Validation and Use Cases for the new Thermal Layer of the V-HAB Crew Model

Abstract

The Virtual Habitat project (V-HAB) at the Technical University of Munich (TUM) aims to develop a dynamic simulation environment for life support systems (LSS). Within V-HAB a dynamic human model interacts with the LSS by relevant metabolic inputs and outputs based on internal, environmental and operational factors. The human model is separated into five sub-models (called layers) representing metabolism, respiration, thermoregulation, water balance and digestion. As V-HAB is evolving, new requirements emerge for the human model. An example is the use in the Virtual Spacesuit project (V-SUIT), which is a spin-off from V-HAB and conducts multi-domain simulations of extravehicular activities (EVA), including the portable LSS (PLSS). Using the thermal layer in such a scenario requires a higher spatial resolution (i.e. more nodes), whereas less nodes are required if e.g. the long-term stability of a larger base is analyzed. Due to these requirements, a new, fully configurable and modular thermoregulation layer was implemented. It models all mass, mass flows, heat capacities and heat flows using the default V-HAB elements and solvers, which are also used to simulate e.g. physio-chemical subsystems. This allows a close interface between the human thermal layer and the environment, in this case the liquid cooling garment (LCG) and ventilation gas within the suit. This paper describes the development, principles and configuration of the first full-body version of this model. Subsequently, validation results based on published experimental data is presented for models with different numbers of nodes. Also, a derived case from V-SUIT was simulated, where a firefighter is exposed to high environmental temperatures. It was determined that the model produces more accurate results than the old layer in various scenarios, and noticeable differences can be observed between simulation runs with different numbers of nodes for e.g. skin temperatures.