Malaysian high-rise cold storage facility improves efficiency sevenfold with low-charge ammonia

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.

Low-charge drivers convince end user

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.