Results of a Dynamic Liquid Cooling Garment Simulation in V-SUIT
Olthoff, Claas T.
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The dynamic portable life support system (PLSS) simulation software Virtual Space Suit (V-SUIT) has been under development at the Technische Universität München since 2011 as a spin-off from the Virtual Habitat (V-HAB). The MATLABTM-based V-SUIT software dynamically simulates space suit portable life support systems and their interaction with a detailed human model, as well as the external environment of the space suit. This paper presents results from the simulation model of a liquid cooling garment (LCG) as a sub module of the V-SUIT simulation. In this first step, only the conductive heat transfer was incorporated into the model. A literature review and study of the thermodynamic processes, main parameters and driving factors involved in the heat transfer between the human skin and the coolant fluid was performed. Results showed, that current models of the human to LCG heat transfer rely on values for several heat transfer coefficients and conductivities that are hard to determine experimentally and are therefore mostly educated guesses or reverse engineered. To create a deeper understanding of the end-to-end process, a flexible, modular model of a generic LCG was created within the V-SUIT framework. Simulations were run for different LCG configurations (number, length and diameter of tubes in the garment, flow rate, and others) and the results are compared to publicly available experimental data and a different LCG model. The presented model enables the analysis of the effect of individual heat transfer coefficients and conductivities on the overall performance of LCGs. The results show good agreement with the experimental data; deviations can mostly be explained by the fact that only one-dimensional heat transfer was modeled. This is a major part of suggested future work. The results also highlight the necessity for more detailed investigation into the area of human sweating since the presence of liquids in the vicinity of the LCG tubes heavily influences the thermal heat transfer from the body to the coolant fluid.