Why is there anyone going into the wrong way of 'a lot of delays'? The author believes that this is related to the lack of deep understanding of the two-phase process of the transformation of refrigeration systems by some professionals. They mixed the gas-liquid two-phase refrigerant in the press process of the press machine and the single-phase liquid pumping process, thinking that it is only a problem of pipe extension, and wants to let the refrigerant flow to where it flows. Where to go, it is a mistake. During the flow of the liquid refrigerant, when the pressure drops to the saturated swallow vapor pressure corresponding to its flux, it begins to change from liquid to vapor, and this vaporization process is the wave of refrigeration. The ideal state of refrigeration is that the liquid refrigerant begins to vaporize when it enters the hair dryer, and it is just vaporized when it exits the hair dryer. The entire vaporization process takes place in the hair dryer, which allows the hair dryer to absorb the maximum latent heat for maximum efficiency. If vaporization is not in the hair dryer or does not occur completely within the hair dryer. Then the work we did was in vain or part of the wave. However, the refrigerant line is as long, how can you control it not to vaporize halfway? Most domestic air conditioners still use a fixed-damped capillary as a throttling decompression element. Now, although there is an electronic expansion valve that automatically adjusts the refrigerant flow, it is not a thermal expansion valve. They can't react to the vaporization conditions in the hair dryer, and are not controlled by the superheat of the Yanfa exit. Therefore, it cannot be guaranteed that the vaporization process must occur in the hair dryer. Therefore, the 'one-to-many' air conditioner The extension of the refrigerant circuit is extremely blind. Since the liquid refrigerants distributed to the respective indoor units are in the same working condition, and the lengths of the pipes leading to the respective hair dryers are different from each other, the resistance and the pressure drop are different. It can be affirmed that the vaporization points will be far from each other, and the near-end, far-end fincher refrigeration. Will be greatly weakened; take care of the far, the liquid refrigerant in the near hair dryer is not complete, will cause liquid impact on the press machine, damage the compressor. The multiplexing of fluids has a feature. That is, the resistance of the road is small, and the fluid goes to the road. If you want to implement a balanced fluid supply to pipelines with different resistances, it is necessary to have a means of regulating the resistance of each road, so that the resistance of each road is basically balanced, that is, it must be set on each pipeline, and the throttle valve. And can be adjusted automatically. However, this is difficult to achieve for refrigeration systems. In summary, the design of the refrigeration system has two major taboos; the refrigerant line is too long, especially the low pressure pipeline. Second avoid the multi-channel distribution of refrigerant. Under such restrictions, the semi-centralized air conditioning scheme for chiller fan coils has emerged. It introduces water as a coolant, and adds pumps and valves to replace the refrigerant with cold water for long-distance and multi-path material delivery, thus bypassing the above-mentioned reclamation area. Although there is a layer of refrigerant. But it makes the plan practical. However, the designers of the air conditioners have left the above two jealousy behind them, so it is a technical solution that has made a low-level mistake, and failure is inevitable. The problem is that we should learn useful lessons from them and invite them to avoid repeating the same mistakes.