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  • Full name: Multi-functional light-weight WALL panel based on ADAPTive Insulation and nanomaterials for energy efficient buildings
  • Acronym: ADAPTIWALL
  • Duration: 48 months
  • Start date: 1 September 2013
  • Total budget: 5.05 M€
  • EC Funding: 3.35 M€

Characterization of a new concept of separator for a total heat exchanger in an Energy Recovery Ventilation system.

From a concept patented in 2012 by CEA, prototypes of separator has been manufactured and characterized in the frame of the ADAPTIWALL EU project. A specific mockup and an experimental loop were set up in this way.

  • In a counter flow configuration, this appliance is a stacking of moisture selective membrane and separator. These ones have to:
  • Assure the mechanical supporting of a thin and flexible membrane.
  • Define air flux channel, and target the good equilibrium between global transfer enhancement and pressure drop generation.

Preserve the mass transfer area by optimizing the contact between separators and membrane.The technology is a honeycomb web where the faces are perpendicular to the sense of the flow, but opening are managed in this same faces. The prototypes were built in polymer by 3D additive method. A shift in the geometry position is managed between two successive separators from one side to the other of the membrane, in the way to increase the mechanical supporting. Unopen faces assure the rigidness of the separator and play a role of flow disturbers in the way to optimize convective effect. Three dimensional pitches of the web are prototyped and compared to a state of the art technology, straight rectangular channels.

THEX membrane

In order to characterize the mass-thermo-hydraulic behavior of lab scale component prototypes of these channel structures, an experimental test campaign is performed. Comparison of experimental data and numerical modelling results help to consolidate the design of THEX and improve prediction of performances.

The pictures hereafter illustrate the experimental test rig. This system allows managing two air fluxes with a controlled flow rate. One is dry and at ambient temperature, the other one is hot and humid. (A humidification column is used plus several heaters).

 

THEX test setup

A mock-up is used for each test, in the way to characterize in the same counter flow configuration and reproducible and controlled air flow conditions. This mock-up, displayed below, represents a stacking of two separators and one membrane where the two air flux can flow with perfect air tightness.

Measures of temperature, pressure, air flow rate and humidity, allow calculating mass, thermal and energy balance.

 THEX mock up

 The graph below shows a comparison for each technology, of the sensible, latent and enthalpy efficiency. This comparison is done in the same condition of air flows (inlets temperature, flowrate and humidity) and for the same global dimension of separator and for a same membrane.

 THEX experimental comparison

The presented results and the ones for the other membrane characterized show a good improvement of global transfer efficiencies in comparison of the state of the art technology. Open honeycomb web separator with a pitch of 20 and 30mm are the configuration where the higher efficiencies are found. The one with the pitch of 10mm is in fact mechanically too weak to be selected for the demonstrator.  Finally, regarding mechanical aspect, the Open honeycomb web separator with a pitch of 30mm is selected to be implemented in the demonstrator. An increase of performance between 10% and 15% can be expected with the new technology comparing to the state of the art technology.

Furthermore, pressure drop estimation of the technology was not achieved due to an unappropriated configuration of the air uptake orifice of the differential pressure sensors at the level of mockup distributors (a difference of static pressure is measured instead of a total pressure difference).

On the demonstrator, Pitot tube sensors will be set up to achieve a more precise measurement (total pressure is withdrawn).