Civil Engineering Reference
In-Depth Information
their fi nal analysis. Considerations such as acoustical impact, space saving and
degree of affecting other trades are examples of these parameters. To include such
parameters in overall system effi ciency the most usual method is relying on expert
interview results as well as literature research, and not as part of the general body of
the simulation (Khazaii
2012
).
In order to reduce the consumed energy of each system, an important step is to
understand which equipment and other elements are used to construct the targeted
system and of course which parts of each equipment or element are the main
energy consumers. After completing this vital step we can concentrate on select-
ing and improving the effi ciency of these equipment and elements in order to
improve the overall system effi ciency. Here I will provide a brief informational
review of some of the most used current HVAC systems and specify its energy
consuming parts.
8.3
A Brief Review of the Most Applicable HVAC Systems
In this section I will investigate some of the most applicable HVAC systems as they
are commonly being utilized for conditioning of commercial buildings such as
offi ce buildings, institutional and healthcare facilities. The main target of this sec-
tion in addition to provide a general understanding about the different available
types of modern HVAC systems is to shed light on the major energy consuming
parts of each system that improving them can be translated to improvement of the
overall effi ciency of the system. For more detail see (Khazaii
2012
).
8.4
Chilled Water Systems (Chillers)
Chillers are the center piece of the chilled water systems which its function is to
generate proper chilled water quantity with proper temperature, in order to facilitate
cooling of the delivered air entering the targeted spaces and to remove the heat from
the inside of the building. This function is done by utilizing the cooling coil at main
air handling unit serving the targeted spaces. This removed heat from the spaces,
increases the chilled water temperature. Warmer chilled water heat then will be
transferred to the outdoor via a water-cooled (including cooling towers and pumps)
(Fig.
8.1
), or air-cooled mechanism. Chilled water systems are usually being utilized
in the larger systems because they have the advantage of better controllability than
the other alternatives such as direct expansion unitary (DX) systems. Chillers are
usually built and tested as package units in the factory, before delivery and installa-
tion on the site. This reduces the risk associated with lower quality fi eld labor and
testing procedure considerably.
In the heart of most of the chillers there is a refrigerant cycle which operates via
circulating an operating refrigerant, which is circulated and changes states to facilitate
