(1) Analysis of electric temperature adjustment function Assume that the ideal flow characteristic curve of the selected electric temperature control valve is linear. As described above, the actual flow characteristic curve of the electric thermostatic valve Deviate from the ideal flow characteristics curve, when it is connected in series with the dynamic flow balance valve, due to the dynamic pressure balance valve partial pressure, the valve power valve to further reduce the degree of deviation from the ideal flow characteristics of the curve to a greater extent. Curve 1 is the ideal flow characteristic curve of the electric control valve, it is the actual flow characteristic curve that the dynamic balance valve is not installed, it is the actual flow characteristic curve after connecting the dynamic flow balance valve in series, so this kind of series system installs the dynamic balance valve, Not only did not increase its electric regulation characteristics, but worse than the average electric control valve, so it can be said that the combination of series to weaken the electric thermostat electric regulating characteristics. (2) Whether there is a dynamic balance function Check whether the combination valve dynamic balance function must understand the dynamic balance function requirements. For this combination valve, the dynamic balance function refers to the end equipment load changes require the electric regulating valve adjusted to a certain opening, regardless of system pressure changes, the valve can dynamically balance the system's resistance, so that its flow from the system Pressure fluctuations and the impact of constant. The design flow of both valves in the valve is the design flow of the air conditioner box. The system adjusts the flow rate between the 0-Q design according to the change of the end equipment load during the actual operation. Therefore, the actual flow rate of the system is lower than the design flow most of the time. As the system requires that the flow be changed between 0-Q design, the dynamic flow balance valve, as shown in Fig. 6, has its actual operating range in the slanted area of ​​non-operating range (pressure difference is 0-P min) In fact the valve of the dynamic balance valve is always in the fully open position, equivalent to a fixed throttle element. If the end equipment load changes require the system actually needs flow Q0, then electric temperature control valve to accept the temperature control signal to the opening of the valve to 57% of the B point, at the same time, dynamic flow balance valve operating point A , The corresponding pressure difference is P0, the flow is Q0, then the dynamic flow balance valve bile in the fully open position. When the system pressure fluctuation fluctuates within a certain range, the dynamic balance valve is always in the fully open position, and can not play the role of balancing the pressure fluctuation of the system and keeping the output of the electric control valve constant. Therefore, this combination does not have the dynamic balance Features. But only rely on the electric thermostat's own regulatory role in the system pressure changes to change the opening to regulate the flow, but this adjustment is very inert for large systems, it is difficult to achieve good results. (3) Whether the current limiting action of the combined valve is an advantage. The combination valve has the function of limiting the flow as described above, but this current limiting is limited to the limit of the maximum flow not exceeding the design flow. Compared with the dynamic balance function of the dynamic balance electric control valve Trivial, but this function is to weaken the electric regulating valve electric adjustment function, increase the cost of resistance. In fact, even without dynamic balance valve installed, electric control valve in the system to increase the pressure so that the flow exceeds the design flow will automatically reduce the opening, thus limiting and regulating flow. Therefore, the limiting effect of the combination valve is only a characteristic rather than an advantage.