hydraulic balancing valve in air-conditioning water system

Air-conditioning water system as an important part of the air-conditioning system, the rationality of its design not only determines whether the entire air-conditioning system can be energy efficient, but also determines whether the air-conditioning system can operate normally and stably. Air conditioning water system after nearly a century of development of the overall theoretical development is more complete, but less research in its adjustability and balance. In the actual project often produces water system regulation is not good and hydraulic imbalance phenomenon.

At present, on the air conditioning energy saving research, a lot of work is mainly aimed at the research and development of high-efficiency refrigeration equipment and building form and air conditioning form of matching, and the water system regulation optimization control and design of insufficient attention, resulting in a good design program but often poorly regulated water system and hydraulic imbalance of the phenomenon.

With the emergence of a variety of new technologies, new equipment, people's control of air-conditioning systems to increase the precision requirements and higher requirements for energy saving, so that the air-conditioning water system has become the focus of recent air-conditioning technology research. In order to achieve the rationality of the system's energy utilization, it is necessary to have a good system of adjustability and balance, which is currently the biggest problem facing the water system.

First, the hydraulic balance of common methods to ensure the good operation of air-conditioning chilled water system, the first should meet the hydraulic balance of the system. At present, with the expansion of the size of the system and the increase in system complexity, hydraulic balance is more and more important. Now there have been numerous groups and scholars on the problem of hydraulic balance has carried out a lot of research.

1.1 Hydraulic balance of constant flow system
Fixed-flow water system is a common hydraulic system in the central air conditioning system does not contain any dynamic valves, the system in the commissioning is completed after the valve openings generally no longer make any changes in the operation of the system in the process of the flow of the various branches of the loop basically remain unchanged.
Fixed-flow system is mainly used for end equipment does not need to be adjusted by the flow of the system, such as end equipment with a three-way control valve, the use of three-speed switching regulation of the fan coiler and the use of variable air volume air-handling unit air conditioning system.
Fixed-flow system only exists in the static hydraulic disorders, there is no dynamic hydraulic disorders, so only need to install static hydraulic balancing equipment in the corresponding position. Fixed-flow system commonly used hydraulic balancing equipment is the throttle orifice plate, manual control valves and static balance valve, dynamic flow balancing valve and other regulatory elements.
When the end of the equipment does not change the amount of water, can be installed in each loop on the return pipe throttle orifice plate, manual control valves and static balancing valve, dynamic flow balancing valve.

1.2 Hydraulic balance of variable flow system
In order to save energy, variable flow water systems are increasingly used in air conditioning projects. During the operation of the variable flow system, the flow rate of each branch loop is changed with the change of load.
Since the air-conditioning system operates under part-load conditions most of the year, the system water flow rate is below the design flow rate most of the time, so the variable flow system is efficient and energy-saving. However, variable flow water system has a major disadvantage is that the woeful nature of the parallel loops, the water force will cause each other to influence the existence of dynamic hydraulic disequilibrium.
To achieve dynamic hydraulic balance, must meet the water system in the flow of each end device to achieve the actual instantaneous load requirements of the flow rate at the same time, the change in its flow rate is only affected by changes in the equipment load, and not subject to the interference of system pressure fluctuations.
Variable flow system of dynamic hydraulic balance aims to ensure that the system supply and demand for water instantaneous consistency (this function is realized by various types of regulating valves), to avoid the end of the equipment flow changes in the mutual interference, so as to ensure that the system is highly efficient and stable flow accurately transported to the various end of the equipment.

Second, the choice of control valves air conditioning system cooling heat output regulation of common methods is the air conditioning system of chilled water throttling. Throttling is accomplished through a variety of control valves, control valves are a component of the piping system, but also an important link in the automatic adjustment system. So in the air conditioning water system in the choice of regulating valve is very important. When the pressure difference between the two ends of the regulating valve changes when the regulating characteristics of the regulating valve will also change. To ensure the reliability of the control valve in the pressure change must consider the valve right degree of the control valve. The valve right degree of the control valve is defined as the control valve in the fully open valve on the differential pressure and the ratio of the total system differential pressure.