psychrometry hvac cnst 305 environmental systems 1 dr. berryman 5cindoor air quality, psychometrics;...
Post on 19-Dec-2015
214 views
TRANSCRIPT
![Page 1: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/1.jpg)
Psychrometry
HVAC
CNST 305 Environmental Systems 1Dr. Berryman
5c 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)
![Page 2: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/2.jpg)
Psychrometry Psychrometry is the science dealing with
the physical laws of air – watermixtures.
When designing an air conditioning system, the temperature and moisture content of the air to be conditioned, and the same properties of the air needed to produce the desired air conditioning effect, must be known.
Once these properties are known, the air conditioning task can be determined.
![Page 3: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/3.jpg)
Psychrometric Chart
![Page 4: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/4.jpg)
Properties of Air Dry-bulb temperature Wet-bulb temperature Dew-point temperature Relative humidity Humidity ratio
![Page 5: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/5.jpg)
Thermometers
Dry Bulb
Wet Bulb
Measured in degrees Fahrenheit (oF)
![Page 6: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/6.jpg)
Dew Point Condensation occurs at the Dew Point Temperature
(oF)
![Page 7: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/7.jpg)
Saturation
Fog• DP, WB, DB same
![Page 8: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/8.jpg)
Relative Humidity
RelativeHumidity
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)
![Page 9: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/9.jpg)
Humidity Ratio Actual weight of water in
an air – water vapor mixture
Pounds of moisture per pound of dry air
7000 grains of water in a pound
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
![Page 10: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/10.jpg)
wet bulb
dew pointdew point
30
Dry-Bulb Temperature (°F)Dry-Bulb Temperature (°F)
Hum
idity
Rat
io (g
rain
s/lb
of d
ry a
ir)Hu
mid
ity R
atio
(gra
ins/
lb o
f dry
air)
25 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110
20
40
60
80
100
120
140
160
180
200
220
humidity ratiohumidity ratio
dry bulbrelative humidity
Air Conditions on the Psychrometric Chart
![Page 11: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/11.jpg)
Specific Volume
14.013.0
13.5
14.5
specific volume lines (cubic feet / pound of dry air)specific volume lines (cubic feet / pound of dry air)
30
Dry-Bulb Temperature (°F)Dry-Bulb Temperature (°F)
Hum
idity
Rat
io (g
rain
s/lb
of d
ry a
ir)Hu
mid
ity R
atio
(gra
ins/
lb o
f dry
air)
25 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110
20
40
60
80
100
120
140
160
180
200
220
![Page 12: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/12.jpg)
Enthalpy The total heat energy in one pound of air
(Btu/lb) at its present condition
Enthalpy (h) = Sensible Heat + Latent Heat
![Page 13: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/13.jpg)
EXAMPLEUsing the Chart Summer Design Conditions
95°F DB (dry bulb) 78°F WB (wet bulb)
Find:
Relative Humidity
Humidity Ratio
Dew Point
![Page 14: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/14.jpg)
Answer
95°F95°F
78°F78°F
50%
50%
40%
40%
72°F72°F
![Page 15: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/15.jpg)
Condensation
EXAMPLEBeach Conditions 92oF 60% RH
Beverage 45oF
![Page 16: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/16.jpg)
Condensation (cont.)
EXAMPLEWinter: Glass surface temperature = 40oF
Inside Design: 77oF 30% RH
![Page 17: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/17.jpg)
Comfort Zone
dry-bulb temperature
humidity ratio
wet-bulb temperature
80°F[26.7°C]
70°F[21.2°C]
60 %
RH
30 % RHA
![Page 18: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/18.jpg)
Air Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999
Effect of Adding Sensible Heat
![Page 19: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/19.jpg)
Air Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999
Effect of Removing Sensible Heat
![Page 20: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/20.jpg)
Air Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999
Effect of Adding Moisture
![Page 21: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/21.jpg)
Air Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999
Effect of Removing Moisture
![Page 22: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/22.jpg)
Air Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999
Removing Sensible Heat and Moisture
![Page 23: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/23.jpg)
AA
Air Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999
Removing Sensible Heat and Moisture
![Page 24: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/24.jpg)
AA
BB
CC
DD
sensible load
sensible load
latent load
latent load
32.732.7
23.523.5
29.629.6
Air Conditioning Clinic TRG-TRC001-ENAir Conditioning Clinic TRG-TRC001-EN© American Standard Inc. 1999
Sensible and Latent Coil Loads
![Page 25: Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. Berryman 5cIndoor Air Quality, Psychometrics; Dry and Wet Bulb; Enthalpy; Condensation; Dew Point](https://reader036.vdocuments.us/reader036/viewer/2022081519/56649d365503460f94a0d6a0/html5/thumbnails/25.jpg)
Next Time Calculating Heating Loads
• Section 2.5 Toa
Heat Transmission