JPH02183734A - Setting of mean of supply temperature for heating medium and circuit for executing the same - Google Patents

Abstract

PURPOSE: To set average supply temperature such that a total average valve passage speed of a heating medium becomes optimum, by determining a start function where supply temperature is changed owing to heating, determining a desired function by changing parameters of the start function, and changing the supply temperature until a heating process fits to the desired function. CONSTITUTION: A heating system comprises three heat radiators 13, 14, 15, and hot water from a boiler 5 flows through the heat radiators 13, 14, 15 and is returned to the boiler 5. When room temperature is lower than set one, thermostatic valves 16, 17, 18 of the heat radiators are opened, but in the opposite case supply of hot water is drawn. Preset means 1 is provided for setting an average value of the supply temperature TV whereby a desired supply temperature value Ts formed. The desired value is changed by a correction amount at an addition point 2. An integrator 3 integrates this signal with time, and a hysteresis switch 4 turns off the boiler 5 when an output value of the integrator 3 exceeds a predetermined first value while turning on the same 5 when the same is lower than a second value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The invention relates to a heating system with at least one adjustable throttling point for the heating medium, which is heated intermittently by a heating medium at a supply temperature of the heating medium. Regarding the method of setting the average value of , the desired feed temperature value depends on external influencing factors to fully open the throttling point and heat the heating medium to the desired feed temperature. Furthermore, the invention also relates to a circuit for implementing this method.

(Prior Art and Its Problems) In such a method, the expected thermal requirements of the system are determined by external factors such as the difference between the outside air temperature, the supply temperature and the return temperature, or the predetermined room temperature of the central room of the house. be evaluated. From these measurements or given values, the feed temperature is calculated with a manually adjustable heating curve. The disadvantage of this method is that the actual load conditions are not taken into account. If a thermostatic valve (automatic temperature control valve) is installed, for example at the entrance to a radiator, the thermostatic valve must always be fully opened when the supply temperature is too low in order to reach the desired room temperature. When the supply temperature is too high, the thermostatic valve remains mostly closed. If the supply temperature is abnormally high, there will be a lot of energy loss (,
If the supply temperature is too low, it will not be possible to adequately heat the room even if the radiator valve is open.

Desirably, the supply temperature is such that the thermostatic valve of the radiator can perform its regulating function, i.e., the supply temperature is such that the valve is partially open or partially closed. It is.

DE 33 45 949 A1 discloses a device for controlling a central heating system, which determines this ideal supply temperature by determining the change in thermal resistance δ11 using a temperature sensor and a flow sensor.

However, this solution requires relatively high investment costs, since a large number of measuring sensors must be arranged.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an automatic adjustment method for setting the average supply temperature to a value such that the total average valve passage velocity of the heating medium is an optimum value.

In a method of the aforementioned type, the aim is to determine a starting function for changing the feed temperature by heating, to vary at least one parameter of this starting function to define the desired function, and to ensure that the heating process is completed at each heating stage. By varying the desired supply temperature value until the desired function is met at
achieved.

Accordingly, in the present invention, the load on the heating system in the "break-in state" is determined by the rate of change of the supply temperature. If a large amount of heating medium is required, ie the supply temperature rises slowly, the opening of the radiator valve is too large, ie not within the optimum adjustment range. In that case, the average value of the supply temperature must be increased. When starting the heating system, it can be assumed that the thermostatic valve is fully open. Therefore, since the flow rate of heating medium flowing through the system is maximum, the load on the boiler is 100
%. Under such load conditions, the supply temperature rises slowly because a large amount of heating medium has to be heated with a constant thermal power. The starting function is defined in this operating condition. After a certain amount of time, the room warms up and the thermostatic valve begins to throttle.

After reaching such normal operation, the course of the supply temperature at the start of operation of the heating device is steeper than at the initial maximum load condition. This heating process of the supply temperature in the normal case expresses whether the flow rate of the installation and the supply temperature are set correctly in relation to the initially determined maximum load curve. By setting in advance a desired function corresponding to the optimum heating process and therefore the optimum flow rate, and by matching the course of the actual supply temperature to this desired function,
Correct average values for optimal flow rate and supply temperature are obtained.

In general, no additional measuring equipment is required as temperature sensors can be utilized to measure the supply and return temperatures. Since this method works automatically, the curve can be reset frequently. It is thus possible to adapt the heating system to the variations required by the seasons.

If pumping is performed before starting the heating device, the return temperature can be determined without the need for a sensor only for the return temperature.If the heating operation is continued long enough, the heating medium will reach the return temperature. The temperature sensor in the supply conduit therefore determines the return temperature, noted t9, to calculate the starting function or desired function.

In a preferred embodiment of the method of the invention, the feed temperature is varied according to a starting or desired function, which is matched with the following auxiliary functions: Here, 7v(L) is the supply temperature, PK is the maximum heat output of the boiler, Cm is the heat capacity of circulating water, t is time, C, is the heat capacity of the boiler, and TI is the return temperature.

This auxiliary function gives a sufficiently close approximation to the actually desired course of the supply temperature. Since heating generally follows a starting function, the steepness and slope ratio between the starting function and the desired function can be easily determined. In the above auxiliary function, each parameter combination Paw/Cm and Cta/C
Since it is sufficient to determine (), the parameters can be determined easily.

Preferably, the parameters of the initiation function are determined in at least three cases by measuring the feed temperature. This provides a sufficient number of values to define the auxiliary function.

The desired function is determined from the starting function by varying the parameter Cm, in particular by decreasing this parameter. This parameter governs the slope of the curve representing the temperature course.

When the parameter Cm is decreased, the curve becomes steeper.

This means that the distribution volume will decrease.

However, if the flow rate is low, the supply temperature must be increased so that a sufficient amount of heat is transferred from the heating device to the radiator.

The optimal setting value at which the thermostic valve of the heatsink is partially throttled is determined by the parameter Cm of the desired function.
is approximately 20% to 40% of the starting function parameter Cm.
Obtained when young. This means that a correspondingly small amount of heating medium is required, i.e. only about 60% of the maximum achievable amount.
This means that between 0% and 80% of the heating medium flows through the heating system.

It is useful to determine the starting function when converting from night driving to day driving. This allows the desired function to be reset every day. In that way, the heating system can include and shut down multiple radiators, and/or the heating system can be better amenable to seasonal variations in heating requirements.

It is advantageous to provide a predetermined dead period between the starting function determination and the desired function determination. This period of death is at least 1
Preferably, it is equal to or longer than the heating amplifier cycle. This allows the room to be heated without delay.

It is advantageous to use the difference between the changed desired supply temperature value and the existing supply temperature value to form an input variable for an integrator that turns on and off the heating device by means of a hysteresis switch. Such a hysteresis switch is known, for example, from DE 34 26 937.

This method facilitates hour wheel adjustments.

Preferably, the critical value of the hysteresis switch is determined from the parameters of the desired function. This is another useful use of auxiliary function parameters. By varying the critical value of the hysteresis switch, the average value of the supply temperature can be easily matched to the desired set point.

The invention also provides a circuit for carrying out the above method, which circuit comprises presetting means for generating a desired supply temperature value signal as a result of an external influencing factor and a modified desired supply temperature value signal. an integrator receiving the difference between the value signal and the existing supply temperature value signal;
a hysteresis switch for generating a boiler control signal to switch the heating system when a predetermined value is exceeded or less than a second predetermined value; parameter specifying means for determining parameters of a starting function; a computer which forms the difference between the function of the heating medium and the measured heating process of the heating medium, and forms an error depending on the desired function formed by the computer and the determined difference; at least one of them, depending on
It consists of an error signal generating device that generates three temperature signal values, one positive and one negative, and a summing device that adds the temperature signal values each time the boiler is turned off. The output is added to the output of the presetting means.

It is advantageous to make the three temperature signal values correspond to temperature changes of -0, 2'0° and +0.2°C.

Therefore, the rate of change of the desired supply temperature value that is changed is relatively small. The heating system follows this change directly.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings, which schematically show a heating system.

(Example) The heating system includes, for example, three radiators 13.14.1
5, hot water from the boiler 5 is supplied to the radiator via a supply conduit 11. After flowing through the radiator 13.14.15, the water returns to the boiler 5 through the return conduit 12. The amount of water flowing through each radiator 13.14.15 is determined by valves 1G, 17, I8. Valve 16.17
．． Reference numeral 18 is an ordinary thermostatic valve. That is, the degree of opening of the valve depends on the temperature of the room heated by the radiator. If the temperature of this room is lower than a set desired temperature, the thermostatic valve of the radiator opens; if it is higher than the desired temperature, the valve throttles the supply of hot water to the radiator.

As usual, the boiler 5 can be, for example, an oil burner,
It consists of a burner such as a gas burner or a heating device such as an electric heating device, and a container for storing water.

The supply temperature Tv and the return temperature TI are measured, for example, in the supply conduit 11 and the return conduit 12 or the boiler 5 by a thermometer 25, and this thermometer is equipped with a measurement value converter that converts the temperature value into an electrical signal. The electrical signals are supplied via conductors 19, 20, 23 and further processed. Although two temperature sensors can be used to accurately measure the supply and return temperatures, it is sufficient to measure the supply temperature with a single temperature sensor (not shown). In order to measure the return temperature, the heating medium in the boiler is pumped through the boiler for a period of time during which the supply temperature becomes equal to the return temperature, prior to starting the heating device. The supply temperature is then stored and used as a constant return temperature during the next heating period.

In order to control the boiler, i.e. to set the average value of the supply temperature Tv, presetting means 1 are provided, in which the external temperature T 11 X L *
Several external influencing factors such as r a a 1 and the slope of the curve H
The desired supply temperature value Ts is formed from . The amount Ts is
For example, it can be formed according to the known formula: %formula%. In this formula, H
is the slope of the curve, reaching relatively low average feed temperatures at low values of H and reaching high average feed temperature values at high values of H. This desired value is changed by a correction amount, which will be described later, at addition point 2 to become a corrected desired value TF. Via the signal line 20, the existing value of the supply temperature Tv is derived from this modified desired value TF at a difference formation point 29. This difference is sent to the input of integrator 3. Integrator 3 integrates this signal over time. The output of the integrator 3 is sent to a hysteresis switch 4 which turns off the boiler 5 when the output value of the integrator 3 exceeds a predetermined first value, and when the output value of the integrator 3 exceeds a predetermined second value. When the value falls below the value, boiler 5 is turned on again.

In the heating amplifier stage, ie when the heating device heats water, the time heating process of the supply temperature Tv can be expressed by the following auxiliary function: Here, 7 V (tゝ is the supply temperature, PK is the maximum heat output of the boiler Cm is the heat capacity of the circulating water, L is the time, CK is the heat capacity of the boiler, and T8 is the return temperature.

The parameter specifying means 7 determines the supply temperature Tv in several cases, preferably in three cases, and from this determines the parameters P, Cl11 and cK. In order to define the auxiliary function precisely, it is generally necessary to use the quotient PK/axis and the coI/C
It is sufficient to determine K. As long-term quantities, the parameter specifying means 7 receives a time signal, a supply temperature Tν via a signal line 26 connected to a signal line 19, and a signal line 2.
A return temperature T8 is supplied via a signal line 24 leading to the temperature T3. The parameter specifying means 7 operates only when the heating medium is heated for the first time, for example, when switching from nighttime operation to daytime operation. Therefore, the parameters determined by the parameter specifying means 7 define the starting function. The parameters are sent to computer 6 where they are modified to form the desired function. In the next heating cycle, the desired function is formed by the modified parameters and the supply temperature T
This calculated course of Tv, which represents the desired time course of heating v, is transmitted via signal line 28 to difference forming point 8.
, and to this point the supply temperature TvO value is sent via signal line 27 leading to signal line 19 . Thus, at difference formation point 8, a difference is formed between the calculated value of Tv and the measured value of Tv. This difference is sent to the error signal generator 9. Error signal generation device 9
is the difference calculated at difference forming point 8 and signal line 3
Determine the error from the value of the desired function supplied through 0. At its output, the error signal generating device 9:
Three temperature signal values A are emitted depending on the determined error according to the following rules: If the error is between -2% and +2%, then A=0. If the amount of error is greater than 2%, then A = 0.2°C. The sign to depends on the sign of the error.

The output of the error generating device 9 is added by the adding device 10 every time the heating device of the boiler 5 is stopped.

The output of the summing device 10 is added to the output Ts of the presetting means l of the summing point 2. Therefore, additional points 2
A changed or modified desired feed temperature value TF is then formed. During normal operation, this modified desired supply temperature value T, is used as described above to form a difference with the existing supply temperature Tv, which is then sent to the integrator 3.

This heating system operates as follows. 16.17.18 When the system is switched from night low load operation to normal daytime operating conditions, all radiator thermostats 16.17.18
are fully open and the maximum amount of water flows through the radiators 13.14.
15 can be assumed to flow. Boiler 5 is started. Then, the supply temperature Tv increases and is measured. Using the measured curves, the constants PX-CLll and CK of the auxiliary functions of the heating system can be calculated in the parameter determination device 7, for example by means of a microprocessor. These constants are calculated at heating system startup, resulting in a starting function or equation that is applied to the heating system at 100% flow.

Using this starting function, a desired function can be calculated, for example by inserting a new value of Cm.

The new value is, for example, 20% to 40%, especially 30%,
smaller than that of the starting function.

The purpose of the regulating device consisting of the integrator 3, the hysteresis switch 4, the boiler 5, the return conduit 20 and the differential point 26 is to keep the feed temperature Tv within the modified desired feed temperature value 12 given by the desired curve. The idea is to set the average value of the supply temperature so that the temperature will drop.

If the feed temperature Tv has the desired profile, a flow rate of about 60% to 80%, preferably 70% of the maximum flow rate is obtained. With this flow rate, the thermostatic valves 16, 17, 18 of the radiator are in a partially throttled state.

That is, the thermostatic valve increases or decreases the degree of opening in response to changes in indoor temperature, thereby exerting its adjustment function.

Each time the boiler is shut down, ie each time the heating device is switched off, the measured course of the feed temperature is compared at several points with the calculated desired function.

Depending on the result of this comparison, the average value of the feed temperature is kept constant, increased by 0.2°C, or decreased by 0.2°C. Since this time is short, there is sufficient time for the heating system to be set to the new limit conditions. While set to daytime operation, the average value is adjusted to the load in this way.

Another advantage of the system is that a so-called alpha value, which can be sent via the signal line 31 to the hysteresis switch 4, can be determined from the calculated constants Cm, C, and P,l. This alpha value is
It serves to fix or vary a predetermined critical value, above or below which a boiler control signal is generated to switch the heating device. This eliminates the somewhat variable manual setting of this value.

Therefore, not only the load of the system is evaluated, but also the actual heat consumption is determined.

The supply temperature TV is controlled in such a way that the radiator thermostat can always remain within its regulation range even as external conditions change. In order to modify the desired value Ts depending on the external conditions during daytime operation, the external temperature T a x t a r a □ and the slope H of the curve, which are sent to the presetting means I, also continue to be used. Therefore, this input of addition point 2 does not need to be constant during the day.

[Brief explanation of the drawing]

The figure is a schematic diagram of a heating system.

Claims (12)

[Claims] (1) A method for setting the average value of the supply temperature of a heating medium that is intermittently heated by a heating device in a heating system, the heating system comprising at least one adjustable throttling point for the heating medium. , the desired value of the feed temperature is determined based on external influencing factors, the heating medium is heated to the desired feed temperature with the throttling point fully open, and upon heating the feed temperature ( Determine a starting function according to which T_V) is to vary, vary at least one parameter (C_m) of this starting function to define the desired function, and the heating process changes at each heating step to the desired function. A method characterized in that the desired supply temperature value (T_F) is varied until it corresponds to T_F. (2) The starting function or desired function according to which the supply temperature (T_V) is to vary is the following auxiliary function: T_V^(^t^)=(P_K/C_m)(1-exp
[-C_m・t/C_K])+T_R, where T_V^(^t^) is the supply temperature, P_K is the maximum heat output of the boiler, C_m is the heat capacity of the flowing water, t is the time, and C_K is the boiler temperature. 2. A method according to claim 1, characterized in that T_R is the reversion temperature. 3. Method according to claim 1, characterized in that the parameters of the starting function are determined by measuring the feed temperature (T_V) on at least three occasions. (4) The desired function is determined from the starting function by changing the parameter C_m.
Or the method described in 3. 5. Method according to claim 4, characterized in that the desired function is determined by decreasing the parameter C_m. 6. The method of claim 5, wherein the desired function parameter C_m is approximately 20% to 40% smaller than the starting function parameter C_m. 7. A method according to claim 1, characterized in that the starting function is determined at each changeover from night-time to day-time operation. (8) The method according to any one of claims 1 to 7, characterized in that a predetermined dead period is provided between the time when the starting function is determined and the time when the desired function is fixed. (9) Using the difference between the changed desired supply temperature value (T_F) and the existing supply temperature value (T_V), the hysteresis switch (4) turns on and off the heating device (5) to the integrator. Claim 1 characterized in that it forms an input quantity.
9. The method according to any one of 8. 10. Method according to claim 9, characterized in that the critical value for the hysteresis switch (4) is determined from the parameters of the desired function. (11) A circuit for carrying out the method according to any one of claims 1 to 10, wherein an external influence factor (H, T_e_x
presetting means (1) for generating a desired supply temperature value signal (T_S) as a result of _t_m_r_n_a_l) and determining the difference between the modified desired supply temperature value signal (T_F) and the existing supply temperature value signal (T_V); The receiving integrator (
3) and a hysteresis switch for generating a boiler control signal to switch the heating system when the output signal of the integrator exceeds a first predetermined value or becomes less than a second predetermined value.
4) and the parameters of the starting function (P_K/C_m, C_
parameter specifying means (7) for determining m/C_K);
a computer (6,
8), forming an error depending on the desired function formed in the computer (6, 8) and the determined difference;
and, in response to this error, at least two temperature signal values (A
), and an summing device (10) that adds the temperature signal value (A) each time the boiler is turned off, the output of this summing device (10) being A circuit characterized in that it is added to the output of the presetting means (1) to modify the desired supply temperature value signal (T_S). 12. The circuit according to claim 11, wherein the three temperature signal values (A) correspond to temperature changes of -0.2°C, 0°C and +0.2°C.