Psychrometric Analysis Software: A Powerful Tool for HVAC Design and Engineering
Latent heat is the energy required to change the state of matter from a solid to a liquid. In the greenhouse and livestock building, this heat is produced by evaporation of water from a surface. The greater the latent heat, the higher the temperature at which this energy is absorbed. On the psychrometric chart, the latent heat values are shown below the dry-bulb temperature scale. Latent heat is also known as specific heat and is given a value of 46.5 joules per pound at 0C (32F).
psychrometric analysis software
The term Moist-Warm Dry Air (MWDA) describes air that is both humid and warm (relative humidity [RH]>50%). On a psychrometric chart, MWDA is shown as a thicker horizontal line, which becomes considerably cooler and steeper when moving from the upper boundary to the lower boundary. The steeper line indicates that this air is holding a greater relative humidity. The series of horizontal lines which extend beneath MWDA display the air's saturation temperature, T sat (or T o saturated), where T sat= T o + 10.5C. If MWDA existed at any one point in the building, then the T satwould be shown at the crossing of the horizontal line and the vertical line. It is unlikely that an air stream within a building would be at the same temperature as the outside air. Thus, the T satof the outside air is typically used as the T satof building air. The upper limit T satmeans that the relative humidity cannot exceed the maximum reading on the chart. The lower limit T satmeans that the relative humidity must not exceed 50% at the specified air temperature (T o).