PPT: Psychrometric Process | Thermodynamics - Mechanical Engineering PDF Download

 Page 1


CONTENTS
? What is PSYCHROMETRY?
? Properties of 
PSYCHROMETRY
? PSYCHROMETRIC Processes
? PSYCHROMETRIC CHART
Page 2


CONTENTS
? What is PSYCHROMETRY?
? Properties of 
PSYCHROMETRY
? PSYCHROMETRIC Processes
? PSYCHROMETRIC CHART
Psychrometry
O Psychrometry is the science dealing 
with the physical laws of air – water 
vapour
mixtures.
O 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.
O In other words, we can say that 
Psychrometry is the study of MOIST 
AIR or mixture of dry air and water 
vapour.
Page 3


CONTENTS
? What is PSYCHROMETRY?
? Properties of 
PSYCHROMETRY
? PSYCHROMETRIC Processes
? PSYCHROMETRIC CHART
Psychrometry
O Psychrometry is the science dealing 
with the physical laws of air – water 
vapour
mixtures.
O 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.
O In other words, we can say that 
Psychrometry is the study of MOIST 
AIR or mixture of dry air and water 
vapour.
PROPERTIES OF 
PSYCHROMETRY
? DEW POINT TEMPERATURE
? RELATIVE HUMIDITY
? HUMIDITY RATIO
? DRY-BULB TEMPERATURE
? WET BULB TEMPERATURE
? HUMIDITY
• Specific humidity
• Absolute humidity
? PSYCHROMETRIC RATIO
Page 4


CONTENTS
? What is PSYCHROMETRY?
? Properties of 
PSYCHROMETRY
? PSYCHROMETRIC Processes
? PSYCHROMETRIC CHART
Psychrometry
O Psychrometry is the science dealing 
with the physical laws of air – water 
vapour
mixtures.
O 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.
O In other words, we can say that 
Psychrometry is the study of MOIST 
AIR or mixture of dry air and water 
vapour.
PROPERTIES OF 
PSYCHROMETRY
? DEW POINT TEMPERATURE
? RELATIVE HUMIDITY
? HUMIDITY RATIO
? DRY-BULB TEMPERATURE
? WET BULB TEMPERATURE
? HUMIDITY
• Specific humidity
• Absolute humidity
? PSYCHROMETRIC RATIO
Dew Point
O The temperature at which moisture starts to 
condense out of the air is known as DEW POINT.
O Dew point is also known as saturation temperature. 
O Dew point temperature is determined by moving 
from a state point horizontally to the left along lines 
of constant humidity ratio until the upper, curved, 
saturation temperature boundary is reached.
Page 5


CONTENTS
? What is PSYCHROMETRY?
? Properties of 
PSYCHROMETRY
? PSYCHROMETRIC Processes
? PSYCHROMETRIC CHART
Psychrometry
O Psychrometry is the science dealing 
with the physical laws of air – water 
vapour
mixtures.
O 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.
O In other words, we can say that 
Psychrometry is the study of MOIST 
AIR or mixture of dry air and water 
vapour.
PROPERTIES OF 
PSYCHROMETRY
? DEW POINT TEMPERATURE
? RELATIVE HUMIDITY
? HUMIDITY RATIO
? DRY-BULB TEMPERATURE
? WET BULB TEMPERATURE
? HUMIDITY
• Specific humidity
• Absolute humidity
? PSYCHROMETRIC RATIO
Dew Point
O The temperature at which moisture starts to 
condense out of the air is known as DEW POINT.
O Dew point is also known as saturation temperature. 
O Dew point temperature is determined by moving 
from a state point horizontally to the left along lines 
of constant humidity ratio until the upper, curved, 
saturation temperature boundary is reached.
Dew Point
OCondensatio
n occurs at 
the Dew 
Point 
Temperature