中央空调水系统水力不平衡的问题

The problem of hydraulic imbalance in the water system of central air conditioning

中央空调水系统中一个较为突出问题是水力不平衡。对于某些规模较大又较复杂的系统，通常有许多控制回路，由于回路大小不一、管线长短不一，稍有不慎就会出现水力不平衡现象。

A prominent problem in water system of central air conditioning is hydraulic imbalance. For some larger and more complex systems, there are usually many control loops. Because of the size of the loop and the length of the pipeline, the hydraulic imbalance will appear slightly.

1.1水力不平衡对冷热源机组的影响

Influence of 1.1 hydraulic imbalances on cold and heat source units

保持冷热源机组的流量在机组规定的限度内可以使设备免受损害，在流量低于机组设计流量时，安全装置将使机组停止运行。时开时停将使机组所提供的出力低于室内负荷所需的功率，同时如果水量突然减小，控制器来不及反应，也来不及调整机组的出力，就有可能发生水在管内冻结，其后果是相当严重的。如果是多台机组并联使用，随着负荷的减小，设计机组容量会是负荷所需容量的几倍。当实际投入运行机组多于实际需要时，部分机组会长期地重复开启和停止，且启停周期很短。这样，将导致机组效率降低及能耗增加，而且缩短了机组的使用寿命。

The flow of the cooling and heat source unit can protect the equipment from damage within the set limit of the unit. When the flow rate is lower than the unit design flow, the safety device will stop the operation of the unit. At the time of opening, the force provided by the unit will be lower than the power required for the load in the room. At the same time, if the water quantity suddenly decreases, the controller is too late to react and can not adjust the output of the unit, it is possible to freeze the water in the tube, and the consequence is quite serious. If multiple units are connected in parallel, with the reduction of load, the designed capacity will be several times the capacity required by the load. When the actual operation of the unit is more than the actual demand, some units will start and stop for a long time, and the start and stop period is very short. As a result, the efficiency and energy consumption of the unit will be increased, and the service life of the unit will also be shortened.

为确保机组良好运行，合理的方法是在每台机组处设置平衡阀，这样可调整流量至设计值。对于并联安装的冷却塔，出水管上应设平衡管，以保证各个冷却塔水量的平衡。

In order to ensure the good operation of the unit, a reasonable way is to set up a balancing valve at each unit, so that the flow rate can be adjusted to the design value. For a parallel installed cooling tower, a balance pipe should be set up to ensure the balance of water consumption of each cooling tower.

1.2水力不平衡对输配系统的影响

The influence of 1.2 hydraulic imbalances on the transmission and distribution system

在输配系统中，距离水泵最远的环路因阻力大其差压为最小，而距水泵最近的环路则具有最大差压值。如果没有任何措施弥补这种差异，那么近水泵段或系统环路阻力小的环路，水流量会大大高于设计流量；反之，则大大低于设计值，整个系统中的水量处于分配不均状态。这种不均匀的水量会使建筑物内室温不均匀，以及室温持续波动；近冷水机组处房间过冷，距离远的则室温偏高；另外流量偏大的环路的房间相对较快地达到要求的室温，流量偏小的环路的房间需较长时间才能达到要求的室温。

In the transmission and distribution system, the maximum distance between the pump and the pump is the largest, and the differential pressure is the smallest, while the nearest loop of the pump has the maximum differential pressure. If there are no measures to make up for this difference, the water flow in the near water pump section or the loop resistance loop of the system will be much higher than the design flow; conversely, it is much lower than the design value, and the amount of water in the whole system is in the unequal distribution state. The inhomogeneous water will make the room temperature inhomogeneous and the room temperature fluctuate continuously; the room near cold water unit is too cold and the distance is far away, the room temperature is high; the room with a large flow rate is relatively fast to the required room temperature, and the loop room with small flow will take a long time to reach the required room temperature.