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Vacuum membrane dehumidification for electronics and high-efficiency air conditioning.

Author(s) : WU S.

Type of monograph: Master thesis

Summary

Dehumidification is pivotal in contemporary society, especially for electronics and buildings. Electronic devices face operational risks due to moisture-related failures, with substantial economic impacts estimated between $0.5 and $5 billion annually from electrostatic discharge (ESD) alone. Around 20% of building electricity consumption is cooling-related, of which more than 50% is usually latent load (removing water in the air). Innovative water vapor-selective membranes offer a distinctive solution for managing latent loads, as the ideal energy requirement for separating water vapor with a membrane is much smaller than the energy required for condensing it out of the air. Vacuum membrane dehumidification (VMD) is a promising alternative dehumidification technology for its quick operation and excellent energy savings. It applies selective membranes that enable water vapor to pass but not air.
This work consists of investigating VMD systems in electronics and building dehumidification. Electronic devices, essential in modern society, face operational risks due to moisture-related failures, with substantial economic impacts estimated between $0.5 and $5 billion annually from electrostatic discharge (ESD) alone. Lack of relative humidity (RH) control is a leading cause of failure, with the critical RH threshold for clean electronic surfaces recognized at 60%. This study investigates Vacuum Membrane Dehumidification (VMD) as a novel dehumidification strategy, targeting the efficient control of RH within small electronic enclosures to mitigate moisture-induced failures. This work involves constructing a thermodynamic model for the VMD system, followed by the assembly of a physical prototype for empirical validation. The model integrates enclosure dimensions and membrane properties to simulate performance across various environmental conditions. Experimental validation of the model is conducted under controlled conditions to establish its accuracy. The results reveal that the VMD system achieves effective moisture removal with a Humidity Removal Fraction (HRF) of 30-65%, significantly influenced by the ambient RH and vacuum pressures. Energy optimization studies compare the VMD with conventional methods, illustrating superior performance in energy efficiency. The VMD system not only demonstrates its efficacy in RH management but also suggests a potential reduction in the operational energy requirements of electronic devices. This work establishes a foundation for membrane-based dehumidification technologies in electronic enclosure design, with broad applications across various sectors dependent on electronic systems.
The building dehumidification work is the first to integrate dual-module VMD with a residential vapor compression system, exploring recirculation air’s impact on energy consumption. Two membrane module designs (flat-sheet and hollow fiber membrane) are explored. A parametric study is conducted to assess the energy consumption of systems at different operation conditions. A practical way to size the membrane based on design conditions like AHRI 340/360 is introduced. Up to 17% of energy savings could be achieved in extremely humid weather conditions.

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Pages: 81 p.

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