Its value is always lower or equal to the dry-bulb temperature because of the cooling effect of the evaporation. The wet-bulb temperature is measured with a moistened thermometer and it will be the lowest temperature that can occur under adiabatic saturation of the air by evaporating water only. By definition, the relative humidity is the ratio of the actual vapor pressure to the vapor pressure of saturated air at the same temperature. This pressure is called the saturation pressure, and at this point, the absolute humidity-the quantity of water in the air (the ratio of the water vapor mass to the dry air mass)-is at its maximum and the relative humidity is 100%. At the point of saturation, the vapor pressure is so high that no more water can evaporate.
The mixture of the water vapor and the air can be considered as an ideal two-component gas system by the widely accepted simplification thus, the chemical potentials are directly proportional to the logarithm of the partial pressures. In other words, the propelling power will be the difference between the chemical potentials of water in the air as a whole and at the surface. The resulting water partial pressure of the air in the closest layer adjacent to the surface is equal to the vapor pressure that determines the total amount of water that can be evaporated into the air at a given temperature. Water vapor then exerts a force on that surface. Note: outer coefficient of heat transfer usually is 3~10, >10 when winds.Water evaporates when air touches its surface.Calculate duct flow resistance, environmental heat exchange, and adiabatic.Export wmf format file, can be opened and printed by image browser softwareas ACDSee, IE, smoothly zoomed.process line is shown in chart, press UpDown button to see process changing.Calculate once recycle and twice recycle air flow, summer and winter state.Range can be changed, Mouse move point calculation.Use IFC-67 equation for water/vapor property calculating, and treat air as ideal gas.Psychrometric Chart + Duct Calculator v1.2 Features Psychrometric chart Add copy(wmf and bmp format), export(Jpg, bmp, wmf, emf format) and print function.Add chart line type, width, color, font properties groups edit and managing.Add constant specific volume and wet bulb temperature line in chart.Add wet air point calculating, drawing and converting.Add process points line and mix point calculating, drawing and managing.Psychrometric Chart + Duct Calculator v2.0 shareware version Updates Option for saving all input data to disk before exit and load them when restarted next time.Save and load data function for each data input grid, this is convenient and not need to input data every time restart program.Add chart toolbar for easily processing chart copy, export, print, pan, zoom, redraw and style selection.Zoom in, zoom out chart by rolling mouse wheel, and pan chart by pressing middle mouse button and moving mouse.Add angle reference of process line ratio for enthalpy-humidity and sensible-total heat.
Add ASHRAE equation support at normal temperature and pressure region, now this psychrometric chart is perfectly consistent with all ASHRAE charts of No.1~7(SI Units) and No.1~5(IP Units).Coordinate system of psychrometric chart is updated to dry bulb temperature and enthalpy.Psychrometric Chart + Duct Calculator v4.4 shareware version Updates
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