Scantec Refrigeration Technologies, an Australian industrial refrigeration system provider, installed a low-charge ammonia/NH3 (R717) system to serve three high-rise freezer rooms at a Malaysian cold storage facility, achieving a specific energy consumption (SEC) more than seven times lower than that of the facility’s previous ammonia liquid-overfeed system.
The energy performance of this installation exceeded expectations, explained Stefan Jensen, Managing Director at Scantec Refrigeration Technologies, who presented this case study during the State of the Industry – SEA online session on the second and final day of the ATMOsphere APAC Summit 2022 on June 28. The conference, which took place in person in Tokyo on June 27, was organized by ATMOsphere, publisher of Ammonia21.com.
Low-charge drivers convince end user
This project came about thanks to Jensen’s in-person presentation at the 2018 ATMO APAC conference in Singapore, which was also attended by the Malaysian cold storage operator. At that conference, Jensen presented a graph detailing the energy performance of cold storage facilities around the world that showed low-charge ammonia facilities’ having superior results. This piqued the interest of the Malaysian delegate, who then approached Jensen to further discuss this solution for his own facility.
The Malaysian operator was expanding its inner-city warehouse, adding a new facility complete with three 32m (105ft)-high high-rise freezer rooms, two anterooms and an automated storage-and-retrieval system (adding to the heat load). The new medium-sized facility would offer a refrigerated volume of 112,000–113,000m3 (3,955,243–3,990,557ft3) to complement the existing 35–40m3 (1,236–1,413ft3) refrigerated space served by a two-stage screw compressor ammonia system with liquid overfeed.
The main drivers for choosing low-charge ammonia for the facility upgrade, according to Jensen’s 2022 presentation, were:
- It demonstrated low SEC in kWhm3/year.
- The recorded SEC for the existing liquid overfeed ammonia system was significantly higher than that of a low-charge ammonia system serving a refrigerated warehouse of a similar volume; the owner wanted to address this problem.
- The proposed new warehouse was a high-rise building with an engine room on the first floor, making it advantageous to minimize the liquid content in the suction dropper to prevent pipe stresses and movements.
- The reduction of the ammonia inventory in the freezer evaporators – by approximately 40 times compared to a liquid overfeed system – is an obvious safety advantage for humans and products; overall ammonia charge was four times less (500kg/1,102lbs).
Guaranteed energy performance
The predicted SEC of the new system was 10.5kWh/m3/year. Giving itself some room for unforeseen circumstances, Scantec guaranteed the system’s SEC at 15kWh/m3/year – if this was exceeded, the operator would get a percentage discount on the total project price. The recorded SEC was even lower at 8.5kWh/m3/year.
Jensen mentioned that the improved performance could partially be because one room was running as a chiller, not a freezer. “I am very confident that we could have achieved the 10.5kWh/m3/year even with two rooms running as a freezer,” he said.
In contrast, the existing liquid overfeed system’s SEC was 60kWh/m3/year. This is nearly six times more than predicted and over seven times more than the recorded SEC of the new refrigeration system. The old system has since been turned off and all refrigerated product moved into the new facility.
Innovative ways to work around Covid restrictions
“This was not an easy project,” Jensen admitted. Although design started in October 2018 with pull-down planned a year later, commissioning and handover only happened late in 2021. This was largely due to construction delays and being unable to leave Australia for in-person commissioning because of the pandemic.
Jensen and his team had to complete the project remotely, relying heavily on local industry professionals. An electrical engineer was flown in from Singapore to commission the programmable logic controls (PLC), but it was hard to explain over the phone, and this slowed things down, Jensen explained.
The pandemic has driven the popularity of Scantec’s containerized ScanPAC solution – a small-scale packaged centralized low-charge ammonia refrigeration system that fits within a 40ft (12m) container. It negates the need for lengthy on-site commissioning, minimizing the risk of situations like being unable to travel because of the pandemic.
Although Scantec is currently focusing on the local Australian market, there is potential for global expansion. Its low-charge systems can support a mixed cold storage facility of approximately 20,000m3 (706,293ft3) and are generally used for small foodservice facilities, said Jensen during the Q&A. “Just 10 years ago, this was not something that anyone would even consider running on ammonia. It would have all been air-cooled R404A with electric defrost. But that is changing.”
Watch the recording of this session where Mark Leong of FFM Engineering also presented results from a successful transcritical CO2 installation in Malaysia.
>>Read more Ammonia-related stories from the ATMO APAC event.
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