Modular Filter-In-Filter Cartridge for Fuel Water Separation
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Solution Overview
Problem
Traditional fuel-water separators are ineffective in removing small water droplets from ultra low sulfur diesel (ULSD) fuel and biodiesel due to larger pore sizes, leading to high pressure drop and insufficient water removal, especially in modern high-pressure common rail fuel systems, and are adversely affected by surfactants that lower interfacial tension and stabilize emulsions.
Innovation Solution
A modular filter-in-filter cartridge system comprising an outer pleated filter element and an inner non-pleated filter element, both made of thermoplastic materials, with specific pore sizes and fiber diameters designed to coalesce and separate water from hydrocarbon fuels, utilizing nanofiber layers and additional media layers to enhance coalescence efficiency and reduce pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional fuel-water separators with larger pore sizes are used, then pressure drop is reduced, but water removal efficiency deteriorates
Solution Approach 1:
The filter element is divided into multiple zones with different pore sizes: a first zone with larger pore sizes for initial filtration and water separation, and a second zone with smaller pore sizes for fine particulate filtration. This segmentation allows each zone to perform its specific function optimally without compromising overall system performance.
Solution Approach 2:
Different regions of the filter element have different local properties - the first zone has larger pores suitable for water coalescence and separation, while the second zone has smaller pores for particulate removal. This local quality variation enables the filter to handle different separation tasks in different areas simultaneously.
2Reliability
If smaller pore sizes are used to remove smaller water droplets, then water removal efficiency is improved, but pressure drop increases
Solution Approach 1:
The filter media is segmented into zones with progressively smaller pore sizes, allowing water droplets to be captured and coalesced in the larger pore zones before passing to finer zones for final separation, reducing the pressure drop compared to using uniformly small pores throughout.
Solution Approach 2:
The filter element incorporates three-dimensional pleated structures that increase the effective filtration surface area without increasing the axial length, allowing more filtration media to be packed into the available space while maintaining lower pressure drop characteristics.
3Reliability
If thicker filter media is used to enhance coalescence, then water removal efficiency is improved, but device complexity and size increase
Solution Approach 1:
The pleated configuration of the filter media increases the effective surface area and thickness of the filtration layer without proportionally increasing the axial length of the filter element, enabling enhanced coalescence efficiency within a compact size.
Solution Approach 2:
The filter element is designed with a nested structure where the pleated media is contained within a cylindrical housing with end caps, creating a compact integrated assembly that maximizes the use of available space while maintaining structural integrity.
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 efficiency in removing at least 93% of water from hydrocarbon fuels with minimal pressure drop and is resistant to surfactants, providing improved coalescence and separation performance in modern fuel systems.
Implementation Method 1
the media should have a surface energy greater than water in order to improve coalescer performance
Implementation Method 2
ultra low sulfur diesel (ULSD) fuel and biodiesel tend to have lower interfacial tensions (IFT), and therefore have smaller droplet size and more stable emulsions
Implementation Method 3
U.S. Pat. No. 4,081,373 discloses that coalescing media should be hydrophobic in order to remove water from fuel
Data Source
AI summary
Disclosed are modular filter-in-filter elements, namely an outer filter element and an inner filter element which may be assembled to form a filter cartridge for use in separation methods and systems. The outer filter element typically functions as a coalescing element and the inner element typically functions as a particulate filter element. The disclosed filter cartridges may be structured for separating water from a hydrocarbon-based liquid fuel as the fuel moves through the cartridge from outside to inside.