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Wet-Bulb Method

When heat is transferred to a wet sohd by convection to hot surfaces and heat transfer by convection is negligible, the solids approach the boiling-point temperature rather than the wet-bulb temperature. This method of heat transfer is utilized in indirect diyers (see classification... [Pg.1180]

It is important to emphasize that, especially in process measurements, radiation can have an essential influence on the wet bulb temperature, and therefore generally the wet bulb temperature is dependent on the mea,surement device and the method of measurement. If the airflow is very low, the radiation can have a remarkable contribution in addition to the convective heat transfer. Basically, an equation analogous to Eq. (4.138) can be empirically determined for each wet bulb temperature and method of measurement. [Pg.91]

The ISO philosophy for the assessment of hot environments is to use a simple, fast method of monitoring the environment, based on the wet bulb globe temperature (WBGT) index (ISO 7243). If the WBGT value exceeds the provided reference value, or if a more detailed analysis is required, then ISO 7933 provides an analytical method of assessment. [Pg.382]

Wet bulb temperature, 9 98, 100 Wet chemical analytical methods, for silver, 22 650-651... [Pg.1019]

The wet-bulb temperature is an important factor in the sizing, selection and design of water cooling equipment. It is defined as the temperature (°F) to which air can be cooled adiabatically to saturation by the addition of water vapor and can be expressed as the lowest temperature to which water can be cooled by the evaporative method. [Pg.104]

The balance between conduction and diffusion still operates for a much larger isolated wet object, provided radiation is excluded. This is the basis of the wet bulb thermometer method for measuring humidity. The actual rate of evaporation now is not as simply determined and is influenced by wind. The wet bulb temperature is almost independent of wind condition, owing to a convenient accident. Heat conduction is a diffusion process, and the diffusion coefficient for water vapor in air (0.24 sq. cm./sec.) is numerically close to the diffusion coefficient of temperature in air (thermal conductivity/specific heat = 0.20 sq. cm./sec.). Hence, the exact way in which each molecular diffusion process merges into the more rapid eddy diffusion process is not important because no matter how complex the transition is, it must be quantitatively similar for the two processes. [Pg.127]

Air at 1 atm and I00°F flows across a wet-bulb thermometer, producing a temperature of 70°F. Calculate the relative humidity of the airstream using Carrier s equation and compare with results obtained by methods of this chapter. [Pg.598]

The accurate determination of the humidity of air is carried out gravimetrically. The water vapor present in a known volume of air is chemically absorbed with a suitable reagent and weighed. In less laborious methods, the humidity is derived from the dew point or the wet-bulb depression of a water-vapor mixture. [Pg.3884]

Methods (v) and (vi) give the adiabatic saturation and wet-bulb temperatures from absolute humidity (or relative humidity) at a given temperature. [Pg.1334]

The gas velocity in the conveying duct must be sufficient to convey the largest particle. This may be calculated accurately by methods given in Sec. 17, Gas-Solids Operations and Equipment. For estimating purposes, a velocity of 25 m/s, calculated at the exit air temperature, is frequently employed. If mainly surface moisture is present, the temperature driving force for drying will approach the log mean of the inlet and exit gas wet-bulb depressions. (The exit solids temperature will approach the exit gas dry-bulb temperature.)... [Pg.1420]

In reverse, by measuring the wet bulb temperature the moisture content XA of the humid air can be calculated using the two equations. The wet bulb hygrometer, sometimes called Assmann s Aspiration Psychrometer works by this method. It consists of two thermometers, one of which is covered by a porous textile, the lower part of which is dipped into a container full of water, so that the bulb of the thermometer is always wet. Air is blown over the thermometer and after some time it reaches the wet bulb temperature Meanwhile the second, so called dry thermometer, indicates the temperature of the air flowing around it. With these measured values the moisture content XA5 of the humid air can be found using equation (1.210) or (1.211). [Pg.90]

WET-BULB TEMPERATURE. The wet-bulb temperature is the steady-state, non-equilibrium temperature reached by a small mass of liquid immersed under adiabatic conditions in a continuous stream of gas. The mass of the liquid is so small in comparison with the gas phase that there is only a negligible change in the properties of the gas, and the effect of the process is confined to the liquid. The method of measuring the wet-bulb temperature is shown in Fig. 23.4. A thermometer, or an equivalent temperature-measuring device such as a thermocouple, is covered by a wick, which is saturated with pure liquid and immersed in a stream of gas having a definite temperature T and humidity ff. Assume that initially the temperature of the liquid is about that of the gas. Since the gas is not saturated, liquid evaporates, and because the process is adiabatic, the latent heat is supplied at first by cooling the liquid. As the temperature of the liquid decreases below that of the gas, sensible heat is transferred to the liquid. Ultimately a steady... [Pg.747]

MEASUREMENT OF HUMIDITY. The humidity of a stream or mass of gas may be found by measuring either the dew point or the wet-bulb temperature or by direct-absorption methods. [Pg.751]


See other pages where Wet-Bulb Method is mentioned: [Pg.1149]    [Pg.1161]    [Pg.972]    [Pg.1322]    [Pg.1337]    [Pg.16]    [Pg.1321]    [Pg.1336]    [Pg.1153]    [Pg.16]    [Pg.1149]    [Pg.1161]    [Pg.972]    [Pg.1322]    [Pg.1337]    [Pg.16]    [Pg.1321]    [Pg.1336]    [Pg.1153]    [Pg.16]    [Pg.1169]    [Pg.1226]    [Pg.1228]    [Pg.84]    [Pg.431]    [Pg.811]    [Pg.812]    [Pg.984]    [Pg.992]    [Pg.1049]    [Pg.1051]    [Pg.113]    [Pg.101]    [Pg.1343]    [Pg.1419]    [Pg.1422]    [Pg.22]    [Pg.98]    [Pg.101]    [Pg.484]   


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