RU2338126C1 - Method of outgoing flow temperature control in blowing devices (versions) - Google Patents

Abstract

FIELD: ventilation.

SUBSTANCE: method of outgoing air flow temperature control in blowing devices consists in charging of air in channel of air blowing device, in which electric heating elements are installed, which communicate to the source of their power supply, and passage of this air flow through mentioned electric heating elements. As electric heating elements semi-conductor resistors are used with positive temperature coefficient, temperature of outgoing air is controlled with turn of semi-conductor resistors at the angle from 0° to 90° in relation to direction of air flow or with the help of relief air valve, sending part of charged air along bypass channel in zone behind semi-conductor resistors. Such arrangement will make it possible to increase affordability and efficiency of heating.

EFFECT: higher affordability and efficiency of heating.

6 dwg, 2 cl

Description

The invention relates to ventilation equipment and relates to the design of household and industrial heating and heating appliances and devices (fan heaters, dryers, duct heaters, air-heating units, etc.). In particular, the invention considers a new method for controlling the temperature of the outgoing air stream in blower devices using PTC thermistors (semiconductor resistors with a positive temperature coefficient) as an electric heating element.

A known method of controlling the temperature of the outgoing air flow in the blower devices, which consists in pumping air into the channel of the blower device, in which there are electric heating elements in communication with their power source, passing the flow of this air through these heating elements and controlling the temperature of the outgoing air flow in the area behind the electric heating elements by changing the physical state of the latter (RU No. 2122689, F24H 3/04, publ. 1998.11.27).

In the known method, the temperature control of the outgoing air flow in the area behind the electric heating elements is carried out by increasing the number of TEN-heaters, which leads to the need to use switching equipment and increased power consumption.

This decision was made as a prototype for both declared objects.

The heating elements in ceramic air heaters are semiconductor resistors with a positive temperature coefficient (PTC thermistors) - semiconductor elements whose electrical resistance, and therefore the heating power, depends on their surface temperature, that is, the higher the temperature of the resistor, the lower the power. This feedback does not allow heating of elements above 250 ° C, thereby ensuring complete fire safety of the heater. The maximum current of the heater, unlike conventional heating elements, is achieved only at low inlet temperatures and high air flow rates. This property of posistors to some extent facilitates the operation of power nodes of control systems and relieves the electrical network from peak power consumption if at the moment the ventilation device is not operating in extreme operating conditions.

PTC thermistor (resistor with a positive temperature coefficient). When an electric current is passed through a thermistor, it heats up. The more the thermistor heats up, the more its electrical resistance grows. Upon reaching the switching point (as the temperature rises), the thermistor (the temperature of the switching point is set during the manufacture of the product mainly from 250 ° C), its resistance increases sharply and a further temperature increase is impossible. This property of PCT heaters makes the device in which it is used fireproof, unlike devices on heating elements or with heaters in the form of a nichrome spiral, where due to the purely resistive properties of these heaters their surface temperature is not controlled by anything.

The same property of semiconductor resistors with a positive temperature coefficient makes it difficult to regulate them with external electrical devices (thermostats). The principle of such temperature control is that the supply voltage to the heater is not supplied continuously, but by pulses, depending on the heat demand, which is determined by the conditionally set temperature at the outlet of the blower device.

The main problem is that a semiconductor resistor with a positive temperature coefficient at the time of the next supply voltage pulse already has time to cool down and its electrical resistance is small. Therefore, the current in the circuit will be very large and will decrease as the thermistor heats up. The life of a semiconductor resistor with a positive temperature coefficient in this electrical control circuit is small, since it operates in the maximum starting currents mode. The use of thermoregulating devices based on the principle of changing the voltage supplied to the heater depending on the heat demand does not have an effect, since the surface temperature of a thermistor does not depend on the voltage supplied to it, but on the characteristics of the switching point that is set during manufacture.

The present invention is directed to solving the technical problem of using semiconductor resistors with a positive temperature coefficient exclusively in the mode of maximum heating of their surface with minimum energy consumption and ensuring air regulation due to the mechanical components of the blower device.

The technical result achieved in this case is to increase profitability, durability and overall performance.

The specified technical result for the first method is achieved by the fact that in the method of regulating the temperature of the exhaust air flow in the blower device, which consists in pumping air into the channel of the blower device, in which are located the electric heating elements in communication with their power source, passing a stream of this air through the electric heating elements and regulating the temperature of the outgoing air flow in the area behind the electric heating elements by changing the physical equilibrium is the latter. A semiconductor resistor with a positive temperature coefficient is used as electric heating elements, and the temperature of the exhaust air is controlled using a bypass air valve, directing part of the injected air through the bypass channel to the area behind the semiconductor resistors with a positive temperature coefficient.

The specified technical result for the second method is achieved by the fact that in the method of controlling the temperature of the outgoing air flow in the blower devices, which consists in pumping air into the channel of the blower device, in which the electric heating elements are in communication with their power source, passing the flow of this air through these electric heating elements and regulating the temperature of the outgoing air flow in the area behind the electric heating elements by changing the physical equilibrium is the latter. As electric heating elements, semiconductor resistors with a positive temperature coefficient are used, and the temperature of the exhaust air is controlled by turning the semiconductor resistors with a positive temperature coefficient by an angle from 0 ° to 90 ° relative to the direction of the air flow.

These signs are significant and interconnected with the formation of a stable set of essential features sufficient to obtain the desired technical result.

The present invention is illustrated by specific examples of execution, which, however, are not the only possible, but clearly demonstrate the ability to achieve the desired technical result.

Figure 1 - blower installation for implementing the first method of regulation, a mixed air supply;

figure 2 is the same as in figure 1, the air supply through the bypass channel;

figure 3 is the same as in figure 1, the air supply through the semiconductor resistors with a positive temperature coefficient;

figure 4 - blower installation for implementing the second method of regulation, the maximum heating of the air;

figure 5 is the same as in figure 4, the mode of absence of air heating;

6 is the same as in figure 4, the mixed air supply.

According to the present invention, a method for controlling the temperature of the outgoing air flow in a blower device is to inject air into the channel of the blower device (for example, by means of a fan), in which electric heating elements, such as semiconductor resistors with a positive temperature coefficient, are in communication with their power source and transmitting the flow this air through the indicated electric heating elements. In semiconductor resistors with a positive temperature coefficient, the heating temperature is brought to the temperature of the switching point and is maintained in a constant power mode. The temperature control of the outgoing air flow in the area behind them is carried out with the help of a bypass air valve, directing part of the injected air through the bypass channel into the zone behind the semiconductor resistors with a positive temperature coefficient.

The essence of the method of controlling the temperature at the outlet of the blower device, the heating element of which is a semiconductor resistor with a positive temperature coefficient, is as follows. Since a semiconductor resistor with a positive temperature coefficient is a fireproof self-regulating element, it can operate in static mode (without air passing through it). In this mode, the current consumed by him is extremely small, since its electrical resistance is high (the temperature has reached the switching point).

It is proposed to install a semiconductor resistor with a positive temperature coefficient in the blower device 1 (Fig. 1) in parallel with the bypass air channel 2 that does not have an electric heater 3, and regulate the temperature of the exhaust air 4 using the bypass air valve 5, directing a portion of the charge air 6 through the electric heater 3 (figure 1), and part of the air - bypassing the bypass channel. The bypass valve is controlled by an electric actuator 7, the signal to which comes from an external thermostat 8 (thermostat).

If it is necessary to exclude heating of the air (Fig. 2), it is sufficient to set the control signal from the transfer of the bypass air valve 5 to the position at which its damper completely blocks the channel in which the semiconductor resistor with a positive temperature coefficient is located. In this case, the entire air flow will be directed through the bypass channel to the outlet of the blower device, bypassing the channel in which the heater is located. Since a semiconductor resistor with a positive temperature coefficient is a self-regulating element, in this mode (without air passing through it) it can operate by consuming minimal current, since its electrical resistance is high (the temperature of the switching point is reached).

If it is necessary to ensure the influx of the maximum heated air into the room, then it is necessary to set the control signal according to which the bypass air valve 5 will switch to the position at which its damper completely blocks the bypass channel. In this case, the entire flow of injected air will pass through a semiconductor resistor with a positive temperature coefficient.

Another control option based on the same principle will be an electric heater rotated by the electric drive through an angle from 0 ° to 90 ° relative to the direction of the air flow (Figs. 4-6). This blower device does not have a bypass channel, and semiconductor resistors with a positive temperature coefficient of 3 are arranged to rotate them from an electric drive 9, which is connected to an external temperature controller 8 (thermostat or).

According to this method, the heating temperature of semiconductor resistors with a positive temperature coefficient is brought to the temperature of the switching point and maintained in a constant power mode, and the temperature of the exhaust air in the zone behind them is controlled by turning the semiconductor resistors with a positive temperature coefficient at an angle from 0 ° to 90 ° relative to the air direction flow.

To obtain the most heated air at the outlet, semiconductor resistors with a positive temperature coefficient are installed perpendicular to the direction of air flow (figure 4). In this case, the entire air flow is passed through the heaters. When turning semiconductor resistors with a positive temperature coefficient by an angle at which these plate-shaped heaters become parallel to the air flow, air heating is minimized (Fig. 5). The temperature control of the outlet stream is provided by turning the plate / n of semiconductor resistors with a positive temperature coefficient by an angle in the range from 0 ° to 90 °, at which part of the air flow is passed through a semiconductor resistor with a positive temperature coefficient, and part passes bypassing this heater (Fig. 6). The mode of mixing the air flow of heated and not heated allows you to economically maintain the set temperature of the mixed air at the outlet of the device.

Benefits:

1. Fire safety design (temperature of the heating element does not exceed 250 ° C).

2. Smaller dimensions of the device compared to devices in which the heater is a heater or a nichrome spiral.

3. The absence in the electrical circuit of powerful switching devices, relays or triacs, which cause interference in the electrical network during switching.

The present invention is industrially applicable, as it can be manufactured in industrial production using well-known technologies commonly used in the manufacture of air heating devices in indoor air exchange systems.

Claims (2)

1. A method of controlling the temperature of the outgoing air flow in the blower devices, which consists in pumping air into the channel of the blower device, in which the electric heating elements are in communication with their power source, passing the flow of this air through these electric heating elements and controlling the temperature of the outgoing air flow in the section electric heating elements by changing the physical state of the latter, characterized in that as electric successive elements using semiconductor resistors with positive temperature coefficient and the heating temperature of the outgoing air is controlled by the bypass air valve, directing part of the charge air to the bypass channel in the zone of semiconductor resistors with a positive temperature coefficient. 2. A method of controlling the temperature of the outgoing air flow in the blower devices, which consists in pumping air into the channel of the blower device, in which the electric heating elements are in communication with their power source, passing the flow of this air through these electric heating elements and controlling the temperature of the outgoing air flow in the area beyond electric heating elements by changing the physical state of the latter, characterized in that as electric successive elements using semiconductor resistors with positive temperature coefficient, and the outlet air temperature is controlled by turning the semi-conductor resistors with a positive temperature coefficient on the angle from 0 ° to 90 ° relative to the direction of airflow.

Images