PsychrometrySlide 2Psychrometric ChartProperties of AirThermometersDew PointSaturationRelative HumidityHumidity RatioAir Conditions on the Psychrometric ChartSpecific VolumeEnthalpyUsing the ChartAnswerCondensationCondensation (cont.)Comfort ZoneEffect of Adding Sensible HeatEffect of Removing Sensible HeatEffect of Adding MoistureEffect of Removing MoistureRemoving Sensible Heat and MoistureSlide 23Sensible and Latent Coil LoadsNext TimePsychrometryHVACCNST 305 Environmental Systems 1Dr. Berryman5c Indoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point Temp.Chapter 2.1 – 2.3 (Toa)2.11 Mathematics and Science - Physics (1hr); 4.11 Analysis and Design of Construction Systems - Mechanical (2 hrs)Psychrometry  Psychrometric ChartProperties of AirDry-bulb temperatureWet-bulb temperatureDew-point temperatureRelative humidityHumidity ratioThermometers Dry BulbWet BulbMeasured in degrees Fahrenheit (oF)Dew PointCondensation occurs at the Dew Point Temperature(oF)SaturationFog•Relative HumidityRelativeHumidityAmount of moisture that a given amount of air is holding=Amount of moisture that a given amount of air can hold50% RH100% RH - Saturated(percentage)Humidity Ratio   at sea level one pound of 70°F air occupies approximately 13.5 cubic feet, and one grain of water in that air weighs about two-thousandths (0.002) of an ouncewet bulbdew pointdew point30Dry-Bulb Temperature (°F)Dry-Bulb Temperature (°F)Humidity Ratio (grains/lb of dry air)Humidity Ratio (grains/lb of dry air)25 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 11020406080100120140160180200220humidity ratiohumidity ratiodry bulbrelative humidityAir Conditions on the Psychrometric ChartSpecific Volume14.013.013.514.5specific volume lines (cubic feet / pound of dry air)specific volume lines (cubic feet / pound of dry air)30Dry-Bulb Temperature (°F)Dry-Bulb Temperature (°F)Humidity Ratio (grains/lb of dry air)Humidity Ratio (grains/lb of dry air)25 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 11020406080100120140160180200220Enthalpy Enthalpy (h) = Sensible Heat + Latent HeatEXAMPLEUsing the ChartSummer Design Conditions95°F DB (dry bulb)78°F WB (wet bulb)Find:Relative HumidityHumidity RatioDew PointAnswer95°F95°F78°F78°F50%50%40%40%72°F72°FCondensationEXAMPLEBeach Conditions 92oF 60% RHBeverage 45oFCondensation (cont.)EXAMPLEWinter: Glass surface temperature = 40oFInside Design: 77oF 30% RHComfort Zonedry-bulb temperaturehumidity ratiowet-bulb temperature80°F[26.7°C]70°F[21.2°C]60 % RH30 % RHAAir Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999Effect of Adding Sensible HeatAir Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999Effect of Removing Sensible HeatAir Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999Effect of Adding MoistureAir Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999Effect of Removing MoistureAir Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999Removing Sensible Heat and MoistureAAAir Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999Removing Sensible Heat and MoistureAABBCCDDsensible loadsensible loadlatent loadlatent load32.732.723.523.529.629.6Air Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999Sensible and Latent Coil LoadsNext TimeCalculating Heating Loads•Section 2.5 ToaHeat