Dual-Heater Fluid Temperature Control for Low-Volume Precision
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Solution Overview
Problem
Existing thermal control systems for fluids face challenges in maintaining precise temperature control, especially with low-volume fluids, due to uncertainties in thermal resistance between the fluid and temperature measuring devices, and the influence of the temperature sensing probe's heat capacity on the fluid's temperature.
Innovation Solution
A thermal control system utilizing a thermally conductive substrate with two heating elements and a temperature sensing probe, where the probe has a second heating element to maintain its own temperature, and a feedback controller adjusts the current to the heating elements to maintain the fluid's temperature within a preselected range, minimizing thermal mass discrepancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensing probe is used to measure fluid temperature, then temperature measurement is enabled, but the probe's heat capacity influences the fluid temperature and thermal resistance uncertainties arise
Solution Approach 1:
A thermally conductive substrate is introduced as an intermediary between the temperature sensing probe and the fluid. The substrate has known thermal properties and acts as a thermal mediator, allowing the probe to measure substrate temperature rather than directly contacting the fluid. This eliminates uncertainties about thermal resistance between the probe and fluid, as the substrate's thermal characteristics are well-defined.
Solution Approach 2:
The system is segmented into distinct thermal zones: the fluid, the thermally conductive substrate, and the temperature sensing probe. Each component has its own heating element or sensing capability, allowing independent temperature control and measurement. This segmentation enables precise control by managing thermal interactions between discrete components rather than treating the system as a uniform thermal mass.
2Temperature
If the temperature sensing probe has significant heat capacity, then the probe can maintain its own temperature, but it causes temperature discrepancies in low-volume fluids
Solution Approach 1:
The thermally conductive substrate serves as a thermal intermediary with controlled thermal mass. Instead of the probe directly interacting with the fluid, the substrate mediates the thermal exchange. The substrate's thermal properties are designed to minimize temperature discrepancies while providing a stable measurement interface for the probe.
Solution Approach 2:
The system changes the thermal parameters of the measurement interface by using a substrate with specific thermal conductivity and heat capacity values. By carefully selecting substrate material and geometry, the thermal response time and temperature stability are optimized to reduce measurement errors in low-volume fluid applications.
3Stability of the object's composition
If feedback control is used to maintain fluid temperature, then temperature stability is improved, but thermal resistance uncertainties reduce control precision
Solution Approach 1:
The thermally conductive substrate provides a well-defined thermal interface for feedback control. Since the substrate's thermal properties are known and stable, the feedback controller can accurately determine the relationship between heating power and temperature change. This eliminates uncertainties about thermal resistance in the control loop, enabling precise temperature regulation.
4Use of energy by moving object
If direct heating of the fluid is attempted, then heating efficiency is high, but temperature control precision is reduced due to thermal mass and heat distribution issues
Solution Approach 1:
The heating function is segmented and applied to different components: the fluid has its own heating element, and the substrate has its own heating element. This allows independent optimization of heating for each component. The substrate heating maintains a stable thermal platform, while fluid heating provides precise temperature adjustment, improving overall control precision without sacrificing efficiency.
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 system enables accurate temperature control of low-volume fluids to within ±0.5°C or ±0.2°C of a target temperature, reducing errors caused by thermal resistance and probe heat capacity, and is applicable in various analytical processes requiring precise temperature management.
Implementation Method 1
a first heating element in contact with said substrate for heating said fluid
Implementation Method 2
a temperature sensing probe configured to measure the temperature of said fluid with a second heating element for heating the probe
Implementation Method 3
a feedback controller for maintaining the temperature of the fluid as measured by the temperature sensing probe within a preselected range by controlling the current applied to the first and second heating elements
Data Source
AI summary
The invention relates to a thermal control system for controlling the temperature of a fluid. In particular, the invention relates to a control system having at least two heating elements, at least one of which is used for directly or indirectly heating a fluid, and at least one of which is used for heating a thermal probe used to determine the temperature of the fluid. The heating systems are controlled by at least one feedback controller.