SU486263A1 - Method for determining air humidity - Google Patents

Description

measuring relative db 100%. 273

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-1.205 50- 15.5-27.5 Example 2. A heat-conducting rod is used to maintain a constant relative humidity in a heat chamber in the temperature range from + 20 ° C to - + - 50 ° C. The limits of regulation of relative humidity from 30% to 100%. 15.5 0.859 /; - 15.5. In order to clarify the essence of the proposed method, let us consider a heat-conducting rod, at the ends of which a constant temperature difference is maintained. The temperature of the “warm end is equal to the air temperature. As well as for the known method of determining the humidity with known assumptions for this case, you can write t; g - А /, herts m - dew point temperature; t is the temperature of the “warm end of the heat-conducting rod; f is the distance from the “warm end” to the boundary of fogging of the heat-conducting rod; k-temperature gradient along the length of the rod. Where follows: f -. kl. This means that the value of t – t can be determined directly from the distance from the “warm end” to the boundary of the condensation of the heat-conducting rod. But the temperature of the “warm end is conditionally equal to the air temperature. Consequently, / -t in this case is the value that, together with the air temperature (or the dew point temperature), uniquely determines the relative humidity. Therefore, at a constant air temperature in this case, not only the value of t-t values, but also the corresponding values of relative humidity values can be directly determined from the boundary of condensation of a heat-conducting rod. However, at a variable air temperature, direct measurement of the relative humidity at the boundary of condensation of the heat-conducting rod is difficult, since different values of relative humidity correspond to the same t-t value at different air temperatures, and vice versa, to a constant value

humidity at different air temperatures correspond to different tt values.

The table below shows the dependence of t-t on air temperature at constant values of relative humidity. As can be seen from the table, with an increase in air temperature from 0 ° C to 40 ° C, the value of / -t increased about the same - 1.33 times for all values of relative humidity. This means that for all values of relative humidity the following equality is valid: (-) 40. ALO, () o Vo, where the subscripts O and 40 are the values corresponding to air temperatures. For convenience, the relative humidity is necessary to / o. This is possible provided that / 240 1.33 yo. But the temperature gradient along the length of the heat-conducting rod is proportional to the temperature difference at its ends. Therefore, for all values of relative humidity, it is possible to obtain if (1.33 (where tx is the temperature of the cold end of the heat-conducting rod. Thus, if the temperature at the "warm end of the ten-wire conducting rod is maintained at the same temperature as the air, and the temperature difference at its ends is change the air temperature from 0 ° C to 40 ° C to increase by 1.33 times, then the limits of fogging of the heat-conducting rod, corresponding to certain values of the relative humidity, will remain at the same places and, therefore, but determine the relative humidity at a new temperature, using the previous scale.In general, the dependence of the temperature difference at the ends of the heat-conducting rod on air temperature is expressed by the formula where a (t-tx) o is the temperature difference at the ends of the heat-conducting rod at air temperature 0 ° C; y 110 is a constant coefficient.

From where

(i-f) - The temperature difference at the ends of the heat-conducting rod at an air temperature of 0 ° C depends on the lower limit of measuring moisture content fmin and is determined by the formula:

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Claims (2)

one - Subject invention A method for determining the humidity of air along the boundary of condensation of a heat-conducting rod, at the ends of which a certain temperature difference is maintained, characterized in that in order to provide a direct reading of the relative humidity along the boundary of the condensation of heat-conducting rod, the temperature is equal to one of the ends of the heat-conducting rod. depending on the change in air temperature, the temperature difference at the ends of the heat-conducting rod. 2. The method according to claim 1, wherein However, the temperature difference at the ends of the heat-conducting rod is regulated by changing the temperature of the "cold end" according to the formula: t (, IIQJ where ty is the temperature of the “cold end of the heat-conducting rod in ° C; t is the air temperature in ° C. 273 but - 20 one where Finn is the lower limit of relative humidity measurement.