Mvac

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  • Topic: HVAC, Heating, ventilating, and air conditioning, Heat transfer
  • Pages : 33 (5793 words )
  • Download(s) : 121
  • Published : February 19, 2013
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BRE 349 Building Service 1
Practices

of

Sustainable

Centralized

Air-Conditioning System in Hong Kong

Bachelor of Science (Hons) in
Building Engineering and Management
Group Members:
Man Kai Chun, Simon

11915174t

Lam Ting Yung, Vincent

11904590t

Lam Wing Kit, Ricky

11923727t

Content pages
1.

Introduction to MVAC System
I. All air system
i.
Single Zone System
ii.
The reheat system
iii.
Variable Air Volume System
iv.
Dual Duct System
v.
Multi Zone System
II. All water system
i.
The Fan Coil Unit
ii.
Water cooling tower
III. Air and water system
i.
Induction System

2.

ii.
Fan-Coil System
iii.
Radiant Panels System
iv.
Two Pipe System
v.
Three Pipe System
vi.
Four pipe Systems
Other Concepts in MVAC system
Air Side Equipments
I.
II.

Displacement ventilation
Heat recovery equipment for air-side equipment
i.
Thermal wheel and Desiccant total energy heat recovery wheel ii.
Heat Pipes
iii.
Run-around coils
III. Liquid desiccant air conditioners
IV. Microchannel heat exchanger
V. Radiant ceiling cooling
Water Side Equipments
VI. Scale control technologies in water-side system
i.
Automatic tube cleaning system
ii.
Dynamic-type pulsed-power devices (PPD)
iii.
Static-type magneto-hydrodynamic devices (MHD)
VII. Heat recovery equipment for water-side equipment
i.
Plate Heat Exchangers
ii.
Heat recovery chiller
VIII. Thermal energy storage

IX. Water-cooled air conditioning system

3.

i.
Cooling Tower Scheme
ii.
Central Sea Water Scheme
iii.
District Cooling Scheme
Case Study
I.

A&A Works for New Advanced Ophthalmology Training and Education Centre on Roof

4.

Conclusion

5.

References

1. Introduction to MVAC System
MVAC.(Mechanical Ventilation and Air-Conditioning)system is designed to change the air temperature and humidity within an area, such as remove the heat from indoor air for thermal comfort,and typically using a refrigeration cycle. The MVAC system can basically divided in two categories,

a) The Direct expansion Systems: It refers to the direct expansion of refrigerant, without the chilled water cooling medium.
b) The Chilled water air conditioning systems:It is commonly used in applications that need large cooling capacity such as the high-rise residential building, commercial building such as offices and factories, because of its cost-effectiveness and efficiency all over the large area, and there are 3 basic system categories. I. - All Air System

II. - All Water system
III. - Air and water system

I. All Air System
All-air systems transfer cooled or heated air from a central plant via ducting,It normally comprises the cheapest equipment cost, but is not necessarily easy to install in a building due to the size of ducting required.

Single Zone System
-One duct system
-Used mostly in small buildings
-All spaces controlled by a single thermostat
-Single air return
-Heating requirement is uniform throughout the structure.

Fig.1.I.1 : Single zone system

The reheat system
-It is a modification of the single-zone system.
-Also is a Single duct system
-The main different with compare to the single zone system is the heat is added as a secondary process to either preconditioned primary air or recirculated room air. The heating medium can be hot water, steam or electricity.

-But there is expensive to operate because of the wastage of energy.

Fig.1.I.2 : Reheat system

Variable Air Volume System
- Used mostly in large buildings
-The variable air volume system compensates for varying cooling loads by regulating the volume of cooling air supplied through a single duct.
-This VAV system consists of a VAV Box-the box that can
hold a variable amount of air. It helps make air conditioning systems more efficient by regulating the amount of cooling targeted toward any specific room or area.

VAV Box

Fig.1.I.3: VAV system

Dual Duct System
-Employs two air ducts to...
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