R22 direct-cooling evaporator

I haven’t come into contact with it before; I found it online. Hope it’s useful. 　Working principle of the barrel pump unit: The high-pressure liquid from the reservoir passes through a specially designed heat exchanger, where it exchanges heat with oil-rich liquid. This is done to ensure the safe operation of the compressor; the oil-rich liquid is vaporized, and the refrigeration oil is drawn in by the compressor. The new barrel pump unit adopts a multi-point oil return system, with three oil return ports provided on the barrel. This ensures the safe operation of the system. In recent years, with the emergence of large-scale logistics warehouses and cold storage facilities, barrel pump units have been widely used. Since such cold storage facilities are mostly low-temperature types, their evaporators are generally aluminum finned tubes. For aluminum fin tubes with a large surface area, if direct expansion feeding is used, a large number of valves and valve components will be required, as each circuit has an appropriate equivalent length and the length of the fin tubes is not very great. This increases the number of potential leakage points, and it also causes great inconvenience in operation and maintenance. To reduce heat loss and construction work, these valves need to be installed as close as possible to the evaporator. In this way, whenever adjustment or replacement is needed, it becomes the situation that maintenance personnel are least willing to deal with. Yet even so, it is difficult to ensure a uniform supply of liquid to the evaporator. Those who have been in many cold storage facilities must have seen instances of uneven frosting on the exhaust pipes. Moreover, in actual construction sites, it is practically impossible to keep all the piping completely horizontal or to achieve a certain slope. This may lead to oil accumulation in low-lying areas, thereby worsening the heat exchange effect and affecting cooling. Structure of the barrel pump unit: The barrel pump unit is generally composed of three main components. The first is the low-pressure circulation tank ； The second is a shielded pump ； The third part is the electronic control system. Then add some valves, level gauges, etc. The function of the low-pressure circulation tank is, firstly, to store low-pressure Freon liquid and maintain a certain net liquid column. Because shielded pumps require a certain suction head. The second function of the low-pressure tank is to act as a gas-liquid separator, which consists of two parts: the first part is for separating the flashed gas after throttling. What also needs to be separated is the Freon gas returning from the evaporator; in fact, this is because the liquid supply volume of the shielded pump is 3 to 6 times that of the evaporation volume in the evaporator. In other words, most of the Freon liquid returns to the low-pressure circulation tank along with the evaporator return gas, so effective gas-liquid separation is very important. The third function of the low-pressure circulation tank is to serve as a liquid discharge tank as well. Currently, this type of barrel-pump combination is mainly used in low-temperature storage facilities. The evaporators in these facilities are almost all coil-type, and the defrosting method employed is essentially thermal fluid defrosting; as a result, a drainage barrel is needed to store the liquid resulting from defrosting. In systems without a barrel pump unit, if heat fluorine defrosting is required, it may be necessary to add a separate drainage barrel. Working principle of the barrel pump unit: The high-pressure liquid from the reservoir passes through a specially designed heat exchanger, where it exchanges heat with oil-rich liquid. This is done to ensure the safe operation of the compressor; the oil-rich liquid is vaporized, and the refrigeration oil is drawn in by the compressor. The new barrel pump unit adopts a multi-point oil return system, with three oil return ports provided on the barrel. This ensures the safe operation of the system. In fact, the screw parallel units we use are all equipped with centrifugal oil separators, and very little refrigeration oil enters the system in the first place. To ensure greater stability and reliability of the system, secondary oil separators are specifically installed in the screw parallel units that use this system. High-pressure liquid enters the low-pressure circulation tank through a filter, solenoid valve, and throttle valve. The liquid from the low-pressure circulation tank enters the shielded pump and is then sent to the evaporator. To protect the shielded pump, pressure difference controllers are installed at both the inlet and outlet of the pump; when the outlet pressure does not reach the set value, the shielded pump stops operating. The function of the automatic bypass valve on the liquid outlet line is to allow excess refrigerant liquid to flow back to the low-pressure tank when there is a slight drop in temperature between the storage tanks.

Oil tank pumps should be selected based on the process flow and water supply/drainage requirements, taking into account five aspects: liquid transfer volume, pump head, properties of the liquid, pipeline layout, and operating conditions. Easy to maintain, reliable in performance, long service life, simple appearance, advanced and rational design, meets international standards, and is capable of transporting liquids free of solid particles. Classification of barrel pumps: manual barrel pumps, electric barrel pumps, pneumatic barrel pumps.