Direct Resistance Liquid Heater With Switched Electrode Power Control
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Solution Overview
Problem
Existing tankless liquid heating devices face issues with 'dry firing', thermal mass and resistance leading to overheating, deposit formation, and power supply fluctuations, which complicate temperature control and increase manufacturing costs.
Innovation Solution
A direct electrical resistance liquid heater with non-uniformly spaced electrodes and a switch matrix that adjusts power delivery based on electrode spacing and the number of active electrode pairs, using semiconductor switches to control current and minimize triac current requirements, thereby achieving flexible and efficient heating power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If resistance type electrical heating elements are used to heat liquid, then heating function is provided, but dry firing occurs causing element failure and safety hazards
Solution Approach 1:
The patent replaces the mechanical/physical resistance heating element with a direct electrical resistance heating method. Instead of using a separate heating element that can dry out and fail, the heating is achieved by passing current directly through the liquid between electrodes, eliminating the dry firing problem entirely since heating only occurs when liquid is present between the electrodes.
Solution Approach 2:
The patent introduces liquid itself as the heating medium and current path. The liquid serves as both the object to be heated and the medium through which current flows to generate heat. This eliminates the need for a separate heating element that could fail from dry operation, as the liquid presence is required for both heating and safe current conduction.
2Power
If resistance type electrical heating elements are used, then heating is achieved, but thermal mass and thermal resistance cause overheating and temperature control difficulties
Solution Approach 1:
The patent eliminates the thermal mass and thermal resistance problems by replacing the resistance heating element with direct electrical resistance heating of the liquid. Without a solid heating element having thermal mass, the system responds immediately to power changes, allowing precise temperature control. The heating occurs directly in the liquid where it is needed, eliminating thermal resistance barriers.
3Power
If resistance type electrical heating elements are used, then heating function is provided, but deposits form on element surface reducing efficiency and causing overheating
Solution Approach 1:
The patent replaces the solid resistance heating element surface where deposits accumulate with direct electrical resistance heating of the liquid bulk. By eliminating the solid-liquid interface, there is no surface for mineral deposits to form on. Heating occurs throughout the liquid volume between electrodes, preventing the deposit accumulation that plagues traditional heating elements.
4Temperature
If heating chamber volume is increased to manage latent heat, then overheating is prevented, but response time to demand changes increases
Solution Approach 1:
The patent eliminates the latent heat management problem by replacing the resistance heating element with direct electrical resistance heating. Without the thermal mass of a solid heating element storing latent heat, the system responds immediately to changes in liquid flow or power demand. The heating power can be rapidly adjusted by changing the electrical current between electrodes, providing fast response time while preventing overheating through precise electrical control.
5Reliability
If flow detection switch is used to prevent dry firing, then safety is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical flow detection switch with direct electrical resistance heating. The heating only occurs when liquid is present between the electrodes to conduct the current, providing inherent safety without requiring additional detection components. The electrical system itself provides the safety function by only allowing current flow (and thus heating) when liquid is present to complete the circuit.
6Reliability
If multiple temperature sensors and flow detectors are used to prevent overheating, then safety is improved, but manufacturing cost and device complexity increase significantly
Solution Approach 1:
The patent replaces multiple temperature sensors and flow detectors with direct electrical resistance heating. The inherent properties of the electrical system provide all necessary safety and control functions: current flow indicates liquid presence, electrical resistance provides heating control, and the system naturally prevents overheating by adjusting power based on liquid flow conditions. This eliminates the need for multiple separate sensing components and their associated complexity and cost.
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 provides a wide range of current and power control, minimizing power supply fluctuations, reducing overheating risks, and maintaining precise temperature control while reducing manufacturing costs and complexity.
Implementation Method 1
A liquid heater comprises a liquid inlet, a plurality of electrodes, the electrodes defining a plurality of channels, the spaces between the electrodes, through each of which liquid flows from the liquid inlet to the liquid outlet and a voltage is applied between electrodes
Data Source
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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.