Thermal Model of Heat Fluxes in a Radiatively Cooled Space Suit

Project for MECHENG 530: Advanced Heat Transfer

A description of the group project is listed below, along with the final presentation. Group member names are omitted.

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There is increasing interest in landing a crewed mission on the surface of Mars. For humans to traverse the Martian surface, spacesuits must maintain safe and stable thermal environments. The current methods of insulation spacesuits work well in space, but are not sufficient in the presence of a significant atmosphere.

The first objective of this study was to create a model of the insulation and thermal behavior of an upper arm necessary to maintain safe temperatures in an Extravehicular Mobility Unit (EMU), on the Martian surface. The model consists of a layup diagram to understand the different layers and heat transfer mechanisms taking place. A thermal resistance model follows to apply different mechanisms of heat transfer into a single system to solve. These mechanisms were used in an optimization calculation to solve the steady-state model of the system and determine the best values for the insulation design. Parameters optimized included the number of MLI layers, mass flow rate of the heat exchanger, and the heat transfer coefficient of the heat exchanger for the resistance network model.

Reflection

There are several limitations on the accuracy and effectiveness of the model. The largest limitation on the model is that the material properties for each of the EMU layers are approximates based on the best available data published by NASA. The exact thermal properties of the materials are not published, so approximates were sourced from various literature sources. As a result, some deviation in the performance of the model vs the real suit are expected. Additionally, the model was generated based on the steady state case. As such, the effects of time spent in EVA, or any significant activity that might alter metabolic heat generation for short intervals were not considered. The model generated was also one dimensional, so effects due to the placement and specific geometry of the liquid cooling garment were also not considered.