The CO2 Chiller System is a very attractive ecological alternative, which today can be used anywhere in the world.
How does the Chiller work with CO2? Subcritical?
The critical point It is the maximum value of temperature, where CO2 can change state, for example from gaseous to liquid phase.
A Subcritical cycle is one that in any state always works below the critical point.
The CO2 cycle is used within a facility with two cascade systems.
The CO2 circuit works at a low temperature and is responsible for cooling the liquid, and another cycle is used to achieve condensation of the CO2 Cycle.
The CO2 in the chiller is always below the critical point.
Transcritical CO2 Cycle Chiller:
The fundamental idea of is the use only of CO2 in the entire installation, so as not to have problems with environmental regulations.
Features of the CO2 Chiller:
- The CO2 chiller works with very high pressures.
- The application of the CO2 chiller has a great future when we think about the environment.
- The Glycol Transcritical CO2 Chiller offers high efficiency and reliability for low temperature cooling.
- As the temperatures reached at the compressor discharge of a CO2 chiller are high, heat recovery can be used for other applications. With heat recovery, in CO2 chillers, water temperatures for other processes of up to 75 ° C can easily be reached.
- The CO2 Chiller is perfectly suited to a wide range of glycol supply temperatures, ranging from -30 ° C to + 12 ° C.
- The transcritical CO2 chiller is used with a flooded evaporator to cool CaCl2, ammonia-water and other industrial brines.
- There are liquid ammonia / carbon dioxide (CO2) chillers, designed for installations that require cold storage or freezer.
- The use of ammonia / CO2 chillers reduces the ammonia load by up to 90% compared to ammonia-only systems.
- Due to the high pressure value, they increase the leakage potential in the chiller with co2.
- The CO2 chiller uses specially designed components.
- Chiller compressors that work with CO2 are special due to their greater cooling capacity.
- The costs of chillers with CO2 and installation are higher either in cascade or transcritical.
- Chiller tubing that works with CO2 includes steel or stainless steel.
- Usually in CO2 chillers, stainless steel pipes are used for all cold pipes.
- Mild steel pipes are used for discharge or hot pipes.
- The components of the CO2 chiller have different joining techniques, due to higher pressure values and different materials.
- Two-stage compression is required for transcritical chillers.
- Inter-stage cooling is essential in very low temperature applications, due to the high discharge temperature of R744.
- Chillers with CO2 need a purity of R744 close to 99.99%
- The wall thickness of tubes and exchangers needs to be increased to handle the higher pressures.
- CO2 refrigerant offers greater cooling capacity than most synthetic refrigerants.
- CO2 chiller needs fewer grams of refrigerant to cool the same amount of water.
- CO2 has low pressure drops, in pipes and heat exchangers favoring C O P.
- The CO2 Chiller has high heat transfer in evaporators and condensers due to the high pressure and density of the refrigerant. Although a CO2 chiller handles very high pressures, the compression ratios are lower.
- CO2 is not corrosive to most materials.
- CO2 chiller with oil has good miscibility with the lubricant.
- Polyol ester lubricants can continue to be used.
- Low toxicity and non-flammable.
- A Refrigerant Charge from a CO2 chiller is cheap.
- The CO2 molecule is stable, which leads to a low potential for decomposition within the refrigeration system.
- They are modern, fully automated equipment.
- Investing in a CO2 chiller eliminates future environmental risk and safety restrictions.
- Financial savings are substantial and generated over the life of the equipment.
- Significant reduction in greenhouse gases. Precise temperature control.
- They are highly reliable systems. Very low maintenance cost.
- Almost total elimination of the risk of ignition and toxicology, which can occur with other refrigerants in another process.
- Many of these machines are currently manufactured to run without oil to maximize efficiency.
- These equipments have less volume, occupying less space in the machine room.
- They have minimal noise levels.
- As they are modern equipment, the use of scroll compressors with a fixed capacity, or with a highly efficient inverter variator, is common.
- Electronic expansion valves help this equipment meet the latest energy requirements.
- Intermediate discharge valves, built into scroll compressors in many of this equipment, and variable speed fans improve efficiency, at part load values.
- CO2 is classified as an A1 refrigerant under ASHRAE Standard 34, which means it is non-toxic and non-flammable.
- A large confined space leak can displace oxygen for breathing. In the presence of atmospheric pressure, CO2 can change to a solid phase, it can occur when opening an overpressure relief valve, for example, the R744 outlet can be blocked by itself.
Where to learn all about chillers?
We have prepared a complete training in chilled water installations with chillers.
