A new transient bioheat model of the human body and its integration to clothing models

A mathematical multi-segmented model based on an improved Stolwijk model is developed for predicting nude human thermal and regulatory responses within body segments and the environment. The passive model segments the body into the 15 cylindrical segments. Each body segment is divided into four nodes of core, skin, artery blood, and vein blood. In any body element, the blood exiting the arteries and flowing into the capillaries is divided into blood flowing in the core (exchanges heat by perfusion in the core) and blood flowing into the skin layer (exchanges heat by perfusion in the skin). The model calculates the blood circulation flow rates based on exact physiological data of Avolio [A.P. Avolio, Multi-branched model of the human arterial system, Med. Biol. Eng. Comp. 18 (1980) 709–718] and real dimensions and anatomic positions of the arteries in the body. The inclusion of calculated blood perfusion in the tissue is based on the pulsating arterial system model and the heart rate is unique for the current model. The nude body model is integrated to an existing clothing model based on heat and mass diffusion through the clothing layers and takes into consideration the moisture adsorption by the fibers. The bioheat human model is capable of predicting accurately nude human transient physiological responses such as the body’s skin, tympanic, and core temperatures, sweat rates, and the dry and latent heat losses from each body segment. The nude and clothed body models predictions are compared with published experimental data at a variety of ambient conditions and activity. The current model agrees well with experimental data during transitions from hot to cold environments and during changes in metabolic rate. Both the nude and clothed human model have an accuracy of less than 8% for the whole-body heat gains or losses; the nude human model has an accuracy of ±0.48 ◦C for skin temperature values. © 2006 Elsevier Masson SAS. All rights reserved.