By Jason Meredith, SCM Ref Africa mechanical engineer
This was an all-new light industrial project which began February 2022 and ended October 2022. What made the project special is that this was the first industrial type CO2 unit manufactured locally by SCM Ref Africa.
Redline Consulting Engineers were approached by a local DC for a national business to design a new state of the art distribution facility in Durban, using the latest technologies and keeping longevity as well as reliability in mind. The project called for the new distribution facility to have a centralised transcritical CO2 (R744) booster unit installed to provide cooling to the two holding rooms onsite, one being a freezer and the other a coldroom.
Result Refrigeration was awarded the project to supply the centralised transcritical CO2 booster unit. Metraclark along with SCM Ref Africa was approached by Result Refrigeration to design and supply the best possible CO2 (R744) transcritical booster rack to service the group’s cold and freezer rooms. The refrigeration system for this project was based on a locally manufactured SCM Frigo transcritical CO2 (R744) refrigeration system. The system is designed to supply 150kWR at -8°C for the coldrooms and 170kWR at -25°C for the freezer rooms.
For added efficiency all leading compressors are fitted with variable speed drives to maintain a steady suction on all temperature lines, and to improve efficiency for warmer days the system was fitted with two parallel compressors. Additionally, a partial heat reclaim BPHE was installed to supplement the hot water required at the facility. The harvesting of the heat rejection from the system to heat water can have major benefits of a system’s coefficient of performance (COP).
The system comprised of 10 Bitzer compressors – four compressors on the medium temperature side, four on the low temperature side and two parallel compressors handling the flash gas experienced in the system.
In respect of elements which helped or hindered the progress of the project being on schedule, from a rack-manufacturing point of view, was the supply of certain CO2 components needing to be imported from Europe. Due to the size of the system at that point in time, larger CO2 components were not readily available locally; this is however changing with the increase in CO2 systems being supplied as of today.
The waiting on componentry as well as “finding” our feet around building our largest system at the time did cause some delays with the manufacturing process, but the assistance received from SCM FRIGO was especially helpful getting us through all of the speed bumps.
With the above said, the transcritical CO2 booster unit was still supplied on time in September of 2022, sticking to the strict timelines, allowing for the facility to be operational as scheduled.
Why a CO2 refrigeration system? CO2 refrigeration systems use carbon dioxide as a refrigerant instead of traditional synthetic refrigerants such as hydrofluorocarbons (HFCs) and chlorofluorocarbons (CFCs). CO2 is naturally occurring and allows for sustainable and energy-efficient refrigeration in everything from warehouses to ice machines.
CO2 has several unique thermo-physical properties that make it an ideal refrigerant. It has an excellent heat transfer coefficient, high energy content, and is relatively insensitive to pressure losses. In practical applications, CO2 systems deliver a very high-performance output. The main reasons are superior heat exchange, smaller piping sizes, low pumping power as secondary fluid, and superior heat recovery.
From an environmental perspective, the facility has future proofed itself by going with a CO2 system, as CO2 is a very attractive refrigerant with zero ozone depletion potential (ODP) and a global warming potential (GWP) of 1. It is a naturally occurring substance and abundant compared to other traditional hydrocarbon refrigerants which carry numbers greater than 4 000 and are gradually being phased out around the world due to their impact on the environment.
We are very grateful for the opportunity to have been a part of this exciting and successful project – well done to all that were involved.
- Heating Centre did the gas coolers and evaporators.
- MetraClark supplied to the contractors.
- The consulting engineer involved was Redline Engineering, Durban.
- SCM Frigo of Italy assisted with the CO2 Transcritical booster rack-design.
PROJECT NAME: FAMOUS BRANDS NORTHFIELDS DURBAN |
List of professionals | Name of company |
Owner | JT Ross Property Group |
Developer | JT Ross Property Group |
Architect / Designer | Axiom Architects |
Project manager | Andre Proctor – JT Ross |
Consulting engineer | Electrical | DBA Consulting Engineers |
Mechanical | Redline Consulting Engineers | |
Wet services | G&N Plumbing | |
Civil | David Vigar and Associates | |
Contractors | Main building | WBHO |
HVAC&R | Result Refrigeration | |
Wet services | G&N Plumbing | |
Product suppliers | Product | Supplier |
Munters | ||
Heating Centre | ||
SCM – CO2 Transcritical rack | ||
Metraclark |
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