In winter, the coil of fresh air conditioning unit in the cold area of North China often appears frost crack, which seriously affects the normal maintenance of the operating room. The following laminar flow operating room decoration company will summarize some skills to prevent the coil of fresh air conditioning unit from freezing in the laminar flow operating room!
There are several main reasons for the cold cracking of coil pipes:
I. when the fresh air conditioning unit stops working, there is no heating measure in the machine room, the temperature is lower than - 0 ℃, the system water pump stops working, and there is no water drainage in the coil of the fresh air conditioning unit, or the water drainage in the coil is not clean due to the unreasonable coil design, or the fresh air close valve is not closed tightly, etc;
II. When the fresh air air conditioning unit is in normal operation, the design of the water system of the air conditioning is out of hydraulic balance, the water flow is insufficient, or the design of the water volume of the coil is too small, or the influence of the evaporation temperature of the double cooling source on the water coil, etc. The measures to prevent freezing of fresh air unit when Xinfeng air conditioning unit stops working are as follows:
During the construction, it is suggested that the hospital should set up heating facilities in the machine room;
Before the arrival of winter, drain the water in the cold coil pipe of the fresh air air conditioning unit, check the closing condition of the fresh air airtight valve regularly, and repair it in time if it is found that the closing is not strict; when ordering the air conditioning unit, select the cold water coil pipe with evacuation design, and set the shutdown heat preservation and antifreeze device (see Figure 8).
In case of normal operation of the fresh air conditioning unit, the measures to prevent freezing of the fresh air unit are as follows:
The hydraulic calculation is carried out in the design of air conditioning water system to avoid the problems of hydraulic imbalance and insufficient water flow;
Set the fresh air power preheating at the air inlet of the fresh air unit to preheat the fresh air to 5 ℃. As the phenomenon of frost cracking of cold coil pipe of fresh air conditioning unit is more common, it also attracts the attention of air conditioning unit manufacturers. There are also good measures in the design of fresh air conditioning unit:
For example, the fresh air bypass design is adopted for the fresh air unit, the cold water coil is of the downstream design (see Figure 9), the layout of the surface cooler and evaporator in the double cold source fresh air air air conditioning unit, the installation of the steam coil vacuum breaking valve and the drain valve, etc.
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