1. The document discusses principles of air conditioning system design, including factors that affect comfort, steps in selecting a system, equipment used, and classifications of systems. 2. Systems are classified by purpose, season, arrangement of equipment, and fluid media used. Common classifications include comfort air conditioning, industrial, unitary, central, all-air, all-water, and air-water systems. 3. Descriptions of specific system types are provided, such as single duct constant volume systems, dual duct systems, and all-water systems.

1. Al-Mustaqbal University Collage
Air Conditioning and Refrigeration
Techniques Engineering Department
Principles of air conditioning
system design
Prepared by
Dr. Qusay Rasheed

2. Air conditioning is the process of altering the
properties of air (temperature and humidity) to more
favorable conditions.
Factors affecting comfort air conditioning
1- Temperature of air:
2- Humidity of air:
3- Purity of air:
4- Motion of air (Air distribution):

3. Steps involved in deciding the system (Selection system):
‫النظام‬ ‫تحديد‬ ‫في‬ ‫المتبعة‬ ‫الخطوات‬
• 1-Calculation of cooling load requirement ‫احتساب‬
‫متطلبات‬
‫حمل‬
‫التبريد‬
• -Physical dimension of space
• -Ceiling height
• -Constriction material
• -Inside room design conditions
• -Ambient conditions
• -Glass area exposed to sun
• -Occupancy
• -Lighting load
• -Equipment load
• -Infiltration of outside air
• 2- Selecting of equipment ‫اختيار‬
‫المعدات‬
• 3- Designing air distribution system ‫تصميم‬
‫نظام‬
‫توزيع‬
‫الهواء‬
• 4- Designing water distribution system ‫تصميم‬
‫نظام‬
‫توزيع‬
‫المياه‬
• 5- Evaluation of system to be used ‫تقييم‬
‫النظام‬
‫المراد‬
‫استخدامه‬

4. Equipment used in an Air Conditioning System
• Air conditioning unit
• Circulation fan
• Supply duct
• Supply outlets
• Return outlets
• Filters

5. • Classification of air conditioning systems:
• According to the purpose ( or applications)
• 1-Comfort air conditioning system: The comfort air conditioning may be
used for homes, offices, supermarkets, restaurants, theaters, hospitals,
schools, aircraft, automobiles, etc.
Recommendations: winter (20 °C to 22 °C) and RH = 40%
summer (22 °C to 24 °C ) and RH = 60%
• 2- Industrial air conditioning system: This system is used in textile mills,
paper mills, electronic products, etc.
• According to the season of the year
• 1- Summer air conditioning system
• 2- Winter air conditioning system
• 3- Year-round air conditioning system

6. According to the arrangement of equipment
1- Unitary air conditioning system
∎Window air conditioner
∎Split air conditioner
∎Package air conditioner
2- Central air conditioning system for single zone or multizone
∎ Central air conditioning system with CAV air-handling units
∎ Central air conditioning system with VAV air-handling units
∎ Central air conditioning system with fan-coil units (All water system)

7. Unitary air conditioning system
:
2 TR)
)
∎Window air conditioner

8. ∎ Split air conditioner (2 -5 TR)

9. ∎Package air conditioner (3-15 TR)

11. Central air conditioning system for single zone or multizone

12. According to the fluid media used in thermal distribution system
1-All air system: These systems can be divided into:
• Single duct systems can be classified into
• 1- Constant volume, single zone systems
• 2- Constant volume, multiple zone systems
• 3- Variable Air Volume (VAV) systems
• Dual duct systems are classified as:
• 1-Constant volume systems and
• 2-Variable air volume systems
2-All water system:
3-Air-water system:
4-Unitary refrigerant-based systems: like window air conditioner, split
air conditioner

13. Single duct systems can be classified into
1- Constant volume, single zone systems
Properties: Simultaneous cooling and heating not possible
Applications : large open areas such as theatres and auditoria
2- Constant volume, multiple zone systems
Properties: Simultaneous cooling and heating not possible
Higher energy consumption
Applications: small space requirements
3- Variable Air Volume (VAV) systems
• Properties: Variable volume of air is supplied to each zone
Lower energy consumption
• Applications: Small space requirements

14. 1-Dual duct systems, constant volume systems (multi-zone):
2-Dual duct, variable air volume systems:
Dual duct systems
Properties: Simultaneous cooling and heating possible
Constant volume of air is supplied to each zone
High energy consumption
Applications: office buildings, schools, or buildings
with a number of floors and zones with varying loads.
Same above but with variable volume flow rate

15. All -water systems (using piping system)
> Cold or hot water is the fluid used in the thermal distribution system (piping system)
 Depending upon the number of pipes used, the all-water systems can be classified
into a 2-pipe system or a 4-pipe system
 A 2-pipe system is used for either cooling only or heating only application.
 A pressure relief valve (PRF) is installed in the water line for maintaining balanced
flow rate.

16. Air-water systems:
• Both air and water processed in a central plant are used for providing required
conditions in the conditioned spaced for example a hydronic system
• . The air supplied from the central plant is called as primary air, while the water
supplied from the plant is called secondary water