Comparison of water cooling, evaporative cooling and air cooling systems
In the refrigeration system scheme, customers often ask which is the best for the air-cooled refrigeration system and the water-cooled refrigeration unit? Here we discuss together. Combined with practical experience, the following discussion is made; (Considering that the number of air-cooled condensers in large refrigeration units is too large, it is usually difficult to arrange them. On the other hand, too small water-cooled refrigeration units are not conducive to use. Compare with the same water-cooled refrigeration unit.)
- System structure
The air-cooled unit adopts the air cooling method (fan cooling);
The water-cooled unit adopts the water cooling method, and the water pump, cooling tower and circulation pipeline are used to cool the unit in circulation.
Therefore, the air-cooled unit only needs an air fan. The water-cooled needs to be equipped with a cooling tower, water pump, and circulating pipeline.
There system , water cooling is more complicated than air cooling.
- cooling capacity
for example, the 20HP Bitzer compressor 4NES-20,
When evaporating temp. is 0 degrees and the condensing temp. is 50 degrees,
Air : cooling 38.6KW /Consumption of 13.65KW
Water：cooling is 44.5 KW/ consumption 12.1KW.
Therefore Water cooled is slightly better than the air-cooled in terms of cooling capacity and electricity consumption.
However, the cooling tower fan and water pump consumption are not considered into.
The air-cooled is suitable for areas where water resources are scarce; the longer the annual operating hours of the refrigeration system, the more advantageous it is to use the air-cooled ; the annual comprehensive cost of the air-cooled refrigeration unit is lower than that of the water-cooled system .
However, if the water-cooled system is properly managed and the water supply is controlled below 3%, the annual cost of the water-cooled unit will be lower than that of the air-cooled system.
The air-cooled chiller adopts the air cooling method, which saves the cooling tower, cooling water pump and piping system that are necessary for the cooling water system, avoids condenser scaling and water pipe blockage caused by poor water quality, and saves water resources. Among the current refrigeration equipment products, maintenance is more economical and simple.
- Disadvantages of water cooling system:
For the open cooling circulating water system, after the cooling water absorbs heat, it contacts with the air, CO2 escapes into the air, and the dissolved oxygen and turbidity in the water increase, resulting in four major problems in the cooling circulating water system: corrosion. , scaling, bacteria and algae growth and sludge. If the water quality is not treated, the refrigeration equipment will be seriously damaged, the heat exchange efficiency will be greatly reduced, and the energy will be wasted. Therefore, it is very important to treat the system water for corrosion inhibition, scale inhibition, sterilization and algae killing. The annual cost of water treatment is high, and it is impossible to achieve 100% descaling.
The quality of cooling circulating water is the key. If the water quality is not treated, it will seriously damage the refrigeration equipment and efficiency
- Disadvantages of the air-cooled system:
The consumption per unit cooling capacity of the air-cooled refrigeration unit is slightly higher than that of the water-cooled , but the annual comprehensive cost of the air-cooled unit is basically the same as that of the water-cooled unit and slightly lower.
Technical and economic analysis show that it is reasonable to configure air-cooled condensers for medium and small refrigeration units. The longer the annual operating time of the refrigeration unit, the more advantageous using the air-cooled .
From the perspective of cooling conditions, the high wet bulb temperature in the southern region is also unfavorable for water-cooled units. The amount of cooling water replenishment of the water-cooled unit is an important factor affecting its cost.
3) Compared with the air-cooled and water-cooled condensers, the evaporative condenser saves about 1/2 of the power consumption, and the circulating water volume only accounts for 1/8 of the water-cooled type. The advantage lies in the cooling medium with excellent heat transfer performance of the condenser. The heat dissipation performance of evaporative condenser is better than that of water-cooled type. The refrigeration system and cooling capacity of water-cooled condenser are larger than those of evaporative condenser, but the unit cooling capacity cost of evaporative condenser is lower and its performance is better.
- The operation and maintenance of the air-cooled condenser is simpler, and the equipment investment is also less, and it is suitable for application in areas where water resources are scarce. Evaporative condensers are more energy-saving and water-saving than air-cooled and water-cooled condensers, and the system is superior. Water-cooled condensers are suitable for occasions with large condensing load and high ambient temperature.
- For application occasions, evaporative condensers can be used in large refrigeration units such as screw and screw, piston parallel systems. (The corresponding method is one unit, one evaporative cooling); and water cooling is suitable for medium and small systems, One tower can be used for multiple units; while air cooling is used in small and medium-sized units, one condenser and one unit.