Membrane Filter Coating for Sea Salt Deliquescence Control

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Solution Overview

Problem

The life of filters in gas supply devices is shortened due to a deliquescence phenomenon caused by sea salt particles, leading to increased pressure loss and potential water ingress, which can damage components like air pumps and valves in coastal or marine environments.

Innovation Solution

A fibrous coating layer is applied to the surface of membrane filters to absorb moisture by capillarity, preventing water film formation and reducing pressure loss, while pleated filters with large passage areas and vertical pleats allow water to drip off, thus extending filter life and preventing water ingress into the air pump and target space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a membrane filter is used in a coastal or marine environment, then filtration is achieved, but sea salt particles cause deliquescence phenomenon leading to shortened filter life and increased pressure loss

Engineering Contradiction:
Improvefilter lifeVSAvoiddeliquescence phenomenon
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The filter element is constructed as a composite structure combining a hydrophobic membrane filter base layer with a superhydrophilic coating layer. This composite material approach allows the filter to maintain its filtration function while resisting the deliquescence phenomenon caused by sea salt particles, thereby extending filter life in coastal and marine environments.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The superhydrophilic coating layer is designed with a porous structure that has strong capillary action. This porous material absorbs moisture quickly through capillary forces, preventing water film formation on the filter surface and reducing the harmful deliquescence effect of sea salt particles.

Inventive Principle:
Principle #31Porous materials

2Reliability

If sea salt particles attach to the filter, then filtration occurs, but deliquescence produces a water film increasing pressure loss

Engineering Contradiction:
Improvefiltration functionVSAvoidpressure loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The porous superhydrophilic coating layer rapidly absorbs moisture through capillary action, preventing the formation of continuous water films that would increase pressure loss. The porous structure allows moisture to be taken up quickly without creating flow resistance.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The surface properties of the filter are changed by applying a superhydrophilic coating that alters how moisture interacts with the filter surface. This parameter change in surface wettability prevents water film formation and the associated pressure loss increase.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If pressure loss becomes too large, then filtration is maintained, but water flows from upstream to downstream space reaching the air pump

Engineering Contradiction:
Improvefiltration barrierVSAvoidwater ingress
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The superhydrophilic porous coating layer absorbs moisture through capillary action before it can accumulate and form continuous water films. This prevents water from flowing through the filter from upstream to downstream spaces, protecting the air pump and other components.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The filter design converts the harmful effect of moisture and sea salt particles into a beneficial effect by using the superhydrophilic coating to rapidly absorb and eliminate moisture through capillary action. This prevents water ingress while maintaining filtration function.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 configuration effectively suppresses pressure loss and extends filter life, preventing water ingress and protecting the air pump and target space from damage, thereby maintaining the integrity and functionality of the gas supply system.

Implementation Method 1

a superhydrophilic coating layer having a strong capillary action is formed on the surface of the membrane filter

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

a gas supply device including a gas passage that supplies gas to a target space, a filter unit provided at an inlet of the gas passage

Methodology Applied
Scientific EffectHydrophobicity: Hydrophobe

Data Source

PatentEP3647694B1Gas supply device, device for controlling air inside vehicle, and refrigeration device for container
Publication Date: 2026.02.18 DAIKIN INDUSTRIES LTD
  • EP3647694B1 patent drawingFigure 1
  • EP3647694B1 patent drawingFigure 2
  • EP3647694B1 patent drawingFigure 3

AI summary

In a gas supply device (30) that supplies gas to a target space (S) through a filter unit (75), the filter unit is composed of a filter box and an air filter (76) housed in the filter box, and the air filter (76) is a filter having a filter substrate (77a, 77b) made of a membrane filter and a fibrous coating layer (78a, 78b) covering a surface of the filter substrate (77a, 77b) through which air is sucked.