The so-called "supercooling" means that the saturated liquid after condensation is re-cooled by a device (such as a supercooler) and a method (or measure) to make its temperature lower than the saturated temperature under the condensation pressure. Comparing the liquid temperature before supercooling with that after supercooling, the difference is "supercooling degree" .

    The purpose of supercooling is to make the refrigerant liquid before throttling reduce the flash gas produced in throttling process, reduce the specific volume of flash gas occupied, and increase the refrigerating capacity per unit, as well as increase the superheat of return gas, to protect the compressor from the wet stroke operation, there are certain benefits.

    In larger refrigeration systems, in order to reduce the temperature of refrigerant liquid entering the throttling valve, reduce the flash gas generated during or after throttling, and improve the refrigeration efficiency appropriately, in the process design, a special equipment for supercooling has been installed after the reservoir (the system using the throttle must have the reservoir) as a supercooler.

    Its structure is casing type, spray type, etc. . The principle is to use cooling water lower than the saturated liquid temperature after condensation (such as deep well water) , generally can be compared before cooling again 3 ~ 5 degrees lower temperature (that is, sub-cooling degree of 3 ~ 5 degrees) . Some small fluorine refrigeration systems, such as small cold storage, although there is no special sub-cooler, but the supply pipe and return pipe wrapped together to keep warm, using the return pipe of the low temperature to lower the liquid temperature in the supply pipe, can also be a section of liquid supply pipe and expansion valve directly installed in the warehouse through re-cooling to achieve supercooling purposes, thereby improving the refrigeration efficiency. At the same time, it also heats the temperature of the air return pipe to avoid the possibility of liquid shock caused by the compressor inhaling moisture vapor.

   A system of capillary throttling, in which the capillary and the Return Airway (the inspiratory airway) are fused together, welded together, sheathed together with hot rubber, passed through the return airway, and wound around the return airway, some of the capillaries or liquid supply pipe directly in the box through. Source: Refrigeration Encyclopedia Public No. CAPILLARY and return pipe heat exchange, so that the liquid refrigerant before throttling and return pipe low temperature refrigerant steam heat exchange cooling and get undercooling, this can not only reduce the return gas pipeline may entrainment of liquid hit compressor, but also to achieve throttling liquid refrigerant before the goal of supercooling. If the condenser deliberately increased, leaving room for re-cooling and supercooling is also feasible. But in the standard design will not do so, the consideration is to minimize the overall volume and weight, reduce manufacturing costs. For small or micro-capillary throttling systems, no special supercoolers will be added.

   Do not talk about the whole condensation process separately. Refer to the inlet or upper part of the condenser as "condensation" and the lower part or the filter as "supercooling" , the difference between the initial temperature and the terminal temperature of the condensation process can not be regarded as the "supercooling degree" , which is wrong! The gas enters from the upper part of the condenser and gradually exchanges heat with the outside world, and the condensing temperature is gradually reduced. Source: Refrigeration Encyclopedia Public Number, finally condensing (liquefying) into a liquid and accumulating in the tail end of the condenser or in the filter, this is the complete condensation process. It can not be said that the upper part of the condenser is condensation and the lower part or some part is supercooling, nor can the inlet temperature of the condenser be subtracted from the outlet temperature as supercooling, or the condensation process of a certain temperature and the outlet temperature difference as the "supercooling" , which is not appropriate, or even wrong, misunderstood the condensation process. Under certain pressure, the temperature is higher than the saturated temperature of the steam, known as superheated steam. Refrigeration compressor exhaust pipe steam temperature, generally higher than the saturation temperature, it is superheated steam, called "exhaust overheating. ".

    Due to the length and insulation of the Return Air Pipe (suction pipe) , the steam in the pipe is heated by external transfer. This phenomenon is called "suction overheating" or "pipe overheating" . This kind of superheat will make the suction temperature of the compressor rise, the specific volume of the intake steam increase, resulting in the unit volume of refrigeration reduction, the compressor of refrigeration reduction, which is detrimental to the refrigeration cycle, in this issue known as "harmful overheating. ". Therefore, the suction pipe must be well insulated, as far as possible to reduce the length of the suction pipe, in order to reduce this harmful overheating.

   In the fluorine refrigeration system using expansion valve, the superheat is used to adjust the opening degree of thermal expansion valve, which is called "beneficial overheating" . Similarly, the fluorine steam after the heat recovery generated by overheating, but also belongs to the beneficial overheating.

   The difference between the saturated temperature before superheating and the saturated temperature after superheating is called superheating degree.

The difference between the saturated temperature before superheating and the saturated temperature after superheating is called superheating degree.

The collation comes from the encyclopedia of refrigeration