HVAC, AC, Heat Air cooling

1. Mahfooz Alam 13 BME 0027
Mohammad Abdul Khaliq 13 BME 0036
Musawwir Alam 13 BME 0044
Nasir Aziz 13 BME 0046
Iftikhar Ahmed 11 MES 30
Design of A/C system for a Multiplex
Under Supervision of Prof. J. A. Usmani
Department of Mechanical Engineering,
Jamia Millia Islamia, New Delhi
Presented by :

2. ⚫INTRODUCTION
⚫TYPES OF AIR CONDITIONING
⚫DESIGN CRITERIA
⚫COOLING LOAD CALCULATION
⚫IMPORTANCE OF DESIGNING HVAC SYSTEMS
CONTENTS

3. The average summer temperatures experienced by most
countries are increasing every year and consequently
the energy needs to provide air-conditioning is also
increasing annually.
The HVAC industry has a challenging task of providing
energy efficient technologies to satisfy this growing
demand with a minimum impact on global warming
and ozone depletion.
INTRODUCTION

4. Humidity vs. Temperature chart

5. Need for Air Conditioning
• Fresh air circulation
• Maintaining Temperature
• Better Health
• Less Noise
• Increase in Efficiency of Humans

6. The comfort air-conditioning systems are divided into
three groups:
⚫ Summer-Air Conditioning System
⚫ Winter Air Conditioning System
⚫ Year Round Air Conditioning System
Comfort air-conditioning systems

7. The problems encountered in summer A/C are:
⚫To reduce the sensible heat
⚫To reduce water vapor content of the air by cooling
and dehumidifying
Summer-Air Conditioning System

8. The problem encountered in winter A/C:
⚫ To increase the sensible heat
⚫ To increase the water vapor content of air
Winter Air Conditioning System

9. Comparison of Winter & Summer air
conditioning system

10. This system assures the control of temperature and
humidity of air in an enclosed surface throughout of the
year, when the atmospheric conditions are changing as
per season. Its functions are :
⚫ Cooling & dehumidification of air in summer
⚫ Heating & humidification of air in winter
Year Round Air Conditioning
System

11. Comfort Air Conditioning Systems

12. For the purpose of designing air conditioning systems,
we consider the following:
✔ Cooling Load
✔ Heating Load
Design Criteria

13. To estimate the required cooling or heating capacities,
one has to have information regarding the following:
⚫ Design indoor and outdoor conditions
⚫ Specifications of the building
⚫ Specifications of the conditioned space
⚫ Any special requirements of the particular application
Cooling Load Calculation

14. Various Load Components

15. For estimating cooling loads, one has to consider the
unsteady state processes, as the peak cooling load
occurs during the day time and the outside conditions
also vary significantly throughout the day due to solar
radiation.
For any building there exists a balance point :
Cooling Load Calculation

16. ⮚ Tout > Tout,bal, then there is a need for cooling the
building
⮚Tout < Tout,bal, then there is a need for heating the
building
⮚Tout = Tout,bal, then there is no need for either
cooling or heating the building
Cooling Load Calculation

17. The assumptions behind design cooling load are as
follows:
1. Design outside conditions are selected from a long-
term statistical database.
2. The load on the building due to solar radiation is
estimated for clear sky conditions.
3. The building occupancy is assumed to be at full
design capacity.
4. All building equipment are considered to be
operating at a reasonably representative capacity.
Cooling Load Calculation

18. The total building cooling load consists of :
⚫Heat transferred through the building envelope
(walls, roof, floor, windows, doors etc.) (External
Load )
⚫Heat generated by occupants, equipment, and
lights(Internal Load).
Cooling Load Calculation

19. Cooling Load Calculation

20. ❑ Heat transfer through opaque surfaces :
where U is the overall heat transfer coefficient and A is
the heat transfer area of the surface on the side of the
conditioned space. CLTD is the cooling load
temperature difference.
Cooling Load Calculation

21. ⚫For sunlit surfaces, CLTD has to be obtained from the
CLTD tables.
⚫For surfaces which are not sunlit or which have
negligible thermal mass (such as doors), the CLTD
value is simply equal to the temperature difference
across the wall or roof.
Cooling Load Calculation

22. ❑ Load due to occupants:
❑ Load due to lighting:
❑ Internal loads due to equipment and appliances:
Cooling Load Calculation

23. Cooling Loads

24. ⮚ Healthy Air
⮚ System Life
⮚ Efficiency
⮚Less Emergency Repairs
⮚Increases Productivity
IMPORTANCE OF DESIGNING
HVAC SYSTEMS

25. Thank You