NIST 3 Megawatt Quantitative Heat Release Rate Facility.
NIST 3 Megawatt Quantitative Heat Release Rate Facility.
(1458 K)
Bryant, R. A.; Ohlemiller, T. J.; Johnsson, E. L.;
Hamins, A.; Grove, B. S.; Guthrie, W. F.; Maranghides,
A.; Mulholland, G. W.
NIST SP 1007; 81 p. December 2003.
Keywords:
heat release rate; oxygen consumption calorimetry;
response time; uncertainty
Abstract:
The 3 Megawatt Heat Release Rate Facility was developed
at NIST as a first step toward having broad capabilities
for making quantitative large scale fire measurements.
Such capabilities will be used at NIST to validate fire
models and to develop sub-grid models. It will also
serve to provide a data base for studying a broader
range of fire phenomena, and to address issues related
to material acceptance and fire codes. An equally
important objective is to provide templates for use by
other laboratories including commercial testing
facilities to improve the quality of their data. The
facility is capable of measuring heat release rates in
the range of 0.10 to 3.0 MW including brief peaks as
high as 5 MW. The expanded uncertainty (95% confidence
interval) is 11% of the heat release rate for fire sizes
larger than 400 kW. The response time of the system is
such that it can accurately resolve dynamic heat release
rate events of 15 seconds or more. Key features of the
design and fabrication of these systems are presented
including detailed schematics and the rationale for the
choices made. Transient response and gas dispersion in
the sampling system, sampling from a non-uniform duct
flow, and making accurate total flow measurements using
bi-directional probes are dealt with in the design. The
design of a natural gas burner for measurement
confirmation, including the special flow control and
flow metering capabilities, is presented. The general
design of the software allowing the display of nearly
real-time heat release rates with corrections for
sampling/instrumental delay and response times is also
described.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899