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Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point.

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Presentation on theme: "Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point."— Presentation transcript:

1 Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor 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)

2 Psychrometry

3 Psychrometric Chart

4 Properties of Air Dry-bulb temperature Wet-bulb temperature Dew-point temperature Relative humidity Humidity ratio

5 Thermometers Dry Bulb Wet Bulb Measured in degrees Fahrenheit ( o F)

6 Dew Point Condensation occurs at the Dew Point Temperature ( o F)

7 Saturation Fog

8 Relative Humidity Amount of moisture that a given amount of air is holding = Amount of moisture that a given amount of air can hold 50% RH 100% RH - Saturated (percentage)

9 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 ounce

10 wet bulb dew point 30 Dry-Bulb Temperature (°F) Humidity Ratio (grains/lb of dry air) humidity ratio dry bulb relative humidity Air Conditions on the Psychrometric Chart

11 Specific Volume specific volume lines (cubic feet / pound of dry air) specific volume lines (cubic feet / pound of dry air) 30 Dry-Bulb Temperature (°F) Humidity Ratio (grains/lb of dry air)

12 Enthalpy Enthalpy (h) = Sensible Heat + Latent Heat

13 EXAMPLE Using the Chart Summer Design Conditions 95°F DB (dry bulb) 78°F WB (wet bulb) Find: Relative Humidity Humidity Ratio Dew Point

14 Answer 95°F 78°F 50% 40% 72°F

15 Condensation EXAMPLE Beach Conditions 92 o F 60% RH Beverage 45 o F

16 Condensation (cont.) EXAMPLE Winter: Glass surface temperature = 40 o F Inside Design: 77 o F 30% RH

17 Comfort Zone dry-bulb temperature humidity ratio wet-bulb temperature 80°F [26.7°C] 70°F [21.2°C] 60 % RH 30 % RH A

18 Air Conditioning Clinic TRG-TRC001-EN © American Standard Inc Effect of Adding Sensible Heat

19 Air Conditioning Clinic TRG-TRC001-EN © American Standard Inc Effect of Removing Sensible Heat

20 Air Conditioning Clinic TRG-TRC001-EN © American Standard Inc Effect of Adding Moisture

21 Air Conditioning Clinic TRG-TRC001-EN © American Standard Inc Effect of Removing Moisture

22 Air Conditioning Clinic TRG-TRC001-EN © American Standard Inc Removing Sensible Heat and Moisture

23 A A Air Conditioning Clinic TRG-TRC001-EN © American Standard Inc Removing Sensible Heat and Moisture

24 A A B B C C D D sensible load latent load Air Conditioning Clinic TRG-TRC001-EN © American Standard Inc Sensible and Latent Coil Loads

25 Next Time Calculating Heating Loads Section 2.5 Toa Heat Transmission


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