Virtual Exhaust Temperature Sensing for Heater Power Modulation
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Solution Overview
Problem
Existing heating systems in fluid flow applications, such as vehicle exhaust systems, face challenges due to harsh environmental conditions like vibration and thermal cycling, leading to sensor instability and reduced heater efficiency, with physical sensors providing uncertain temperature readings and requiring large safety margins, resulting in lower watt density and increased costs.
Innovation Solution
A control system that modulates power to electric heaters based on various inputs including temperature readings, mass flow rate, and physical characteristics, allowing for continuous variable power output and predictive temperature modeling without physical sensors, thereby improving heater performance and reducing safety margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical sensors are used in harsh environments, then temperature measurement is achieved, but sensor stability and reliability deteriorate due to vibration and thermal cycling
Solution Approach 1:
The patent replaces physical mechanical sensors with a virtual sensing system that uses mathematical models and calculations to determine temperature. The system computes temperature based on power input, flow rate, and thermal characteristics rather than using physical sensors that are vulnerable to vibration and thermal cycling damage.
Solution Approach 2:
The patent introduces an intermediary computational model that acts as a bridge between measurable parameters (power, flow rate) and the desired temperature information. This virtual intermediary avoids direct exposure to harsh environmental conditions while still providing accurate temperature data.
2Reliability
If large safety margins are applied in heater design, then heater reliability improves, but heater size and cost increase
Solution Approach 1:
The patent implements a feedback control system that continuously monitors actual temperature conditions and adjusts heater power accordingly. This real-time feedback eliminates the need for large static safety margins by dynamically optimizing heater operation based on actual system state.
Solution Approach 2:
The patent transitions from static safety margins to dynamic power adjustment. The heater power is continuously modulated based on real-time temperature measurements and system conditions, allowing the system to operate efficiently without excessive safety margins while maintaining reliability.
3Ease of operation
If on/off control or PID control from external sensor is used, then temperature control is achieved, but response time deteriorates due to thermal resistances
Solution Approach 1:
The patent performs preliminary calculations of temperature based on power input and thermal models before actual temperature changes occur. This predictive approach allows the system to anticipate temperature changes and adjust control actions proactively, reducing response time delays.
Solution Approach 2:
The patent replaces physical temperature sensors that suffer from thermal resistance delays with a computational model that calculates temperature instantaneously from power and flow data, eliminating the thermal lag inherent in physical sensing.
4Reliability
If heaters are operated with safety factor to avoid failure, then heater reliability improves, but heat output efficiency deteriorates as heating elements operate below maximum capacity
Solution Approach 1:
The patent implements dynamic power adjustment that allows heaters to operate at optimal capacity based on real-time conditions. Instead of static safety factors limiting output, the system dynamically modulates power to match actual heating needs, maximizing efficiency while maintaining reliability through continuous monitoring and adjustment.
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 solution enables quicker response times, higher temperature operation, and reduced uncertainty in heater performance, leading to improved reliability and efficiency while minimizing the need for additional sensors and safety margins, thus enhancing the overall heating system's performance and reducing costs.
Implementation Method 1
at least one electric heater disposed in an exhaust fluid flow pathway
Data Source
AI summary
A control system includes an electric heater disposed within an exhaust fluid flow pathway, and a control device for receiving at least one input selected from the group consisting of temperature readings along the exhaust fluid flow pathway, alternator power/current/voltage, battery power/current/voltage/state of charge, IAT and EAT profiles, mass flow rate of an exhaust fluid flow, NH3 slip, TCR characteristics of the heater, alternator speed, engine speed, state of aging of an aftertreatment component, state of aging of engine, aging degradation characteristics, a dosing rate and a temperature of DEF, NH3 storage condition of aftertreatment system, an ambient temperature, and combinations thereof. The control device modulates power to the heater based on the at least one input such that the heater provides different power output as a function of the at least one input and a continuously variable power output during operation of the exhaust system.