The Chillking Ultra Low Temp Chiller is a very heavy-duty piece of equipment. It has a cascade cooling system. This chiller has a primary compressor that is very large; it is rated at 5 tons (60,000 BTU) although the amount of heat removed steadily declines as the temperature drops. The 2 ton compressor removes heat from the primary 5 ton compressor’s condenser. The heat is then discharged out the side of the chiller.
The 5 ton compressor will remove heat from ambient temperature and downward to well below 0F. Both compressors will continue to cycle until the desired below 0F temperature is reached.
The smaller compressor is rated at 2 tons (24,000 BTU) and has but one duty: it cools the condenser of the primary compressor. By keeping the condenser cool of the primary compressor, the primary compressor can reach lower temperatures and quicker. Liquid to gas/liquid cooling is much quicker that air across a gas/liquid condenser.
Each compressor has its own independent refrigeration circuit. The primary large compressor has a very wide operating range. It is rated as 5 tons; however, as the temperature drops the BTU output is greatly reduced. This is because there is less heat to remove. For every 20F to 25F drop there is a performance penalty of 50%. From 55F to 30F the compressor performance gradually drops to 2.5 tons then from 30F to 5F it decreases another 50%. The compressor performance decreases to around 1.25 tons at 5F.
Performance decrease isn’t meant to imply the compressor is doing less. The compressor actually works harder as the temperature drops. The decrease in performance results from the law of thermal dynamics. It takes 1 BTU to change 1 pound of water 1F in 1 hour. The process of the compressor and its refrigeration circuit is the heat removal device. If there is 50% less heat in the liquid it will take twice as long to remove the same amount of heat. One hour becomes two. It will take more time to achieve ultra low temperatures. Plan accordingly.
Two different refrigerants are used in the Ultra Low Temperature Chiller. The largest compressor is rated for five tons (60,000 BTU). The 5 Ton compressor uses refrigerant 404a. This refrigerant has been on the market for twenty years and has proven its range of operation. The refrigerant has the ability to carry extreme differentials in temperature range. Refrigerant 404a will achieve extremely low temperatures.
The smaller compressor is rated at two tons (24,000 BTU). It has one purpose, to cool the refrigerant of the primary 5 ton compressor. This compressor uses 410a. 410a is the most popular refrigerant now being used in most refrigeration systems. This refrigerant is very environmentally friendly and is a blend of three refrigerants. This refrigerant is one of the most energy efficient refrigerants in the marketplace.