Multi-Channel Liquid Heater With Resistance-Wire Temperature Sensing
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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 measurement and control, especially in tankless heating systems where instantaneous heating is required.
Innovation Solution
A fluid heater design featuring a channel structure with electrodes and a temperature-sensing wire extending across the channels, where the control circuit monitors the wire's electrical resistance to control power application, ensuring uniform heating and minimizing thermal lag by using a control circuit that adjusts current levels in a step-wise progression to maintain desired fluid temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor with thermal mass is used to measure fluid temperature, then the sensor can provide stable temperature readings, but thermal lag occurs delaying the temperature measurement and control response
Solution Approach 1:
The patent changes the physical parameters of the temperature sensor by using a wire with extremely low thermal mass and high surface area-to-volume ratio. This allows the sensor to reach thermal equilibrium with the fluid almost instantly, eliminating thermal lag while maintaining measurement stability through continuous thermal contact with the flowing fluid.
Solution Approach 2:
The patent replaces traditional contact式 temperature sensors with a resistance wire that functions both as a heating element and a temperature sensor. The wire's electrical resistance changes with temperature, providing immediate temperature feedback without the thermal mass problems of conventional sensors. This substitution of the sensing mechanism eliminates the trade-off between stability and responsiveness.
2Power
If multiple electrodes are used to provide sufficient heating capacity for maximum flow rate, then the heater can heat fluid to desired temperature at maximum demand, but device complexity increases
Solution Approach 1:
The patent makes the temperature sensor wire serve multiple functions: it acts as both the temperature sensing element and one of the heating electrodes. The wire is electrically connected to the power supply and positioned within the fluid flow path, allowing it to both heat the fluid locally and sense the temperature for control feedback, thereby reducing the total number of separate components needed.
Solution Approach 2:
The patent merges the temperature sensing function and the heating function into a single integrated component - the resistance wire. By combining these two functions into one element, the patent reduces device complexity while maintaining both heating capacity and temperature control capability. The wire serves dual purposes simultaneously.
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 provides instantaneous and precise temperature control by minimizing thermal lag, ensuring efficient heating of fluids as they flow through the system, with the temperature-sensing wire accurately reflecting the final fluid temperature without delay, thus enhancing the control system's responsiveness and accuracy.
Implementation Method 1
the control circuit being arranged to monitor an electrical resistance of the wire
Implementation Method 2
minimizing thermal lag by using a control circuit that adjusts current levels
Implementation Method 3
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.