Sizing, Operating and Maintaining 150 Ton HVAC Chillers

Overview of 150 Ton Chillers

Chillers are mechanical devices designed to remove heat from water or other liquids in order to provide air conditioning and refrigeration in large facilities. A chiller with a cooling capacity of 150 tons has the ability to remove 150 tons of heat energy per hour. This makes 150 ton chillers ideal for large commercial buildings, industrial facilities, hospitals, data centers, and more.

What is a Ton of Cooling?

When discussing chillers, capacity is measured in "tons." But this doesn't refer to physical weight. A "ton of cooling" is defined as the amount of heat energy transfer needed to melt one short ton (2000 lbs) of ice in a 24 hour period. It's an antiquated measure but still commonly used to rate cooling equipment. A chiller that has a 150 ton capacity can remove 150 tons worth of heat energy per hour.

Typical Applications of 150 Ton Chillers

Some facilities that often utilize 150 ton chillers include:

• Large office buildings
• Hospitals and medical centers
• Universities and campus facilities
• Hotels
• Shopping malls
• Data centers and server rooms
• Television studios
• Industrial manufacturing plants

A chiller of this size may also be found in district cooling systems that distribute chilled water to multiple buildings from a central plant location.

How 150 Ton Chillers Work

While large in size, 150 ton chillers utilize the same basic refrigeration cycle as an air conditioning unit or refrigerator, just on a much bigger scale. The core components include:

Compressor

An industrial grade compressor circulates refrigerant through the system. It raises the temperature and pressure of the refrigerant gas as part of the heat transfer process.

Condenser

The condenser removes heat from the gaseous refrigerant, condensing it into a liquid state, which is still under high pressure.

Expansion Valve

After going through the condenser, the liquid refrigerant passes through an expansion valve. This causes a drop in temperature and pressure.

Evaporator

The low pressure liquid refrigerant in the evaporator absorbs heat from the water or fluid passing through the chiller barrels. This causes the refrigerant to boil and vaporize again, allowing the cycle to repeat.

Key Components of 150 Ton Chillers

Some of the major components and systems that make up a 150 ton chiller include:

Refrigeration System

As described above, a 150 ton chiller will contain a full refrigeration system with a compressor, condenser, expansion device, and evaporator sized appropriately for its cooling capacity.

Water Pumps

Large water pumps circulate chilled water from the chiller into a building's air handler units or other cooling systems and back through the chiller again. Variable speed drives allow capacity to match demand.

Microprocessor Controls

Today's large chillers utilize sophisticated computerized controls to monitor operation, regulate temperatures and pressures, diagnose faults, and integrate with building automation systems.

VFDs

Variable frequency drives control the speed of the compressor motor and cooling tower fans. This allows capacity to match a building's internal heat loads more precisely.

Corrosion Resistant Components

Parts that come into contact with water are coated or made from corrosion-resistant materials to maximize service life in harsh cooling tower conditions.

Types of 150 Ton Chillers

There are a few different types of chillers with 150 ton capacity on the market. Some key examples include:

Air-Cooled Chillers

Air-cooled chillers use ambient air pushed through a condenser coil, eliminating the need for cooling towers. Lower efficiency but good for smaller spaces.

Water-Cooled Chillers

In water-cooled systems, water from a cooling tower removes heat from refrigerant gases. More complex but higher efficiency.

Scroll Compressor Chillers

Scroll compressor chillers are compact, quiet, and vibration free. Well suited to quiet environments like hospitals.

Centrifugal Compressor Chillers

Centrifugal compressor chillers can achieve very high capacity and efficiency. Ideal for industrial and district cooling applications.

Sizing Considerations for 150 Ton Chillers

Selecting the correctly sized chiller is crucial for any HVAC system. Oversizing leads to short cycling and energy waste while undersizing cannot meet peak loads. Key factors in sizing a 150 ton chiller include:

Peak Cooling Load

An accurate peak heat load calculation for the warmest design day is vital. Rules of thumb should not be used.

Location and Climate

Ambient temperature directly impacts chiller performance and ideal sizing calculations.

Future Expansion Plans

New equipment, occupants, and internal heat gains should be accounted for if facility growth is expected.

Operational Requirements

Required chilled water supply temperatures and other factors influence chiller selection.

Redundancy Needs

Backup or spare capacity may be desired for critical cooling applications.

Installing 150 Ton Water-Cooled Chillers

Installing very large chillers like 150 ton capacity units takes careful planning, preparation, and expertise. Key aspects include:

Structural Support

Chillers weighing tons require reinforced roofs or ground mounts capable of handling the load without vibration.

Equipment Rigging

Cranes and rigging equipment are needed to lift chillers through roofs or onto mounting pads if no external access exists.

Piping Considerations

Large diameter supply and return piping must be connected from the chiller to cooling loads throughout a building.

Cooling Tower Basins

Cooling towers for water-cooled systems may need concrete basins built for condenser water storage.

Power Supply

Electrical rooms must have sufficient capacity, panels, conduits, and wires to supply power to 150 ton chillers.

Maintaining and Servicing 150 Ton Chillers

Preventative maintenance is crucial for large chillers to ensure peak efficiency, reliability and long operational life. Recommended service tasks include:

Water Treatment

Water chemistry must be tested and controlled to prevent scale, corrosion, and biological growth issues.

Refrigerant Leak Checks

Early refrigerant leak detection allows for minor repairs before major issues occur.

Bearing Lubrication

Bearings should be re-lubricated on a prescribed schedule to prevent premature failures.

Sensor Calibration

Sensors can drift over time, throwing off the accuracy of temperature and pressure regulation.

Leak Inspections

Visible inspections check for signs of water, refrigerant leaks, oil leaks, corrosion and component wear.

Operational Testing

Running chillers through full cycles checks that components work properly through warm-up, loading, and cool-down.

Summary

In review, 150 ton chillers provide large-scale cooling with 150 ton capacity for commercial HVAC and process applications. Though complex, 150 ton chillers utilize a standard vapor compression refrigeration cycle to provide chilled water or other secondary coolant. Proper sizing, installation, operation and maintenance are key to ensure these systems meet facility needs while maximizing up-time and service life.

FAQs

What types of facilities use 150 ton chillers?

Some facilities that typically utilize 150 ton chillers include hospitals and medical centers, universities and campus facilities, data centers and server rooms, shopping malls, hotels, office buildings, and manufacturing plants.

How is a 150 ton chiller capacity measured?

Chiller cooling capacity is measured in "tons", which refers to the equivalent amount of heat energy transfer required to melt one short ton (2000 lbs) of ice in 24 hours. So a 150 ton chiller can remove 150 tons of heat energy per hour.

What is the difference between air-cooled and water-cooled chillers?

Air-cooled chillers remove heat through the use of ambient air blowing through a condenser coil, while water-cooled chillers use water from a cooling tower to cool refrigerant gases in the condenser.

What types of maintenance does a 150 ton chiller require?

Key 150 ton chiller maintenance needs include water treatment, refrigerant leak checks, bearing lubrication, sensor calibration, leak inspections, and operational testing.

What are some sizing considerations for a 150 ton chiller?

Critical factors in sizing a 150 ton chiller correctly include the peak cooling load calculation, climate conditions, future facility expansion plans, required chilled water temperatures, and redundancy requirements.