Bill Stankiewicz

7 years ago · 3 min. reading time · ~100 ·

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Typical Ammonia/CO2 Cascade System, Freezing Application , by Bill Stankiewicz, Savannah Supply Chain Guy

Typical Ammonia/CO2 Cascade System, Freezing Application , by Bill Stankiewicz, Savannah Supply Chain Guy

Richard Worzel is a futurist and a professional member of the World Future Society. We talk about his bio & background a little later in my post here.  We will explore some of the reasons why co2 cascade systems continue to grow worldwide.


                                                   Typical Ammonia/CO2 Cascade System, Freezing Application

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In 1866, an American, T.S.C. Lowe became the first known user of CO2 in a mechanical refrigeration system. Up until the 1940s, a large number of installed refrigeration systems used CO2 as the refrigerant. However, users had trouble with these systems because:  The operating pressure for CO2 is very high , the triple point for CO2 (~ 70 psig [4.8 barg] and –70°F [–57°C]) is above atmospheric pressure  and the  critical point is at a relatively low temperature (~1080 psig [74.5 barg] and 88°F [31°C]), with an added note the automatic control systems did not exist at the time.

A few years ago, when CO2 was reintroduced to the industrial refrigeration world, the system configuration was different from what had been used in the past. To avoid very high pressures, cascade designs were specified, in which CO2 is only used in the low stage. Another refrigerant, typically ammonia, is used in the high stage. To move heat between the two stages, a cascade heat exchanger (CHE) is used. The CHE serves as condenser for the CO2 side and as an evaporator for the ammonia side. The CHE can be installed in parallel with the intercooler in a conventional two-stage plant; the two are different in that for the CHE to exchange heat, the temperature of the two refrigerants must be different. Resistance to heat flow in the CHE causes an efficiency penalty that a conventional two-stage system does not experience. However, in most low temperature applications, this efficiency loss is more than redeemed by the greater efficiency of the CO2 compressor.


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Why do people look at using Ammonia/CO2 Cascade System?

Refrigeration systems are most efficient at 100% load. But the refrigeration systems in most processing and cold storage facilities don’t run at full load for much of the time. During these times of partial loading, energy efficiency is more difficult to achieve. A CO2/NH3 cascade system uses less energy per ton of refrigeration when compared to other refrigeration systems at full load, but the difference can be even better at part load, especially when operating at evaporating temperatures of -35oF to -60oF.

You also see lower energy costs. Using CO2 instead of ammonia for lower temperatures takes advantage of CO2’s unique physical properties, resulting in smaller pipes, smaller pumps, less insulation, and less installation labor when compared to two-stage ammonia systems.  A cascade system allows designers to limit ammonia charge to the machine room. Only CO2 is present in the processing and/or storage areas. For large low-temperature freezing systems, the reduction in ammonia charge can be significant. We have seen trends where many owners are considering propylene glycol, a secondary refrigerant chilled by ammonia or another refrigerant, as a strategy to reduce ammonia charge for the higher temperature (above freezing) storage and process loads. For these applications, CO2 brine, often already part of the low-temperature cascade system, can be circulated to higher temperature storage loads serve as an efficient and less-expensive alternative to glycol.

The trends have been for frozen foods processors to often seek lower process freezing temperatures to enable faster freezing, which optimizes food quality and enables increased throughput. With cascade systems, lower temperatures (and higher production yields) are achievable with less investment and less operating costs than conventional refrigeration systems.


GARDEN CITY KANSAS AMMONIA REFRIGERATION TRAINING TEAM 2017

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                                           The man that is in the know with refrigeration & trends in sustainability


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Richard Worzel is a futurist and a professional member of the World Future Society. He is known for helping corporations and industry associations plan intelligently for the future. Worzel challenges organizations to examine the future and plan for the dizzying changes to come. In his compelling presentations, Worzel equips groups with the ability to understand the changes they will face in the years ahead, and with the tools to leverage those changes. He is known for his captivating speeches, workshops & Seminars and Innovative sessions. His clients include Coca-Cola, Ford, IBM, Bell, The U.S. Navy Department of Medicine & Surgery, the National Research Council, the Clerk of the House of Commons of Canada, and many other. Worzel is a Chartered Financial Analyst and best-selling author of Who Owns Tomorrow? 7 Secrets for the Future of Business and a Canadian Native.

Thank you for reading my posts here & have a great day, be kind, help someone.


regards,


Bill Stankiewicz

Savannah Supply Chain Guy

Controller

Portfresh Logistics

Office: 1.404.750.3200

Email: bstankiewicz@portfreshlogistics.com

www.beBee.com  BRAND AMBASSADOR

www.twitter.com/billstankiewicz


tags: Cold Logistics, Food Logistics, SCM, Supply Chain Management, AIB, PRIMUS, Bakery, Beef/Pork, Beverage, CASCADE CO2/AMMONIA SYSTEMS, Dairy, electrical & plumbing (MEP), Foodservice, mechanical, Mechanical and Utility, packaged refrigeration equipment, Poultry, public refrigerated warehouse, Ready-to-eat, Refrigeration Services, Retail, Seafood, sustainable solutions


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Comments

Bill Stankiewicz

7 years ago #2

Georgia growing see: https://www.linkedin.com/pulse/savannah-georgia-1-spot-distribution-southeast-bill-stankiewicz-?published=t

Bill Stankiewicz

7 years ago #1

cool unit, makes cool air. :~))

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