Design and Analysis of Central Air-Conditioning System With Air Cooled Chiller of Multi-Storey Office Building
Design and Analysis of Central Air-Conditioning System With Air Cooled Chiller of Multi-Storey Office Building
Design and Analysis of Central Air-Conditioning System With Air Cooled Chiller of Multi-Storey Office Building
Chillers:
A chiller is a machine which removes heat from a liquid via a vapor compression or absorption
refrigeration cycle. This liquid can then be circulated through a heat exchanger to cool air or
equipment as required. As a necessary byproduct, refrigeration creates waste heat that must be
exhausted to ambient or, for greater efficiency, recovered for heating purposes. Concerns in
design and selection of chillers include performance, efficiency, maintenance, and product life
cycle environmental impact.
The Modern Industrial Chiller is basically a cooling system which removes heatfrom one
element (water/glycol/air) and deposits into another (ambient air or water). The standard design
is a system that cools 60° F water (water/glycol, or air) to 50° F and deposits the heat into the
ambient air at 95° F (or water at 85° F). This chilling technology is used by various industries to
cool down the process machinery and the process using a Freon chiller to cool a medium like air
or water.
A Chiller is a machine that produces chilled water (usually mixed with ~20% glycol and
corrosion inhibitors) which is used to cool and dehumidify air in commercial and industrial
facilities. A typical chiller is rated between 15 to 1000 tons (180,000 to 12,000,000 BTU/h or 53
to 3,500 kW) incooling power.
There are basically four different types of chillers: Reciprocating, centrifugal, or
screwdrivenchillers are mechanical machines that can be poweredby electric motors, steam, or
gas turbines. Absorption chillers are powered by a heat source (such as steam or hot water). They
have very low electrical powerrequirements veryrarely above 15 kW combined consumption for
both the solution pump and the refrigerant pump.
Chilled water is then distributed to air handling units as a refrigerant. The air handling unit is a
heat exchanger consisting basically of a fan, a filter bank, andheating/cooling coil, inlet/outlet
chilled water port, and air inlet port. These air handling units provide air conditioning to the
building by running the incoming warm air through the coil of chilled water, transferring the heat
from the air to the chilled water, thus, cooling the air.
Chillers can be aircooledor watercooled.Watercooledchillers incorporate the use of cooling
towers which improve heat rejection more efficiently at thecondenser than aircooledchillers.
Fig.1 chiller.
A chiller consists of the following six main components:
Evaporator- cools the water, water/glycol or air by transferring the heat to a refrigerant
which is turned into a gas.
Compressor- takes this gas and increases its pressure so that ambient air or water can
remove the heat.
Condenser- rejects heat gained by the gas using ambient air or cooling tower water to
condense the gas back to a liquid for use again by the evaporator.
Holding Tank holds-the circulating coolant, usually water (can be water/glycol), tank is
sized large enough to prevent turbulent flow in tank causing pump cavitation.
Pump circulates-coolant from the holding tank to the evaporator and from the
evaporator to the machine or process being cooled and back to the tank.
Control Panel houses-temperature controller, compressor contactor, pump starter,
3phase fuses, control transformer, safety controls, run and fail lights.
The building has nine floors for which heat load calculation is done. We used Air cooled chillers
air-conditioning. We used the HAP, psychometric chart, ASHRAE and CARRIER hand book for
heat load calculation.
DATA ANALYSIS & LOAD CALCULATION:
Similarly using the same process for the other floors of the buildings, the result of these floors is
shown in results.
RESULT AND DISCUSSION
1. Finding the change of load (Tonnage of Refrigeration).
In this project we have taken the office building and calculate the heat load calculation of the
ground floor to 9th floor (Second floor to 9th Floor are typical floors).
Air Cooled Chiller have been suggested for the building due to the non-availability
of the water in some areas. The same is also suggested because in some areas we
have to use RO system in case there is availability of water which increases the
rate of power consumption thus making air cooled chillers more convenient than
that of water cooled chillers.
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architecture drawing.
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