Usage of pouches with phase change materials (PCMs) to increase the thermal performance of a firefighter jacket - development and thermal behaviour evaluation of the multilayer system

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The growth in size and duration of wildland fires in recent years and the increasingly demand for high-performance protective clothing, has led Thermal Protective Clothing (TPC) research and development to seek solutions to minimise firefighter thermal load and skin burns. In this context, the present work was developed under the framework of the DIF-Jacket project (https://difjacketproject.fe.up.pt), with the main goal being the development of a new multilayer system with phase change materials (PCMs) to be used in a jacket of wildland firefighters and the subsequent development of an experimental procedure to evaluate its transient behaviour. For that purpose, a small-scale multilayer system was developed. It consisted of three layers: an outer textile layer, a pouch with PCMs (intermediate layer) and an inner textile layer. The pouch with PCMs was incorporated into the multilayer system to absorb the incoming heat from the environment, to increase the time that a firefighter can be exposed to it. Subsequently, an experimental set-up was then developed to evaluate the transient behaviour of the solution with PCMs, simulating the different phases to which a firefighter is exposed to (i.e., direct exposure to a radiative heat flux followed by a post-fire period). Therefore, the effect of some pouch-related parameters on the multilayer system thermal behaviour was studied, namely different geometries of the pouches (square and rectangular) and two types of PCMs. As main conclusions, similar tendencies were obtained with the square and rectangular pouches. The best temperature homogeneity of the PCM pouches was obtained with the macroencapsulated PCM. The incorporation of PCMs in the multilayer system significantly delays its heating. Further research must be conducted to delay even more the increase of temperature during exposure time. Nevertheless, the described set-up can be used to analyse several opposing requirements of a multilayer system with PCM pouches integrated, allowing the correlation of geometrical features, and properties of the system components (either textiles or PCM pouches) with the system transient temperature behaviour.