Psychrometrics and Moist Air Properties Flashcards
7 cards from real ASHRAE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Psychrometrics and Moist Air Properties flashcards as text
What is the dry-bulb temperature of air?
Answer: Temperature measured by a standard thermometer shielded from radiation and unaffected by moisture evaporation
Dry-bulb temperature is the temperature of air measured by a standard thermometer shielded from radiation and not influenced by moisture content or evaporation.
What does wet-bulb temperature primarily indicate about an air sample?
Answer: The cooling effect of evaporation, which correlates with the moisture content of the air
Wet-bulb temperature measures the cooling effect of water evaporating from a wetted thermometer wick, providing an indirect measure of the air's moisture content.
On a standard psychrometric chart, what does the saturation curve (outer boundary) represent?
Answer: All states where relative humidity equals 100%
The saturation curve is the locus of all air states at 100% relative humidity, representing fully saturated air at each dry-bulb temperature.
How is humidity ratio (W) defined in psychrometrics?
Answer: Ratio of water vapor mass to dry air mass
Humidity ratio W is defined as the mass of water vapor per unit mass of dry air (lb_w/lb_da or kg_w/kg_da), and remains constant during sensible heating or cooling.
What is the dew point temperature of an air sample?
Answer: The temperature to which air must be cooled at constant pressure for condensation to begin
Dew point is the temperature at which air, cooled at constant pressure and constant humidity ratio, reaches saturation and water vapor begins to condense.
In psychrometrics, what does enthalpy (h) represent?
Answer: Total heat content per unit mass of dry air including both sensible heat and latent heat of water vapor
Enthalpy in psychrometrics is the total heat content (sensible + latent) referenced per unit mass of dry air, encompassing both dry air energy and the energy of the associated water vapor.
What standard atmospheric pressure does ASHRAE use as the baseline for psychrometric calculations?
Answer: 14.696 psia (101.325 kPa)
ASHRAE uses the internationally recognized standard atmospheric pressure of 14.696 psia (101.325 kPa) as the baseline for all psychrometric tables, equations, and charts.