When the air sample is pre-saturated with water, the WBT will read the same as the DBT. In practice this is the reading of a thermometer whose sensing bulb is covered with a wet sock evaporating into a rapid stream of the sample air (see Hygrometer). Wet-bulb temperature (WBT)is that of an air sample after it has passed through a constant-pressure, ideal, adiabatic saturation process, that is, after the air has passed over a large surface of liquid water in an insulated channel. The SI units for temperature are kelvins or degrees Celsius other units are degrees Fahrenheit and degrees Rankine. It is typically plotted as the abscissa (horizontal axis) of the graph.
#Carrier psychrometric chart answers for hvac series
This is the series of articles that describes psychrometric chart and various psychrometric processes like sensible heating, sensible cooling, humidification, de-dumidification, evaporative cooling etc.Dry-bulb temperature (DBT)is that of an air sample, as determined by an ordinary thermometer.
The outermost curve along the left side indicates the Wet Bulb (WB) temperature scale.
The horizontal lines starting from this vertical scale are constant moisture lines. The moisture present within the air is indicated by the vertical scale located towards the extreme right. Moisture content is the water vapor present in the air and is measured in gram per kg of dry air (gm/kg of dry air). The vertical lines shown in the chart are the constant DB temperature lines and all the points located along a particular vertical line have same DB temperature.
The DB temperature increases from the left to the right. The dry bulb temperature scale is shown along the base of the shoe shaped psychrometric chart forming the sole. The various lines shown in the chart are as follows (please refer the figs below): The psychrometric chart looks like a shoe. For other pressures relevant corrections have to be applied. Various Lines and Curves in the Psychrometric ChartĪll the properties of air indicated in the psychrometric chart are calculated at the standard atmospheric pressure. You will also understand its worth when you actually use it considering the fact that you won’t have to use any formulae to find the properties of air in different conditions, all you will have to know is two parameters of air and the rest are easily found on the chart. The psychrometric chart looks complicated with vast numbers of lines and curves in it, but is very easy to understand if you know the basic properties of air. By using psychrometric charts HVAC engineers can graphically analyze different types of psychrometric processes and find solution to many practical problems without having to carry out long and tedious mathematical calculations. Psychrometric charts are graphic representations of the psychrometric properties of air. The behavior of the air can be studied very conveniently and accurately by using a psychrometric chart. We shall now see how the air behaves when it is subjected to changes in temperature and humidity to suit the various applications for which the air conditioning is meant. The series of articles on properties of air discussed important properties of air like relative humidity, dry bulb temperature, wet bulb temperature, dew point temperature, sensible heat and latent heat.
0 kommentar(er)
