DE3328188A1 - Method for controlling the feed or return temperature in a heating system - Google Patents

Abstract

The present invention relates to a method for controlling the feed temperature of a heating system as a function of the external temperature in accordance with the function <IMAGE> theta v signifying the feed temperature in DEG C, omega the difference between the design room temperature desired value and the minimum external temperature, n the radiator coefficient, zeta the arithmetic mean between the maximum feed temperature and the maximum return temperature, reduced by the value of the design temperature desired value, PHI half the difference between the feed and return temperature maximum value, t the difference between the room temperature and the external temperature, and theta R the room temperature. The invention consists in that the minimum external temperature theta Amin is determined in accordance with the relationship <IMAGE> theta V signifying the mean feed temperature, theta R the mean room temperature and DELTA theta V the difference.

Description

Procedure for controlling the flow or return temperature

the heating system The present invention relates to a Method for controlling the flow or return temperature of a heating system according to the generic terms of the ancillary main claims.

It is known that the flow temperature can be determined according to the relationship according to equation (1) as a function of the design room temperature setpoint, the minimum outside temperature, the maximum flow temperature, the maximum return temperature, the room temperature, the outside temperature and the radiator coefficient.

The maximum output of the heat source in a heating system will usually determined by a heat demand calculation. Here the minimum Outside temperature 5tA min set at which due to the power of the heat source the design room / target temperature can still be achieved.

Because heating systems are often too large in terms of their output this means that the control is dependent on the outside temperature a heating curve is usually driven for the heating system that is not with corresponds to the heating curve that is actually to be specified.

The heating curve is characterized by its starting point (flow temperature, Room temperature and outside temperature are the same) and their end point is defined, where at the end point at the minimum outside temperature, the maximum possible flow temperature must be achieved. Since the starting point of the heating curve is therefore fixed, the end point but found in accordance with the present invention can then be measured by measuring some Points, but at least two points, the curve found the correct heating curve will.

It is therefore an object of the present invention to apply to an existing one Heating system to find the end point of the heating curve, that is, the value of A min to determine the minimum outside temperature at which the design target room temperature should be achieved at the maximum flow temperature and such a relationship set up, which is calculated by conventional microprocessors without further effort can be.

The solution to this problem lies in the characterizing parts of the secondary main claims.

Further refinements and particularly advantageous developments of the invention are the subject matter of the subclaims or are based on the following Description which has an embodiment of the invention to the content.

The figure shows a diagram with the dependence of the flow temperature V from the outside temperature A at constant room temperature. So three curves are 1, 2 and 3, which differ in that the maximum flow temperature V max is reached at different minimum outside temperatures 9A min. There in the method according to the invention for an existing one in its design initially unknown heating system a flow temperature-dependent control can be created should, the procedure is such that, with room temperature remaining constant, R and, for example With the outside temperature remaining constant, a first measured value Lt is initially approached, to which a certain flow temperature V 4 and a certain currently prevailing Outside temperature A 4 belong. These values are measured and saved.

12 'If the outside temperature changes to a value A 5, this results a curve point 5 to which a corresponding flow temperature value V V 5 belongs. This value is also saved. From the difference between the two measured values 14th and 5 can now, in a manner to be described, the slope of curve 1 between the points 4 and 5 are determined. If the slope is known, it is possible to continue In a manner still to be described, the end point of curve 1 can be concluded that means at which minimum outside temperature min for curve 1 # R4 the maximum Flow temperature max max is reached. Accordingly, by measuring at least two points determine the heating curve, which the system from random dependencies describes as a control characteristic. If the measuring points 6 and 7 would be as just described Manner in making the measurement, one would be based on knowledge Using equation 1, you can determine that the maximum flow temperature for this heating curve V max that of another minimum outside temperature, namely outside temperature A. 2 min, is to be assigned. The same applies to measured values 8 and 9 on the third curve 3.

The following describes how to evaluate the two measuring points the minimum outside temperature # A min can be determined at which the maximum Flow temperature #V max must be reached.

In the event that between the measurements of points 4 and 5 the Room temperature R has changed from R 4 to R 5 due to the system, will not the point 5, but the value 5 on the curve 1 around the room temperature change value shifted curve 1 obtained. So in later too descriptive Way, by introducing the change in room temperature, the curve 1 is closed again will.

It is based on equation (1), where V is the flow temperature in OG, & J the difference between the setpoint of the design room temperature and the minimum outside temperature according to equation 2. The dimension is again ° C.

(2) W RNA amine means the mean temperature between pre and Return minus the design room temperature setpoint in ° C according to the equation (3).

(3) # = #Vmax + #RLmax - #RNS 2 t represents the difference between the room and outside temperature according to equation 4, the dimension is 00.

(4) t = WR A {means the mean temperature between the maximum Flow and return temperatures according to equation (5) in ° C.

(5) # = #Vmax - #RLmax 2 n means a radiator coefficient, it will calculated with the value of 1.3, which is dimensionless and for convectors and Radiators is applicable. By definition, A min is the value at which the design room temperature setpoint value is just reached.

The outside temperature-dependent control has a room temperature sensor, an outside temperature sensor, a flow temperature sensor or a return temperature sensor on.

The maximum flow and return temperatures are set. Partial differentiation of equation (1) according to the outside temperature results in equation (6).

A partial differentiation of equation (1) according to AR results in equation (7).

Equation (8) results from equations (6) and (7), which can be converted into equations (9) and (10). Solving equation (10) for # -1 / n gives equation (11).

It must be noted here that if d -1 is equal to d #A, the expression # -1 / n becomes indefinite because the corresponding term in equation (10) becomes 0. Substituting equation (11) into equation (1) gives equation By transforming equation (12), equation (13) is obtained.

By solving equation (13) for w, equation (14) is behaved, where again it applies that α # R must not be equal to α # A. At the same time there is a transition from the differential to a measurable difference.

Since according to equation (2) and the minimum outside temperature are related via the design room temperature setpoint, equation (114) can be written according to equation (15).

It has thus been proven that the minimum outside temperature at which the maximum flow temperature is to be reached can be determined by measuring two points.In the event that the control of the heating system does not control the flow temperature as a function of the outside temperature, but rather the return temperature as a function of the outside temperature , equation (16) applies. After partial differentiation and resolution for X, the following dependency according to equation (17) can thus be obtained for the return temperature.

In the event that there are any mixed temperatures in the heating system started depending on the outside temperature should be must equations (15) and (17) depending on the type of mixing temperature with each other be merged.

L e r s e i t e

Claims (1)

Claim 1. A method for controlling the flow temperature of a heating system as a function of the outside temperature according to the function where V is the flow temperature in OC, X the difference between the design room temperature setpoint and the minimum outside temperature, n the radiator coefficient, 9 the arithmetic mean between the maximum flow temperature and the maximum return temperature, reduced by the value of the design temperature setpoint, # halved difference between the flow temperature maximum value and the return temperature maximum value, t is the difference between the room temperature and the outside temperature and 9R is the room temperature, characterized in that the minimum outside temperature (A min.) is determined according to the following relationship: where #V is the mean flow temperature, R is the mean room temperature, ## V is the difference.