Membrane Module Counterflow Design for Hydrocarbon Capture

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Solution Overview

Problem

Existing evaporative emissions systems are ineffective in reducing diurnal breathing loss (DBL) of hydrocarbons from vehicle fuel tanks, especially at lower vapor concentrations, due to limitations in adsorbent materials and system design.

Innovation Solution

A modular filter assembly with counterflow design, featuring membranes and flow guides that create a counterflow across the membrane, enhancing separation efficiency by equalizing partial pressure gradients and increasing residence time of fuel vapors, thereby improving hydrocarbon capture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a canister packed with hydrocarbon adsorbent material is used to control evaporative emissions, then hydrocarbons are captured efficiently at high concentration, but the system becomes less effective when fuel vapors are present in lower quantity

Engineering Contradiction:

Improvehydrocarbon capture effectivenessVSAvoideffectiveness across different vapor concentrations

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The filter assembly is divided into multiple modules, each containing a frame with a membrane that creates separate feed and sweep channels. This segmentation allows independent optimization of each module's flow paths and membrane surfaces, enabling the system to handle varying vapor concentrations more effectively across different operating conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a single-channel adsorption approach to a dual-channel counterflow arrangement with membranes. The feed channel carries hydrocarbon-laden vapor while the sweep channel provides clean gas flow in the opposite direction, creating a two-dimensional flow configuration that enhances mass transfer and improves capture efficiency across a broader concentration range.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If conventional adsorbent capture systems are used, then the system structure is simple, but the system fails to effectively reduce diurnal breathing loss

Engineering Contradiction:

Improvesystem structureVSAvoiddiurnal breathing loss reduction

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The counterflow arrangement pre-conditioning the vapor stream as it passes through the membrane channels, equalizing partial pressure gradients before the main adsorption process. This preliminary action enhances the effectiveness of subsequent hydrocarbon capture, particularly during diurnal breathing loss conditions where vapor concentrations fluctuate.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The membrane structure acts as an intermediary element between the feed and sweep channels, facilitating controlled mass transfer of hydrocarbons while maintaining separate flow paths. This intermediary structure enables enhanced separation efficiency without requiring direct contact between the vapor stream and adsorbent materials, improving overall system performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If multiple adsorbent capture elements are added downstream to capture less concentrated hydrocarbons, then capture effectiveness improves, but device complexity increases

Engineering Contradiction:

Improvecapture effectiveness at low concentrationsVSAvoidnumber of capture elements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Each membrane module is designed to perform multiple functions simultaneously: separation of hydrocarbons, flow distribution, and concentration equalization. The counterflow arrangement within each module handles both high and low concentration vapors, eliminating the need for separate capture elements for different concentration ranges and reducing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 modular filter assembly effectively reduces hydrocarbon emissions by enhancing the separation efficiency of hydrocarbons, capturing a broader range of concentrations and improving overall emission control.

Implementation Method 1

membranes define at least one feed channel and at least one sweep channel in the filter assembly

Methodology Applied

Scientific EffectPermeation: Permeation

Implementation Method 2

enhancing separation efficiency by equalizing partial pressure gradients

Methodology Applied

Scientific EffectPartial pressure gradient equalization: Pressure Gradient

Implementation Method 3

the feed flow guide and the sweep flow guide may each define a curved channel therein, the respective curved channels being aligned in the filter assembly in such a way as to create a counterflow across the membrane

Methodology Applied

Scientific EffectCounterflow: Convection

Data Source

PatentUS11439948B2Membrane module for mitigating evaporative fuel emissions of automobiles

Publication Date: 2022.09.13 MAHLE INT GMBH

AI summary

A modular structure for a mitigating evaporative fuel emissions, such as for an automobile, is described. The structure may include a plurality of frames and membranes for flowing fuel vapor and reducing the emission of hydrocarbon therefrom. The structure may include flow guides that provide a meandering flow path for both the fuel vapor and a permeate. A flow guide providing parallel flow paths is also described.