Psychrometric chart includes so many axis which represent different parameters of air. Now we are going to learn two of those axis, dry bulb temperature and wet bulb temperature.
When dry bulb temperature and wet bulb temperature are known, we can determine the relative humidity, absolute humidity, and enthalpy. Dry bulb temperature tells the actual room temperature.Psychrometric chart - Full tutorial
It is defined as air temperature. When we measure the temperature of air, we refer the dry bulb temperature. Also, Dry bulb temperature can be measured by exposing a thermometer to the air.
Dry bulb temperature axis on psychrometric chart is located at bottom of the psychrometric chart and it is a horizontal line. Constant dry bulb temperatures appear as vertical lines in the psychrometric chart.
Dry bulb temperature lines are vertical lines. We have marked three different dry bulb lines for 200C, 300C, 400C in following figure.
The wet Bulb temperature is the adiabatic saturation temperature. Wet bulb temperature curve
Wet bulb temperature is lower than dry bulb temperature or equal to the dry bulb temperature. This equality occurs at only in air become saturated.
Wet bulb temperature axis is highlighted in following figure. Constant wet bulb temperatures appear diagonally from the upper left to the lower right in the Psychrometric chart.
Wet bulb temperature lines are inclined lines. (not vertical or horizontal). We have marked three different wet bulb lines for 100C, 200C, 300C in following figure.
When wet bulb temperature and dry bulb temperature are given, your first step is drawing correct lines of wet bulb temperature and dry bulb temperature. Then these two lines will meet at one point.
We discuss few examples to understand how this process is done.
You are advised to find air properties from a psychrometric chart. You are given a psychrometer which can be used to measure dry bulb temperature and wet bulb temperature. You have observed that temperatures are 280C and 240C for dry bulb and wet bulb respectively. Identify the point on psychrometric chart where other air properties can be calculated?
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