deliverable 1.3. : Proof of principle of cooling protective textiles
Authors: J. Eversdijk, N. Papen-Botterhuis, S. Wiegersma, A. Wypkema, TNO; Herman Reezigt, Capzo
Rationale
The goal is to develop or select a mixture of salts that absorp moisture in order to enhance the capability of evaporating sweat from the skin and at the same time minimize the absorption heat.
Methods
A literature search was used to select the salts that fulfill the criteria. Hereafter, the salts were evaluated in a lab setting using a hot plate and absorption measurements.
Results
Two prototypes of encapsulation have been developed based on the concept of using endothermic dissolving, hygroscopic salt.
The macro encapsulated proof of principle consists of a salt in a pouch of semi-permeable membrane. Regeneration is possible for at least 3 times and research shows that the amount of salt per m2 should be small for a high cooling effect in the first period of use.
Secondly, we have succeeded in producing micro encapsulated salts in a semi-permeable shell material.
The proof of principle produced with the resulting capsules showed a water vapour uptake of 1,02 gram water per gram powder in the first hour of use. Regeneration is possible for at least 3 times in normal room conditions.
Assuming a surface area at the inside of the garments of about 1.5 m2 we can accomodate about 300 gram of salt in a working suit.
It is planned to have an outside shield over the PPE to protect against heat for work with strong heat radiators (e.g. metal industry). This PCM Pad gives a high heat absorption arround the phase change of the PCM inside the pad.
Applicability
The results may be applied at the inside of protective garments (impermeable and maybe also semi-permeable) to enhance the human capacity to evaporate sweat. The micro-encapsulated sample will be used in the vest as developed by BelConfect.
Conclusion
We conclude that the selected salts look promising as a cooling device on the inside of protective clothing and work in a laboratory setting