DA-88-28-4 -- A Methodology for Implementing a Psychrometric Chart in a Computer Graphics System PDF

A methodology is presented for plotting psychrometric charts by the use of a commercially available computer graphics system. This methodology also includes the presentation of the fundamental equations of psychrometrics, specifically the interrelationships between various thermodynamic properties of atmospheric air. Three entry parameters are selected in order to define the boundaries and scale of the chart. These parameters are the barometric pressure, the range of dry-bulb temperatures, and the upper limit for humidity ratio. The ranges of wet-bulb temperatures, enthalpies, and specific volumes are then determined by the computer program in accordance with the input parameters. Procedures for plotting lines of constant relative humidity wet-bulb temperature, enthalpy, and specific volume are illustrated by using a commercially available computer graphics system. A scale for sensible heat ratio is also constructed for use in air-conditioning processes. This method can be used to solve problems involving basic HVACp rocesses so that engineering students can better understand applied thermodynamics.

Units: Dual