Applied thermal engineering 1 (psychometric, AC systems)

Applied Thermal Engineering - I

UNIT – V (Part – A)

Psychrometry and Air-Conditioning

,Contents:
• Introduction

Psychrometry • Psychrometric terms
• Psychrometric chart
• Psychrometric processes

• Summer A/C system
A/C systems
• Winter A/C system
• Year around A/C system

,Psychrometry:
The art of measuring the moisture content of air is termed
‘Psychrometry’.


Psychrometric:
The science which investigates the thermal properties of moist air,
considers the measurement and control of the moisture content of
air, and studies the effect of atmospheric moisture on material and
human comfort may properly be termed ‘psychrometric’.

, Psychrometric terms
Dry air:
When there is no water vapour contained in the air, it is called dry
air. Dry air is never found in practice. Air always contains some
moisture. Hence the common designation “air” usually means moist
air.
Moist air:
When there is water vapour present in the air, it is called moist air.
Saturated air:
Saturated air is the moist air where the partial pressure of water-vapor
(PV) equals the saturation pressure of steam (PVS) corresponding to the
temperature of air.