The principles ofheat transfer in engineering systems can be applied to the human body in order to determine how the body transfers heat.When a person engages in elevated levels of physical activity, the body requires additional fuel which increases the metabolic rate and the rate of heat transfer. The body must then use additional methods to remove the additional heat produced in order to keep the internal temperature at a healthy level.

Heat transferby convection is driven by the movement of fluids over the surface of the body. This convective fluid can be either a liquid or a gas. Forheat transfer from the outer surface of the body, the convection mechanism is dependent on the surface area of the body, the velocity of the air, and the temperature gradient between the surface of the skin and the ambient air.

Heat transferoccurs more readily when the temperature of the surroundings is significantly less than the normal body temperature. This smaller temperature gradient between the surface temperature and the ambient temperature will cause a lower rate ofheat transfer than if the skin were not covered.

Latent heat loss, also known as evaporative heat loss, accounts for a large fraction of heat loss from the body. The liquid is then transformed into vapor which removes heat from the surface of the body.The rate of evaporation heat loss is directly related to the vapor pressure at the skin surface and the amount of moisture present on the skin.

Therefore, the maximum ofheat transfer will occur when the skin is completely wet. In all, the body continuously loses heat by evaporation. But we can keep the body warm by the heat transfer.