The ATMOsphere Review Board has selected case studies from Carnot Refrigeration, CAREL Industries and KAV Consulting for ATMOsphere America 2015. These case studies will highlight innovation and efficiency in commercial refrigeration applications and data centers.

Aquilon is emerging at Bell Canada by Carnot Refrigeration

Telecommunication giant Bell Canada has teamed up with Carnot Refrigeration to remove HCFCs from its server rooms. The challenge was to develop the first CO₂ transcritical refrigeration system for server rooms, which have very high standards of quality and reliability, as the data stored in these facilities is critically important. To meet this challenge, Carnot reinvented the refrigeration of server rooms by creating the first Aquilon system at one of Bell Canada’s server rooms in Ottawa.

The project involved replacing an R-22 refrigeration system with a CO₂ transcritical system of 105 kW. The R-22 system had to remain in operation until the last setting of the Aquilon system. When designing the system, Carnot considered every way to minimize both the cost and time of installation on site.

The new Aquilon system is greener, more energy efficient and uses 100% CO₂. It has less expensive maintenance and is less likely to cause refrigerant leakage. The installation of the Aquilon was a turnkey project in terms of electricity, refrigeration, structure, ducting, commissioning and also in obtaining permits and accreditations of TSSA. Several other projects between Bell Canada and Carnot Refrigeration are already underway, demonstrating that the first results were very impressive.

New alternatives for natural refrigerants in US market: DC compressors waterloop system by Tommaso Ferrarese, CAREL Industries

Over the past few years, the U.S. market has seen a growing interest in the use of natural refrigerants in commercial refrigeration. CO₂ as a unique refrigerant for subcritical and transcritical compressor racks and propane for small plug-in units are becoming real solutions deployed in the market. But there is another alternative that has attracted the interest of several main players, a solution that is already being deployed in the European market and is now starting to be used in the U.S. as well.

The new concept is very simple: water-cooled self-contained refrigeration units equipped with DC compressors. This system is able to combine the advantages of plug-in watercooled units with the top level efficiency of DC compressors, already largely used in the HVAC&R industry. The main benefits of this kind of system are similar to energy efficiency of independent plug-in units with DC compressors: the simplicity of installation, the reduction of installation and operational costs, the flexibility improvement and the possibility of reducing the refrigerant leakage. These are all extremely important factors for the worldwide refrigeration industry, which is why one of the most important players in the U.S. market has decided to invest in this technology, testing the solution first in its laboratory for several months and now with a trial that will be commissioned during the summer.

This type of system has already been deployed in Europe using HFC refrigerant. CAREL, as a pioneer in this new technology, is researching and developing ways to be able to provide full DC waterloop systems with natural refrigerants as soon as possible. The two main options for this are propane and CO₂. Propane has a very good efficiency but its usage is limited as, due to its flammable nature, the maximum charge of a refrigeration system equipped with propane depends on local legislation. CO₂ is well accepted by the market as the future refrigerant for compressor racks; however, it’s drawbacks are that energy efficiency is strongly dependant on outside temperatures and UL certifications can slow down the availability of components.

This presentation will show how a DC compressor waterloop system, starting in Europe, can become the new frontier for the application of natural refrigerants in commercial refrigeration for the U.S. market. A comparison of the application of different refrigerants (R410A, CO₂ and propane) will be presented, considering general advantages and disadvantages of the solution, legislation, political and psychological aspects, as well as energy efficiency comparison with data coming from field installations, lab testing and advanced SW simulation.

A desktop study into the energy efficiency and environmental benefits of CO₂ refrigeration in USA supermarkets by Klaas Visser, KAV Consulting

According to Green Chill, the U.S. EPA’s advanced refrigeration partnership, the average U.S. supermarket with a floor area of 46,000 square feet consumes electricity at the rate of 51 kWh/ft²/annum, which generates CO₂ Global Warming Emissions (GWE) of 66.3lbs/ft²/annum. Twenty five percent annual leakage from a typical 3,500 lb R404A refrigerant charge contributes a further 74.6 lbs/ft² GWE. This gives a total GWE of 141 lbs/ft² in the average U.S. supermarket.

U.S. Energy Information Administration data published by MGE shows that 57% of electrical energy is used for refrigeration, 23% for lighting, 5% each for cooling (AC) and ventilation, 2% for heating and 1% for water heating. Thus, refrigeration consumes 0.57 x 51 kWh = 29 kWh/ft²/ annum. An air cooled R404A refrigerating system has an estimated annual average COP of 3 for MT chilling duties and about 1.5 for LT refrigeration duties.

This study shows that the specific electrical energy consumption per square foot of supermarket floor area would be reduced by 20 to 30% when using integrated Multi Function Two Stage Trans-Critical CO₂ Refrigerating Systems with Parallel Compression (MF2STTCCO2RSPC) employing hybrid evaporative condensers and gas coolers for CO₂ condensing and gas cooling. These large projected reductions in energy consumption are due to the fact that the annual average COPs for MF2STTCCO2RSPC MT refrigeration is about 6, and about 2.5 for LT refrigeration, which are double and nearly double the R404A COPs of 3 and 1.5 for MT and LT refrigeration respectively.

This would result in annual electrical energy cost savings of $47,000 to $70,000 at an electrical energy cost of $0.10/kWh. The higher end savings are based on both AC and the electrical water heating being carried out by the MF2STTCCO2RSPC. Total GWEs would reduce by 91 to 95 lbs/ft² (4,1860,000 – 4,370,000 lbs/annum [1,898 – 1,982 metric tonnes/annum]) (64 to 67%) due to the absence of annual R404A leaks of 25% of the system charge.

The Specific Annual Natural Gas Consumption (SANGC) amounts to 41 cubic feet² of supermarket floor area (41,000 BTUs/ft²). Sixty-nine percent of this (28,290 BTUs/ft²) is used for space heating. A further 6% (2,460 BTUs/ft²) is used for water heating. At the low gas price of $0.93/therm ($8.81/GJ), it is unlikely that recovery of heat from the MF2STTCCO2RSPC would be a cost effective proposition.

To find out which other case studies have been selected for ATMOsphere America 2015, check out the following articles:

ATMOsphere Review Panel announces first case study selections

More case studies announced for ATMOsphere America 2015

About ATMOsphere America 2015

25 & 26 June at The Grand Hyatt Atlanta in Buckhead – Atlanta, Georgia

THE forum for HVAC&R industry experts to discuss the latest natural refrigerant market, technology and regulatory trends in North America returns for its 4^th edition. With a record 300-350 stakeholders expected to attend, the event promises better discussions and bigger results than ever before. Highlights include a series of parallel sessions featuring panel discussions and technology case study presentations for a variety of applications including light commercial, commercial & industrial refrigeration, food service and more.

Don’t miss out, register today at www.ATMO.org/america2015/registration

For general information about the event, please visit www.ATMO.org/america2015