Electrostatic Nozzle Height Control for Uniform Edible Coating
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Solution Overview
Problem
Existing electrostatic coating systems for fruits and vegetables face challenges with nozzle flow rate variations due to viscosity changes, thrust issues from droplet impact, fixed nozzle positions, and non-uniform coverage, especially when dealing with high viscosity and conductive liquids.
Innovation Solution
A system with adjustable nozzle height and orientation, twin-phase air-assisted and forced-liquid flow, and pressure sensing for thrust correction, ensuring uniform deposition and efficient use of viscous liquids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrostatic spraying is used to reduce coating material waste, then coating efficiency and uniformity are improved, but thrust from droplet impact causes material to drift away and creates uncoated spots
Solution Approach 1:
The nozzle height is made dynamically adjustable through a servo motor-driven mechanism. The system continuously monitors thrust force from droplet impact and automatically adjusts the nozzle-to-target distance in real-time, transforming a static nozzle position into a dynamic, adaptive configuration that maintains optimal coating uniformity despite varying thrust conditions
Solution Approach 2:
A thrust force sensing mechanism is integrated into the system to provide real-time feedback on droplet impact force. This feedback signal is fed to a controller that adjusts the servo motor to modify nozzle height, creating a closed-loop control system that automatically corrects coating uniformity deviations caused by thrust-induced material drift
2Manufacturing precision
If air-assisted nozzle is used to spray coating material, then coating coverage is improved, but variation in air pressure and material viscosity changes nozzle flow rate
Solution Approach 1:
The system employs a twin-phase flow mechanism that independently controls both air pressure and liquid coating material flow rate. By separately regulating these two parameters, the system can compensate for viscosity variations in the coating material while maintaining stable overall flow rate, allowing adaptation to different material properties without compromising coating coverage
3Device complexity
If fixed position nozzle is used for spraying, then device complexity is reduced, but coating uniformity and coverage are compromised
Solution Approach 1:
The nozzle positioning system transitions from a fixed, static configuration to a dynamic, adjustable mechanism driven by a servo motor. This enables the nozzle to automatically change its height position in response to real-time thrust force variations, maintaining optimal coating uniformity without requiring complex manual intervention or overly complicated mechanical structures
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
Achieves uniform and efficient coating with minimal material waste, enhancing shelf life and nutritional value by using servo-motors for precise nozzle control and pressure sensing to maintain free fall deposition.
Implementation Method 1
pressure sensing for thrust correction
Implementation Method 2
The process of electrostatic coating involves generating a high electric field within the spray nozzle at atomization and charging zone, which imparts charge to liquid jet passing through a charging ring electrode
Implementation Method 3
the charged coating material gets attracted effectively to the object to be coated
Implementation Method 4
twin-phase air-assisted and forced-liquid flow based nozzles
Data Source
AI summary
An electrostatic coating system including of a novel technique of height adjustment through pressure sensing and feedback mechanism in twin-phase air-assisted and forced-liquid flow based electrostatic nozzle(s). A variable height electrostatic edible coating system provides uniform and efficient coating to ensure shelf-life extension, improved nutritional value and enhanced sensory attribute.