With the continuous improvement of people's living standards and awareness of energy saving, variable flow systems occupy an increasingly important position in the HVAC engineering, and at the same time, a new type of hydraulic system - a comprehensive and balanced hydraulic system also HVAC engineering get more widely used. The overall balance of the hydraulic system is generally through the homeostasis electric regulating valve regulating the flow of the terminal equipment (such as air conditioning box) to regulate the temperature of the target area, it can dynamically balance the system pressure changes, so that the traffic between the two or more terminal equipment regulation does not interfere with each other, so this system is energy efficient.
In some air conditioning project, some designers to achieve the same functionality in the design, selection of dynamic flow balance valve and electric control valve combination system instead of the dynamic equilibrium of the electric control valve, and declared that the two kinds of configurations have the same functionality. Dynamic flow balance valve and electric control valve combination can replace the dynamic equilibrium of the electric control valve it, following some analysis and comparison of the features of these two configurations.
Scope: construction, chemical industry, metallurgy, petroleum, pharmaceutical, food, beverage, environmental protection and copyright dedecms
Dynamic equilibrium electric control valve to a dynamic equilibrium electric control valve performance analysis:
Dynamic equilibrium electric control valve is a new generation of products, is different from the traditional electric control valve dynamic equilibrium with electrically adjustable integration products, it has the following characteristics:
With excellent electric adjustment function:
Electric adjustment means that the valve can change according to the control signal of the temperature of the target area to automatically regulate the degree of opening of the valve, thereby changing the water flow, and finally to the actual temperature and the set temperature of the target area.
Evaluation electrically adjustable good or bad is the electric control valve flow characteristic curve. Adjust the the ideal valve flow characteristic curve is a straight line in the air-conditioning system, used electric or percentage. But for general electric control valve, the smaller valve authority in the actual use of the process, making the actual flow curve deviates from the ideal flow characteristic curve. As shown in Figure 3, an electric control valve ideal flow characteristic curve is linear (curve 1), but after installation to the system piping, the actual flow rate characteristic curve approaching fast-open type (curve 2), regulating the characteristics deteriorate.
Dynamic balance of electric control valve because of the unique valve structure, in the actual use of the engineering the valve authority substantially 1, the actual flow rate characteristic curve and the desired flow characteristic curve consistent, no deviation and therefore has excellent electric adjustment function .
Homeostasis function: the homeostasis function means according to the terminal equipment changes in load requirements electrically adjustable valve bile was adjusted to a certain degree of opening, regardless of how the system pressure changes, the valves are able to dynamically balance the system's resistance to flow regardless of system The pressure fluctuations and is kept constant. As shown in Figure 1, for a group of more than one air handler parallel loop (Figure drawn only 2-way). Return air temperature of each channel through dynamic balance electric valve to adjust the target area, which the regional setting temperature of 25 ℃, the the regional second set temperature of 27 ° C.
Assumed to be in summer conditions, the area a has been adjusted to the equilibrium state, i.e., the temperature T1 of the target area has stabilized at 25 ° C, when homeostasis the opening degree of the electric valve unchanged to output a constant flow is maintained at a certain position.
Region II also in an unstable state, measuring the return air temperature T2 below the set temperature of 27 ° C to 24 ℃, this time measuring the temperature and the set temperature in the temperature controller compares the output signal dynamic balance electric valve off a small in order to reduce the amount of cold water of the flowing air PROCESSING II, then the cooling capacity will be reduced, so that the measured temperature T2 is increased, close to the set temperature; this same time, the system riser C, D two points of the differential pressure will increase, air handlers First Ring Road, the dynamic balance of electric valve the DV1 ends C, B1 two-point differential pressure will also increase accordingly. However, due to the dynamic equilibrium of the dynamic balance function of the electric valve (the dynamic balance spool PV1 constant pressure difference), the valve to adjust the spool two-terminal A1, B1 point of differential pressure does not change, so the air handlers First Ring Road traffic unchanged refrigeration same amount, the corresponding zone one is still in a state of equilibrium (Figure 2 is a dynamic balance of electric control valve homeostasis curve).
As seen above, the the air handlers regulation of the Second Ring Road did not interfere with air handlers balanced First Ring Road, there is no dynamic hydraulic imbalance between the two loops. For multi-loop systems, any loop regulation are not interested in the other loop interference while loop will not be any other loop regulation system the greater the characteristics of this dynamic equilibrium more Obviously, each loop only by their own regional load changes from fluctuations in system pressure, so it is easy to reach and maintain a state of equilibrium.
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