Virtual Heater Temperature Sensing for Harsh Fluid Flow Heating
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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 external sensors causing delays and potential component failures, and heaters being oversized to account for safety margins, resulting in lower watt density and increased cost.
Innovation Solution
A heating system with a microprocessor-controlled electric heater that determines temperature based on fluid flow and heater inputs, including physical characteristics like resistance wire diameter and heat transfer coefficients, allowing for precise power modulation without external sensors, using equations to calculate sheath and outlet temperatures, thereby reducing the need for physical sensors and improving response time and accuracy.
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 creates a virtual copy of the physical temperature sensor by using a thermal model that replicates sensor behavior through mathematical equations. This virtual sensor copies the temperature measurement function without the physical vulnerabilities, allowing the system to maintain measurement capability while avoiding the reliability issues of physical sensors in harsh environments
Solution Approach 2:
The patent replaces the mechanical/physical sensor system with a computational model-based system. Instead of using physical components that are susceptible to vibration and thermal cycling, the system uses mathematical models and calculations to determine temperature, substituting the physical measurement mechanism with a computational approach that is immune to environmental harshness
2Measurement precision
If external sensors are used for temperature control, then temperature monitoring is achieved, but response time deteriorates due to thermal resistances and delays
Solution Approach 1:
The patent performs preliminary calculations using a thermal model to predict temperature conditions before actual temperature changes occur. By using the model to anticipate temperature states based on known system parameters and heat transfer equations, the system obtains temperature information without the delay inherent in physical sensor response, effectively performing the measurement action in advance of when a physical sensor would detect the condition
3Reliability
If safety margins are increased in heater design, then heater reliability improves, but heater size and cost increase
Solution Approach 1:
The patent implements a feedback mechanism where the virtual sensor continuously monitors temperature and feeds this information back to the control system. This real-time feedback allows for precise control of heater operation, enabling the system to maintain reliability through active control rather than passive oversizing, thereby eliminating the need for excessive safety margins that would increase heater size
4Measurement precision
If physical sensors are installed in exhaust systems, then temperature detection is achieved, but system complexity and potential failure points increase
Solution Approach 1:
The patent extracts the temperature measurement function from the physical sensor hardware and relocates it to a virtual model implemented in software. By taking out the measurement capability from the physical domain and placing it in the computational domain, the system eliminates the need for physical sensor installation, mounting hardware, and associated complexity while maintaining the temperature detection function
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 more efficient and cost-effective heating by allowing higher watt density, reduced safety margins, and improved reliability, with quicker response times and diagnostic capabilities, eliminating the need for external sensors and enhancing system performance.
Implementation Method 1
a first convective heat transfer coefficient between the fluid and the heater sheath
Implementation Method 2
a second convective heat transfer coefficient between the heater element and the heater sheath
Implementation Method 3
at least one electric heater disposed within the fluid flow system
Data Source
AI summary
A heating system includes at least one electric heater disposed within a fluid flow system and a control device that is configured to determine a temperature of the at least one electric heater based on a model, at least one fluid flow system input, and at least one heater input. The at least one heater input includes at least one physical characteristic of the heating system, the at least one physical characteristic includes at least one of a resistance wire diameter, a heater insulation thickness, a heater sheath thickness, a conductivity, a specific heat and density of the material of the heater, an emissivity of the heater and the fluid flow pathway, and combinations thereof. The control device is configured to provide power to the at least one electric heater based on the temperature of the at least one electric heater.