How much do you know about the application analysis of evaporators

How much do you know about the application analysis of evaporators

As one of the four major components of refrigeration, the evaporator plays a vital role in the entire refrigeration system. Therefore, the compressor and evaporator can only be matched reasonably to make the entire refrigeration system play a better effect. Therefore, the choice of evaporator It is very important to be allocated to the entire refrigeration system. The two common types of evaporators in low-temperature refrigerators are air coolers and pipes. Actual coolers and pipes have their own advantages and disadvantages:

　　 enclosure structure

　　Whether the cold storage adopts civil construction or steel structure, the load-bearing capacity of the top must be considered, which is called suspended load in the design. When seamless steel pipes are used to make pipes, the reference value of the design suspension load is 70~80Kg/㎡; if aluminum alloy pipes are used to make the top pipe, the reference value of the design suspension load is 40~50Kg/㎡; if air coolers are used At this time, only the suspended load of the air cooler needs to be considered locally.

The air cooler occupies a small area and the internal volume is relatively small, so the fluorine capacity of the air cooler does not take up a large proportion of the entire refrigeration system; the diameter of the exhaust pipe generally ranges from Φ22 to Φ38, and the larger the pipe diameter The larger the fluorine capacity of the entire refrigeration system increases.

　　The exhaust pipe library generally requires 2~4 times more Freon than the fan library. In the future, the price of Freon continues to rise and Freon is updated, the cost of Freon is also a part that cannot be ignored.

　　Initial investment

　　From the evaporator selection alone, the initial investment of aluminum piping is generally greater than that of the air cooler. The overall cost of the system with air cooler is about 15%~25% lower than that with aluminum piping, and the larger the system, the more obvious the price difference between the two. Generally, the construction period of pipe making and hoisting is 3 to 4 times longer than that of installing air coolers, so the labor cost for making pipes and installing is much higher than the labor cost for installing air coolers. Air coolers are used in low-temperature cold storages in developed countries to cool down. This factor is also taken into consideration on the one hand (foreign labor costs are much higher than domestic labor costs).

　　 defrost method

　　 At present, the common defrosting methods of cold storage air coolers are: natural defrost, water frost, electric defrost and hot fluorine defrost. The automatic defrosting of the air cooler is relatively easy to achieve, and the defrosted water flows out of the cold storage along the defrosting downpipe of the air cooler. Aluminum alloy pipes are mostly used for hot fluorine defrosting, but the pipes are distributed in the warehouse and the water droplets will fall when defrosting. Therefore, the goods should be transferred or covered with waterproof plastic cloth during defrosting. It is not as good as air cooler. Frost is so flexible and convenient.

　　 Electricity consumption later

Under the same other conditions, the forced convection of the air cooler relies on the motor to drive the fan and the air cooler defrosts 1 to 2 times a day to produce a certain amount of power consumption; for the exhaust pipe, the exhaust pipe belongs to natural convection, and the general exhaust pipe After removing the frost twice a year, compared with the electricity consumption in the later period, the aluminum tube is relatively cheaper than the air cooler.

　　 cold storage capacity

　　The air cooler belongs to forced convection, and the cooling speed is fast; the aluminum pipe belongs to natural convection, and the cooling speed is relatively slow. Therefore, in the actual cold storage operation, if the main refrigeration equipment matches are basically the same, the start time of the compressor in the cold fan library and the tube library is similar.

　　The cold storage capacity of aluminum platoons does not play a big role in maintaining the overall storage temperature. The key to maintaining the storage temperature is the storage enclosure structure and insulation practices, as well as the storage capacity of the stored goods. The low-temperature cold storage that adopts multi-layer, the internal polyurethane foam spraying of the civil construction frame will save much more electricity than the assembled cold storage structure of single-layer, steel structure and polyurethane sandwich double-sided color steel plate.

　　Dry goods consumption

　　The main factors affecting the dry consumption of goods are: heat transfer temperature difference, wind speed, evaporator working time and packaging method.

　　 Generally speaking, the dry consumption of goods stored in the cold storage using the air cooler is greater than that of the cold storage using the piping. But it should be noted that the main body of dry consumption refers to the goods rather than the cold storage or evaporator. Therefore, which evaporator z* is reasonable, the key question is what kind of goods are stored and how to pack them. Goods sealed in plastic bags do not have to consider dry consumption.

　　 Fund utilization

I mentioned the gap in the construction period between the air cooler and the piping. The construction period of the piping is long, and there is a situation of occupying capital. The short construction period of the air cooler can be quickly invested, and the return on investment can be obtained earlier. Occupy the market. If the cold storage rent is about 3 yuan/day square meter, the monthly rent return is not a small figure.

　　Efficiency and quality stability

The air cooler is a stereotyped and mature product. It is assembled by professional skilled workers and assembly lines in the factory, while the pipes are assembled on site. The assembly level of the workers has a great influence on the uniformity of liquid supply of the pipes. The uniformity of liquid supply of the coolers is relatively relatively it is good.

The failure point of the air cooler is mainly the motor and electrical components as the running parts. As long as the well-known brand products are used, such as EBM, Xerox Bai, Siemens, Schneider and other products, the failure rate is greatly reduced; and the pipe, especially the aluminum alloy pipe, Because the welding process requires high requirements and the rigidity is relatively poor, if the welding is not good or the force is uneven during hoisting, the probability of leakage of the pipe is very high. As the safety of the refrigeration system is paid more and more attention, the quality control of equipment will become more and more standardized, and standardized production and management will become an insurmountable threshold for piping.