If you cool this compressed air, it will continue to be saturated, ie, RH=100% at the new conditions, even as more moisture condenses out. Humidity ratio or absolute humidity is defined as ( ) ( ) 0 622 ( ) ( ) 0.622 ( ) ( ) 0 622 P- P T P T. The compressed air would thus be saturated with a RH=100%. Now, by simply animating back and forth between the two chart types, most of that explanation becomes pretty obvious as you get to see very clearly the majority of psychrometric processes change from straight lines under the absolute humidity axis to complex curvilinear lines under relative humidity. Since you started with about 0.004 lb water/lb dry air, as read from a psychrometric chart, some water would condense out and would probably have to be removed. we found that a major hurdle was trying to convincingly explain why the psychrometric chart uses absolute humidity in the vertical axis instead of the more familiar metric of relative humidity, and why its characteristic curved layout is so important. The total pressure is: 90+14.7 = 104.7 psia at the compressor's exit.Ĭonvert to specific humidity: 0.622x0.5068/(104.7-0.5068)=Ġ.622 is the ratio of molecular weights for water and air. Humidification process along with cooling or heating is used in number of air conditioning applications.From tables obtain the vapor pressure of water at 80 deg F: 0.5068 psia.
The process in which the moisture or water vapor or humidity is added to the air without changing its dry bulb (DB) temperature is called as humidification process. RH (Absolute humidity/water saturation capacity at particular temperature)) 100.
It is based on ASHRAE correlations and is more than accurate enough for HVAC. They are often used to assess the properties of moist air. You can calculate these properties in any Excel spreadsheet: Enthalpy (h) Dewpoint Temperature (dp) Relative Humidity () Humidity Ratio (W) Specific Volume (v) Wet Bulb Temperature (wb) Can also quickly and easily plot points on a psychrometric chart. Get Psyched will allow you to do psychrometric calculations in MS Excel. Psychrometric charts are complex graphs that can be used to assess the physical and thermodynamic properties of gas-vapour mixtures at a constant pressure. Similarly one may ask, what is a psychrometric chart used for? A psychrometric chart can be used in two different ways. Check the vertical or Y axis for the humidity ratio. Psychrometric processes include physical and thermodynamic properties such as dry bulb temperature, wet bulb temperature, humidity, enthalpy, and air density. To read a psychometric chart, find the dry bulb temperature on the horizontal or X axis. Likewise, what do you mean by psychrometric chart? A psychrometric chart is a graphical representation of the psychrometric processes of air. Some of the common psychrometric processes carried out on air are: sensible heating and cooling of air, humidification and dehumidification of air, mixing of various streams of air, or there may be combinations of the various processes. Likewise, people ask, what are the psychrometric process in HVAC? It helps to describe climate data and human thermal comfort conditions. The Psychrometric Chart is a graphic representation of the relationship between air temperature and humidity.