Causes of air conditioning circulating water pump failure

The paper discusses how to choose the pump to ensure the air conditioning system running well and reduce the power consumption.
First, the cause of excessive capacity of air conditioning circulating water pump failure:
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Circulating water pump capacity is too large in our country is a common problem, its capacity is often up to 2-4 times the actual needs, resulting in serious waste of investment and operating costs. The main reasons are as follows:
Design cooling load is too large:
The design of the cooling load is the main basis for the selection of equipment, so it is very important to correctly calculate the cooling load of the building. At present, the calculation method of air conditioning load in the textbook and design manual is not only to calculate the wall load of the envelope, but also the load of the door and window. However, the capacity of the air-conditioning system is determined based on the cooling load of the whole building. Because of the different directions of the room, the location, the use function and the heat source of the building, the time of the maximum cooling load of each room is not the same. Therefore, the maximum value of building cooling load should be the maximum value of the hourly load superposition of each room. According to the survey in our country some designers in the calculation of building cooling load is simply the maximum cooling load of each room is superimposed, resulting in the calculation results are much larger than the actual demand load. Therefore, we must pay enough attention to the design of the load is more reasonable and correct.
System circulation resistance is too large:
In the calculation of system circulation resistance, due to lack of experience designers to make some calculations parameters are too conservative, resulting in the calculated circulation resistance, what is more, in the construction design stage estimation method used to determine vascular resistance, resulting in calculation of circulation resistance value more than twice as large than the actual. The air conditioning system is full of water to run, the pump inlet and outlet under the same hydrostatic pressure. Therefore, the selected pump head can only overcome the resistance of the pipeline system can be. However, some designers are also included in the hydrostatic pressure resistance of the cycle, which of course will make the capacity of the circulating water pump increases a lot.
System static pressure:
The air conditioning system is full of water to run, the pump inlet and outlet under the same hydrostatic pressure. Therefore, the selected pump head can only overcome the resistance of the pipeline system can be. However, some designers are also included in the hydrostatic pressure resistance of the cycle, which of course will make the capacity of the circulating water pump increases a lot.
Hydraulic balance problem:
Due to the design of the system is not seriously hydraulic balance calculation, after the completion of the project did not meet the requirements of a comprehensive debugging, often resulting in the system hydraulic imbalance, the phenomenon of hot and cold. Some technical personnel mistakenly believe that the cause of this phenomenon is that the capacity of circulating water pump is too small, the result is simply to increase the use of water pumps to solve the problem, naturally also makes the pump capacity increases.
Two, the design of the pump operating point along the pump curve to the right deviation:
Right shift in the pump operating point, circulating pump generated head lower, this is the normal operation of the system is extremely unfavorable, especially in the most unfavorable loop system, will lead to further reduce the flow of the loop, affecting the normal use function. There are two main reasons for the shift to the right:
1, the first is the design of hydraulic calculation using too large safety factor and the actual pressure drop calculation method
2, followed by the design of the system did not carry out a careful calculation of hydraulic balance, and after the construction of the system has not been strict debugging. Therefore, in order to make the system run according to the design conditions, in addition to the related detail should be carefully calculated, it should select the pump in the pump's operating point will select the best operating point on the left in the appropriate position, to prevent the pump work beyond a certain range of operating conditions is not the economy, affecting the normal operation of the system.