| 摘要 |
The Heat Stress Calculator is a manually operated, mechanical computer and program for determining human thermal discomfort or heat stress, reported as an equivalent heat stress temperature (HST), for any given summer air temperature, relative humidity, wind velocity, sky condition, time-of-day, terrain, and individual physical activity level. The calculator consists of six circular and partial discs concentrically mounted for adjustment of their scales by rotation to various positions relative to each other and to stationary front and back windowed panels. The Heat Stress Temperature is the equivalent air temperature under standard moderate thermal and activity conditions that would result in the same heat stress produced by the actual conditions experienced. Under these standard conditions, the equivalent heat stress temperature represents a constant sweat rate-sweating being a principle indicator of thermal discomfort-and is read from isohids (lines of constant sweating) plotted on a grid of the body's heat load which must be dissipated by the evaporation of sweat, to the environment's cooling capacity to perform this evaporation. The body's evaporative heat load requirement is computed as the sum of heat generated by the level of physical activity plus solar heat gain, less heat loss by convection. Solar heat is computed by aligning the observed sky condition with the time-of-day, and then adjusting for terrain. Convective cooling is computed by aligning wind velocity with the observed air temperature (line) on a wind velocity-convective cooling grid. The environment's evaporative cooling capacity is computed by setting wind velocity, and then aligning relative humidity with the observed air temperature (line) on a humidity-evaporative cooling capacity grid.
|
