Enthalpy exchanger for ground-coupled heat exchanger
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Solution Overview
Problem
Conventional climatic wells primarily focus on heat exchange between the ground and air, failing to control the humidity level of the air supplied to buildings, which is crucial for thermal comfort as the temperature-humidity couple governs the feeling of well-being.
Innovation Solution
An enthalpy exchanger for climatic wells featuring an air duct with a waterproof breathable membrane and a porous outer layer that traps a buffer volume of air, enabling both temperature and humidity regulation through energy and water vapor transfer via a temperature and humidity gradient between the ground and the air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional geothermal wells are used for heat exchange between ground and air, then temperature control is achieved, but humidity control is lost
Solution Approach 1:
The patent employs a porous outer layer that allows water vapor to pass through while maintaining structural integrity. This porous material enables the system to control humidity by allowing moisture exchange between the buffer air volume and the surrounding ground, while the hydrophobic membrane prevents liquid water penetration. This resolves the contradiction by adding humidity control capability to the existing temperature control function.
Solution Approach 2:
The invention combines multiple materials with different properties: a hydrophobic breathable membrane that blocks liquid water but allows vapor transmission, and a porous outer layer that facilitates moisture exchange. This composite structure enables simultaneous temperature control (through the closed-loop air duct) and humidity control (through vapor-permeable layers), resolving the limitation of conventional geothermal wells.
2Temperature
If air duct is made impermeable to maintain thermal exchange, then temperature control is improved, but water vapor exchange is prevented
Solution Approach 1:
The patent applies different permeability properties to different layers of the air duct structure. The inner hydrophobic membrane is impermeable to liquid water but permeable to water vapor, while the outer porous layer is permeable to both air and moisture. This local differentiation of material properties allows the system to maintain thermal exchange efficiency while enabling necessary water vapor exchange with the ground.
Solution Approach 2:
The invention uses a thin hydrophobic breathable membrane as the inner layer of the air duct. This thin film structure provides thermal insulation while allowing water vapor to pass through via diffusion, resolving the contradiction between maintaining thermal exchange (impermeability) and enabling moisture exchange (permeability).
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 exchanger significantly improves thermal comfort by controlling both temperature and humidity, enhancing energy transfer and water vapor exchange, thus addressing the limitations of conventional climatic wells.
Implementation Method 1
a breathable waterproof membrane disposed on an outer surface of the side wall of the air duct or on an inner surface of this side wall
Implementation Method 2
a porous outer layer, permeable to water vapor and designed to trap a buffer volume of air
Implementation Method 3
the heat exchanger according to the invention ensures sensible energy transfer, due to a temperature gradient between the ground and the airflow passing through the duct, via the buffer air volume in thermal equilibrium with the ground
Implementation Method 4
the heat exchanger also ensures water vapor transfer due to a gradient between the partial pressure of water vapor contained in the ground and the partial pressure of water vapor in the airflow, again via the buffer air volume contained in the porous outer layer and in hygroscopic equilibrium with the ground
Data Source
Figure 1~2
Figure 3~4
Figure 5a~6
AI summary
The invention concerns an enthalpy exchanger (10) for a ground-coupled heat exchanger, comprising: - an air conduit (24) comprising a side wall provided with openings; - a breathable membrane (26) arranged on an outer surface of the side wall of the air conduit or on an inner surface of said side wall; and - a porous outer layer (28), permeable to water vapour and designed to trap a buffer air volume, the porous outer layer covering the assembly formed by the side wall of the air conduit and the breathable membrane (26).