How To Choose Air Cooled Cold Room And Water-Cooled Cold Room?

A few days ago, readers left a message on refrigeration encyclopedia, asking how to choose air cooled cold room and water-cooled cold room?

In fact, this problem is well explained. If it is a large refrigeration system, it is recommended to choose a water-cooled refrigerator. If it is a small and medium-sized high-temperature refrigerator, it is recommended to use an air cooled cold room. In fact, according to the actual needs of refrigeration and the size of the cold storage, we know what refrigeration system to choose. Let's briefly explain the selection of refrigeration system.

1、 Analysis and comparison of water-cooled cold storage and air cooled cold room

From the perspective of system structure: the air-cooled unit adopts the air cooling mode (fan cooling); the water-cooled unit adopts the cooling water cooling mode, and the water pump, cooling tower and circulating pipeline are used to cool the unit. Therefore, the air cooled cold room group only needs air-cooled condenser or fan. The water-cooled chiller needs to be equipped with cooling tower, water pump and circulating pipeline. Water cooling is more complicated than air cooling in structure.

In terms of cooling capacity: for example, the cooling capacity of 4ncs20.2 of 20HP bizel medium and high temperature compressor is 38.6kw when the evaporation temperature is 0 ℃ and the condensation temperature is 50 ℃, and the power is 13.65kw, while the cooling capacity of water cooling is 44.5kw and the power is 12.1KW under the same working condition. It is slightly better than air cooled cold room unit in terms of cooling capacity and power consumption. But the power of cooling tower fan has not been included in the calculation.

From the scope of application: the air cooled cold room is suitable for the area where the water source is tight; the longer the annual operation hours, the more favorable the air cooled cold room is to use; the annual comprehensive cost of the air cooled cold room is lower than that of the water-cooled system, but if the water-cooled system is managed properly and the water replenishment is controlled below 3%, the annual cost of the water-cooled unit is lower than that of the air-cooled system. The air-cooled chiller adopts the air cooling mode, which eliminates the necessary cooling tower, cooling water pump and pipeline system of the cooling water system, avoids the condenser scaling and water pipe blocking caused by the poor water quality area, and also saves the water resources. It is the most economical and simple model in the current refrigeration equipment products for maintenance and repair.

Disadvantages of water-cooled cold storage: for the open cooling circulating water system, because the cooling water absorbs heat, contacts with the air, CO2 escapes into the air, and the dissolved oxygen and turbidity in the water increase, there are four major problems in the cooling circulating water system: corrosion, scaling, bacteria and algae breeding and sludge. If the water quality is not treated, the refrigeration equipment will be seriously damaged, and the heat exchange efficiency will be greatly reduced, resulting in energy waste. Therefore, it is very important to treat the system water with corrosion inhibition, scale inhibition, sterilization and algae control. The annual cost of water treatment is high, and the effect can not reach 100% scale removal. The quality of cooling circulating water is the key. If the water quality is not treated, the refrigeration equipment and efficiency will be seriously damaged.

Disadvantages of air cooled cold room: the power consumption per unit cooling capacity of air cooled cold room is slightly higher than that of water-cooled refrigerator, but the annual comprehensive cost of air cooled cold room is basically the same as that of water-cooled refrigerator. The results of technical and economic analysis show that it is reasonable to install air cooled cold room for medium and small refrigeration units. The longer the annual operation time of refrigeration unit is, the more favorable the air-cooled condensation mode is. The air-cooled units are more suitable for refrigeration in South China. From the cooling conditions, the high wet bulb temperature in South China is also unfavorable to the water-cooled units. The amount of water make-up for cooling water of water-cooling unit is an important factor affecting its cost.

Analysis of evaporative condenser, air-cooled condenser and water-cooled condenser.

Compared with air-cooled condenser and water-cooled condenser, the power consumption of evaporative condenser is about 1 / 2, and the circulating water is only 1 / 8 of that of water-cooled condenser. The advantage of water-cooled condenser and evaporative condenser is that the condenser has excellent cooling medium and heat transfer performance. The cooling performance of evaporative condenser is better than that of water-cooled condenser. The coefficient of cooling system and capacity of water-cooled condenser is larger than that of evaporative condenser. However, the cost per unit cooling capacity of evaporative condenser is the lowest and its performance is the best.

The operation and maintenance of air-cooled condenser is the most simple, and the equipment investment is also small, so it is suitable for application in the areas where water resources are scarce. Compared with air-cooled condenser and water-cooled condenser, the evaporative condenser is more energy-saving, water-saving and superior in system. The water-cooled condenser is suitable for the occasion of high ambient temperature with large condensing load.

For applications, evaporative condenser can be used in large refrigeration units such as screw, screw and piston parallel system. (the corresponding mode is one unit one steam cooling); and the water-cooled cold room is suitable for medium and small systems. The air cooled cold room can be used in small and medium-sized units, one condenser and one unit.