EE201400032A - Autonomous control system for central heating system and autonomous control method for central heating system - Google Patents

Abstract

The present invention provides an autonomous control system of central heating system and autonomous adjusting method of central heating system, in order to reduce thermal energy used for heating of rooms. The heating system of the invention comprises a heat exchanger 1, having heat exchanger 2 of the heat producer, heat exchanger 3 of the heat consumer or apartment house, radiator 13 equipped with thermostatic valve 14, adjusting valve 4 of heating water flow amount of the heat producer, controlled by the incoming signal from control/adjustment unit 5, as well as the circulation pump 10, which is integrated with or is connected in series with the reflux amount sensor 11, which is connected to electronic circuit located in the control/adjustment unit. Electronic circuit 12 located in the control/adjustment unit 5 is configured to receive signals sent from reflux amount sensor 11 and adjust according to flow amount through the circulation pump the adjusting valve 4 of the heat producer, which ensures that based on the work of the thermostats 15 is adjusted the amount of the heating energy taken from the heat producer, wherein thermostats 15 respond to changes in room temperature, thus during operation of the heating system is taken into consideration, for example, so called free energy produced by the sun, and the cooling effect of the wind to rooms on the windy sides of the building.

Description

Technical field

The present invention belongs to the field of energy and energy saving technology, more specifically to the field of a house heating system and its regulation method, with the aim of reducing the thermal energy consumed for heating rooms.

Background of the invention

The heating system of a typical apartment building (see Fig. 1) consists of the following main parts: central heating piping (one-pipe system, two-pipe system), radiators, each radiator being equipped with a radiator valve (hereinafter referred to as valve) and a radiator thermostat (hereinafter referred to as thermostat), a heating water circulation pump, which is controlled based on preset heating schedules, a heating water regulation control module, and various control valves necessary to balance the entire heating system, for example, control valves installed on the heating pipe risers between floors of the house.

The operation of the house's heating system is currently set based on outdoor temperature schedules, which do not take into account specific factors affecting the internal temperature of the house (sun, wind, heat radiated into the room by residents, etc.). In addition, the heating schedules are made with an unreasonably large margin. On average, it is estimated that 150 kWh of heat energy is consumed per square meter of a typical apartment building per year.

In the apartments, each radiator has a valve controlled by a thermostat. Currently, the heating system is tuned according to the outdoor temperature, based on which the supply and return temperatures of the heating water are set, taking into account the temperature dependence graph of the thermostat.

The task of the circulation pump, which is part of the heating system, is to keep the water in the heating system circulating. The required heating water flow rates are calculated according to the house's heating class (based on the EV regulation) A 21+-1, B 21+-2 and C21+-3 °C. For example, the heating water flow rate may be set to 3 liters per second, i.e. 10.8 m³ per hour.

State of the art

CA1313558 discloses a method for regulating the performance of a circulation pump installed in a water heating system, wherein the pump is controlled by an electric motor with a variable speed. According to the method, the speed of the heating water flowing in the system is measured, converted into an electrical signal corresponding to the speed and applied to a voltage regulator, which regulates the operation of the electric motor of the pump.

In the known heating systems used today, the heat energy consumption of buildings is regulated according to a so-called heating schedule. This schedule is linear and sets the heating water supply temperature of the heating system for each outdoor temperature value. Therefore, the temperature inside the building is essentially determined by only one variable parameter - the outdoor temperature.

However, many studies have shown that in addition to the outdoor temperature, the building's heat energy consumption also depends significantly on other weather factors. For example, strong wind increases energy consumption by up to 30%, while solar radiation can compensate for up to 100% of the heat energy needed to heat a building during a certain period of time. The existing (traditional) heating system does not respond at all to these factors, and as a result, under certain conditions, the consumer is forced to increase the heating water supply temperature by a margin or, under certain conditions, consciously cool rooms that are heated too hot. The above-mentioned examples of various weather factors are some of the reasons why buildings overheat and an unjustified overconsumption of heat energy by an average of 10-20% during the heating season occur. The situation should be improved by regulating the radiators of the heating system using thermostatically controlled valves. However, the above-described method of regulating the heating system based on the outdoor temperature practically does not respond to the operation of thermostats at all. Therefore, the potential for saving heating energy that could be achieved by using thermostats to prevent overheating remains unused.

The essence of the invention

Depending on the room temperature, thermostats either open the valves more or close them. This affects the flow rate of the heating water in the entire house. With modern circulation pumps, it is possible to see what the instantaneous real flow rate is (for example, calculated per hour), and in addition, it is possible to see what the pressure difference in the system is. From these circulation pump indicators, it is possible to calculate what the optimal supply and return temperatures of the heating water could be. Currently, there is no such possibility in known heating systems that the regulation of the heating system of the house is not based on the outside temperature, but on the inside temperature. As a result of the operation of the thermostats of the heating system according to the invention, the change in the flow rate of the heating water in the heating system, which can be measured either directly by the circulation pump or with a return flow meter installed in series with it, generates feedback from the circulation pump to the heating water control/regulation center, which in turn regulates the amount of heat energy taken by the heat generator. Installing such feedback and, based on this, additional automatic regulation of heating water using the control system and its controller, allows you to respond to changes in room temperature in heated rooms (for example, the cooling effect of the wind) and take into account the so-called free heat (especially solar energy), which can significantly save heating costs.

At the same time, the heating system of the invention takes into account the specific characteristics of individual apartments in the house (for example, a strong wind blowing from one direction can cool certain apartments beyond a reasonable limit and the traditional heating water control system of the heating system cannot respond to this).

List of illustrations

A more complete overview of the present invention can be obtained by reading the following detailed description of an exemplary embodiment, together with the accompanying drawings, in which:

Figure 1 shows the main parts of the central heating system of the present invention and the means for regulating the central heating system;

Figure FIG 2 shows the operating curves of the thermostatic valve and the dependence of the flow rate and temperature of the thermostatic valve according to different preset settings of the valve;

Figure 3 shows the relationship between the flow rate of the circulation pump and the pressure drop of the liquid.

Example of carrying out the invention

The heating system according to the invention, which in the preferred embodiment concerns the heating system of an apartment building, includes the following main parts (see Figure FIG 1): a heat exchanger 1, which has a heat exchanger 2 on the heat producer side, a heat exchanger 3 on the heat consumer or apartment building side, a heat producer heating water flow regulator valve 4, which is controlled by a signal from the control/regulation center 5. The heating water in the heat producer heat exchanger 2 passes through a water flow meter 6, to which is connected a heat meter 7, which is connected to two temperature sensors 8, 9, so that the temperature sensor 8 measures the temperature of the heating water going from the heat producer heat exchanger to the consumer and the temperature sensor 9 measures the temperature of the heating water from the heat producer after leaving the heat exchanger. The part of the heating system on the heat consumer side includes a circulation pump 10, into which a flow sensor 11 is integrated or connected in series with it, which is connected to an electronic circuit 12 located in the control/regulation center 5 (for example, a controller, in the preferred embodiment a PID controller or Proportional-Integral-Derivative controller or PID controller). Heat consumers are radiators 13 located in the rooms, which are equipped with a thermostatic valve 14 and a thermostat 15. The temperature of the heating water of the heat consumer is measured by a supply temperature sensor 16, which is also connected to the control/regulation center 5. In an alternative embodiment of the invention, a temperature sensor 18 is installed on the outer wall 17 of the building to measure the outside temperature. The change in the volume of the heating water due to the possible expansion of the heating water in the piping on the heat consumer's side is compensated by an expansion tank 19 connected to the system. The electronic circuit 12 located in the control/regulation center 5 is configured to receive signals sent from the flow sensor 11 and to regulate the flow rate of the heating water of the heat generator 4 according to the flow rate passing through the circulation pump, which ensures that the amount of heating energy taken by the heat consumer from the heat generator is regulated based on the operation of the thermostats 15, whereby the thermostats 15 react to changes in the room temperature, thus their operation depends on for example, from the so-called free heat generated in the room by the sun, but on the other hand, the operation of the thermostats 15 depends on the cooling effect of the wind on the windward rooms of the building. The electronic circuit 12 (for example, a controller) is also connected to an outdoor temperature-dependent temperature sensor 18 located on the outer wall of the building. The electronic circuit 12 located in the control/regulation center 5 is in one case configured to regulate the control valve 4, based on the control signals arriving from the flow sensor 11. In this case, the signals arriving from the outdoor air temperature sensor 18 can be displayed in the control/regulation center 5 as information, based on which it would be seen to what extent the control valve 4 would have been regulated taking into account only the outdoor temperature. Alternatively, it is possible to control the operation of the control valve 4, based on the signals of the flow sensor 11, the outdoor air temperature sensor 18 and the supply temperature sensor 16.

The thermostat regulates the flow of heating water through the radiator according to the room temperature, but this process does not occur linearly. The operation of the thermostat is characterized by a closing point, which determines from which room temperature the thermostat begins to intensively limit the flow of heating water through the radiator, and this closing point value can be changed on the thermostat valve. Figure FIG 2 shows the operating graphs of the thermostat valve with different closing points GN (data are provided by the thermostat manufacturers). The graphs show that the range from the closing point to almost complete closing of the thermostat corresponds to an increase in the room temperature by only two degrees. At the same time, the flow of heating water decreases in this range from 0.8Gmax-0.25Gmax practically linearly. For example, curve a corresponds to a thermostat setting where the room temperature fluctuates between +18 and +20 °C. The parameters of the A-class heating system specified by the law of the Republic of Estonia ( t= +22 °C ± 1 °C ) can be achieved by selecting a closing point of the thermostat at +21 °C (line a'). The optimal operating zone of the thermostat is in the range of 0.8Gmax-0.5Gmax , where Gmax is the maximum heating water flow rate. In this mode, the temperature in the room remains constant (within plus or minus 1 °C) and allows ensuring both comfort and economy. However, as already mentioned, the existing building heating systems and control systems are not capable of ensuring this.

The closing and opening of the thermostat piston (not shown in the figures) occurs linearly within a certain range. This process also ensures that the resistance of the entire heating system changes according to a linear law. However, closing the piston can also cause unpleasant noise in the system, especially when the flow drops below 0.5Gmax. In order to eliminate this negative effect, special circulation pumps with frequency converters have been developed that ensure a so-called constant pressure difference in the heating system. The graphs of different variants of such a circulation pump are shown in Figure FIG 3A, B, C. If the building thermostats are set to operate in a linear range, as described above, and the indoor temperature begins to increase, then the resistance of the entire system begins to increase. The pump automation responds to this increase in resistance and reduces the pump speed and, as a result, the heating water flow rate in order to keep the pressure drop in the system constant. If the room temperature exceeds the thermostat closing point, then the heating flow rate in the entire system begins to decrease according to a linear law, as shown in Figure FIG 2.

Knowing the design data for the heating system flow rate Gmax and the values of the closing point of the building's thermostats, a heating system can be built in which the heating water flow rate depends on the building's internal temperature.

For example, if the building's Gmax is 10 m³/h and the closing point GN is +21 °C, then it can be assumed that if the average indoor temperature in the rooms is +21 °C, then the flow rate in the system will be 8 m³/h, if the average indoor temperature in the rooms is +22 °C, then the flow rate in the system will be 5 m³/h.

The heating system and its control method of the present invention are based on the principle that the adjustable thermostats of the heating system of the building are set in the same way and the heating water supply temperature of the system is controlled in such a way that these thermostats operate in an optimal mode at all times. To achieve this goal, a circulation pump is installed to maintain a constant pressure difference in the system and a heating water flow sensor is installed in series with it, which is connected to the system's control and control center (see Figure FIG 1), which controls the primary part of the heat exchanger, i.e. the heat exchanger of the company that mediates the heat energy, i.e. the heat producer. Using the controller in the control and control center of the heating system, the supply temperature is raised or lowered so that the heating water flow rate is, for example, in the range of 0.5Gmax -0.8Gmax at all times.

Since the change in the flow rate of the heating water in the system is essentially a function of the internal temperatures of the building's rooms, this means that the regulation of the heating system of the house is not based on the outside temperature, but on the inside temperature. Thus, based on the operating modes of the circulation pump 10 (using signals sent from the return flow sensor 11 to the electronic circuit 12), control signals are generated, which allow the internal climate of the building to be directly controlled/managed. Since the internal temperature of the building's rooms is not only the result of heating with radiators, but also the result of the influence of so-called free heat (for example, the sun), the new system and method allow maximum use of the energy potential of these sources as well.

Claims (6)

1. An autonomous control system for a central heating system, comprising a heat exchanger (1) comprising a heat exchanger on the heat producer side (2) and a heat exchanger on the heat consumer side (3), a heat producer heating water flow control valve (4), a control/regulation center (5), a circulation pump (10), radiators (13) equipped with thermostats, characterized in that a return flow sensor (11) is integrated into the circulation pump or connected in series with it, which is connected to an electronic circuit (12) that is configured to control the heat producer heating water flow control valve (4) autonomously, without an outside air sensor, based on a signal from the return flow sensor (11). 2. An autonomous control system for a central heating system according to claim 1, characterized in that the electronic circuit (12) is a controller. 3. An autonomous control system for a central heating system according to claim 1, characterized in that the electronic circuit (12) is a proportional-integral-derivative controller or PID controller. 4. An autonomous control system for a central heating system according to claim 1, characterized in that the circulation pump (10) is adjusted to maintain the flow rate of heating water so that the thermostat valves are in the linear part between 0.8Gmax - 0.5Gmax. 5. An autonomous control method for a central heating system, in which the amount of heat energy consumed by the heat generator is controlled based on the heating system parameters received by the control/regulation center (5), characterized in that it includes the following steps: - the thermostat valves of the room radiators are adjusted to operate in a range where the dependence between the heating water flow rate and the room temperature is linear; - the amount of heating water passing through the circulation pump is measured; - the measurement data is transmitted to the electronic circuit of the control/regulation center (5); - a control signal is generated in the control/regulation center; - the control signal is used to control the heating water flow rate regulator valve (4) of the heat generator. 6. A method for regulating a central heating system of a house according to claim 6, characterized in that the supply temperature is controlled by the electronic circuit of the control/regulation center (5).