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2022

The working principle and application of temperature control valve

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The temperature control valve is the most important adjustment device for the flow adjustment of the heating system. If a heating system is not equipped with a temperature control valve, it cannot be called a heat metering and charging system. This paper introduces the structure and principle of the temperature control valve. By analyzing the flow characteristics of the temperature control valve, combined with the flow characteristics of the radiator, and introducing the concept of valve authority, it expounds the thermal characteristics of the radiator, the flow characteristics of the temperature control valve and the valve authority. How to ensure the effectiveness of the adjustment of the radiator system under the joint action of the temperature; and the installation scheme of the temperature control valve is introduced; finally, the energy saving effect of the temperature control valve is expounded.

1. The structure and working principle of the radiator temperature control valve The temperature control in the user's room is realized by the radiator temperature control valve. The radiator thermostatic control valve is composed of a thermostatic controller, a flow regulating valve and a pair of connectors. The core component of the thermostatic controller is the sensor unit, that is, the temperature bulb. The temperature bulb can sense the change of ambient temperature to produce volume change, drive the valve core of the regulating valve to produce displacement, and then adjust the water volume of the radiator to change the heat dissipation of the radiator. The set temperature of the thermostatic valve can be adjusted manually, and the thermostatic valve will automatically control and adjust the water volume of the radiator according to the set requirements, so as to achieve the purpose of controlling the indoor temperature.

2. The adjustment characteristics of the radiator are jointly determined by the thermal characteristics of the radiator, the flow characteristics of the temperature control valve and the valve authority. The ratio g/gmax of the flow rate of the temperature control valve under a certain opening degree to the fully open flow rate is called the relative flow; the ratio l of the stroke of the temperature control valve under a certain opening degree to the full stroke is called the relative stroke. The relationship between the relative stroke and the relative flow is called the flow characteristic of the thermostatic valve, namely: g/gmax=f

(l). The relationship between them is represented by several characteristic curves such as linear characteristic, quick opening characteristic, equal percentage characteristic and parabolic characteristic. For the radiator, from the perspective of hydraulic stability and thermal management, the relationship between heat dissipation and flow is a cluster of upward throwing curves. With the increase of flow g, heat dissipation q gradually tends to be saturated. In order to make the system have good regulation characteristics, it is easy to use a regulating valve with equal percentage flow characteristics to compensate for the nonlinear influence of the radiator itself

(1). The effect of valve authority on regulating characteristics. The adjustable ratio r is the ratio between the maximum flow rate and the minimum flow rate that the temperature control valve can control: r=gmax/gmin gmax is the flow rate when the temperature control valve is fully opened, which can also be regarded as the design flow rate of the radiator; gmin varies with The degree of authority of the thermostatic valve varies. In the radiator system, since the temperature control valve and the radiator are connected in series, the relationship between the adjustable ratio r and the valve authority is: r=rmax

(2) Taking a certain type of temperature control valve and radiator as an example, the flow capacity of the radiator is 5m3/h, the valve authority of the temperature control valve is 88%, the actual adjustable ratio is 28, and the corresponding flow adjustable range 100%-4%. The actual adjustable range of heat dissipation of the radiator under different inlet and outlet temperature differences is shown in the table.