Cetane Number Calculation via Combustion Delay Data Point
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Solution Overview
Problem
Existing methods for measuring the derived cetane number of liquid hydrocarbon samples, such as diesel fuel, are prone to high uncertainty due to the influence of fast and slow burning fuel components, and often require multiple cycles to achieve accurate results, necessitating more efficient and accurate calculation methods.
Innovation Solution
A method using a constant volume combustion chamber that selects a single data point from the combustion pressure profile representing the combustion delay to calculate the derived cetane number, reducing the impact of fast burning components and requiring fewer measurement cycles, with a combustion delay defined as the elapsed time to the midpoint of the net pressure increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple data points from combustion pressure curves are selected to calculate cetane number, then the quality of cetane number calculation is improved, but the measurement time and complexity increase
Solution Approach 1:
The invention extracts only the essential information needed for accurate cetane number calculation by selecting specific key data points (ignition delay point and combustion delay point) from the combustion pressure curve, rather than using multiple points. This extraction approach maintains calculation quality while reducing measurement time and complexity.
Solution Approach 2:
The combustion process is segmented into distinct phases (ignition delay period and combustion delay period), with each phase represented by a single characteristic data point. This segmentation allows accurate representation of the combustion process using minimal data points, resolving the contradiction between precision and time.
2Reliability
If multiple measurement cycles are repeated for each sample, then the uncertainty of derived cetane number is reduced, but the measurement efficiency decreases
Solution Approach 1:
The invention replaces the mechanical approach of repeating multiple measurement cycles with a computational approach that uses a refined calculation method based on key data points. This substitution reduces uncertainty through improved data selection and processing rather than through repetition, thereby maintaining reliability while improving productivity.
3Device complexity
If ignition delay data point is used to calculate cetane number, then the calculation is simplified, but the accuracy is reduced due to influence of fast burning components
Solution Approach 1:
The invention merges two complementary data points (ignition delay point and combustion delay point) to calculate the cetane number. This combination compensates for the limitations of using either point alone, particularly the influence of fast burning components on ignition delay measurements, thereby improving accuracy while maintaining reasonable calculation simplicity.
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
This approach provides a more accurate and efficient calculation of the cetane number compared to traditional methods, using a single data point from the combustion pressure profile, thereby reducing uncertainty and improving measurement efficiency.
Implementation Method 1
combusting the sample in the combustion chamber
Data Source
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AI summary
A method and apparatus for calculating the derived cetane number of a liquid hydrocarbon sample is disclosed. The method comprises combusting (19) the sample in a constant volume combustion chamber (45). The method comprises obtaining (23) a pressure versus time combustion profile (69) of the sample wherein the profile comprises a first region (81) and a second region (83), the first region (81) including the start of combustion, and the second region (83) relating to a later time than the first region. The method comprises selecting a single data point from the second region (83) of the combustion profile (69), said data point representing a combustion delay (CD) of the combustion profile; and calculating a derived cetane number for the sample using the time value associated with said single data point.