Psychrometric Charts . .. . ASHRAE Fundamentals Handbook (SI) Mass of water added per unit mass of dry air is (W.* – W), which. AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR- CONDITIONING ENGINEERS, INC. T. SENSIBLE HEAT. 0. 5. DRY BULB TEMPERATURE – °C. 5.

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In meteorology and psychrometrics the word temperature by itself without a prefix usually means dry-bulb temperature. The thermodynamic wet-bulb temperature is a thermodynamic property of a mixture of air and water vapor. The dew point temperature is equal to the fully saturated dry bulb or wet bulb temperatures.

In addition, you can double-tap a point to display the point properties and then edit them. Architectural acoustics Architectural engineering Architectural technologist Building 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 chary Refrigerant reclamation Testing, adjusting, balancing.

These lines are oblique lines that differ slightly from the enthalpy lines.

A chart is valid for a given air pressure or elevation above sea level. Heating, ventilation and air conditioning. From any two independent ones of the six parameters dry bulb temperature, wet bulb temperature, relative humidity, humidity ratio, specific su, and specific volume, all the others can be determined.

However, in psychrometrics, the term quantifies the total volume of both the dry air and water vapour per unit mass of dry air.


Knowing both the dry-bulb temperature DBT and wet-bulb temperature WBTone can determine the relative humidity RH from the psychrometric chart appropriate to the air pressure.

Retrieved from ” https: Many substances are hygroscopicmeaning they attract water, usually in proportion to the relative humidity or above a critical relative humidity. As you move your finger around the graph, the psychrometric properties at the top of the screen dynamically update.


However, no warranty, either expressed or implied, is given with respect to the accuracy or the sufficiency of the information provided herein, and the user must assume all risks and responsibility in connection with the use thereof.

In psychrometrics, the term quantifies the total energy of both the dry air and water vapour per kilogram of dry air.

The term dry-bulb is customarily added to temperature to distinguish it from wet-bulb and dewpoint temperature. Also, you can create templates that you can reuse over and over again. 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. Also, create custom labels anywhere on the chart.

Load Calculation Applications Manual, 2nd ed. Android app no longer available. This page was last edited on 10 Mayat 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.

Industries that use these materials are concerned with relative humidity control in production and storage of such materials. A simplified definition is the temperature at which the water vapour turns into “dew” Chamunoda Zambuko The Mollier diagram coordinates are enthalpy and humidity ratio. Box Dayton, OH Email: The enthalpy coordinate is skewed and the lines of constant enthalpy are parallel and evenly spaced.

These are oblique lines drawn diagonally downward from left to right across the chart that are parallel to each other. 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.

Some psychrometric charts use dry-bulb temperature and humidity ratio coordinates. At the end of the calculation, the user has the option to convert from the English to the SI or vice versa unit system.


Dayton ASHRAE On-Line Psychrometrics

Molds and fungi can be controlled by keeping relative humidity low. The user then enters a desired Dry Bulb temperature and one of three humiditymetrics: The dry-bulb temperature is the temperature indicated by a thermometer exposed to the air uhits a place sheltered from direct solar radiation.

Retrieved 18 September Humid heat is the constant-pressure specific heat of moist air, per unit mass of the dry air. Pressure Liquid water Avogadro’s law Nucleation Thermodynamic equilibrium.

ASHRAE psychrometric chart SI [chart] – Catalog – UW-Madison Libraries

Usually the level at which water vapor changes into liquid marks the base of the cloud in the atmosphere hence called condensation level. The outer scale gives the ratio of enthalpy difference to humidity difference. Common atmospheric pressure values are: Common atmospheric pressure values are:. You show a ‘Virtual’ Temperature under Thermodynamic properties. 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 in value.

What is the difference between the six different humidity metrics shown? Easily plot HVAC and other psychrometric processes while out in the field, save the graphs, and then email the graph and results to yourself or clients. 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.

Technically, the temperature registered by the dry-bulb thermometer of a psychrometer. These intersect the saturation curve at DBT point.

The ratio of the vapor pressure of moisture in the sample to the saturation pressure at the dry bulb temperature of the sample.