Latent heat fluxes through nano-engineered porous materials

Micro- and nano-scale truss architectures provide mechanical strength, light weight, and breatheability in polymer barriers. Liquid evaporation and transport of resulting vapor through truss voids (pores) cools surfaces covered by the barriers, suggesting the possibility for simultaneous protection of humans from mechanical and thermal stresses. Design of real systems employing this technique requires quantitative understanding of vapor transport within the truss pores and accompanying latent heat lift under ambient temperature and pressure. One application is desert Soldier protection. Need exists to clarify whether smaller pore diameters affect surface cooling and water vapor transport owing to fluid rarefaction or surface interactions. Contrasting previous studies where pressure within capillaries of fixed diameter was modulated, in this thesis Knudsen Number (Kn) was systematically varied by changing pore diameter at constant pressure (one atmosphere). Cooling efficacy was assessed for porous membranes with pore diameters ranging from 39 to 14,400 nm, varied in regular increments. Evaporative cooling experiments simulated combined daytime desert solar and metabolic thermal load on humans by heating an evaporation chamber partially filled with liquid water and capped with a porous membrane.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Traum, Matthew J. (Matthew Jason), 1977-

Advisor dc:contributor.advisor

• William A. Peters and Edwin J. Thomas.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/40361

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/40361