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Teaching Psychrometry To Undergraduates

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2007 Annual Conference & Exposition


Honolulu, Hawaii

Publication Date

June 24, 2007

Start Date

June 24, 2007

End Date

June 27, 2007



Conference Session

Thermodynamics and Fluid Mechanics Instruction

Tagged Division

Mechanical Engineering

Page Count


Page Numbers

12.1369.1 - 12.1369.13



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Paper Authors

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Michael Maixner U.S. Air Force Academy

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James Baughn University of California-Davis

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NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

Teaching Psychrometry to Undergraduates by Michael R. Maixner United States Air Force Academy


James W. Baughn University of California at Davis


A mutli-faceted approach (lecture, spreadsheet and laboratory) used to teach introductory psychrometric concepts and processes is reviewed. During introductory lectures, basic thermodynamic principles are employed in the presentation of elementary psychrometric processes; various process lines are shown not only on traditional psychrometric charts, but also on temperature- volume diagrams, with which the students are already familiar. During their first exposure to psychrometry, most students usually find the layout and interpretation of the psychrometric chart particularly difficult to comprehend; in the current approach, an interactive psychrometric chart (written in Excel™ using Visual Basic for Applications) allows students to use sliding bars to visualize in real time how lines of constant relative humidity, specific volume, and wet bulb temperature vary; the effect of varying barometric pressure may also be viewed by using another sliding bar. Students are then required to construct their own psychrometric charts in a parametric fashion, producing lines of constant relative humidity, specific volume, and wet bulb temperature; these charts are produced for the prevailing barometric pressure, rather than for standard atmospheric pressure. The instruction is supplemented with a simple laboratory, wherein wet and dry bulb temperatures are measured inside the classroom and outside, and which are, in turn, used to calculate relative humidity, specific humidity, and other parameters associated with the building air conditioning process. An integral part of this laboratory is that the psychrometric chart previously produced by each student in Excel™ is employed in the analysis—since it was constructed for the barometric pressure which was recorded during the experiment, students may use it in their data reduction, rather than the chart provided in their text (for standard atmospheric pressure). This synergistic approach has been found to enhance student understanding of the basic psychrometric and HVAC processes.

Maixner, M., & Baughn, J. (2007, June), Teaching Psychrometry To Undergraduates Paper presented at 2007 Annual Conference & Exposition, Honolulu, Hawaii. 10.18260/1-2--1568

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