‘Ultra-Low-Charge’ Ammonia Chiller Boosts Efficiency 40% for Sake Producer

Japanese sake producer Takara Sake has installed an “ultra-low-charge” ammonia (R717) chiller that is 40% more efficient than a baseline R507A chiller at the same production plant in Berkeley, California (U.S.). 

These results were provided by Ammi Amarnath, Senior Technical Executive at the Electric Power Research Institute (EPRI) during a panel on utilities and incentives at the online ATMOsphere America conference on October 21.  

The installation, part of a pilot project, employs the AuRa, an air-cooled chiller from Japanese manufacturer Mayekawa, with a charge of 1.5lbs per TR (0.2kg/kW), and a capacity of 50TR (176kW). The chiller at the Takara Sake plant is used to cool sake fermentation tanks.

The research pilot project is mainly funded by the California Energy Commission, with EPRI and Mayekawa as partners. It was part of an effort to find out whether ultra-low-charge ammonia chillers are also sufficiently energy efficient to qualify for utility incentives programs. “The big question was, are these new technologies more efficient than the baseline of existing technologies,” said Amarnath.

In a comparison of COP (coefficient of performance), the answer is yes.

The baseline system used for the comparison is a water-cooled R507A chiller, with a capacity of 82.5TR (290kW), which is used to cool a sake liquefaction tank on the same site in California. Both chillers were instrumented to evaluate their performance under similar operating conditions, having the same chilled water supply temperature, ambient temperatures and chiller percent capacity.

The evaluation was made under the following operating conditions: Chillers working at 70-80% capacity, in an ambient temperature of 65-70°F (18.3-21°C), and having a chilled water supply temperature of 43-46°F (6-7.8°C). Under these conditions, the R717 chiller achieved the 40% higher efficiency.

Apart from the energy efficiency, the R717 chiller also has another advantage, which is particularly important in a state like California regularly suffering from droughts. The AuRa is air cooled, rather than water cooled, meaning it saves Takara 3.38 gallons (12.8L) of water per kWh electricity used, an average of 14,000 gallons (53,000L) of water a month for the company. Being air cooled also means there is no need for chemical water treatment or a cooling tower, all in all leading to a smaller carbon footprint. 

The AuRa chiller integrates innovative technologies like microchannel heat exchangers and a semihermetic compressor. The microchannel heat exchangers have flat tubes with air side-fins, making them “small, light and efficient,” Amarnath told his audience. The AuRa’s semi-hermetic compressor has aluminum instead of copper windings, and is “practically leak free, with no route for refrigerant to escape,” Amarnath added.