R410A chillers just got bigger
R410A has been applied to large chillers with capacities up to 760 kW by Carrier with the development of the AquaSnap Puron range. New levels of efficiency have been achieved.
R410A continues to replace R407C with its use in a new range of chillers offering up to 760 kW of cooling.The environmental and efficiency benefits of refrigerant R410A have been applied to large chillers by Carrier. The launch of the AquaSnap Puron range [Puron is Carrier’s name for R410A] is said to be the first air-cooled chiller for large commercial applications specifically designed to operate with this refrigerant. The new range covers cooling capacities from 190 to 760 kW, in cooling-only and heat-pump versions. These new chillers achieve an energy-efficiency ratio that is 13% higher than the previous generation of AquaSnap chillers (30GK with R407C as the refrigerant). R410A is a 50/50 blend of two components (R32 and R125); it is more stable than other refrigerant blends and practically behaves like a pure refrigerant, simplifying maintenance. Rotary scroll compressors are used, which is believed to be the first application of such compressors with R410A in equipment of this size. A COP of 2.8 is achieved at full load at nominal conditions. A range of techniques is used to maximise efficiency at part-load conditions that prevail for most of the year, resulting in a seasonal energy-efficiency ratio of about 4.5. Two to four compressors are connected in parallel in each refrigerant circuit, and they are energised or de-energised in response to the cooling load. The Carrier Pro-Dialog control system, linked to an electronic expansion valve, permits cooling operation at a lower condensing pressure and optimised use of the surface of the evaporator heat exchanger at part load. The overall effect is an integrated-part-load value for energy-efficiency of 4.35 for 99% of operating time. A patented direct-expansion free-cooling system further boosts performance. An EER of 13 is achieved at an outside temperature of 0°C. (water leaving temperature of 10°C). This free cooling is based on the use of outside cold air to produce cold water using as little energy as possible. These new chillers are based on the natural migration of refrigerant in the evaporator to the condenser. To ensure the continuity of the refrigeration cycle, a small pump moves the liquid refrigerant in the condenser to the evaporator. Chilled water is produced without using compressors when the outside temperature falls below 5°C. Noise levels have been halved [–3 dB(A)] compared with existing models. A super-low-noise option achieves –7 dB(A). AquaSnap Puron chillers have a small footprint. Pumps, valves, expansion vessels and other accessories are all integrated within the hydraulic module, without altering its physical size. This ‘packaging’ simplifies the design process and minimises installation complexity to such an extent that a 500 kW chiller can be operational in three days, including commissioning.
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