Dynamic balance electric control valve range and performance

With the continuous improvement of people's current living standards and energy-saving awareness, variable-flow systems occupy an increasingly important position in HVAC engineering. At the same time, a new type of hydraulic system—a fully balanced hydraulic system is also in HVAC engineering. It is getting more and more widely used.

A fully balanced hydraulic system typically regulates the temperature of the target area by dynamically balancing the electric control valve to regulate the flow of the end device (such as an air conditioning box). It dynamically balances the pressure changes in the system to allow flow between two or more end devices. Adjustments do not interfere with each other, so this system is energy efficient.

At present, in some air-conditioning projects, some designers use a combination of dynamic flow balancing valve and electric regulating valve instead of dynamic balancing electric regulating valve in order to achieve the same function, and claim that these two configurations have the same function. Then the combination of dynamic flow balancing valve and electric regulating valve can replace the dynamic balancing electric regulating valve. The following analysis and comparison of the functional characteristics of these two configurations are carried out.

Scope of application

Urban construction, chemical, metallurgy, petroleum, pharmaceutical, food, beverage, environmental protection

Performance Analysis of Dynamic Balance Electric Control Valve

The dynamic balance electric control valve is a new generation product that is different from the traditional electric control valve. It is a product of dynamic balance and electric regulation. It has the following characteristics:

1 has excellent electric adjustment function:

The electric adjustment function means that the valve can automatically adjust the opening of the valve according to the change of the temperature control signal of the target area, thereby changing the water flow rate, and finally making the actual temperature of the target area coincide with the set temperature.

It is the flow characteristic curve of the electric control valve that evaluates the electric adjustment function. In an air conditioning system, the ideal flow characteristic curve of a commonly used electric regulating valve is straight or equal. However, for a general electric control valve, the actual flow characteristic curve deviates from the ideal flow characteristic curve due to the small valve weight in actual use. As shown in Fig. 3, the ideal flow characteristic curve of an electric regulating valve is linear (curve 1), but the actual flow characteristic curve is close to the quick opening type (curve 2) after being installed on the system piping, and the adjustment characteristics are deteriorated.

Due to the unique valve body structure, the dynamic balance electric valve has a valve weight of 1 in the actual use engineering. Therefore, the actual flow characteristic curve is consistent with the ideal flow characteristic curve without deviation, so it has excellent electric adjustment function. .

2 with dynamic balance function:

The dynamic balance function means that when the electric control valve is adjusted to a certain opening according to the change of the end equipment load, the valve can dynamically balance the resistance of the system regardless of the system pressure, so that the flow rate is not affected by the system pressure fluctuation. keep constant.

It is assumed that in the summer condition, the area has been adjusted to the equilibrium state, that is, the temperature T1 of the target area has stabilized at 25 ° C, at which time the opening of the dynamic balance electric valve is maintained at a certain position to maintain a constant flow rate.

Zone 2 is still in an unstable state, measuring the return air temperature T2 is 24 ° C, lower than the set temperature of 27 ° C, then the measured temperature will be compared with the set temperature in the temperature controller, the output signal will dynamically balance the electric valve to close In order to reduce the amount of cold water flowing through the air handler 2, the amount of cooling will be reduced, and the measured temperature T2 will be raised to approach the set temperature; at the same time, the pressure difference between the two points of the system risers C and D will increase. The pressure difference between the two ends C and B1 of the first-loop dynamic balance electric valve DV1 of the air handler is also increased accordingly. However, due to the dynamic balance function of the dynamic balance electric valve (the constant pressure difference of the dynamic balance valve core PV1), the pressure difference between the two ends A1 and B1 of the electric control valve core of the valve does not change, so the air handler has a loop The flow rate remains unchanged, the cooling capacity is constant, and the corresponding area is still in equilibrium (Fig. 2 is the dynamic balance curve of the dynamic balance electric control valve).

It can be seen from the above that the adjustment of the second loop of the air handler does not interfere with the loop of the already balanced air handler, so there is no dynamic hydraulic imbalance between the two loops. For multi-loop systems, the adjustment of any one loop will not interfere with other loops, and any loop will not be affected by other loop adjustments. The larger the system, the more the dynamic balance characteristics Obviously, each loop is only affected by the load changes in its own area, and is not affected by system pressure fluctuations, so it is easy to achieve and maintain equilibrium.