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Chen and Holmes model

In another study on the bio-heat model, Chen and Holmes [159] considered that blood vessels can be divided into two categories: (1) large vessels (arteries, veins) and (2) small vessels (vessels underlying the skin or capillaries). In this model, they assumed that the metabolic heat transfer between small vessels to skin tissue occurs in three modes: perfusion, convection, and conduction. Firstly, the perfusion mode establishes an equilibration between blood and tissue temperature. Secondly, the convective mode predominates when equilibrium has already been established between blood and tissue temperature. At this stage, the blood flow transfers the heat against a tissue temperature gradient. Thirdly, the thermal conduction occurs due to small temperature fluctuations that happen along the tissue temperature gradient. By considering all these modes, the metabolic heat transfer between the blood and tissue can be represented using Eq. (3.5), where qmet = metabolic heat (J); Ta = arterial temperature (°C); T = tissue temperature (°C); ю = perfusion rate of blood through tissue (m3/s/m3of tissue); (p)b = blood density (kg/m3); (c)b = blood-specific heat (J kg °C); kp = perfusion conductivity tensor (W m/°C); p = net volume flux vector permeating a unit area of control surface (m3 m-2 s-1); 5T/5t=change of temperature (T) with respect to time (t) (°C/s).

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