Capacitive Deionization Resonant Frequency Control
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Solution Overview
Problem
Conventional desalination methods, such as reverse osmosis and thermal processes, are energy-inefficient for brackish water desalination, and existing capacitive deionization (CDI) systems lack optimal operational efficiency due to limited exploration of control waveform shapes and variable flow rates, leading to suboptimal performance in salt removal and energy consumption.
Innovation Solution
A capacitive deionization system utilizing a sinusoidal forcing signal with a Fourier series representation, where the fundamental frequency is within a factor of 10 of the resonant frequency, optimized to achieve balanced salt removal and energy efficiency by controlling the electrical forcing signal between electrodes, allowing for sinusoidal voltage or current operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional constant current or constant voltage operation modes are used in CDI systems, then operational simplicity is maintained, but salt removal efficiency and energy consumption are suboptimal
Solution Approach 1:
The patent applies dynamics by transitioning from static constant current or constant voltage operation to dynamic sinusoidal forcing function operation. The sinusoidal signal continuously varies the electrical forcing applied to the CDI cell, enabling the system to operate at resonant frequencies that maximize salt removal efficiency while minimizing energy consumption. This dynamic approach allows the system to adapt its operating conditions in real-time to achieve optimal performance.
Solution Approach 2:
The patent implements periodic action through the use of sinusoidal forcing functions with specific frequencies and duty cycles. By applying periodic electrical forcing at resonant frequencies, the system achieves enhanced salt removal during charging phases and efficient regeneration during discharging phases. The periodic nature of the sinusoidal signal creates optimal conditions for ion adsorption and desorption cycles, improving overall system efficiency compared to continuous constant mode operation.
2Adaptability or versatility
If arbitrary periodic forcing functions are explored for CDI operation, then operational flexibility and performance optimization are improved, but system complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying key operational parameters including sinusoidal frequency, amplitude, and duty cycle to optimize CDI performance. The system explores different frequency ranges to identify resonant frequencies specific to each CDI cell configuration, and adjusts amplitude and duty cycle parameters to balance salt removal efficiency with energy consumption. These controlled parameter variations enable performance optimization without requiring complex system architecture changes.
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 system achieves high salt removal efficiency and low energy consumption by operating at resonant frequencies, demonstrating superior performance compared to conventional constant current or voltage methods, and generalizing resonant frequency operation for various waveform shapes.
Implementation Method 1
CDI involves coupling of multiple time scales and phenomena. CDI salt removal dynamics are determined by the interplay between electrical charging/discharging
Implementation Method 2
CDI salt removal dynamics are determined by the interplay between electrical charging/discharging, which depends on cell ionic and electrical resistances and capacitance
Implementation Method 3
CDI is inherently periodic because electrical charging and discharging forcing functions result in periodic salt removal and regeneration phases
Data Source
AI summary
The present disclosure relates to a capacitive deionization (CDI) system for desalinating salt water. The system may have a capacitor formed by spaced apart first and second electrodes, which enable a fluid flow containing salt water to pass either between them or through them. An input electrical power source is configured to generate an electrical forcing signal between the two electrodes. The electrical forcing signal represents a periodic signal including at least one of voltage or current, and which can be represented as a Fourier series. One component of the Fourier series is a constant, and a second component of the Fourier series is a sinusoidal wave of non-zero frequency which has the highest amplitude of the additive components of the Fourier series. The amplitude of the sinusoidal wave component is between 0.85 and 1.25 times the amplitude of the periodic signal.