What is Dry-Bulb Temperature in an HVAC system?
Dry-bulb temperature (DBT) is the temperature of air measured by a thermometer which is freely exposed to the air while it is shielded from radiation and moisture. It is usually thought of as air temperature, and it is the true thermodynamic temperature. It is a measurement of heat intensity independent of humidity and a dry-bulb thermometer is used to measure it.
The temperature is usually given in degrees Celsius (°C) or degrees Fahrenheit (°F).
In an HVAC system, dry bulb temperature can be important to consider when trying to maintain a comfortable environment. For example, if the dry bulb temperature in a room becomes too high, it can be uncomfortable for people in the room. On the other hand, if the dry bulb temperature drops too much, those in the space may become uncomfortable.
What is the difference between dry-bulb temperature and wet-bulb temperature?
The difference between dry-bulb temperature (DBT) and wet-bulb temperature (WBT) is that the wet-bulb temperature takes humidity into account. DBT is the temperature of air measured while it is shielded from radiation and moisture, whereas WBT is the temperature of air measured by a thermometer which is freely exposed to the air while it is shielded from radiation and moisture and has a wetted wick inside of it.
What is WBT used for?
Wet-bulb temperature (WBT) is used to calculate the dew point and to measure the relative humidity of air. It is also used in psychrometry, which is the study of the thermodynamic properties of moist air.
Why is wet bulb temperature lower than dry bulb?
The wet bulb temperature is lower than the dry bulb temperature because when the air comes into contact with the wetted wick, some of the moisture in the air will evaporate and cool the thermometer. This is why WBT is used to calculate the dew point and to measure the relative humidity of air.
What is Dew Point Temperature?
Dew point temperature (DPT) is the temperature at which the air will reach 100% relative humidity. It is the temperature at which condensation will form on a surface.
An HVAC system can help to maintain a comfortable environment by controlling the dry bulb temperature.
Which temperature measurement should an HVAC Technician use?
All of these temperature measurements (DBT, WBT and DBT) are useful in determining the state of humidity in the air, including the content of water vapor and the sensible and latent energy (enthalpy).
An HVAC Technician should typically use the dry bulb temperature to measure the air temperature in an HVAC system. This is because it is the true thermodynamic temperature and it is a measurement of heat intensity independent of humidity.
Related Links
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