2010 HVACR/Plumbing Instructors Workshop Practical Psychrometrics Presented by Richard Wirtz, Associate Director of Education Heating, Air conditioning & Refrigeration Distributors International (HARDI) Thank you for being here today. For Everyone’s Consideration What seems to be the problem? Who teaches psychrometrics on a normal basis? Why is this area not taught more? Confusion? Misunderstanding? Intimidation? Let’s eliminate the confusion – Right Now. Air properties: Composition Weight Wet or Dry Specific Heat Pressure Volume The Chart Willis Carrier December 3, 1911 “Rational Psychrometric Formulae” ASME Psychro = cold Metrics = measure of Different temperature ranges Different elevations “Points on a Map” North H West East South Points on the “Map” Dry Bulb Wet Bulb Enthalpy Dew Point Relative Humidity Specific Volume Specific Density Specific Humidity (Grains of Moisture) Sensible Heat Dot Sensible Heat Factor Where’s Waldo??? North West East South Process line shows grains of moisture change as well as temperature change. Heating & Humidification Sensible Heating Only Cooling & Dehumidification Dry Bulb Enthalpy Wet Bulb Grains of Moisture Dew Point Relative Humidity Specific Volume Sensible heating only No change in the dew point or the grains of moisture. Let’s Do Some Quick Math Qs = Quantity of Sensible Heat 64,000 Net Output = 1.08 x CFM x ▲T 64,000 = 1.08 x CFM x 40 1481 CFM 64,000 = 1.08 x 1,481 x 40 Continuing QL = Quantity of Latent Heat QL = .68 x CFM x ▲Grains of Moisture QL = .68 x CFM x 0 QL = 0 QT = 4.5 x CFM x ▲Enthalpy QT = 4.5 x CFM x (31.62 – 21.79) QT = 4.5 x 1,481 x 9.83 QT = 65,911 64,000/65,512 = 97.69% or 2.31% difference Let’s Do Some More Quick Math Qs = Quantity of Sensible Heat 23,680 = 1.08 x CFM x ▲T 23,680 = 1.08 x 1,096 x 20 1.08 x 20 = 21.6 23,680/21.6 = 1,096 CFM Continuing QL = Quantity of Latent Heat QL = .68 x CFM x ▲Grains of Moisture QL = .68 x 1,096 x 8 QL = 5,962 Btu QT = 4.5 x CFM x ▲Enthalpy QT = 4.5 x 1,096 x (26.80 – 20.58) QT = 4.5 x 1,096 x 6.22 QT = 30,677 29,600/30,677 = 96.49% or 3.51% difference “Created Equal” does not mean “Equal Outcome” Additional Information Free software @ handsdownsoftware.com or from a manufacturer or wholesaler or someone here. Just ask someone. Carrier SST-03 “Air Properties and Measurement” Questions??