5 types of systems of low-charge packaged refrigeration equipment

Packaged refrigeration series.

03/29/2016


These low-charge chillers use ammonia or CO2 and a secondary refrigerant to provide a safer method for refrigeration. Courtesy: Stellar Food for ThoughtAs the Environmental Protection Agency continues to phase out the use of hydrofluorocarbons such as R22 or R134A, the food processing industry is turning to packaged refrigeration equipment. Why? These low-charge chillers use ammonia or CO2 and a secondary refrigerant to provide a safer method for refrigeration.

In last week's post, I outlined the benefits of using low-charge packaged refrigeration equipment. However, there are many different types of these systems. The system best fit for your facility is dependant on how many tons of refrigeration you need and at what temperature. (If you're unsure, reach out to your packaged refrigeration equipment provider for clarification).

Below are five types of refrigeration systems that can be incorporated into low-charge packaged refrigeration equipment:

  1. Recirculation system—A recirculated system utilizes a centralized refrigeration machine room where pumps recirculate expanded, cooled liquid from a vessel. Typically, excess liquid refrigerant is provided to the evaporators (cooling coils) to increase heat transfer in the evaporators. If there is excess liquid fed to the evaporators (known as overfeed) it is carried back to the vessel in the suction line (known as wet suction).
  2. Direct expansion (DX) system—A DX system uses the pressure differential provided by the refrigerant compressors to move room-temperature, high-pressure liquid from the centralized refrigeration machine room to the evaporators. The refrigerant is expanded, and therefore cooled, directly at the unit. Typically, the liquid is fed to the evaporator at a rate that allows the refrigerant to evaporate so there is typically no liquid found in the suction line (known as dry suction).
  3. Cascade system—A cascade system uses a combination of two centralized refrigeration systems (secondary refrigerant) to work in unison to provide cooling to evaporators. The high-temperature refrigeration system (usually ammonia) pulls heat away from the lower-temperature refrigeration system. The lower-temperature refrigeration system (usually CO2) typically uses recirculated liquid to provide cooling to the evaporators.
  4. Distributed system—A distributed refrigeration system uses localized refrigeration systems located near the evaporator to keep the refrigerant charge lower. Each evaporator has its own compressors and condensers.
  5. Secondary system—A secondary refrigerant system uses a centralized refrigeration system to chill large amounts of a secondary coolant (also known as secondary brine or glycol). The secondary coolant is then pumped out to each air handling unit. Primary refrigerant does not leave the machine room, so the refrigerant charge is minimized and the risk of exposure to plant personnel is greatly reduced.

- Brandon France is a director of packaged solutions at Stellar. This article originally appeared on Stellar Food for Thought. Stellar is a CFE Media content partner. Edited by Erin Dunne, production coordinator, CFE Media, edunne@cfemedia.com. 

Stellar is a CSIA member as of 11/30/2015. 



Top Plant
The Top Plant program honors outstanding manufacturing facilities in North America.
Product of the Year
The Product of the Year program recognizes products newly released in the manufacturing industries.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
October 2018
Tools vs. sensors, functional safety, compressor rental, an operational network of maintenance and safety
September 2018
2018 Engineering Leaders under 40, Women in Engineering, Six ways to reduce waste in manufacturing, and Four robot implementation challenges.
July/Aug
GAMS preview, 2018 Mid-Year Report, EAM and Safety
October 2018
2018 Product of the Year; Subsurface data methodologies; Digital twins; Well lifecycle data
August 2018
SCADA standardization, capital expenditures, data-driven drilling and execution
June 2018
Machine learning, produced water benefits, programming cavity pumps
Spring 2018
Burners for heat-treating furnaces, CHP, dryers, gas humidification, and more
October 2018
Complex upgrades for system integrators; Process control safety and compliance
September 2018
Effective process analytics; Four reasons why LTE networks are not IIoT ready

Annual Salary Survey

After two years of economic concerns, manufacturing leaders once again have homed in on the single biggest issue facing their operations:

It's the workers—or more specifically, the lack of workers.

The 2017 Plant Engineering Salary Survey looks at not just what plant managers make, but what they think. As they look across their plants today, plant managers say they don’t have the operational depth to take on the new technologies and new challenges of global manufacturing.

Read more: 2017 Salary Survey

The Maintenance and Reliability Coach's blog
Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
One Voice for Manufacturing
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Maintenance and Reliability Professionals Blog
The Society for Maintenance and Reliability Professionals an organization devoted...
Machine Safety
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
Research Analyst Blog
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Marshall on Maintenance
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
Lachance on CMMS
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
Material Handling
This digital report explains how everything from conveyors and robots to automatic picking systems and digital orders have evolved to keep pace with the speed of change in the supply chain.
Electrical Safety Update
This digital report explains how plant engineers need to take greater care when it comes to electrical safety incidents on the plant floor.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
Randy Steele
Maintenance Manager; California Oils Corp.
Matthew J. Woo, PE, RCDD, LEED AP BD+C
Associate, Electrical Engineering; Wood Harbinger
Randy Oliver
Control Systems Engineer; Robert Bosch Corp.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
Design of Safe and Reliable Hydraulic Systems for Subsea Applications
This eGuide explains how the operation of hydraulic systems for subsea applications requires the user to consider additional aspects because of the unique conditions that apply to the setting
click me