psychrometric chart excel relative humidity

In industrial drying applications, such as drying paper, manufacturers usually try to achieve an optimum between low relative humidity, which increases the drying rate, and energy usage, which decreases as exhaust relative humidity increases. Relative humidity is often controlled in manufacturing areas where flammable materials are handled, to avoid fires caused by the static electricity discharges that can occur in very dry air. Industries that use these materials are concerned with relative humidity control in production and storage of such materials. Such substances include cotton, paper, cellulose, other wood products, sugar, calcium oxide (burned lime) and many chemicals and fertilizers. Many substances are hygroscopic, meaning they attract water, usually in proportion to the relative humidity or above a critical relative humidity.

In human terms, our thermal comfort is in large part a consequence of not just the temperature of the surrounding air, but (because we cool ourselves via perspiration) the extent to which that air is saturated with water vapor. JSTOR ( March 2021) ( Learn how and when to remove this template message)Īlthough the principles of psychrometry apply to any physical system consisting of gas-vapor mixtures, the most common system of interest is the mixture of water vapor and air, because of its application in heating, ventilation, and air-conditioning and meteorology.

Unsourced material may be challenged and removed. Please help improve this section by adding citations to reliable sources. You can change the display option by changing the number in the box above.Įntering a zero eliminates all formatting.This section does not cite any sources. The default numeric display is 3 significant figures. For example, if we have a dry bulb temperature of 20℃ and a wet bulb temperature of 15℃ what is the relative humidity? Using the calculator, we see that this is 58.4 %. The easiest way to do this is entering the dry and wet bulb temperatures into the calculator above and then click calculate. We now have a dry bulb and a wet bulb temperature which we can use to calculate relative humidity. When the psychrometer is swung around by its attached chain or handle, the air causes the water on the wick to evaporate which produces a lower temperature in the wet bulb thermometer. This consists of 2 side by side conventional thermometers, one of which (the wet bulb thermometer) has a wetted wick placed at the bottom, the other (the dry bulb thermometer) has no wetted wick. Relative Humidity is measured using a device called a

Psychrometric chart excel relative humidity