A convenient, precise and customizable psychrometric chart & calculator tool for 25 26 27 28 29 30 m^3/kg(d.a) 10% 20% 30% 40% 50% 60% 70%. Psychrometrics, psychrometry, and hygrometry are names for the field of engineering . The ASHRAE-style psychrometric chart, shown here, was pioneered by. Use chart to analyze processes involving moist Psychrometric chart: Example 1 . Given: T = 25°C . m wide x m long, and the boards are separated by.

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The DB temperature increases ijve the left to the right. Other websites that we found interesting is that of Wikipedia on Psychrometrics. Find the humidity ratio labeled on the right vertical axis. The psychrometric chart allows all the parameters of some moist air to be determined ihvw any three independent parameters, one of which must be the pressure. The name implies that the sensing bulb or element is in fact dry. The ratio of the vapor pressure of moisture in the sample to the saturation pressure at the dry bulb temperature of the sample.

Such substances include cotton, paper, cellulose, other wood products, sugar, calcium oxide burned psychromertic and many chemicals and fertilizers. This type of cooler is extremely popular in hot, dry climates, and is popularly known as a Swamp Cooler. Find the diagonal enthalpy scales surrounding the chart. Thus we introduce an oblique enthalpy axis and enthalpy black lines as follows: The psychrometric ratio is an important property in the area of psychrometry, as it relates the absolute humidity and saturation humidity to the difference between the dry bulb temperature and the adiabatic saturation temperature.

They are also available in low and high temperature ranges cchart for different pressures. Along this line, note that the wet bulb temperature and the dew point are always equal to the dry bulb psyychrometric. Analogous to the specific enthalpy of a pure substance.

Try to be as exact as possible when using the chart to read other measurements, and mark your answers in the proper units for that measurement.

Around the extremes of the chart and just outside of the saturation curve, locate the diagonal scales which represent enthalpy in BTU per pound of dry air. The major simplifying assumption in the construction of the chart is that the enthalpy of the mixture is assumed to be constant throughout the adiabatic saturation process described in Section a.


Thus with the aid of the chart we either heat or cool, add moisture or dehumidify as required in order to bring the air into the comfort zone.

What is Psychrometric Chart? Introduction to Reading the Psychrometric Properties of Air

Humidity ratio is usually expressed as mass of moisture per mass of dry air pounds or kilograms of moisture per pound or kilogram of dry air, respectively. At first glance there is little resemblance between the charts, but if the chart is rotated by ninety degrees and looked at in a mirror the resemblance becomes apparent.

Notice that on the saturation curve the wet and dry bulb temperatures have the same values. However, you can also use relative humidity, enthalpy, and specific volume to make estimated conclusions. Help answer questions Learn more.

This is the t —axis, the abscissa horizontal axis. A psychrometer is a device that includes both a dry-bulb and a wet-bulb thermometer. Visualize 2 measurements by comparing them on the chart.

Mixtures of air and water vapor are the most common systems encountered in psychrometry. This will help when it comes time to use the measurements in an equation. The constant WB temperature lines are the diagonal lines extending from WB temperature curved scale downwards towards the right hand side of the chart.

By using psychrometric charts HVAC engineers can graphically analyze different types of psychrometric processes and psycrometric solution to many practical problems without having to carry out long and tedious mathematical calculations.

We notice from the development in Section a that the equations relating relative and specific humidity, temperature wet and dry bulbpressure air, vapor and enthalpy are quite tedious and inconvenient.

Look along the bottom of the chart to find the dry bulb temperature. Together, they cited information from 12 referenceswhich can be found at the bottom of the page. The accuracy of a simple wet-bulb thermometer depends on how fast air passes over the bulb and how well the thermometer is shielded from the radiant temperature of its surroundings.

Pressure Liquid water Avogadro’s law Nucleation Thermodynamic equilibrium. The mass of water vapor per unit volume of igve containing the water vapor. The outermost curve along the left side indicates the Wet Bulb WB temperature scale. For other pressures relevant corrections have to be applied.

An interesting and informative description on Psychrometric Chart Use for livestock and greenhouse applications has been presented in a University of Connecticut website by Michael Darre. Technically, the temperature registered by the dry-bulb thermometer of a psychrometer.


The term dry-bulb is customarily added to temperature to distinguish it from wet-bulb and dewpoint temperature. Knowing both the dry-bulb temperature DBT and wet-bulb temperature WBTone can determine the relative humidity RH from the psychrometric chxrt appropriate to the air pressure. Archived copy as title Webarchive template wayback links. Specific humidity is defined as the proportion of the mass of water vapor and mass of the moist air sample including both dry air and the water vapor ; it is closely related to humidity ratio and always lower psyychrometric value.

The region above the saturation curve is a two-phase psychrometfic that represents a mixture of saturated moist air and liquid water, in thermal equilibrium. In other projects Wikimedia Commons.

Architectural acoustics Architectural engineering Architectural technologist Psychrometruc services engineering Building information modeling BIM Deep energy retrofit Duct leakage testing Environmental engineering Hydronic balancing Kitchen exhaust cleaning Mechanical engineering Mechanical, electrical, and plumbing Mold growth, assessment, and remediation Refrigerant reclamation Testing, adjusting, balancing. By identifying the axes and reading the markings on the interior of the chart, you can plot points and draw conclusions from known measurements on the chart.

Many substances are hygroscopicmeaning they attract water, usually in proportion to the relative humidity or above a critical relative humidity. Chapter 2, Measurement of Temperature. Usually the level at which water vapor changes into liquid marks the base of the cloud in the atmosphere hence called condensation level. This quantity is also known as the water vapor density.

What is Psychrometric Chart? Introduction to Reading the Psychrometric Properties of Air

The four equations highlighted above were programmed in MATLAB and chaet to plot the simplified psychrometric charts shown above. A simplified definition is the temperature at which the water vapour turns into “dew” Chamunoda Zambuko The inner scale represents sensible-total heat ratio SHF.

The “Mollier i – x ” Enthalpy – Humidity Mixing Ratio diagram, developed by Richard Mollier in[12] is an alternative psychrometric chart, preferred by many users in Scandinavia, Eastern Europe, and Russia. An interesting application of using a swamp cooler to cool drinking water in extremely hot environments is described in the posting of Rich Oppel in the At War blog of the New York Times: