Microscale Fire Calorimeter Flameless Premixed Combustion
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Solution Overview
Problem
Current methods for measuring combustion products of solid fuels at different stages of a fire are imprecise and unable to accurately determine the toxic potency of smoke generated during fires, especially in confined spaces, due to limitations in controlling fuel-to-oxygen ratios and measuring local combustion conditions in microscale combustion calorimeters.
Innovation Solution
A microscale fire calorimeter (MFC) device that uses milligram-sized solid fuel samples for flameless premixed combustion at precise fuel-to-oxygen ratios, generating combustion products at high temperatures and controlled conditions to measure the type, amount, and nature of combustion products, including toxic gases, over the full range of fire stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to measure combustion products of solid fuels, then measurement can be performed, but measurement precision is poor and local combustion conditions cannot be accurately determined
Solution Approach 1:
The apparatus segments the combustion measurement process into distinct functional zones: a reaction zone where fuel decomposes and combusts at controlled equivalence ratios, and a separate analysis zone where combustion products are measured. This segmentation allows precise local measurement of combustion products at defined Φ values without requiring complex full-scale fire test equipment.
Solution Approach 2:
The patent introduces an intermediary gas flow system that carries combustion products from the reaction zone to the analysis zone. This intermediary mechanism enables indirect measurement of local combustion conditions without directly inserting sensors into the high-temperature combustion zone, thereby maintaining measurement precision while avoiding excessive device complexity.
2Adaptability or versatility
If independent control of burning rate and oxygen flow rate is attempted to adjust fuel/oxygen ratio, then fuel/oxygen ratio can be adjusted, but local fuel/oxygen ratio in combustion zone remains unknown and equivalence ratio is only a global value
Solution Approach 1:
The patent changes the control parameter from independent control of burning rate and oxygen flow rate to direct control of equivalence ratio Φ through controlled oxygen injection. By defining Φ as a primary control parameter and adjusting oxygen flow accordingly, the system achieves both adaptability in fuel/oxygen ratio control and precise knowledge of local equivalence ratio in the combustion zone.
Solution Approach 2:
The system implements feedback control where the equivalence ratio Φ is calculated based on measured oxygen consumption and fuel decomposition rates, and this information is used to adjust oxygen injection rates. This feedback mechanism ensures that the local equivalence ratio in the combustion zone is precisely maintained at desired values while providing accurate measurement of combustion products.
3Quantity of substance
If microscale combustion calorimeter is used, then test size is reduced to milligram samples, but capability to accurately determine combustion products is still limited
Solution Approach 1:
The microscale apparatus segments the measurement process into controlled decomposition and separate combustion stages, with each stage optimized for minimal sample requirements. The reaction zone is designed to completely combust milligram-sized samples while the analysis zone provides sensitive detection of combustion products, achieving both microscale operation and accurate product determination.
Solution Approach 2:
The patent replaces mechanical full-scale fire test equipment with a microscale thermal and chemical analysis system. By substituting physical fire exposure with controlled thermal decomposition followed by controlled combustion in a precisely monitored environment, the system achieves accurate combustion product measurement using only milligram samples.
4Object-affected harmful factors
If complete combustion conditions are maintained, then non-toxic products are produced, but inability to simulate fuel-rich conditions limits fire safety research capability
Solution Approach 1:
The apparatus dynamically adjusts the equivalence ratio Φ by varying oxygen injection rates during the combustion process. This dynamic control enables simulation of both fuel-lean conditions (producing non-toxic complete combustion products) and fuel-rich conditions (producing toxic incomplete combustion products), providing versatility for fire safety research while maintaining control over harmful factors.
Solution Approach 2:
The system changes the combustion parameter equivalence ratio Φ from fixed stoichiometric values to variable values ranging from fuel-lean (Φ<1) to fuel-rich (Φ>1) conditions. This parameter change capability allows systematic study of how combustion product toxicity varies with oxygen availability, enhancing both fire safety research versatility and control over harmful factors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The MFC device enables accurate and convenient generation and determination of combustion products, allowing for the analysis of toxic potency and fire safety assessment by producing soot and gaseous products under controlled conditions, simulating fire-like conditions and providing data for toxicity models.
Implementation Method 1
a pyrolyzer for thermally decomposing a milligram-sized sample of a solid material under anaerobic conditions to generate fuel gases
Implementation Method 2
an ultra-high temperature combustion furnace for combusting the premixed volume of the generated fuel gases and oxygen at the range of flame temperatures in order to produce gaseous and solid combustion products
Data Source
AI summary
Embodiments described herein provide for the flameless premixed combustion of the pyrolysis gases of a milligram-sized sample of solid material in a microscale fire calorimeter (MFC) at high temperatures of combustion and under precisely controlled fuel-to-oxygen ratios. The microscale fire calorimeter (MFC) device and techniques set out herein provide for the generation of fuel gases from solids and the mixing of those fuel gases with oxygen under controlled conditions to obtain precise fuel/oxygen ratios during combustion. Combustion is conducted under flameless, premixed conditions in a rapid test that can generate soot and other products of incomplete combustion, which may then be analyzed to determine their type and nature. This allows for microscale, accurate, and convenient techniques for the generation and determination of the type and nature of combustion species produced over the full range of fire stages from early stage (over-ventilated) fires to late-stage (under-ventilated/high-toxicity) fires.