Why is the wet bulb temperature normally lower than the dry bulb temperature?
At 100% relative humidity, the wet-bulb temperature is equal to the air temperature (dry-bulb temperature); at lower humidity the wet-bulb temperature is lower than dry-bulb temperature because of evaporative cooling.
When there is no difference in the reading of the wet and dry bulb thermometer then?
In this case, however, there was NO difference between the readings of the wet bulb and the dry bulb thermometers. This means there is absolutely no room at this temperature for water to evaporate, indicating the humidity of the air is saturated, or full. So the relative humidity is 100%.
How does the wet cloth wick affect the wet bulb thermometer?
If you wrap the bulb of the thermometer in wet cloth, by contrast, the evaporating water from the wet cloth will cool the thermometer down, and its temperature will be cooler than it would be otherwise. The lower the wet bulb temperature compared to the dry bulb temperature, the lower the humidity.
What is the meaning of dry bulb temperature?
The Dry Bulb Temperature refers basically to the ambient air temperature. It is called “Dry Bulb” because the air temperature is indicated by a thermometer not affected by the moisture of the air.
How do you calculate dry bulb temperature?
Dry-bulb temperature – Tdb, can be measured using a normal thermometer freely exposed to the air but shielded from radiation and moisture. The temperature is usually given in degrees Celsius (oC) or degrees Fahrenheit (oF).
At what condition the dehumidification process will start?
Dehumidifying Moist Air – Latent Cooling If the temperature on a cold surface is lower than the dew point temperature – tDP – of the humid air, vapor in the air condensates on the surface. Latent heat – vapor – is removed from the humid air. This process is indicated in the Mollier diagram as below.
How does a wet and dry bulb thermometer work?
A dry thermometer has the bulb exposed to air. A wet thermometer has the bulb covered with a muslin cloth which is dipped in water. It is used to measure the relative humidity of temperature. When air is saturated, evaporation stops and the two bulbs show the same reading.
What is the other name for wet and dry bulb thermometer?
The wet and dry bulb thermometer is therefore also known as the wet and dry bulb hygrometer, since the hygrometer is the instrument used for measuring the humidity.
How do you calculate wet bulb depression?
A quick technique that many forecasters use to determine the wet-bulb temperature is called the “1/3 rule”. The technique is to first find the dew-point depression (temperature minus dew-point). Then take this number and divide by 3. Subtract this number from the temperature.
How do you read a wet bulb?
Wet Bulb temperature can be measured by using a thermometer with the bulb wrapped in wet muslin. The adiabatic evaporation of water from the thermometer bulb and the cooling effect is indicated by a “wet bulb temperature” lower than the “dry bulb temperature” in the air.
What is indoor wet bulb temperature?
The temperature is usually given in degrees Celsius (°C) or degrees Fahrenheit (°F). Wet bulb temperature is the temperature indicated by a moistened thermometer bulb exposed to the air flow. Wet bulb thermometer can be measured using a thermometer with the bulb wrapped in wet muslin.
Where is the indoor wet bulb temperature?
Take indoor wet bulb temperature measurements as close to the inlet of the evaporator coil as possible. In many cases there is an air filter before the evaporator onto which a wet bulb thermocouple can be clipped. Take the measurement as close to the center of the air stream as possible.