Humidification Calculation & Formula

There are Different Types of Methods to calculate the RH (Relative Humidity)  and Temperature in Humidification Plants.
Basically Two types are used   

1. Manual 

1. Automatic

Automatic How it Works ?

• In Automatic we using Sensor,Digital Meter, to Measure the RH and Temperature . To placed the Sensor or Digital Meter in center of department or where you want to measure the Rh & Temp in plant fixed it to that place.

Thermostats

QFM 2016 SIEMENS SENSOR

• There are lot of sensor's and Digital Meters is available in Market .Sensor signal  is 0-10v dc (voltage) or 4-20 ma (current).  After the signal is send to controller.  PLC Controller are display the values in percentage %.

Manual How it Works ?

The whirling hygrometer also known as a  sling psychrometer is made out of

two thermometers mounted on a frame which rotates around a handle, so it can be

whirled in the air by hand.

One thermometer is covered with a tight-fitting muslin sock which is kept wet

by preferably with distilled water.

 

This type of thermometer is known as the wet-bulb thermometer. The other is

the dry bulb thermometer and exposed to the atmosphere directly.

How it works ?

The psychrometer is whirled to let air past the bulbs which in turn makes water

evaporate from the muslin cloth, This in turn cools down the wet bulb temperature.

The amount of cooling that occurs dependent on the amount of relative
humidity. With high relative humidity the wet bulb will cool less than in dryer air
where the water in the muslin will evaporate faster. 
The dry bulb indicates the temperature of the air. The wet bulb helps determine the
relative humidity.
With air less than 100 per cent relative humidity, the wet bulb will display a lower
temperature than the dry bulb and is known as wet-bulb depression.
 A special chart is used to convert the wet-bulb depression to relative humidity or
the relative humidity can be determined by correlating the readings with those on a
simple slide rule, which is supplied with each instrument.

USING YOUR WHIRLING HYGROMETER

1. Fill the reservoir with distilled water.

2. Check that the wick covers the bulb of the wet thermometer fully and is saturated with water.

3. Hold the handle of the hygrometer and whirl it for 20 to 40 seconds.

4. Quickly read the wet thermometer and whirl the hygrometer again.

5. Repeat steps 3 and 4 until consecutive readings are the same. Read the wet & dry thermometers.

6. Calculate the wet bulb depression, ie, the difference between the dry and wet bulb temperatures.

7. Use the table to find Relative Humidity (%RH)

Formula

Using Fahrenheit Hygrometer

Dry-Wet (divided by) Dry (Multiply with) 300 (Subtract) 98

e.g

• 98-88 = (10)

• 10 / 98 =(0.10204081633)

• 0.10204081633 * 300 =(30.612244898)

• 30.612244898 - 98 = (-67.387755102)

• RH is (67 %)

Fahrenheit to Celsius

5 (Divided by) 9 (Multiply with) Dry (Subtract) 32

e.g

• 5/9 = 0.555
• 98 - 32 =66
• 0.555 * 66 = 36.63 Celsius

 

If you Know More About Hygrometer in Tamil Click this Link

https://youtu.be/QQ-frWfuayk