in seconds) it occurs during each test
• Total heat released during the first 2 minutes of each test
• Radiant heat flux to the specimen
HR2: HEAT RELEASE TEST METHOD
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Test Report (Continued)
• Calibration factor Kh (kW/mV )
• Average mV baseline for each specimen tested
• Melting, sagging, delaminating, or other behavior that affected the exposed surface area or mode of burning that occurred and the time(s) at which such behavior occurred
• Total number of materials tested
• Total number of materials passed
HR2: HEAT RELEASE TEST METHOD
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
Requirements
• Quantity of Samples – Minimum of three samples must be tested and 80% or greater must pass
HR2: HEAT RELEASE TEST METHOD
Example
Total Samples Tested
Must Pass %
3 3 100%
4 4 100%
5 4 80%
6 5 83%
7 6 86%
8 7 88%
9 8 89%
10 8 80%
11 9 82%
12 10 83%
Federal AviationAdministration
Heat Release Rate Test ApparatusJune 2014
QUESTIONS?
What is full of holes, but can still hold a lot of water?Answer: Sponge