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An aircraft environmental control system (ECS) is commonly designed for a cabin that has been divided into several thermal control zones; each zone has an air flow network that pulls cabin air over an isolated thermocouple. This single point measurement is used by the ECS to control the air temperature and hence the thermal environment for each zone. The thermal environment of a confined space subjected to asymmetric thermal loads can be more fully characterized, and subsequently better controlled, by determining its “equivalent temperature.” This paper describes methodology for measuring and controlling cabin equivalent temperature. The merits of controlling a cabin thermal zone based on its equivalent temperature are demonstrated by comparing thermal comfort, as predicted by a “virtual thermal manikin,” for both air-temperature and equivalent-temperature control strategies.

This paper presents methodology for predicting body core temperature using the ASHRAE two-node thermoregulation model. Predicted changes in core temperature can be used to certify that, during a heat stress event, the temperature and humidity within an aircraft will not exceed values that are hazardous to the occupants. The use of ASHRAE model was validated by comparing its predictions to experimental data for subjects that were exposed to hot (33° to 48°C) environments. The model has been used to predict body core temperature in the cockpit and cabin during three different environmental ventilation system failure simulations for an aircraft that uses atmospheric air from the ram air duct in the event of a dual pack failure.

A fast, semi-automated method for visualizing the time-varying effects of radiative heat transfer, including obscuration and multiple reflections, is presented. Starting with a finite element surface description, an analyst assigns “groups” to a model by indicating which elements have the same material and surface properties. The elements within each group are combined into isothermal nodes. View factors are then calculated using a variant of the hemi-cube method. Transient nodal temperatures are calculated using an implicit solution to the finite difference equations derived from the thermal properties of each node and the radiation exchange between nodes.