EFFECTIVE TEMPERATURE

From Big Medical Encyclopedia

EFFECTIVE TEMPERATURE — the indicator characterizing combined effect on the person of temperature and humidity of an ambient air.

AA. t. it is used at complex assessment of influence of a microclimate (see) on heat exchange of the person, on to-ry influence separately or combined following factors: temperature, humidity, speed of the movement of air, the weighted average temperature of the surfaces surrounding the person, and also the nature of activity of the person and heat-protective properties of clothes.

Along with effective temperature at complex assessment of a microclimate also other indicators are used: operational, or

equivalent, temperature, equivalent and effective temperature, resultant, or radiation equivalent and effective, temperature. Each of these indicators reflects the combined impact on an organism of two or more factors. So, operational temperature characterizes combined effect on the person of temperature and speed of the movement of air, and also a caloradiance of the environment. The resulting temperature allows to estimate combined effect on the person of temperature, humidity and speed of the movement of air, and also infrared (thermal) radiation of the environment. Equivalent and effective temperature indicates combined effect of temperature, humidity and speed of the movement of an ambient air. Taking into account the given indicators a number of methods of modeling of complex assessment of a microclimate is developed, but any of them does not consider the combined influence of the listed factors that limits broad use of these methods in a gigabyte. to practice. Depending on the used principle conditionally allocate methods of biological, physical and mathematical modeling.

Method biol. modeling it is based on data of the reactions of an organism reflecting a condition of heat exchange and received in microclimatic cameras at influence of various combinations of factors. Reak-

tion of an organism express in indexes. The method of definition E belongs to number of the most known methods of biological modeling. t., assessment of thermal feeling of the person at different combinations of temperature, humidity and speed of the movement of air is the basis to-rogo. Index E. t. it is designated by air temperature at a speed of its movement up to 10 — 15 cm! sec. and 100% of relative humidity. On the basis of numerous researches of thermal feeling at various combinations of microclimatic factors schedules with the main scale (for the naked person) and a normal scale were constructed (for easily dressed person performing easy work).

At an effective temperature from 17,2 to 21,7 ° most of examinees felt thermal comfort that allowed to consider this range a zone of comfort. For definition E. t.



Fig. use the nomogram (fig.). Nomogram of a normal scale of effective temperatures.

having 4 scales: scales of degrees of dry and wet thermometers, scale of speed of the movement of air and scale of degrees of effective temperature. Indications of thermometers connect a ruler and on crossing with a scale of the movement of air find the corresponding effective temperature. For calculation E. t. also mathematical formulas are offered, to-rye are used at design of devices of heating, ventilation and air conditioning in residential and public buildings. Method of definition E. t. does not consider the radiation temperature, the nature of activity of people and some other circumstances. For the purpose of elimination of nek-ry shortcomings of this method E. t. a number of its modifications was offered, from to-rykh the greatest interest caused the method of the resulting temperature developed by A. Missenard.


Attempts to develop complex assessment of a microclimate with use of objective indicators of a thermal condition of the person are made. So, Mac-Ardl (V. McArdle) with sotr. offered a method of definition of the P4SR index («the predicted four-hour intensity of sweating») with the nomogram allowing to calculate the average amount of sweat which is marked out by the faces of young age adapted to heat in 4 hours of stay in conditions of a certain microclimate. This method is applicable for complex assessment of a microclimate in hot workshops at relative humidity of air not lower than 40%.

A number of researchers recommend to define the index of physiological effect characterizing complex influence of microclimatic conditions on a cardiac rhythm, temperature of skin, rectal temperature and a potovydeleniye.

The method of physical modeling is based on use of a heated blackened physical body of cylindrical or spherical shape, a cut is capable to lose heat due to heatcarrying out, radiations, and during the wetting due to evaporation. Heat waste by a physical body (i.e. the cooling conditions of the environment) is expressed in kal / sec. with 1 cm2 (J/sec. with 1 cm2) or in indexes. Use such devices as katatermometr Hilla, the spherical thermometer, frigorimetr, eupateoskop and others. For each device establish dependence between an index and a thermal condition of the person. To create the device reacting to microclimatic conditions it is similar to a human body, still it was not possible. However in some cases it is possible to use the adequate device. So, when the person is affected by radiant heat, use the spherical thermometer of Vernon — Yokla with a polyurethane covering, a cut can be humidified and imitate heat waste by evaporation. This device is widely used in the USSR. At complex assessment of a microclimate

methods of mathematical modeling gain ground. It is connected with achievements in the field of the microcomputer equipment and mathematical modeling of thermal control of an organism. Methods of mathematical modeling are based on the simplified formula of a heat balance of M ± With ± R — E = ± S where M — metabolic heat, heat production at the expense of a metabolism and the performed physical activity, C and R — heat exchange by convection and radiation, E — a thermolysis evaporation of sweat, S — the amount of heat received from the outside


and given to external environment in these microclimatic conditions at the thermal optimum of S equal to zero. To the USSR and abroad methods of calculation of a heat balance were detailed and specified, formulas of calculation are as a result developed for various conditions (residential and public buildings, hot workshops, the open atmosphere, cabins of spaceships, etc.) taking into account the work performed by the person and heat-protective properties of clothes. In GDR the method of automatic measurement of all microclimatic conditions (temperature, humidity, mobility of air, radiation heat) with use of the computer is offered that allows to receive data (in the form of indexes) about extent of accumulation or a lack of heat of an organism and, therefore, about a thermal condition of the person. Bibliography: And yes e in A. N, Fiziologogigiyenichesky aspects of action of high and low temperatures, M., 1979; B and N - x and d and L. A thermal microclimate of rooms, lane with Wenger., M., 1981; In and a TT of e N. K. Thermal exchange of the person and his hygienic value, Kiev, 1956; Gorodinsky S. M., Bavro G. V., and E. I. K Smith to a problem of portability person of thermal loading „Tousle. biol. and medical, t. 4, No. 1, page 30, 1970; JI and about according to T. N. and C and c e N to about G. V. Climatic conditions and thermal

condition of the person, «JI., 1971; R at -

l and to To., etc. New method of integral assessment of a microclimate, Doctor, business, No. 9, page 105, 1983; The Factors influencing health in working conditions at high temperatures, the Report of science team of WHO It is gray. tekhn. dokl. No. 412, M., 1970. R. D. Gabovich, F. M. Shleyfman.

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