Cross-Flow Plate Core Assembly for Heat and Moisture Exchange
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Solution Overview
Problem
Current energy recovery ventilation (ERV) systems, particularly those with cross flow plate cores, face challenges in manufacturing complexity, material durability, and safety standards such as UL900 Class 2 and UL 94-V0, while requiring efficient heat and moisture transfer without air or particulate exchange between air flows.
Innovation Solution
A cross flow plate ERV core design featuring a unique flat spacer construction with laminated membranes, where left and right hand wafers form recessed steps for air stream direction and are made of low melt polyvinyl chloride to facilitate easy assembly and meet safety standards, with membranes that are non-porous and hydrophilic to prevent air leakage and withstand water exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional cross flow plate core design is used, then heat and moisture transfer is achieved, but manufacturing complexity increases and assembly becomes difficult
Solution Approach 1:
The core is divided into multiple discrete plates, each with integrated flow channels formed by raised portions. These plates are stacked in alternating orientation to create the complete heat exchange assembly, simplifying manufacturing and assembly while maintaining functional complexity.
Solution Approach 2:
Each plate serves multiple functions: it provides structural support, defines flow channels through its raised portions, acts as a mounting surface for membranes, and participates in heat and moisture transfer. This multi-functionality reduces the number of separate components needed.
2Reliability
If conventional membrane materials are used, then air streams are separated, but material durability and safety standard compliance become problematic
Solution Approach 1:
The membrane is constructed as a composite material combining a base layer with a fire-retardant coating or treatment. This composite structure maintains the membrane's primary function of separating air streams while providing the fire safety properties required to meet UL 900 Class 2 and UL 94-V0 standards.
Solution Approach 2:
The membrane material is treated or constructed to be fire-retardant, converting the potential harm of fire exposure into a beneficial safety feature. The material is designed to restrict air flow during fires, turning a harmful scenario into a controlled, safe condition that meets safety standards.
3Quantity of substance
If porous membranes are used for moisture transfer, then moisture exchange is enabled, but air leakage occurs
Solution Approach 1:
The membrane utilizes porous material structure with controlled pore sizes and distributions. The porosity is optimized to allow water vapor molecules to pass through via diffusion while maintaining a continuous phase structure that blocks larger air molecules, enabling selective moisture transfer without air leakage.
Solution Approach 2:
The membrane exhibits different properties at different scales: at the molecular level, it has porous characteristics that allow moisture diffusion, while at the macro level, it maintains structural integrity that prevents air leakage. This local quality differentiation enables simultaneous achievement of moisture transfer and air tightness.
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 design simplifies manufacturing, enhances durability, meets safety standards by restricting air flow during fires, and maintains effective heat and moisture transfer without air or particulate exchange, offering a cost-effective and operationally efficient ERV core.
Implementation Method 1
The surface area is the medium for the sensible heat transfer... Desiccants transfer moisture through the process of absorption which is primarily driven by the difference in the partial pressure of vapor within the opposing air-streams
Implementation Method 2
The surface area is the medium for the sensible heat transfer... As rotary wheel core 8 rotates between the supply and exhaust air streams 10, 12 it picks up heat energy and releases it into the colder air stream
Data Source
AI summary
This invention relates in general to air exchange systems and, in particular, to an improved energy recovery ventilator, a cross flow plate core associated therewith and a method of conditioning air for a building. In one aspect, the invention provides a cross flow plate core comprising: a left hand wafer comprising a left hand spacer with a first of a plurality of membranes bonded thereto, the left hand spacer comprising a plurality of parallel curvilinear rails which form channels for receiving a first stream of air; and a right hand wafer comprising a right hand spacer with a second of the plurality of membranes bonded thereto, the right hand spacer comprising a plurality of parallel curvilinear rails which form channels for receiving a second stream of air, wherein the left hand spacer of the left hand wafer is bonded to the top of the membrane of the right hand wafer.