PSYCHROMETRIC CHART

Abscissa is the dry bulb temperature. The right hand side ordinate provides humidity ratio. The equation (35.13) shows a direct relationship between w and P_w

According, the vapour pressure can also be shown as the ordinate (Figure 36.3). The curves of constant relative humidity are also drawn on the Psychometric Chart. On figure 36.3, the curves are labeled as Φ = 100%, 60% etc. Psychometric Charts also gives values of the mixture enthalpy per unit mass of dry air in the mixture. The constant wet bulb temperature T_WB lines run from the upper left to lower right of the chart. The relationship between the wet bulb temperature and other chart quantities are provided by using Eqn (35.22)

(36.9)

The lines of wet bulb temperature are approximately the lines of constant mixture enthalpy per unit mass of dry air.