Installing Chiller Systems: Chapter 1
Introduction
By the end of this module, you should be able to describe: What chiller systems are, Types of chiller systems, and Parts of a chiller system. Skip to quiz!
Introduction
Recall that a chiller system is a machine that is used to produce cold water. This cold water is used to cool buildings or industrial equipment. While small ACs are used in homes and chillers are used in large buildings. Let’s have a look at the types of chillers.
Chiller Types
There are two types of chillers:
Air-cooled chiller, and
Water-cooled chiller.
Air-cooled and water-cooled chillers differ by how the refrigerant is cooled in a condenser. Air-cooled chillers are installed on the roof, while the water-cooled chillers are installed inside the buildings.
If a condenser uses air to cool, then it’s an air-cooled chiller. If it’s cooled by water, it’s a water-cooled chiller.
Chiller Parts
We know the basic components of an AC, now let’s look at chiller components. The main components of a chiller are:
Evaporator,
Condenser,
Compressor, and
Metering device.
Recall that a compressor’s work is to increase the pressure of a refrigerant. The following types of compressors are used in chillers:
Reciprocating compressors,
Scroll compressors,
Screw compressors, and
Centrifugal compressors.
Compressors are used based on the refrigeration capacity. All the chiller system ranging from 100 to 2000 tons of refrigeration capacity uses a screw and centrifugal compressors. Due to their high capacity, compressors produce huge noise like an airplane.
Recall that a condenser work is to cool down the refrigerant. The main types of condensers in chiller systems are:
Fin and tube condenser,
Microchannel condenser, and
Shell and tube condenser.
These condensers are classified based on their structure.
Fin and tube condenser is similar to a residential air conditioner’s condenser and used widely in air-cooled chillers. Generally, fins are made up of aluminum, and tubes are made up of copper. The hot refrigerant flows through the tubes, and fins help to cool the refrigerant by distributing the heat to the outside air.
Microchannel condensers are made of thin zig-zag aluminum fins. These condensers work similarly to fin and tube condensers but are more efficient.
Shell and tube condensers consist of a series of copper tubes inside a larger shell. Water flows in the tubes, and hot refrigerant flows in the shell. Running water in the tube cools down the refrigerant inside the shell.
In water-cooled chillers, both the condenser and evaporator are made up of shell and tube coils. The refrigerant is cooled in the condenser and gets heated in the evaporator, and the cycle repeats.
Recall that a metering device work is to decrease the pressure of the refrigerant. Chillers mainly use two types of metering devices:
Thermal expansion valves and
Electronic expansion valves.
Thermostatic expansion valves are also called TEV or TXV. These are used in residential HVAC systems, as well as chiller systems. It controls the amount of refrigerant that flows into the evaporator based on the evaporator outlet temperature.
Thermal expansion valves are used in smaller capacity chillers. The sensing bulb of a TEV is attached to the outlet of the evaporator. TXV increases or decreases the refrigerant flow into the evaporator based on the temperature measured by the sensing bulb.
Electronic expansion valves are also called EEVs or EXVs. They provide the best performance because they are electrically operated metering devices.
Chiller systems usually contain a shell and tube type of evaporator. Recall that shell and tube evaporators consist of a bundle of copper tubes inside a large metal shell.
In chiller systems, the evaporator coils filled with refrigerant have water flowing over them instead of air. This is how the refrigerant cools the water! A shell and tube evaporator has two parts:
An outer shell and
Inner tubes.
The outer shell is a large metallic cylinder. The shell performs two main functions:
Protecting the inner tubes and
Providing a seal to the fluid in the shell.
It has two openings, an inlet and an outlet for the fluid to flow in and out of the shell.
The inner copper tubes enter the outer shell from one side and leave through the other side. Recall that copper is an excellent conductor of heat. Copper tubes allow heat transfer from the fluid inside to the fluid outside the tube.
Water flows inside these tubes, while the outer shell is filled with refrigerant. The two fluids do not mix with each other, and only heat transfers take place between the fluids. In some chillers, the refrigerant may flow through the inner tubes, and water flows in the outer shell.
In an evaporator, the water transfers heat to the liquid refrigerant and boils it into vapor. As the water transfers its heat to the refrigerant, it cools down. This is how we get cold water!
A chiller system is a machine that is used to produce cold water. The main components of a chiller are:
Evaporator,
Condenser,
Compressor, and
Metering device.
Chillers are of two types:
Air-cooled chiller, and
Water-cooled chiller.
If the condenser is cooled by air in a chiller, then it is an air-cooled chiller. If it’s cooled by water, it’s a water-cooled chiller.
Installation Prerequisites
By the end of this module, you should be able to:
List out installation requirements of the chiller systems, Explain types of mountings, and Describe safety requirements during installation. Skip to quiz!
Site Preparation
The basic requirements for chiller installation are:
The unit should not be close to fire and explosives,
Select the sites where the temperatures are not extremely high or low,
Select the site with less dust, and
The site should be bright for easy maintenance and inspection.
The evaporator and the condenser heat exchanger tubes are needed to maintain, inspect, and clean during routine maintenance. So there should be enough space around the unit for maintenance as per manufacturer guidelines. For easy lift and maintenance, it is necessary to ensure that the machine room is high enough.
The surrounding of the unit and the whole machine room can be drained completely. Approval from the building owner, Architect, and Engineer is required before installing the unit. The unit location depends on the design of the building and cannot change afterward.
The chillers are installed on the ground or roof. When a large building is constructed, the chiller location may be inside or at a distance far from the main building. Some high-rise buildings consist of space between floors or a special floor dedicated to chiller and maintenance purpose.
The chiller requires minimum space for installation and maintenance. So the chiller is installed at a place called plant room which is specially designed for the installation and maintenance of equipment.
A plant room is a room or space in a building dedicated to mechanical equipment. It is also associated with electrical and plumbing equipment and consists of rooms intended for human occupancy or storage. The plant room consists of many types of equipment that are required for building maintenance services.
Mounting and Leveling
Are mountings required for chillers? If yes, please provide some reasons. Let’s now find out the requirements for chiller mountings.
The chiller mountings requirements are as below:
The maximum altitude difference (levelness) should be within 3mm.
For easy maintenance and inspection of the refrigerant unit, the base should be higher than one meter (100 mm).
It is necessary to install a drain around the refrigerant unit.
There should be no space between the base steel and the footplate of the refrigerant unit.
The installation base of the unit must be a concrete or steel structure, which can bear the running weight of the machine.
Insert the adjusting shim (rubber gasket or pad) between the base steel and the concrete base. Adjust the base steel to be horizontal, and the difference should be within 0.5mm every meter. Besides, the top should be horizontal, and it is better to provide a slope in the installation base to drain.
The chiller mountings can be described as:
Concrete slab,
Raised curb, and
Elevated Installation.
Let’s have a look at all these mountings.
Concrete Slab: If the Chiller is to be mounted on a concrete slab, the surface of the slab must be level, or slope must be provided. Leveling legs are provided on all chillers for final leveling after placing the chiller.
Raised Curb: A raised curbing around the outside of the chiller is recommended to contain any condensate, leakage, or cleaning fluid during maintenance from the unit. A curb height of two (2) to three (3) inches is sufficient for the chiller.
Elevated Installation: Some installations require mounting the chiller at an elevation above grade. A structural steel platform capable of supporting the running load of the chiller is provided. It is recommended for chiller connections below the unit.
Safety
Safety is the essential requirement for any installation work. Personal protective equipment (PPE) is the most important for one person during the construction and installation. Some safety notes are found on each page of chiller manuals, like warnings, caution, and important note.
Important: Indicates hazards or unsafe practices which could cause personal injury or product or property damage.
Warning: Indicates severe personal injury or death will result if instructions are not followed.
Caution: Indicates a strong possibility of severe personal injury or death if instructions are not followed. Use of 5 point harness for working at heights and on the roof of the buildings. The harness is hooked to the building structure or tied with ropes to support it.
Always follow the below instructions while installing the chiller system:
Read the manual first,
Use common sense and be careful,
Sufficient workforce,
Use of proper tools,
Check for safety warnings on all equipment, and
Follow directions and procedures as per manuals.
Chillers are installed on mountings for the better work performance of the unit. Chillers are installed in the plant room, which is specially designed for maintenance purposes. Safety during chiller installation is a must, and it cannot be neglected, so read the safety manual first.
Question #1: What are chiller systems used for?
Cool water
Fry cookies
Bake bread
Paint coils
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Answer: Cool water
Chiller systems are used to cool water.
Question #2: What are the two types of chillers? (Select all that apply)
Air-cooled
Air-water cooled
Water-gas cooled
Water-cooled
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Answer: Air-cooled
Water-cooled
The chillers are of two types:
Air-cooled chiller, and
Water-cooled chiller.
Question #3: Which type of compressors are found in the large capacity chillers? (Select all that apply)
Scroll
Screw
Centrifugal
Reciprocating
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Answer: Screw
Centrifugal
All the chiller systems ranging from 100 to 2000 tons of refrigeration capacity screw and centrifugal compressors are used.
Question #4: Which type of condenser is used in air-cooled chillers?
Fin and tube condenser
Tube and tube condenser
Shell and tube condenser
Plate type condenser
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Answer: Fin and tube condenser
Fin and tube condensers are used widely in air-cooled chillers.
Question #5: Which type of condenser uses water to cool refrigerant inside it?
Fin and tube
Shell and tube
Microchannel
Spine fin
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Answer: Shell and tube
Shell and tube condenser uses water to cool refrigerant inside it.
Question #6: Which type of metering device can be controlled electrically and is used in chillers?
Capillary tube
Thermal expansion valve
Electronic expansion valve
None of the above
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Answer: Electronic expansion valve
An electronic expansion valve is used in chillers and can be controlled electrically. Electronic expansion valves provide greater efficiency and are controlled by electrical inputs.
Question #7: Which type of evaporators are used in the chillers?
Bare tube
Plate surface
Finned tube
Shell and tube
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Answer: Shell and tube
Shell and tube type evaporators are used in chillers.
Question #8: The minimum requirements for the chiller installation are?
Enough space around the unit for maintenance
No space for maintenance
Enough space to add a new chiller
Space only on the side of the control panel
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Answer: Enough space around the unit for maintenance
The evaporator and the condenser heat exchanger tubes are needed to maintain, inspect, and clean during routine maintenance. So there should be enough space around the unit for maintenance as per manufacturer guidelines.
Question #9: Where are the chillers installed in a building?
Top room
Lobby area
Plant room
Studio room
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Answer: Plant room
A plant room is a room or space in a building dedicated to mechanical equipment. Chillers are installed in the plant room.
Question #10: The chiller mounted on the base should be?
Less supported
Inclined
Uneven or rough
Level
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Answer: Level
The chiller mounted on the base should be level.
Question #11: Types of mountings are: (Select all that apply)
Cantilever Beam
Concrete slab
Elevated tower
Elevated Installation
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Answer: Concrete slab
Elevated Installation
The chiller mountings can be described as:
Concrete slab,
Raised curb, and
Elevated Installation.
Question #12: Some safety notes are found on each page of chiller manuals, such as? (Select all that apply)
Warnings
Equipment details
Cautions
Machine label
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Answer: Warnings
Cautions
Some safety notes are found on each page of chiller manuals, like warnings, caution, and important note.