Membrane Energy Exchanger Layout for Uniform Desiccant Flow
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Solution Overview
Problem
Conventional liquid-to-air membrane energy exchangers (LAMEEs) face challenges in achieving optimal energy transfer due to mal-distribution of fluid flows, which leads to sub-optimal performance, particularly in counter-flow configurations, and have not been designed to meet specified performance factors as per international standards.
Innovation Solution
The design incorporates a housing with panels forming desiccant and air channels, where the desiccant channels are configured to channel desiccant from the inlet to the outlet in either counter-flow or cross-flow directions, with specific geometric and operational parameters to ensure uniform flow distribution and enhanced heat and water vapor transfer, including predetermined exchanger aspect ratios, membrane deflection ranges, and salt solution concentration ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LAMEEs are used with standard geometric parameters, then the device complexity is reduced and ease of manufacture is improved, but the energy transfer effectiveness deteriorates due to mal-distribution of fluid flows
Solution Approach 1:
The patent applies parameter changes by optimizing specific geometric parameters of the LAMEE, including the aspect ratio of the energy exchange area (defined as height/length ratio of 0.1 to 0.5), membrane deflection ranges, and salt solution concentration ranges. These parameter modifications ensure uniform flow distribution of desiccant and air streams, directly improving energy transfer effectiveness while maintaining manufacturability through standardized design specifications
2Productivity
If counter-flow configuration is implemented to enhance energy transfer, then the energy transfer effectiveness is improved, but the device complexity increases due to requirements for headers on each end and tighter design specifications
Solution Approach 1:
The patent resolves the contradiction between counter-flow configuration and device complexity by specifying an optimized aspect ratio range (0.1 to 0.5) for the energy exchange area. This parameter change allows the counter-flow design to achieve high energy transfer effectiveness while simplifying the overall device structure and reducing the stringency of design specifications, making it more practical for implementation
3Productivity
If the exchanger aspect ratio is optimized to improve energy transfer, then the energy transfer effectiveness is improved, but the manufacturing precision requirements increase to maintain uniform flow distribution
Solution Approach 1:
The patent addresses the contradiction by defining a specific aspect ratio range (0.1 to 0.5) for the energy exchange area that balances performance and manufacturability. Within this range, the design achieves uniform flow distribution of desiccant and air streams without requiring excessive manufacturing precision, as the geometric parameters are selected to provide inherent flow uniformity
Solution Approach 2:
The patent employs composite construction by integrating multiple functional components including semi-permeable membranes, desiccant channels, air channels, and structured support elements into a unified panel assembly. This composite approach allows the system to achieve complex flow distribution patterns while using standardized, manufacturable components that do not require ultra-precise manufacturing
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
This approach results in improved energy transfer effectiveness, meeting the required performance factors and achieving steady-state standard test results, thereby enhancing the efficiency of the energy exchange system.
Implementation Method 1
The panels have a semi-permeable membrane forming an energy exchange area of the panel... facilitate heat and water vapor transfer through the semi-permeable membranes
Implementation Method 2
The desiccant channels are configured to channel the desiccant from the desiccant inlet to the desiccant outlet in at least one of a counter-flow or cross-flow direction with respect to the direction of the air stream to facilitate heat and water vapor transfer through the semi-permeable membranes
Implementation Method 3
energy in the form of heat and water vapor is transferred between the LAMEEs in the supply and exhaust ducts, which is interpreted as the transfer of sensible and latent energy between the exhaust air and the supply air
Data Source
AI summary
An energy exchanger is provided. The exchanger includes a housing having a front and a back. A plurality of panels forming desiccant channels extend from the front to the back of the housing. Air channels are formed between adjacent panels. The air channels are configured to direct an air stream in a direction from the front of the housing to the back of the housing. A desiccant inlet is provided in flow communication with the desiccant channels. A desiccant outlet is provided in flow communication with the desiccant channels. The desiccant channels are configured to channel desiccant from the desiccant inlet to the desiccant outlet in at least one of a counter-flow or cross-flow direction with respect to the direction of the air stream.