The low-charge system employs R723, a rarely used mixture of 60% ammonia and 40% dimethyl ether with a GWP of eight.
The ammonia/ether system in Slovak dairy Milsy a.s.
Slovakian dairy company Milsy a.s. has installed a cooling system that runs on the rarely used refrigerant R723, a mixture of 60% ammonia (R717) and 40% dimethyl ether (RE170) that has a GWP of eight.
ABC Food Machinery, from Bratislava, Slovakia, installed the TwinEco 300 R723 system, which provides a cooling power of 141 kW and a heating power of 187 kW. The dairy, which produces 100,000 liters of milk per day, uses the system to cool down production and storage areas to 4°C; waste heat is used for 2 m3 of domestic hot water, the cloak room, a 420 m2 dining room and defrosting.
ABC Food Machinery told ammonia21.com that it currently sells around one to two of these systems every year, but “the demand for R723 is increasing.”
The dairy installation consists of three different refrigeration circuits, which are mounted on one frame. Each has a R723 charge of 1.9 kg. The independent cycles are packaged in one unit and connected by plate heat exchangers, using glycol as brine.
A control system can switch from one to three cooling cycles, based on demand. Each system can be maintained separately, without influencing the others. The systems also all have their own oil return and oil separator.
The design uses piston compressors by HKT Goeldner and plate heat exchangers from Alfa Laval.
The other option considered was an HFC system. However, the dairy opted for R723, due to the very low charge and the use of condensation heat.
The energy efficiency of the R723 system is 40% better than the considered HFC solution according to ABC Food Machinery.