Direct Resistance Liquid Heater With Switched Electrode Control
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Solution Overview
Problem
Existing tankless liquid heating devices using resistance type electrical heating elements face issues such as 'dry firing', excessive thermal mass, deposit formation, and power supply fluctuations, leading to inefficiencies and safety concerns, while direct electrical resistance (DER) heaters struggle with accommodating varying liquid conductivities and flow rates.
Innovation Solution
A direct electrical resistance liquid heater with a plurality of thin, spaced electrodes and an adjustable switch matrix that controls power delivery based on electrode spacing and configuration, utilizing semiconductor switches and a thermal sensing element to manage current and temperature effectively, minimizing latent heat and preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If resistance type electrical heating elements are used, then heating function is provided, but dry firing occurs leading to overheating and safety issues
Solution Approach 1:
The patent replaces the mechanical/thermal resistance heating element system with an electrical field-based direct electrical resistance (DER) heating system. In this system, electrical current is passed directly through the liquid between two electrodes, eliminating the need for a physical heating element that can overheat. The heating occurs directly in the liquid through Joule heating, and the system includes flow detection mechanisms that prevent operation when liquid flow is insufficient, thereby preventing overheating and dry firing conditions.
2Power
If heating elements with substantial thermal mass are used, then heating capability is provided, but response time to flow rate changes is slow
Solution Approach 1:
The patent eliminates the thermal mass issue by replacing the solid heating element with a direct electrical resistance heating system where current passes through the liquid. This electrical field-based system has negligible thermal mass compared to traditional heating elements, allowing immediate response to changes in liquid flow rate. The heating power can be rapidly adjusted by controlling the electrical current, providing fast response times while maintaining adequate heating capability.
3Temperature
If larger heating chamber volume is used, then liquid overheating is prevented, but difficulty in responding to demand changes increases
Solution Approach 1:
The patent replaces the volume-based overheating prevention approach with an electrical control-based approach. The DER heating system uses electrical current control to precisely regulate heating power, combined with temperature sensing and feedback control. This allows the system to maintain liquid temperature within safe limits while using a compact heating chamber volume, and responds rapidly to demand changes through electrical control rather than relying on thermal mass or volume.
4Reliability
If flow detection switches are used to prevent dry firing, then safety is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical flow detection switches with a simpler electrical field-based system. The DER heater uses the liquid itself as the heating medium and electrical conductor, and incorporates flow detection through means such as measuring electrical conductivity changes or using simple level sensors that detect the presence of liquid between electrodes. This eliminates the need for complex mechanical switches that carry full heating current, reducing device complexity and cost while maintaining dry firing prevention capability.
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
The solution provides rapid and efficient heating with minimal response time to flow rate changes, reduces power supply fluctuations, and prevents overheating, achieving precise temperature control and cost-effectiveness by optimizing electrode spacing and switch configurations.
Implementation Method 1
the liquid being heated when a voltage is applied between electrodes
Data Source
AI summary
The Direct Electric Resistance Liquid Heater comprises a liquid heating chamber containing a plurality of electrodes. The electrodes are spaced apart to create a plurality of channels through which the liquid to be heated passes. The electrodes are each connected to a power supply by one or more switches. A controller controls the switches based upon data received from a temperature sensor, sensing the temperature of the liquid, and/or an electric current sensor, sensing the current utilized by the liquid heater. Selection of the number and spacing of the electrodes, and the number of switches, provides the controller with various current levels options to apply to the liquid to be heated. The current levels available due to the number and spacing of the electrodes and the number of switches, span the range from minimum current to maximum current such that the controller can incrementally increase or decrease the current applied to the liquid to be heated without disrupting other users of the same power source.