Software Tools to Calculate Moist Air Properties for Psychrometric Process Analysis

초록

Purpose: This study aimed to develop software tools for psychrometric education and analyzed the accuracy of used models. Methods: Two psychrometric software tools were developed. One tool is based on an ASABE standard and calculates moist air properties and displays state point migration on a psychrometric chart pane according to user input sequences. The other tool is mainly based on ASHRAE equations with a few modifications to improve accuracy. It calculates moist air properties when two property values out of nine are provided in 1 out of 13 parameter combinations. The accuracy of the tools is addressed at 15 selected state points referring to a real gas model for a temperature range of 5–50 °C. Results: The first tool showed an accuracy of 99.12%. However, at an extremely cool and dry condition (5 °C and 2.02% RH), it failed because of extrapolation beyond the applicable range of saturation line equation. The second tool showed an accuracy of 99.68%. Among the situations of input properties, the best performance was obtained with an accuracy of 99.85% wherein dry-bulb and dew-point temperatures are provided. When dry-bulb temperature and specific volume are provided, the lowest accuracy of 99.20% was obtained. Conclusions: Both tools can be used in air-conditioning and psychrometric courses for analyzing and visualizing moist air processes with sufficient accuracy. © 2021, The Korean Society for Agricultural Machinery.

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