Psychrometry

Question 1

psychrometry is the study of:

Answer 1

thermodynamic behaviours of water vapor mixtures

Question 2

What instruments are used to measure relative humidity?

Answer 2

hygrometer

sling psychrometer

Question 3

The common psychrometric parameters: (5)

Answer 3

wet bulb temp, 
dry bulb temp, 
RH%, 
absolute humidity, 
dew point

Question 4

What tool is use to relate psychometric variables to each other?

Answer 4

psychrometric chart

Question 5

Describe where each variable is located on the chart:

Answer 5

absolute humidity: right y axis
relative humidity: curved diagonal lines
dew point: dry bulb temp at which RH = 100% (at that absolute humidity)
dry bulb: x axis
wet bulb: straight diagonal lines

Question 6

How does wet bulb and dry bulb temperature compare, in value and measurement method?

Answer 6

measurement:
dry bulb use normal thermometer, wet bulb has wetted wick
wet bulb will be COOLER, due to water evaporating; temperature difference will draw heat from air -> reach dynamic equilibrium

Question 7

Can wet bulb temperature and dry bulb temperature be the same?

Answer 7

yes, if RH = 100%

Question 8

A minimum of ___ psychrometric variables is needed to determine all other variables by plotting the ____ ____.

Answer 8

2

state point

Question 9

Psychrometry calculations are important in what applications?

Answer 9

Heating/Cooling
Humidification/Dehumidification
Dehydration

Question 10

Changing temperature without affecting absolute humidity is: _____. What happens to RH?

Answer 10

adiabatic (humidification/dehumidification)
temp increase -> RH decrease
temp decrease -> RH increase

Question 11

What is isothermal humidification/dehumidification?

Answer 11

changing absolute humidity without affecting temperature