Diesel Filter Bed Temperature Estimation via Dynamic Heat Radiation
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Solution Overview
Problem
Existing diesel engine exhaust gas after-treatment systems face challenges in accurately estimating and controlling the filter bed temperature during regeneration, which can lead to abnormal high temperatures damaging the catalyst and filter, and inefficient particulate combustion due to variations in exhaust gas flow rates.
Innovation Solution
A regeneration control system that detects temperatures upstream and downstream of the filter, calculates the hypothetical bed temperature using a first-order delay model, and adjusts the heat radiation coefficient based on the exhaust gas flow rate to estimate the filter bed temperature precisely, preventing overheating and ensuring efficient regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the filter bed temperature is estimated using simple inlet or outlet temperature measurements, then the measurement process is simple, but the temperature estimation precision is insufficient leading to inaccurate regeneration control
Solution Approach 1:
The filter bed temperature estimation is divided into multiple segments: inlet temperature measurement, outlet temperature measurement, heat radiation coefficient calculation, and iterative correction calculation. Each segment processes specific temperature data independently before integrating results to achieve comprehensive bed temperature estimation.
Solution Approach 2:
The system uses feedback by calculating the difference between actual outlet temperature and estimated outlet temperature, then using this difference to correct the bed temperature estimation. The correction amount is fed back to refine the bed temperature calculation, improving precision iteratively.
2Adaptability or versatility
If the exhaust gas flow rate varies significantly, then the engine can operate under different load conditions, but the heat radiation from the filter varies causing inaccurate temperature estimation
Solution Approach 1:
The heat radiation coefficient is made dynamic by calculating it based on the exhaust gas flow rate. As the flow rate varies with engine operating conditions, the heat radiation coefficient is updated accordingly to maintain accurate temperature estimation across different operating scenarios.
Solution Approach 2:
The system changes the parameter of heat radiation coefficient according to exhaust gas flow rate variations. By adjusting this parameter dynamically, the system adapts to different operating conditions while maintaining temperature estimation accuracy.
3Reliability
If the filter regeneration is performed without precise temperature control, then the regeneration process is simple, but abnormal high temperatures can damage the catalyst and filter
Solution Approach 1:
The regeneration control system uses feedback by continuously monitoring outlet temperature and comparing it with estimated bed temperature. When the temperature approaches dangerous levels, the system adjusts fuel injection or air supply to prevent overheating, protecting both catalyst and filter.
Solution Approach 2:
The system replaces direct mechanical temperature sensing throughout the filter bed with a distributed estimation model using inlet/outlet temperature sensors combined with heat radiation calculations. This substitution provides comprehensive temperature monitoring without requiring complex physical sensor networks.
4Measurement precision
If the heat radiation coefficient is not adjusted for exhaust gas flow rate variations, then the calculation is simple, but the temperature estimation becomes inaccurate during regeneration
Solution Approach 1:
The heat radiation coefficient is calculated in advance based on exhaust gas flow rate before the temperature estimation is performed. This preliminary calculation ensures that the correct coefficient is available for accurate temperature estimation during regeneration, avoiding the need for complex real-time adjustments.
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 allows for accurate estimation and control of the filter bed temperature, preventing catalyst deterioration and filter damage while ensuring complete particulate combustion, even with varying exhaust gas flow rates, thereby improving the regeneration process.
Implementation Method 1
calculates the heat radiation coefficient from the filter to the external atmosphere according to the exhaust gas flow rate
Implementation Method 2
the after-treatment device raises the filter temperature and combusts the particulates accumulated in the filter
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A diesel engine exhaust gas after-treatment device comprising a first temperature sensor that detects the temperature either upstream or downstream from a filter as a first temperature and detects the filter's other temperature as a second temperature, and a microcomputer. The microcomputer calculates the filter's hypothetical bed temperature from the temperature of either of the first and second temperatures; calculates the heat radiation coefficient from the filter to the external atmosphere according to the exhaust gas flow rat; and calculates the second temperature's estimated temperature based on the heat radiation coefficient and the above-described one first temperature. The filter's estimated bed temperature is found based on the above-described hypothetical bed temperature and the above-described detected second temperature and the above-described second temperature's estimated temperature. The microcomputer regenerates the filter based on the estimated bed temperature.