Combined Membrane Dehumidification with Heat Exchangers Optimized Using CFD for High Efficiency HVAC Systems

Area of Science:

• Thermodynamics
• Chemical Engineering
• Mechanical Engineering

Background:

• Traditional air conditioning (AC) systems are energy-intensive due to dehumidification via condensation.
• Membrane-based AC systems offer an alternative by separating sensible and latent heat loads.
• These systems utilize specialized membranes for water vapor transport, excluding air.

Purpose of the Study:

• To develop a computational fluid dynamics (CFD) model for a novel active membrane-based energy exchanger (AMX).
• To predict heat and mass transfer performance and concentration polarization within the AMX.
• To investigate the AMX's performance across various operating conditions and identify optimal design parameters.

Main Methods:

• Development of a CFD model to simulate heat and mass transfer in the AMX.
• Validation of CFD heat transfer results against established empirical correlations.
• Parametric study of the AMX performance under diverse operating conditions.

Main Results:

• Optimal channel length identified between 0.6-0.8 m.
• Optimal coil diameter to channel height ratio determined to be approximately 0.5.
• Peak water vapor transport occurs near the turbulence transition (Reynolds number of 3000-5000).

Conclusions:

• The novel AMX design integrates membrane-based vapor removal and air cooling into a single unit.
• CFD modeling provides accurate predictions for AMX performance.
• Optimal design parameters and operating conditions were identified for efficient energy exchange.