For the two common cooling methods of water chillers, many people will be curious about air cooling and which is better. Let's discuss together. Combine the practical experience to make the following discussion. Considering the large number of air-cooled condensers for large refrigeration units, it is usually difficult to arrange them. On the other hand, too small water-cooled refrigeration units are also not conducive to use. Therefore, medium air-cooled units and the same water-cooled refrigeration units are used. Compare.
1. Structure comparison
Air-cooled unit adopts air cooling method (fan cooling); water-cooled unit adopts cooling water cooling method, water pump plus cooling tower and circulation pipeline to cool down the unit circulation.
From the point of view of water cooling installation, it can be divided into two types: built-in water cooling and external water cooling. For the built-in water cooling, it is mainly composed of radiators, water pipes, water pumps, and sufficient water sources. This means that most water cooling systems have a large "volume" and require sufficient space inside the chassis. Therefore, the air-cooled unit only needs an air-cooled condenser or fan. The water-cooled chiller needs to be equipped with a cooling tower, water pump, and circulation pipeline. Structurally, water cooling is more complicated than air cooling.
Air-cooled refrigeration units are suitable for areas where water resources are tight, and the more advantageous the use of air-cooled refrigeration units for the longer the annual operating hours of the refrigeration system. 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 managed properly and the make-up water volume is controlled below 3%, the annual cost of the water-cooled unit is lower than that of the air-cooled system.
Second, the advantages and disadvantages of water cooling and air cooling system:
Disadvantages of the water cooling system: For the open cooling circulating water system, because the cooling water absorbs heat and contacts 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, formation Scale, 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 energy will be wasted. Therefore, it is very important to carry out corrosion inhibition, scale inhibition, sterilization and algaecide treatment on the system water.
Disadvantages of the air-cooled system: The power consumption per unit of cooling capacity of the air-cooled refrigeration unit is slightly higher than that of the water-cooled unit, but the annual comprehensive cost of the air-cooled unit is basically the same as that of the water-cooled unit. The results of 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 it is to use air-cooled condensation.
Third, the technical and economic comparison of the two units
Example 1: Taking BLD-20AD and BLD-20WD as examples, the cooling capacity is 38.6KW when the evaporation temperature is 0 degrees and the condensation temperature is 50 degrees, the power is 13.65KW, and the water cooling is 44.5KW and the power is 12.1 under the same working conditions. KW. Slightly superior to air-cooled units in terms of cooling capacity and electricity consumption. However, the power of the water-cooled water pump power cooling tower fan has not been added to the calculation.
Example 2: Compare a certain type of water-cooled refrigeration unit with the same air-cooled refrigeration unit as the main unit and evaporator. The annual operation time of the compressor is from 1000 hours to 3000 hours, and the annual operation time of the cooling tower and the water pump is correspondingly from 1400 hours to 4200 hours.
Operation cost of air-cooled refrigeration unit: annual power consumption cost of air-cooled refrigeration unit = (compressor power consumption + fan power consumption) × operating time / year × electricity price.
Operation cost of water-cooled refrigeration unit:
Annual water fee for water-cooled refrigeration unit = (total circulating water × number of water changes + replenishment volume × total circulating water volume × operating time/year) × water price.
Water cooling unit annual power consumption cost = (compressor power consumption + cooling tower fan power consumption + cooling water pump power consumption) × running time / year × electricity price.
4. Conclusion
The initial investment of the air-cooled refrigeration unit is relatively high, and the power consumption per unit of cooling capacity is also slightly higher than that of the water-cooled unit, but the annual comprehensive cost of the air-cooled unit is basically the same as that of the water-cooled unit. The longer the annual operation time of the chiller, the more beneficial it is to the air-cooled unit, and the initial investment payback period of the air-cooled unit is shorter than that of the water-cooled unit. The amount of cooling water make-up of a water-cooled unit is an important factor affecting its cost. Strengthening maintenance management and reducing water consumption is an important aspect of reducing the cost of water-cooled units.