Psychrometry HVAC CNST 305 Environmental Systems 1 Dr. 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)
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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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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)
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.
Psychrometric Chart
Properties of Air Dry-bulb temperature Wet-bulb temperature Dew-point temperature Relative humidity Humidity ratio
Thermometers
Dry Bulb
Wet Bulb
Measured in degrees Fahrenheit (oF)
Dew Point Condensation occurs at the Dew Point Temperature
(oF)
Saturation
Fog• DP, WB, DB same
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)
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
wet bulb
dew pointdew point
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Dry-Bulb Temperature (°F)Dry-Bulb Temperature (°F)