DE4421969A1 - Measurement of thermal output of hot-water radiators with valves - Google Patents

Abstract

The water heated in a boiler (11) is pumped (26) through a flowmeter (25) to the individual radiators (38) whose inlet and outlet temps. are measured (34, 35) and transmitted through interfaces (31) and a bus system (47) to a central microcomputer (40), together with ambient temp. (36) in each apartment. Water entering and returning from the pipe network is monitored by sensors of flow (21, 23) and temp. (22, 24). Simple admission valves (32) are used in a two-pipe circuit, and bypass valves (33) in a single-pipe system.

Description

The invention relates to a method for determining the a fluid transferred to individual heat consumers quantity with the features of the in the preamble of claim 1 Neten genus and an arrangement for performing the method. The Fluid, usually a liquid, has the function of Heat transfer medium.

The heat consumers are usually heating surfaces or heat exchanger, e.g. B. for hot water heating in the difference Lichsten embodiments can be integrated in a heating system. This is particularly important in heating systems in apartment buildings that of individual heat consumers or at least of individual heat consumer groups (apartment unit removed from the heating system and transferred energy of interest to a consumption based heater to be able to carry out cost allocation that is required by law.

The determination of the proportionate amount of heat transfer (Q _i ) to an individual heat consumer (i) in an arrangement of heat consumers is known to be carried out using various methods. In the first place, the heat meters working as measuring devices are to be mentioned, which allow the amount of heat transferred to be determined very precisely via the temperature difference between incoming and outgoing fluid and directly or indirectly measured fluid flow. None of the methods described below achieve this accuracy. The measurements of the fluid temperatures required here can be carried out easily. The disadvantage of this method, however, is the outlay for the flow measurement. Each consumer must be equipped with its own flow sensor. In addition to the considerable costs, such an installation is also associated with corresponding maintenance and susceptibility to failure. Due to this effort, such a realization is only possible when several heat consumers are combined to form a group, e.g. B. housing unit to justify. Such a summary, however, is generally not possible retrospectively, particularly in the case of system integration in older line networks. For this reason, in many processes that take each heat consumer into account separately, individual variables are measured in a simplified manner or replaced by determining physical substitute variables. This is mainly a replacement of the complex flow measurement.

In DE 35 29 257 who the entire flow conditions of the pipe network for this purpose kes calculated. The measured positions of the individual valves of the individual Heat consumers are calculated with the help of the valve characteristics gene included. A distribution of the partial consumption is then with knowledge of Total consumption that is determined when feeding into the pipe network leaves, possible. The disadvantage of this method is that the structural Ausle the network structure must be completely known. This is at existing older pipeline networks are generally not given. Even with be Known parameters of the network structure will change due to aging and increasingly lead to incorrect measurements. These are set by themselves Parts of the pipe network, especially at connection points, caused. Here Of particular importance are the valves and their characteristics affected. This procedure uses the, for the correct calculation of a transferred amount of heat required knowledge of the flow mit flow, determined by measuring the auxiliary variable, "valve position". At at their procedures are further simplified by procedural engineering led, with the actual measurements of the actually relevant phy sical sizes are omitted and instead physical substitute sizes, how surface temperatures of heating surfaces etc. are determined. Here below are both the so-called heat cost allocators after evaporation principle as well as the increasingly used electronic heat cost allocators to understand with one, two or even three temperature sensors. The procedure technical expenditure is directly related to the costs and  the achievable accuracy. These devices are more or less theirs Designation "heat cost allocator" fair, since he with the help of these devices mean consumption of individual heat consumers more or less with the correlate actual consumption. Error influencing factors are wrong here dimensioned and incorrectly placed devices with regard to the the heat consumer. Especially for heating systems with low pre Running temperatures are carried out with such heat cost allocators Due to the system's cost distributions, there are considerable errors. Current and in future, however, heating systems with low fluids will be used temperatures such as underfloor heating and condensing boilers. The Determining heating costs with such heat cost allocators is therefore completely un satisfactory or impossible and is obviously only accepted because since so far only in this way with reasonable effort an approximate knockout distribution is possible at all.

The invention has for its object to provide a measuring system with which the heat transfer (Q _i ) to individual Wärmverbrau cher (i) can actually be determined. The process should be suitable for new plants as well as for retrofitting existing plants. It is particularly important to take into account that the pipe run of existing systems can be determined, but the exact design parameters are unknown or have changed due to aging. The design should also be robust to other changes in the system, such as aging, and should make maintenance easy. It is also required that the process works fully automatically and that errors in the system and manipulations can be detected. The entire structure of the arrangement is to be made possible, in particular in the case of heat consumers, by means of proven and technically simple and sophisticated elements.

According to the characterizing part of patent claim 1, this task is solved in that, at predetermined time intervals (τ), the instantaneous heat transfer inflow temperatures (T _Vi ) and heat transfer outflow temperatures (T _Ri ), at least the heat consumers whose valve is open, and the determined instantaneous are measured Total heat transfer mass flow ( _Σ ), taking into account the structure of the pipe network and the current state of all valves, can be divided into the individual heat transfer mass flows ( _i ) of the individual heat consumers (i). The individual valves are operated exclusively in the "fully open" and "fully closed" positions. Through an identification process, the functional relationships of the individual heat carrier mass flow distributions to one another are known for all combinatorially possible states of open and closed valves and permissible total heat carrier mass flows. The respective heat carrier mass flow distribution can thus be calculated or is known by preliminary calculation. With the thus determined heat transfer medium mass flows ( _i ) and the heat transfer inflow (T _Vi ) and heat transfer outflow temperatures (T _Ri ), taking into account the specific heat capacity (c), a partial heat quantity (Q _{τ i} = (T _Vi -T _Ri ) _i c τ) can be calculated. Accumulated and recorded over the operating time, this results in the amount of heat transferred to the heat consumer i (Q _i = ΣQ _{τ i} ).

It is achieved by the exclusive operation of the valves assigned to the heat consumers in the "fully open" or "fully closed" positions that definitive, quasi-steady-state conditions arise. There are no intermediate positions relevant to the operation. Suitable, electrically operated valves are available in various versions from industry. The hydraulic resistances of the individual sections of the pipe network which arise during operation can be determined by identification methods with specification of the pipe network structure. Thus, only information about the arrangement of heat consumers, pipe connections and pipe branches to each other are required, but not, as with other processes, design parameters such as pipe lengths and / or pipe diameters. Neither is it necessary to provide information on the design of valves and heat consumers. This is equivalent to an electrical network in which the interconnection of the electrical components is known, but the characteristics of which are unknown. The consumers actually available for each Wärmever heat transfer partial mass flows _i, are having a function of the heat carrier total mass flow _Σ and to stand the valves of n consumers predictable. Alternatively, for the possible 2 ⁿ combination options of open / close positions of the valves of the n heat consumers for various heat transfer medium mass flows relevant in operation _Σ the distribution to the total heat transfer mass flows m _i can be calculated in advance and stored in a table. To actually determine the flow rate for the heat consumers, table values only have to be accessed as a function of the total mass flow and the condition of the valves. In order to determine the temperature difference required for calculating the partial heat quantity Q _{τ i} , the inflow temperature (T _Vi ) and the outflow temperature (T _Ri ) of the fluid are measured directly at the heat consumer. Industrial products are also available for this. The repeated measurements at time intervals τ finally enable an accumulating registration of the partial heat quantity Q _{τ i} over time (Q _i = ΣQ _{τ i} ), which corresponds to an integration.

A possible implementation for the practical feasibility of the identification method is further explained by claim 2. The goal of obtaining the knowledge required for the calculations of the behavior of the hy draulic resistances of individual line sections is carried out by simultaneous measurements of the total heat transfer mass flow and pressure measurements at the heat transfer inflow and heat transfer outflow. These measurements must be carried out for all 2 ⁿ combination options of open or closed valves. Furthermore, for each of these combination options, the total flow from the minimum to the maximum total heat transfer mass flow must be varied in order to determine the dependence of the pressure / flow ratio, or the hydraulic partial resistances, of the flow itself. The implementation of the entire method is expediently controlled by a process computer or microcomputer using an algorithm. With the specification of a model for the overall system, which is based on the pipe network structure, the parameters of this model can then be calculated, ie identified.

The method described can thus, as stated in claim 3, especially for the distribution of heating costs in two-pipe hot water heaters be set. The vast majority of central heating systems are realized as two-pipe hot water heaters.

An application to central heating systems, according to claim 4, according to the principle of single pipe hot water heating is also un possible to a limited extent if the valves here, as is usual in such systems, are designed as a bypass valve and ensure that the heating medium flow either flows through a heat consumer in total or around flows.

Claim 5 describes as a consequence of claims 3 and 4 arbitrary combination of the pipe network from parts of two-pipe and Single pipe heating systems.

The fundamentally given for the possibilities of the heat transfer medium total flow measurement ( _Σ ) both in the heat transfer and heat transfer outflow is set out in claim 6. This flow measurement can be determined both directly and indirectly, for example with the help of the measured energy consumption of an already existing pump, taking into account the specific pump characteristic.

With the help of pumps controllable in performance it is effected according to claim 7 that on the one hand any, required for the identification process che, total heat carrier flow rates ( _Σ ) can be set and on the other hand the circulation work required for the operation is applied for the fluid.

The ongoing constant changes of the entire system by old people tion and wear counteracts the method of claim 8. Here after the identification process becomes automatic at certain intervals repeated. This means that the parameters of the pipe network are constant be updated and the permanent accuracy of the whole procedure is guaranteed and is unaffected by aging and wear. These Identification processes can be divided into several sub-processes, so that this time is the same as the actual intended heating operation possible are. The functions to be operated occasionally in other functions Valves, as required by the heating situation, ie "closed" instead of "open" and "Open" instead of "close" do not have any disadvantageous effects, especially since heating systems are sluggish in terms of control engineering.

Claim 9 describes further pressure measurements at the inflow and outflow of the heat carrier feed also during operation. With the parameters of the pipe network known through the identification and the knowledge of open and closed valves, a simulation is carried out, which calculates values for the pressures at the inflow (p * _{V Σ} ) and outflow (p * _{R Σ} ) of the heat carrier feed. These simulated values are then compared with the actual values (p _{V Σ} , p _{R Σ} ) and may indicate errors in the system, such as. B. Valves that no longer close completely or reduced flow rates through dirty valves close. Furthermore, manipulations of the system or changes of a general nature can be identified.

This simulation, which is initially related to the pressure profiles, is extended in claim 10. Additional models and corresponding identification of extended model parameters can also be used to simulate the temperature profile (T * _Vi , T * _Ri ) of fluid inflow and outflow at the heat consumers. These simulated values can then in turn be compared with the actual measured variables (T _Vi , T _Ri ) and evaluated with the aim of identifying errors and / or manipulations in the overall system.

The valves of the heat consumers, which were previously only used for heat distribution and the identification process were used according to claim 11 also to regulate the A operated with the respective heat consumer unit, such as B. living space, heat exchanger, etc., can be used. Next the forwarding of the control effected by corresponding signals the registration unit to determine the amount of heat given off, it is important that access to the valves takes precedence over the identification process the controller has.

Claim 12 relates to a possible arrangement for performing the method described. A central evaluation unit, which is equipped with a microcomputer, is used, which is arranged at a central point, preferably in the vicinity of the heat carrier feed. The signals of the heat transfer and outflow temperatures of all n heat consumers are directed to this evaluation unit. The evaluation unit then provides the control signals for the valves of the heat consumers. If necessary, the signals from temperature controllers or temperature sensors, if a temperature control is additionally implemented by this evaluation unit, are led to this evaluation unit. Furthermore, the pressure measurements (p _{V Σ} , p _{R Σ} ) of the heat transfer fluid are fed to the evaluation unit and the pump or pumps are controlled by the evaluation unit. The necessary calculations for the distribution of the total heat transfer mass flow ( _Σ ) to heat transfer partial mass flows ( _i ) and the assignment to individual heat consumers is carried out with a program running in the microcomputer. This program also serves to carry out and evaluate the identification process and finally to allocate and register heating costs to individual heat consumers or heat consumer groups.

As indicated in claim 13, the one used in the arrangement can Microcomputers with control inputs to the signals from Tempera  door regulators. These temperature controllers are used to control the Heat emission of the individual heat consumers, e.g. B. with the aim in egg to maintain a constant temperature in the environment to be heated. These Temperature controllers can also be integrated in the microcomputer, so that only temperature sensors are connected to the microcomputer have to. In both cases, the valves also take on the function of Actuators in the control loop then implemented.

Indirect measurement of the total heat transfer mass flow ( _Σ ) with measuring devices that measure the volume flow ( _Σ ), compensation is possible by measuring the temperature of the fluid.

The arrangement according to claim 15 represents a possibility for installation. The execution of the cable routing as a bus system simplifies the installation considerably. In particular, can usually, based on egg nen heat consumer, the control signal for the valve and the measurement signals of the temperature sensors for the heat transfer inflow T _Vi and the heat transfer outflow T _Ri and a sensor for the ambient temperature, with a Kop pelinterface on a bus system. The connection that would otherwise have to be established with individual connections is then omitted. Appropriate addressing and detection in the coupling interfaces can be used to selectively communicate with the sensors or valves.

With claim 16 results in a method which the use of described arrangement for hydraulic balancing of a heating system enables. This concerns the new installation of a heating system, in particular but the modernization of existing systems or the exchange of individual components of a heating system. By the possibility of all heat Switching consumers on and off individually with the microcomputer can be done with a remote control for this microcomputer, for the z. B. also that before mentioned bus system can be used, this possibility at everyone Location where heat consumers are located can be used. This is of great importance since it usually directly affects the heat consumption  throttle valves to be adjusted manually, their tuning for the entire system must function properly.

The invention is illustrated below with reference to the drawings ten explanations explained in more detail. It shows

Fig. 1 is generally related to the heat transferred physical quantities of interest amount of heat consumers,

Fig. 2 shows a possible embodiment for an arrangement for performing the method.

With the physical quantities shown in FIG. 1 on heat consumers, the transferred heat consumption can be calculated using the relationship

Q = ∫ (T _V -T _R ) c dt ≈ Σ (T _V -T _R ) c τ

and if necessary

= _{ρ | TR}

calculate. Please note that the temperature difference (ΔT) is sufficient for the basic calculation. However, since the predominantly available flow meters are not devices for mass flow measurement () but devices for volume flow measurement (), a correction calculation for the correct calculation of the mass flow is taking into account the density ρ for the temperature T _R existing on the flow _meter required. For this reason, separate processing of the temperature signals from T _V and T _{R is} preferable.

The embodiment in Fig. 2, according to first by a division into four groups I, II, III and VI of the affiliation of the Einzelkompo components of the entire assembly in. Group I represents the components for energy generation. This is given here, for example, by a boiler 11 with heat being supplied by a burner 12 . However, it does not have to be about the supply from a separate boiler, but also the energy supply through a strand of a superordinate, larger heating system is possible. The supply by district heating is particularly to be understood here. The components of group II are required for feeding the heat transfer medium into the pipe network system via connections 27 and 28 . The controllable pump 26 is required to maintain the fluid flow required for the operation, depending on the state of the valves 32 and 33 of the heat consumers 38 . Furthermore, certain operating points for the identification process are approached with this. The flow meter 25 is used to determine the heat transfer medium mass flow. The temperature sensor 22 or 24 is used to measure the heat carrier inlet temperature or heat carrier outlet temperature. The dimensions at the feed to the pipe network are carried out with the sensor 21 for the inlet and with the sensor 23 for the outlet. Group III means all components of the pipe network. In Fig. 2, two heat consumers 38 are indicated. The consumer shown in the upper part represents the structure of a two-pipe heating system and the consumer in the lower part that of a single-pipe heating system. The heat transfer medium is supplied via the valve 32 or the bypass valve 33 . Sensor 34 measures the temperature at the inlet and sensor 35 measures the temperature at the outlet. The ambient temperature of the environment supplied with the heat consumer 38 can be determined via temperature sensor 36 . The input device 37 enables the preselection of a desired ambient temperature. All sensor signals and the control signal for the valves are coupled to a bus system 47 via an interface 31 . Finally, in area IV, the components for controlling and evaluating the method are arranged. 40 describes the central evaluation unit, which also contains the microcomputer. The communication with sensors and actuators of the pipe network is effected via bus 47 . Furthermore, the sensor signals of group II are processed and the control signals for this group are generated. Control of heat generation in Group I is also effected. The component 41 is designed as an input unit so that the required commands can be transferred to the system. The output unit 42 is used for further communication and interactive operation, with which the current heat consumption units of the individual heat consumers can also be represented. The clock described with component 43 is used for real-time control and enables the allocation of faults at the times they arise. Extensions through documenting output devices 44 and communication units 45 for controlling and maintaining the system through higher-level control centers or remote transmission of the heat consumption units with, for. B. Modems 46 are possible.

Claims (16)

1. A method for determining the amount of heat given off via an inflow and an outflow line arranged heat-flow-through heat consumers with a valve, in which the structure of the line network, the current position of the valves, the current temperatures of inflow and outflow of heat transfer medium and the instantaneous of that Heat carrier feed supplied, total heat transfer mass flow to determine the heat quantities transferred over the operating time of individual heat consumers are evaluated, characterized in that the instantaneous heat transfer inflow temperatures (T _Vi ) and heat transfer outflow temperatures (T _Ri ) of at least the heat consumers are measured in predetermined time intervals (τ) , the valve of which is open, and the instantaneous total heat transfer mass flow ( _Σ ) determined by measuring the feed of the heat transfer stream, taking into account the structure of the pipe network and the current State of all valves, which are finally operated in the working positions on and off, are divided into individual heat transfer medium mass flows ( _i ) of the individual heat consumers (i), the heat transfer mass flow distributions for all possible states of open and closed valves and permissible total heat transfer medium mass flows by an identification method are known or the functional relationships are known by means of an identification method, so that the heat carrier mass flow distribution can be calculated, and that a partial heat quantity (Q _{τ i} = (T _Vi -T _Ri.) for each heat consumer from the thus known heat carrier mass flows and the heat carrier inflow and outflow temperatures ) _i c τ) is calculated and added up over the operating time and registered. 2. The method according to claim 1, characterized in that for the identification process on the heat carrier feed pressure measurements in the total heat carrier inflow (p _{V Σ} ) and outflow (p _{R Σ} ) in dependence on a total heat carrier mass flows to be delivered ( _Σ ) and all possible, by an algorithm Controlled, combinations of open and close positions of the individual valves are carried out and thus the relationship between the heat carrier mass flow and pressure drop of the individual line network sections can be identified, so that the parameters of the heat carrier mass flow dependent flow losses for a calculated heat carrier mass flow distribution for any combination of open and closed Closed positions of the individual valves are available. 3. The method according to claim 1 and 2, characterized in that the structure the pipe network is given as a two-pipe hot water heater. 4. The method according to claim 1 and 2, characterized in that the structure the pipe network is given as a single-pipe hot water heater. 5. The method according to claim 1 and 2, characterized in that the Structure of the pipe network as a combination of single pipe and Two-pipe hot water heating is given. 6. The method according to any one of claims 1 to 5, characterized in that the total heat transfer mass flow ( _Σ ) is measured in the heat transfer total inflow or total heat transfer outflow. 7. The method according to any one of claims 1 to 6, characterized in that the heat transfer mass flows ( _Σ ) required for the intended operation and implementation of the identification process are effected with one or more controllable pumps. 8. The method according to any one of claims 1 to 7, characterized in that the identification process is repeated cyclically, so that the method is adaptive to the overall system. 9. The method according to any one of claims 1 to 8, characterized in that during the heat output measurements by comparing pressure measurements (p _{V Σ} , p _{R Σ} ) of the heat carrier feed with pressures (p * _{V Σ} , p * _{R Σ} ), the through the determined heat carrier mass flow dependent flow losses and the state of the individual valves can be calculated by simulation, errors in the system as well as manipulations and changes in the overall system can be determined. 10. The method according to any one of claims 1 to 8, characterized in that the entire system of heat consumers is simulated with a simulator during the heat quantity determination so that at least for the measured quantities measured for heat quantity determination (T _Vi , T _Ri ) also simulation values (T * _Vi , T * _Ri ) are determined so that they can be used with the measured variables for the purpose of error detection and manipulation in the system. 11. The method according to any one of claims 1 to 10, characterized in that that one or more valves also as actuators for temperature controls the facilities or environments heated by the heat consumers are used, but a prioritized operation by the Identi fication process is guaranteed and the positions of the valves (on / off) Determination of the heat carrier mass flow distribution from the measuring system regi be treated. 12. Arrangement for performing the method, according to one of claims 1 to 11, characterized in that by a central evaluation device, the signals with signals from Wärmeträgerzufluß Temperaturmessun (T _Vi ), heat carrier discharge temperature measurements (T _Ri ) and the Druckmes solutions (p _{V Σ} , p _{R Σ} ) of the heat carrier feedable inputs, outputs for controlling the valves and furthermore a device for determining the current total heat carrier mass flow ( _Σ ) through the line network and a microcomputer with a program for determining the heat carrier partial mass flows ( _i ) of the individual heat distributors need (i), a program for carrying out the identification process and a program for determining partial heat quantities (Q _{τ i} ) from the product of partial heat mass flow ( _i ), heat capacity c, time interval (τ) and the temperature difference existing at the heat consumer (T _Vi -T _Ri ) as well as for Aufsummi Generation and registration of these partial heat quantities (Q _{τ i} ) over the operating period. 13. The arrangement according to claim 12, characterized in that the micro computer can be influenced by signals from temperature controllers or itself includes temperature controller, so that the valves additionally the radio tion of actuators for temperature control. 14. An arrangement according to one of claims 1 to 13, characterized in that the device is designed for measuring the instantaneous Wärmeträgergesamtmas senstromes _(Σ) as Volumenstrommeßgerät _(Σ). 15. Arrangement according to one of claims 1 to 14, characterized in that the connections between the individual valves and sensors and the Evaluation unit are designed as a bus system. 16. The method according to any one of claims 1 to 15, characterized in that in particular the identification process as an aid to the hydraulic Adjustment of a heating system is used.