Multi-Channel Liquid Heater with Thin-Wire Temperature Feedback
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Solution Overview
Problem
Existing fluid heaters, such as direct electric resistance liquid heaters, suffer from thermal lag due to the thermal resistance and mass of temperature sensors, which delays temperature feedback and affects control precision.
Innovation Solution
A fluid heater design featuring a temperature-sensing wire extending across multiple channels, with a control circuit monitoring the wire's electrical resistance to control power application, and an exit structure with slots and collection chambers to prevent bubble attachment, allowing for instantaneous temperature measurement and improved control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature sensors with thermal mass are used, then temperature measurement is achieved, but thermal lag occurs delaying temperature feedback
Solution Approach 1:
The patent extracts the harmful thermal mass from the temperature sensing system by using a thin wire sensor instead of a bulky conventional sensor. The wire sensor has minimal thermal mass and thermal resistance, allowing it to rapidly equilibrate with the fluid temperature without significant delay, thus removing the thermal lag problem while maintaining measurement capability
Solution Approach 2:
The patent employs a thin wire as the temperature sensing element, which acts as a thin-film sensor. This thin-wire configuration minimizes thermal mass and thermal resistance, enabling rapid thermal response and eliminating the thermal lag associated with conventional thick-sensed temperature measurement devices
2Power
If multiple electrodes are connected to provide high current heating, then heating capacity is improved, but control precision deteriorates due to limited switching elements
Solution Approach 1:
The patent divides the heating system into multiple independently controllable electrode pairs, each with its own switching element. This segmentation allows the control system to selectively activate specific electrode pairs based on real-time temperature feedback from the wire sensor, enabling precise temperature control while maintaining the ability to deliver high total power when needed
Solution Approach 2:
The patent implements a feedback control system where the thin wire temperature sensor continuously monitors fluid temperature and feeds this information back to the control logic. The control logic uses this real-time temperature data to dynamically adjust which electrode pairs are activated, ensuring precise temperature control even at high power levels by preventing overshooting and allowing rapid response to temperature changes
3Measurement precision
If temperature sensors with thermal resistance are used, then temperature sensing is achieved, but control response time deteriorates
Solution Approach 1:
The patent removes the harmful thermal resistance from the sensing system by using a thin wire sensor configuration. This wire sensor has minimal thermal resistance between the sensing element and the fluid, allowing rapid heat transfer and instantaneous temperature detection, thus eliminating the response time delay inherent in conventional sensors with significant thermal resistance
Solution Approach 2:
The thin wire sensor acts as a thin-film temperature detection element that minimizes thermal resistance. The thin-wire configuration allows rapid thermal equilibrium with the surrounding fluid, enabling fast temperature sensing and rapid control response without the thermal resistance bottleneck present in conventional sensor designs
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 design minimizes thermal lag, enabling precise temperature control and efficient heating by accurately measuring the final fluid temperature before mixing, reducing overshooting and maintaining set-point temperatures effectively.
Implementation Method 1
a temperature-sensing wire extending across the plurality of channels... a control circuit connected to the energy application elements and the wire, the control circuit being arranged to monitor an electrical resistance of the wire
Implementation Method 2
electrical power is applied between electrodes immersed in the liquid to be heated so that current flows through the liquid itself and power is converted into heat due to the electrical resistance of the liquid itself
Data Source
AI summary
A liquid heater such as a direct electrical resistance liquid heater having multiple flow channels is provided with a temperature-sensing element in the form of a wire extending across numerous channels, preferably all of the channels, near the downstream ends of the channels. The resistance of the wire represents the average temperature of the liquid passing through all of the channels, and hence the temperature of the mixed liquid exiting from the heater. A bubble suppressing structure is provided in the vicinity of the wire.