DE102021125574B4 - METHOD FOR OPERATING A HEATING SYSTEM WITH FUEL CELL AND HEATING SYSTEM WITH FUEL CELL - Google Patents

Abstract

Heating system (1) for a building (G), comprising:a primary circuit in which a first fluid heat transfer medium circulates;a secondary circuit in which a second fluid heat transfer medium circulates;a heat exchanger (7) for transferring heat between a flow (VP) of the primary circuit and a flow (VS) of the secondary circuit and between a return (RP) of the primary circuit and a return (RS) of the secondary circuit; a first heat sink (4) arranged in the primary circuit, which absorbs heat from the first fluid heat transfer medium; one arranged in the secondary circuit second heat sink (5), which absorbs heat from the second fluid heat transfer medium; a fuel cell (2) arranged in the primary circuit for generating electrical current and providing the heat generated thereby to the first heat sink (4) or the second heat sink (5); a switching valve (9 ) for switching between a first state in which the heat of the fuel cell (2) is supplied to the first heat sink (4), and a second state in which the heat of the fuel cell (2) is supplied to the second heat sink (5); one Return temperature sensor (8) for measuring a return temperature in the return line (RS) of the secondary circuit; anda control device (10) for controlling the heating system (1), wherein the control device (10) is configured: to switch the changeover valve (9) to the first state or the second state depending on the measured return temperature;to set the return temperature with a predetermined limit value compare; andswitching the changeover valve (9) to the first state if the return temperature is equal to or greater than the limit value; orswitching the changeover valve (9) to the second state if the return temperature is less than the limit value, wherein:a volume flow sensor is arranged in the secondary circuit for measuring a volume flow in the secondary circuit; andthe limit value is determined depending on the measured volume flow in the secondary circuit and/or depending on the performance of the heat exchanger (7).

Description

The present invention relates to a heating system for a building and a method for operating a heating system. In particular, the aim is to prevent a return temperature from rising above a limit value, which could lead to a fuel cell in the heating system being switched off.

Fuel cells have been increasingly used in heating systems for buildings in recent years. A fuel cell converts chemical reaction energy of a continuously supplied fuel (e.g. hydrogen) and an oxidizing agent (e.g. oxygen) into electrical energy. Additional usable heat can be generated here. A fuel cell can therefore be advantageously used in a heating system with combined heat and power.

An exemplary heating system for providing electricity and hot water for a one- to two-family house combines a fuel cell with a second heat generator, e.g. a peak-load boiler. The fuel cell, for example, uses hydrogen, which is obtained from natural gas, as fuel. Oxygen from the ambient air can be used as an oxidizing agent. The hydrogen reacts with the oxygen in the air to form water in the fuel cell, producing a direct current that can be converted into a usable alternating current using an inverter. Furthermore, usable heat is generated, which can be transferred to a fluid heat transfer medium (water) and then, for example, via a heat exchanger to a buffer storage tank or directly to a heating circuit.

The German patent application DE 103 40 891 A1 discloses a heating system with a fuel cell heater, an additional heater, a heating circuit with a thermal consumer, a main storage that is connected to the heating circuit via a circuit and a heat exchanger, and a pre-storage that has a heat exchanger and the circuit with flow and return of the fuel cell heater are connected. The fuel cell heater and additional heater are connected in parallel with a hydraulic switch. The heating circuit is connected to this hydraulic switch on the secondary side. If a certain temperature is exceeded, the return temperature should be reduced. This is possible because in addition to the return water from the circuit, return water from the heating circuit is also mixed in.

The European patent EP 3 073 200 B1 relates to a heating system that includes a primary heat generator, a heating circuit and an external heat generator. The external heat generator is coupled to the heating circuit via a hydraulic switch. A change in temperature is detected at the hydraulic switch, which means that the temperature behavior of the hydraulic switch can be observed particularly effectively. If no increase or decrease in temperature is detected, this is interpreted as a decrease in heat in the heating circuit. This is particularly the case if there is a volume flow in the heating circuit and therefore also inside the hydraulic header.

In general, the longest possible running times and as few shutdown processes as possible are desired for fuel cells. However, it is necessary that the heat generated finds a buyer, as most fuel cells cannot tolerate high return temperatures. This can mean that the fuel cell's running times depend heavily on the outside temperature in the building's surroundings.

If there is a high consumption of warm drinking water and/or a high demand for heating power, especially at low outside temperatures (e.g. below 15°C), it may happen that the heat generated by the fuel cell is not sufficient. In this case, the peak load boiler (e.g. a gas condensing boiler) can be switched on, the heat generated from which can also be used to charge the buffer storage.

If there is low consumption of warm drinking water and/or if there is little need for heating power, especially at medium to high outside temperatures (e.g. above 15°C), it may happen that the heat generated by the fuel cell cannot be sufficiently dissipated. If the return temperature then exceeds a certain switch-off temperature (e.g. 50°C), the fuel cell must be switched off, which can lead to a reduction in the running time of the fuel cell.

On the one hand, it is advantageous to maximize the running time of a fuel cell in order to ensure the most efficient generation of electricity and heat. On the other hand, it is desirable to reduce switching on and off of the fuel cell, since a high number of switching processes can be harmful to the fuel cell.

The present invention is therefore based on the object of specifying a heating system and a method for operating a heating system that avoids exceeding a switch-off temperature in the return to the fuel cell and thus prevents the fuel cell from being switched off undesirably Fuel cell prevented, so that the number of switching operations can be minimized and the running time of the fuel cell can be optimized.

According to a first aspect of the present disclosure, the problem according to the invention is solved by the heating system according to claim 1. According to a second aspect of the present disclosure, the problem according to the invention is solved by the method for operating a heating system according to claim 6. Further aspects are the subject of the dependent Claims, the following description of exemplary embodiments and the attached drawings.

The heating system according to the invention is used in particular to provide heat and electrical power for a building, in particular a commercial building, such as an office building, or a residential building such as a single-family house, a semi-detached house, an apartment building or the like, or one or more residential units in one Building.

The heating system can be configured to provide other forms of energy in addition to heat, such as cold and/or electrical energy. The heating system can in particular be a heating, ventilation and air conditioning (HVAC) system. In addition, the heating system can provide warm water as service water, for example for the kitchen and bathroom and the like.

A heating system according to the invention for a building comprises a primary circuit, a secondary circuit, at least one heat exchanger, a first heat sink, a second heat sink, at least one fuel cell, at least one switching valve, at least one return temperature sensor and a control device. In preferred embodiments, the heating system can have more than two heat sinks, each of which can have separate circuits for a heat transfer medium.

A first fluid heat transfer medium circulates in the primary circuit. A second fluid heat transfer medium circulates in the secondary circuit. The first and second heat transfer medium are, for example, water. The primary circuit can also be referred to as the producer circuit and the secondary circuit can also be referred to as the consumer circuit.

The fluid heat transfer medium is used to transport the heat. A gas or a liquid is usually used as a heat transfer medium, especially water. For example, the primary circuit and secondary circuit can each use water as a heat transfer medium. The heat exchanger decouples the mass flow (or volume flow) of the heat transfer medium in the primary circuit from the mass flow (or volume flow) of the heat transfer medium in the secondary circuit.

The heating system includes a heat exchanger for transferring heat between the primary circuit and secondary circuit. In particular, the heat exchanger transfers heat between a flow of the primary circuit and a flow of the secondary circuit and between a return of the primary circuit and a return of the secondary circuit. For this purpose, the first heat transfer medium of the primary circuit and the second heat transfer medium of the secondary circuit flow through the heat exchanger. The heat exchanger is also referred to in particular as a heat exchanger. For example, a separation heat exchanger or a plate heat exchanger can be used as a heat exchanger.

The first heat sink is arranged in the primary circuit and then absorbs heat from the first fluid heat transfer medium. The second heat sink is arranged in the secondary circuit and accordingly absorbs heat from the second fluid heat transfer medium. In alternative embodiments that do not fall under the present invention, the first heat sink can also be arranged in the secondary circuit. More preferably, several heat sinks can be arranged in the secondary circuit and/or in the primary circuit.

The fuel cell is arranged in the primary circuit and generates electrical power and can thereby provide the heat generated to the first heat sink or the second heat sink. The fuel cell serves in particular as a heat generator.

The switching valve, which can be a controllable three-way valve, for example, serves to switch between a first state in which the heat of the fuel cell is supplied to the first heat sink and a second state in which the heat of the fuel cell is supplied to the second heat sink.

In preferred embodiments with more than two heat sinks, additional controllable switching valves can be present in the heating system, so that one or more heat sinks can be specifically supplied with heat. In such embodiments, there may accordingly be a third (fourth, etc.) state in which the heat from the fuel cell is supplied to a third (fourth, etc.) heat sink. Furthermore, there can be conditions in which fixed combinations of heat sinks are supplied with heat, in which more than one changeover valve is switched accordingly. The basic idea of the invention is described below using an embodiment with two heat sinks and a changeover valve.

If both the first and second heat sinks are arranged in the secondary circuit, which is not covered by the present invention, the switching valve can still be arranged so that it can switch between the first state and the second state. For this purpose, the secondary circuit can have two correspondingly branched hydraulic circuits, with the first heat sink being arranged in the first circle and the second heat sink being arranged in the second circle.

The first heat sink and the second heat sink can absorb different amounts of heat. Depending on the operating state of the heating system, the first heat sink or the second heat sink can absorb more heat. According to a preferred embodiment, the first heat sink can dissipate, store or consume more heat than the second heat sink.

In a preferred embodiment, the first heat sink may be a subset of the second heat sink. Alternatively, the second heat sink may be a subset of the first heat sink. The only decisive factor for the solution according to the invention is that the first heat sink and the second heat sink have a different heat absorption capacity, so that the return temperature to the fuel cell can be reduced by switching between the first state and the second state in order to avoid switching off the fuel cell. It should be noted that the heat absorption capacity of the heat sinks can vary over time. By measuring temperatures in and/or volume flows through the respective heat sink, the control device can determine which heat sink currently has a higher residual heat absorption capacity, so that the control device can switch the switching valve in order to avoid an undesirable increase in the return temperature to the fuel cell.

Process engineering releases can be defined for both heat sinks, which must be met in order to switch the changeover valve to the corresponding heat sink. The preferred position of the switching valve can be set, for example, in the direction of the first heat sink (first state). This position can be active, for example, if both heat sinks do not meet their release conditions. If only one of the two heat sinks meets its release conditions, the switching valve is switched in the direction of this released heat sink. If the release conditions of both heat sinks are met, the heat requirement of the individual heat sinks determines in which direction the control device switches the changeover valve.

The return temperature sensor is used to measure a return temperature of the heat transfer medium that flows towards the fuel cell. According to the invention, the return temperature sensor is arranged in the return of the secondary circuit, for example in the flow direction just before the heat exchanger. In an alternative embodiment, the return temperature sensor can be arranged between the heat exchanger and the fuel cell, i.e. in the return of the primary circuit.

A further temperature sensor can be arranged in the flow direction of the fluid heat transfer medium in front of the heat exchanger in the flow of the primary circuit and measure a first temperature of the fluid heat transfer medium in the primary circuit. This first temperature is also referred to as the flow temperature or boiler temperature in the primary circuit. Essentially, this temperature sensor can measure the temperature at which the heat transfer medium is provided in the primary circuit, for example to the heat exchanger.

In addition to the return temperature sensor, a flow temperature sensor can be arranged in the flow of the secondary circuit and measure a flow temperature of the second fluid heat transfer medium in the secondary circuit. Based on the flow temperature of the secondary circuit and the flow temperature of the primary circuit, for example, a heat transfer from the primary circuit to the secondary circuit and/or a heat transfer coefficient of the heat exchanger can be determined or calculated. The heat transfer coefficient describes how efficiently the heat exchanger transfers heat from the primary circuit to the secondary circuit. The flow temperature of the secondary circuit can also be referred to as the outlet temperature of the heat exchanger.

According to a preferred embodiment, the heating system may have an outside temperature sensor for measuring an outside temperature of the building. An outside temperature can be used in particular when the heating system is operated under weather conditions. In particular, a heating characteristic can be determined based on the outside temperature.

The control device is used to regulate the heating system. In particular, the control device controls the switching valve in order to switch to the first state or to the second state. The switching valve is controlled by the control device in such a way that, on the one hand, the heat requirement of the heat sinks is optimally covered, for example depending on predetermined target temperatures, and on the other hand, the return temperature to the fuel cell remains below the switch-off temperature in order to thus optimize the running time of the fuel cell.

The control device is wired via suitable signal lines and/or wirelessly connected to the fuel cell, to the switching valve and to the temperature sensors. The control device can therefore, among other things, receive measured values and/or transmit control or regulation signals.

The control device receives the return temperature measured by the return temperature sensor and compares it with a limit value that is specified. If the measured return temperature is equal to or greater than the limit value, the control device switches the changeover valve to the first state. If the measured return temperature is lower than the limit value, the control device switches the changeover valve to the second state. In the first state, more heat can preferably be dissipated from the heat transfer medium, so that a faster and/or larger drop in the return temperature can occur in the first state.

The limit value of the return temperature essentially serves to protect the fuel cell and in particular a so-called stack of the fuel cell from damage or overheating. If the return temperature is greater than a switch-off temperature of the fuel cell of, for example, 50 ° C, the fuel cell switches off to protect itself. The switching off can be done, for example, by an internal control of the fuel cell or by the control device of the heating system.

The limit value can in particular be set so that the switch-off temperature of the fuel cell is not reached even if the return temperature reaches or slightly exceeds the limit value. For example, the limit value can be an offset smaller than the switch-off temperature of the fuel cell. In addition, the limit value can also be determined depending on a heat transfer coefficient of the heat exchanger and / or depending on a mass or volume flow in the return of the secondary circuit, which will be described in more detail later.

Switching to the first state or operating the heating system with the changeover valve in the first state should advantageously lead to a reduction in the return temperature or to a lower maximum value of the return temperature, so that the return temperature drops below the limit value or does not rise above the limit value , so that switching off the fuel cell can be avoided.

Switching to the second state or operating the heating system with the changeover valve in the second state can lead to an increase in the return temperature or to a higher maximum value of the return temperature, so that the return temperature can rise above the limit value, so that the fuel cell can be switched off may become necessary.

Alternatively, if the measured return temperature is less than the predetermined limit value, it can also be permitted for the control device to switch the changeover valve to the first state. This can be done, for example, depending on other operating parameters of the heating system. This version is not covered by the claims and is for illustrative purposes only.

The control device can thus determine, depending on the measured return temperature, or depending on a deviation of the measured return temperature from the limit value, whether the heat generated by the fuel cell should be provided to the first heat sink or to the second heat sink. One of the two states can be set as preferred.

In the secondary circuit, for example in the flow and/or in the return, a mass or volume flow sensor is arranged, which measures a mass flow or a volume flow of the second fluid heat transfer medium in the secondary circuit. The limit value is then also determined depending on the measured mass flow or volume flow in the secondary circuit and/or depending on the performance of the heat exchanger and/or a heat transfer coefficient. For this purpose, for example, corresponding characteristic curves can be stored or stored in the control device. Alternatively, the control device can calculate the limit value depending on one of the parameters mentioned or depending on a large number of parameters.

The first heat sink in the primary circuit is preferably a heat storage device arranged in the primary circuit. The heat storage can have at least one temperature sensor for measuring an actual temperature in the heat storage. Preferably, a plurality of temperature sensors are arranged in the heat storage in order to measure a temperature distribution in the heat storage.

Alternatively, the heat storage can be arranged in the secondary circuit of the heating system and obtain and store heat from the fluid heat transfer medium circulating in the secondary circuit. The heat storage can generally be viewed as a heat consumer. In such an embodiment, the second heat sink is also arranged in the secondary circuit, with the switching valve then also being arranged in the secondary circuit in order to switch between supplying the first heat sink or the second heat sink with heat. This version with first and second heat sinks in the secondary circuit is not covered by the claims and is for illustrative purposes only.

According to a preferred embodiment of the invention, the secondary circuit with the second heat sink is a heating circuit that has a plurality of radiators and/or at least one underfloor heating system. The plurality of radiators and/or the at least one underfloor heating are heat consumers and are summarized by the term second heat sink.

A first exemplary release condition of the second heat sink (heating circuit) can be that there is no error in the heating circuit sensors (e.g. temperature sensors and volume flow sensors).

Another exemplary release condition for the heating circuit is that the volume flow in the heating circuit is greater than a parameterizable threshold value. For example, if a second heat generator in the primary circuit of the heating system (peak load boiler described later) needs to be calibrated, the return temperature in the heating circuit must not be greater than a volume flow-dependent threshold value that can be specified via a calibration characteristic curve.

Another exemplary release condition for the heating circuit is: that the return temperature in the heating circuit must not be greater than a parameterizable threshold with a volume flow-dependent offset. This threshold corresponds to the aforementioned limit value of the return temperature in the secondary circuit. The aim of this offset is to use the return temperature in the secondary circuit and the volume flow to detect an increase in the return temperature to the fuel cell as early as possible and to switch to the first heat sink accordingly. By switching to the first heat sink and the residual heat capacity present therein, the return temperature to the fuel cell can be reduced and the fuel cell can be prevented from being switched off.

Release conditions can also be defined for the first heat sink, which must be met so that switching to the first state is permitted. A first release condition can be that there is no error in the sensors (e.g. temperature sensors in the heat storage) of the heat storage. A further exemplary release condition of the heat storage can be that a storage temperature or at least two storage temperatures measured in the heat storage must be below a parameterizable threshold value.

Preferably, the control device switches the switching valve depending on at least one measured actual temperature in the heat storage (storage temperatures) and/or depending on a target temperature in the heat storage. For example, if the actual temperature in the heat storage is below the target temperature, the control device can switch the switching valve to the first state in order to supply the heat storage with heat from the fuel cell. If the target temperature is reached or if an actual temperature above the target temperature is determined in the heat storage, the control device can switch the changeover valve to the second state in order to supply the heating circuit with heat from the fuel cell. In particular, the switching valve can be controlled depending on a deviation between the actual temperature and the target temperature.

According to a preferred embodiment, the control device switches the switching valve depending on the measured flow temperature in the secondary circuit and/or depending on a predetermined target temperature in the flow (target flow temperature) of the secondary circuit. For example, if the actual temperature in the flow of the secondary circuit is below the specified target temperature, the control device can switch the changeover valve to the second state in order to supply the heating circuit with heat from the fuel cell. If the target flow temperature is reached or if an actual temperature above the target flow temperature is determined in the flow of the heating circuit, the control device can switch the changeover valve to the first state in order to supply the heat storage with heat from the fuel cell.

In a preferred embodiment, the heating system can have a second heat generator for generating and releasing heat to the first fluid heat transfer medium in the primary circuit. The second heat generator can be any heat generator, in particular a gas boiler, an oil boiler, a condensing boiler, a biomass boiler, a heat pump, a combined heat and power plant (CHP) or another heat generator ger for heating the first fluid heat transfer medium.

In the following, this second heat generator can also be referred to as a “peak load boiler”, although this term is not to be understood as limiting the type and/or functionality of the second heat generator. However, the peak load boiler can be put into operation in particular if the heat generated by the fuel cell is not sufficient to reach a target temperature.

The control device can control and/or regulate the second heat generator depending on the measured actual temperature and/or the target temperature in the heat storage and/or depending on the measured flow temperature in the secondary circuit and/or the target temperature in the flow of the secondary circuit.

In a preferred embodiment, the heating system can have a data processing device that is communicatively connected to the control device and has a storage device for storing data and a computing device for processing data. For the transmission of data over a network, the computing device, the storage device and the computing direction can each have suitable network interfaces.

The data processing device can be located locally, for example in the same building as the heating system, or geographically distant. In particular, the data processing device or the computing device can be a server, a computing cluster or act like that.

The storage device can be a local memory of the data processing device. Additionally or instead, the storage device can be implemented, for example, as cloud storage and/or network storage. The cloud storage and/or network storage can be communicatively connected to the data processing device, in particular to the computing device, and the control device of the heating system or several control devices of a plurality of heating systems via the Internet and/or the other network. The data exchange between the control device and the data processing device (computing device and storage device) can take place via the respective network. For this purpose, the individual components have corresponding interfaces.

The advantage of a data processing device connected via the Internet is that data from a large number of heating systems that may be geographically distant from each other (e.g. in different buildings) can be received, stored and processed. This can involve a variety of similar or different heating systems with identical, similar or different heat exchangers. In particular, it can be advantageous to evaluate data from a large number of identical or similar heating systems, which in particular have identical or similar heat exchangers, in order to carry out a specific statistical evaluation of received and stored temperature measurements for a specific type of heat exchanger.

Another advantage of the data processing device connected via the network is that a central evaluation of the data from the heating system can be carried out, regardless of how many heating systems are connected to the data processing device. In particular, machine learning algorithms can also be used.

In a preferred embodiment, the control device can be configured to regularly transmit a large number of measured values, which are in particular temperature measured values, to the data processing device. In addition, mass flows or volume flows of the first and/or second heat transfer medium can also be measured and/or transmitted in the primary circuit and/or in the secondary circuit. The control device can, for example, transmit a large number of measured values about the operating state of the heating system to the data processing device several times per second, several times per minute, several times per hour or several times per day. A large number of measured values can thus be generated and a time course of the operating state of the heating system can be monitored and/or evaluated based on the measured values.

According to a preferred embodiment, the control device can be configured to receive control parameters for controlling the at least one heat generator from the data processing device. The control parameters received can then be stored locally by the control device and used to further regulate and/or control the fuel cell, the second heat generator and/or the switching valve. Additionally or alternatively, the Control device can also use locally stored control parameters, for example if communication with the data processing device is (temporarily) not possible. The control parameters stored locally by the control device can be the last control parameters transmitted by the data processing device and/or control parameters for normal operation and/or emergency operation can be stored in the control device.

The data processing device can be configured to store the measured values received from the control device in the storage device or in the cloud storage. The received measured values can therefore be made available at any time for further processing by the computing device.

The computing device of the data processing device can be configured to calculate a heat transfer coefficient of the heat exchanger depending on the stored measured values. The heat transfer coefficient can be derived from the measured values in various ways. The higher the heat transfer coefficient of the heat exchanger, the more heat the heat exchanger can transfer from the primary circuit to the secondary circuit.

For example, a heat transfer coefficient of the heat exchanger becomes smaller as the degree of contamination increases. The heat transfer coefficient quantifies the ability of the heat exchanger to transfer heat from the heat transfer medium of the primary circuit to the heat transfer medium of the secondary circuit.

Furthermore, the heating system can be connected to a hot water pipe to provide warm drinking water (service water). Heated water can be supplied to the open drinking water circuit via a separate supply for drinking water. A drinking water flow temperature can also be used by the control device as a further operating parameter or control parameter.

The peak load boiler can be, for example, a gas condensing boiler or the like, which can be switched on in particular when the heat given off by the fuel cell is not sufficient to achieve a target flow temperature or a target storage temperature. This can be particularly the case at low outside temperatures when a high heating output is required to maintain a target room temperature. Furthermore, the peak load boiler can be switched on when hot water consumption is high. The peak load boiler can be operated in particular in a weather-compensated manner. The target flow temperature of the peak load boiler can be determined using a characteristic curve.

The heat storage can, for example, be a buffer storage that stores heat by being loaded with the heated heat transfer medium. In principle, a buffer storage can store heat that is not needed in the meantime for later consumption as needed. Heating water or hot water buffer tanks can mainly be used where heat is not constantly required to the same extent. Peak times for heating or hot water in an average household are particularly the morning and evening hours. A buffer storage can also reduce the cycling (switching on and off) of heat generators. It can therefore help ensure that the fuel cell can be operated with a long runtime and a low number of switching operations. In particular, the heat storage is a bivalent drinking water storage.

The control device monitors and regulates or controls the operation of the heating system. To monitor operation, the control device can in particular record a large number of measured values or sensor signals, in particular temperature measured values, for example in the flow of the primary circuit, in the flow of the secondary circuit, in the return of the primary circuit, in the return of the secondary circuit, at one or more locations in the buffer memory, in the heated rooms of the building as well as an outside temperature of an area surrounding the building. For this purpose, the heating system can have a large number of temperature sensors or receive corresponding measured values from external temperature sensors or a server.

In addition to the temperatures in the heating circuit (or hot water flow), a volume flow (or mass flow) of the heat transfer medium can also be recorded at one or more points, for example in the flow and / or in the return of the heating circuit and / or in the flow of the hot water pipe, for example through one or more flow sensors.

Furthermore, the control device can monitor a variety of operating parameters of the peak load boiler and the fuel cell. This includes, in particular, their operating states (on/off), switching on and off processes and respective times, heating outputs and the electricity emitted by the fuel cell. In addition, respective limit values can be recorded as operating parameters.

In particular, the control device can monitor at least one operating parameter from the following list: an outside temperature of the building, a primary circuit flow temperature, a flow temperature in the secondary circuit, a target flow temperature, a return temperature in the primary circuit, a return temperature in the secondary circuit, a target return temperature, a temperature in the buffer storage, a temperature distribution in the buffer storage, a volume flow of the heat transfer medium in the flow and/or in the return of the secondary circuit, an operating state of a circulation pump in the heating system. The operating state of the circulation pump indicates in particular whether the circulation pump is switched on or off. Furthermore, the operating state of the circulation pump can indicate a speed of the circulation pump.

The outside temperature in the area surrounding the building can be detected, for example, via one or more outside temperature sensor(s) arranged in the area around the building, which output(s) a corresponding sensor signal to the control device. The flow temperature of the heat transfer medium can be detected, for example, via one or more temperature sensors arranged in the flow, which outputs a corresponding sensor signal to the control device.

The same applies to the return temperature of the heat transfer medium. The target temperatures for flow and return can also be used as control parameters. The temperature in the buffer storage can be recorded at several points in the buffer storage using temperature sensors. A temperature distribution in the buffer storage can be determined from several temperatures measured in the buffer storage. Depending on the temperatures of the heat transfer medium, a volume flow or mass flow in the flow and/or return of the secondary circuit can also be recorded using suitable flow sensors. A circulation pump can be arranged in the heating circuit and/or in the open hot water circuit.

All recorded measured values, limit values and parameters are usually recorded and saved together with a corresponding time and date, so that further processing can also take place depending on the time and/or the date or the season.

In addition, the heating system can have an inverter to convert the direct current emitted by the fuel cell into usable alternating current.

The control device can be communicatively connected to a network via a suitable interface. The control device can send or receive a variety of data via the network. Furthermore, a central server and/or a cloud and a (particularly mobile) terminal device of a user of the heating system or a resident of the building can also be communicatively connected to the network via suitable interfaces, so that the control device, the server and the terminal device each receive data can send and receive. The network can be, for example, the Internet. The interface of the control device can accordingly be an Internet gateway.

The user's (mobile) end device can in particular be a smartphone, laptop, tablet computer or another internet-enabled device with a display and an input device (e.g. touch screen and/or keyboard and/or trackpad and/or mouse) on which an application (app) is executed that serves as a human-machine interface and allows the user to view and/or change operating parameters of the heating system or to execute algorithms for controlling or regulating the heating system.

The server and/or the cloud can each receive a variety of operating parameters of the heating system as well as temperature measurements via the interface. Accordingly, the control device can receive parameters for controlling or regulating the heating system from the server or the cloud, in particular a heating curve or setpoints, in particular for temperatures in the flow of the secondary circuit, return of the secondary circuit and / or buffer storage.

In one step of the method, a graphical user interface is displayed on the user's terminal as a human-machine interface for inputting and/or outputting information. For this purpose, in particular, a dedicated application (“app”) can be run on the end device. Alternatively, the application can also be executed via an Internet browser or the like. In particular, the application outputs information about an operating status of the heating system or instructions to the user and can receive entered data from the user and, for example, transmit it to the server.

For example, the application can display operating parameters of the fuel cell, such as a running time and/or a number of switching operations and/or a generated electrical energy or current of the fuel cell. The application can therefore serve as a front-end for a program (algorithm or method), which is executed, for example, as a back-end on the server or by the control device.

The control device regulates in particular an operating state of the fuel cell and the peak load boiler. The control device can regulate the fuel cell and the peak load boiler in particular so that the fuel cell is switched on and off as rarely as possible, so that the running time of the fuel cell is as long as possible. The control device can also take user behavior into account, for example. For this purpose, the control device can record the operating parameters together with corresponding times and transmit them to the server, where an evaluation can be carried out. For example, the server can carry out a statistical analysis of a large number of data. In particular, a large number of similar or identical heating systems in different buildings can be evaluated. Machine learning can also be used in the evaluation, for example to recognize user behavior.

Functions and processes described herein that are carried out by the control device can in particular be carried out in whole or in part by the server and/or the cloud.

A heating system according to the invention is preferably configured to carry out a method according to the invention.

BRIEF DESCRIPTION OF THE FIGURES

Further advantageous embodiments are described in more detail below using an exemplary embodiment shown in the drawings, to which the invention is, however, not limited.

• 1 1 illustriert ein Heizungssystem gemäß einem ersten Ausführungsbeispiel der Erfindung.
• 2 2 illustriert ein Heizungssystem gemäß einem zweiten Ausführungsbeispiel der Erfindung.

It shows schematically:

• 1 1 illustrates a heating system according to a first embodiment of the invention.
• 2 2 illustrates a heating system according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION USING EXAMPLES OF EMBODIMENTS

In the following description of a preferred embodiment of the present invention, the same reference numerals designate the same or comparable components.

1 shows a simplified schematic drawing of a heating system 1 according to the invention according to a first exemplary embodiment of the invention. The heating system 1 is arranged in a building G and comprises a primary circuit and a secondary circuit, in each of which a fluid heat transfer medium, for example water, circulates. The hydraulic lines of the primary circuit are indicated in simplified form with solid arrows. The hydraulic lines of the secondary circuit are shown in simplified form with dotted arrows. The present representation of the hydraulic lines is to be understood as an example and can be adapted in other versions in an expedient manner depending on the needs and design of the heating system 1.

The primary circuit has a flow VP and a return RP, which are coupled via a heat exchanger 7 to a flow VS and return RS of the secondary circuit. The secondary circuit here is a heating circuit for heating building G.

The heating system 1 includes a fuel cell 2 in the primary circuit (generation circuit), a peak load boiler 3 as a second heat generator and a buffer storage. The fuel cell 2 generates electrical power and releases the heat generated into the fluid heat transfer medium. The peak load boiler 3 also generates heat and transfers it to the heat transfer medium. The buffer storage serves as a first heat sink 4 and can be loaded with the heated heat transfer medium in order to store heat.

The heating system 1 includes a control device 10, which can monitor and store operating parameters of the heating system 1 and regulate the heating system 1 depending on control parameters. Signal lines for sending and/or receiving measured values and/or control signals and/or other data between the control device 10 and other components of the heating system 1 are indicated by thin dotted arrows.

A large number of consumers, for example a large number of radiators and/or underfloor heating, can be arranged as a second heat sink 5 in the hydraulic heating circuit. Hot water flows via the flow VS of the secondary circuit to the consumers, which take heat from the heat transfer medium and deliver it to the rooms in building G. The water flows back to the heat exchanger 7 via the return RS of the secondary circuit. In the flow VS of the secondary circuit and/or in the return RS of the secondary circuit, there can be temperature sensors for measuring a flow temperature or a return temperature and/or flow sensors for measuring a volume flow or a mass flow of the heat transfer medium. In 1 Only the return temperature sensor 8 is shown in the return of the heating circuit.

The control device 10 controls a switching valve 9, which can be a controllable three-way valve, for example, and for switching between a first state in which the heat of the fuel cell 2 is supplied to the buffer storage and a second state in which the heat of the fuel cell 2 is supplied to the consumers is supplied in the heating circuit.

The control device 10 is connected to a network 40 via an interface (e.g. gateway) in order to exchange data with a user's terminal T and/or a server 20 and/or a cloud 30. The network 40 may be a LAN, a WAN, an intranet, or the Internet, or a combination of such networks.

The heating system 1 can also have one or more pumps (not shown) to generate a volume flow in the primary circuit. Furthermore, one or more pumps (not shown) can be provided in the heating system 1 in order to generate a volume flow in the secondary circuit.

The buffer storage and the consumers in the heating circuit can absorb different amounts of heat. Depending on the operating state of the heating system 1, the first heat sink 4 or the second heat sink 5 can absorb more heat.

The return temperature sensor 8 is used to measure a return temperature of the heat transfer medium that flows towards the fuel cell 2. In 1 The return temperature sensor 8 is located in the return RS of the secondary circuit, just before the heat exchanger 7 in the flow direction.

A further temperature sensor can, for example, be arranged in the flow direction of the fluid heat transfer medium in front of the heat exchanger 7 in the flow VP of the primary circuit and measure a flow temperature of the fluid heat transfer medium in the generator circuit.

In addition to the return temperature sensor 8, a flow temperature sensor can be arranged in the flow VS of the heating circuit and measure a flow temperature in the heating circuit. Based on the flow temperature of the heating circuit and the flow temperature of the generator circuit, a heat transfer and/or a heat transfer coefficient of the heat exchanger 7 can be calculated.

The heating system 1 also includes an outside temperature sensor 6 arranged outside the building G for measuring an outside temperature of the building G. The outside temperature is used in particular in the weather-controlled operation of the heating system 1. A target flow temperature is determined from a heating curve based on the outside temperature.

The control device 10 serves to control the heating system 1. In particular, the control device 10 controls the switching valve 9 in order to switch to the first state or to the second state.

The control device 10 is connected by wire via suitable signal lines and/or wirelessly to the fuel cell 2, to the switching valve 9 and to the temperature sensors 6, 8. Thus, the control device 10 can, among other things, receive measured values and/or transmit control or regulation signals. The signaling pathways are in 1 indicated by thin dotted arrows.

The control device 10 receives the return temperature measured by the return temperature sensor 6 and compares it with a predetermined limit value. If the measured return temperature is equal to or greater than the limit value, the control device 10 switches the changeover valve 9 to the first state. If the measured return temperature is smaller than the limit value, the control device 10 switches the changeover valve 9 to the second state. In the first state, more heat can usually be removed from the heat transfer medium, so that a faster and/or larger drop in the return temperature can occur in the first state.

The limit value of the return temperature essentially serves to protect the fuel cell 2 and in particular a so-called stack of the fuel cell from damage or overheating. If the return temperature is greater than a switch-off temperature of the fuel cell 2 of, for example, 50 ° C, the fuel cell 2 switches off in order to protect itself. Switching off is done here by the control device 10 of the heating system 1.

The limit value is set so that the switch-off temperature of the fuel cell 2 is not reached even if the return temperature briefly reaches the limit value or slightly exceeds it for a short time. For this purpose, the limit value is set by an offset smaller than the switch-off temperature of the fuel cell 2.

In addition, the limit value also depends on a heat transfer coefficient th of the heat exchanger 7 and/or depending on a mass or volume flow in the return of the secondary circuit.

There is an in in the flow VS of the heating circuit 1 Volume flow sensor, not shown, which measures a volume flow of the heat transfer medium in the heating circuit. The control device 10 then determines the limit value depending on the measured volume flow and/or depending on the heat transfer coefficient of the heat exchanger 7. For this purpose, for example, corresponding characteristic curves can be stored or stored in the control device 10. Alternatively, the control device 10 can receive the limit value via the network 40.

The control device 10 can switch the switching valve 9 depending on at least one measured actual temperature in the buffer storage and/or depending on a target temperature in the buffer storage. For example, if the actual temperature in the buffer storage is below the target temperature, the control device 10 switches the switching valve 9 to the first state in order to supply the buffer storage with heat from the fuel cell 2. If the target temperature is reached or if an actual temperature above the target temperature is measured in the buffer storage, the control device 10 switches the changeover valve to the second state in order to supply the heating circuit with heat from the fuel cell 2.

In addition, the control device 10 can control the switching valve 9 depending on the measured flow temperature in the heating circuit and/or depending on a predetermined target temperature in the flow VS (target flow temperature) of the heating circuit. If the actual temperature in the flow VS of the heating circuit is below the specified target temperature, the control device 10 switches the changeover valve 9 to the second state in order to supply the heating circuit with heat from the fuel cell 2. If the target flow temperature is reached or if an actual temperature above the target flow temperature is measured in the flow VS of the heating circuit, the control device 10 switches the changeover valve 9 to the first state in order to supply the buffer storage with heat from the fuel cell 2.

The control device 10 controls the peak load boiler 3 depending on the measured actual temperature and/or the target temperature in the buffer storage and/or depending on the measured flow temperature in the heating circuit and/or the target temperature in the flow VS of the heating circuit.

Preferably, the server 20 or the cloud 30 can receive, store and evaluate data from a large number of different or identical (similar) heating systems 1 with fuel cells 2 via the network 40. In this way, for example, data can be evaluated as in 2a until 2e be generated. The server 20 or the cloud 30 can in particular carry out a statistical evaluation of the data and also use algorithms that have been trained by machine learning. By using artificial intelligence and large amounts of data from a variety of systems, the running time of fuel cells can be further optimized.

The server 20, the cloud 30 and/or the user's terminal T can partially or completely take over functions of the control device. All method steps that are described in the present application as part of the method according to the invention can be carried out partially or completely by the control device 10, by the server 20, by the cloud 30 and / or by the terminal T. In this respect, the server 20, the cloud 30, the network 40 and the terminal T can be understood as a (geographically distant but functionally related) part of the control device 10.

The control device 10 controls the heating system 1 depending on control parameters. The control parameters can include, for example, a heating curve, a target flow temperature, a target return temperature, a target storage temperature, etc.

In one step of the method, a large number of operating parameters of the heating system 1 are recorded. These include, in particular, an outside temperature of the building G, a flow temperature, a target flow temperature, a return temperature, a target return temperature, a temperature in the buffer storage, a target storage temperature, a volume flow of the heat transfer medium in the flow and / or in the return of the secondary circuit and / or a speed of a circulation pump in Heating system 1. This means that control parameters can also be understood as operating parameters at the same time.

A variety of temperatures can be measured in the buffer storage, as the temperature distribution can exist in layers with the appropriate load. In particular, a first temperature is measured in an upper third of the buffer memory and a second temperature is measured in a lower third of the buffer memory. The first (upper) temperature is usually higher than the second (lower) temperature.

2 shows a simplified schematic drawing of a heating system according to the invention tems 1 according to a second exemplary embodiment, which has a slightly modified hydraulic scheme. Only differences are described below.

From the heat exchanger 7, the return RP of the primary circuit flows to both the fuel cell 2 and the peak load boiler 3. Furthermore, both the fuel cell 2 and the peak load boiler 3 feed warm water into the flow VP of the primary circuit, which goes to the changeover valve 9. The switching valve 9 can be used to switch between supplying the heat storage and the heating circuit coupled via the heat exchanger 7.

In the drawing of the 2 Only a hot water supply WW is shown based on the heat storage. However, the heat accumulator can also be connected to the heating circuit and/or to another secondary circuit or several other secondary circuits via further hydraulic lines, another switching valve or several switching valves and/or another or several further heat exchangers.

The features disclosed in the above description, the claims and the drawings can be important both individually and in any combination for the implementation of the invention in its various embodiments.

Claims (9)

Heating system (1) for a building (G), comprising: a primary circuit in which a first fluid heat transfer medium circulates; a secondary circuit in which a second fluid heat transfer medium circulates; a heat exchanger (7) for transferring heat between a flow (VP) of the primary circuit and a flow (VS) of the secondary circuit and between a return (RP) of the primary circuit and a return (RS) of the secondary circuit; a first heat sink (4) arranged in the primary circuit and which absorbs heat from the first fluid heat transfer medium; a second heat sink (5) arranged in the secondary circuit and which absorbs heat from the second fluid heat transfer medium; a fuel cell (2) arranged in the primary circuit for generating electrical current and providing heat generated thereby to the first heat sink (4) or the second heat sink (5); a switching valve (9) for switching between a first state in which the heat of the fuel cell (2) is supplied to the first heat sink (4) and a second state in which the heat of the fuel cell (2) is supplied to the second heat sink (5) is supplied; a return temperature sensor (8) for measuring a return temperature in the return line (RS) of the secondary circuit; and a control device (10) for controlling the heating system (1), the control device (10) being configured: to switch the changeover valve (9) to the first state or the second state depending on the measured return temperature; to compare the return temperature with a specified limit value; and to switch the changeover valve (9) to the first state if the return temperature is equal to or greater than the limit value; or to switch the changeover valve (9) to the second state if the return temperature is lower than the limit value, where: a volume flow sensor is arranged in the secondary circuit for measuring a volume flow in the secondary circuit; and the limit value is determined depending on the measured volume flow in the secondary circuit and / or depending on the performance of the heat exchanger (7). Heating system (1). Claim 1 , wherein the first heat sink (4) is a heat storage device which has a temperature sensor for measuring an actual temperature in the heat storage device. Heating system (1). Claim 1 or 2 , wherein: the secondary circuit with the second heat sink (5) is a heating circuit with radiators and / or underfloor heating; and a flow temperature sensor for measuring a flow temperature in the secondary circuit is arranged in the flow (VS) of the secondary circuit. Heating system (1). Claim 2 or 3 , wherein the control device (10) is configured: to switch the switching valve (9) depending on the measured actual temperature in the heat storage and / or a target temperature in the heat storage; and/or to switch the switching valve (9) depending on the measured flow temperature of the secondary circuit and/or a predetermined target temperature in the flow (VS) of the secondary circuit. Heating system (1). Claim 4 , further comprising: a second heat generator (3) for generating and releasing heat to the first fluid heat transfer medium in the primary circuit, wherein the control device (10) is configured depending on the second heat generator (3). to control the measured actual temperature and/or the target temperature in the heat storage; and/or the measured flow temperature in the secondary circuit and/or the target temperature in the flow (VS) of the secondary circuit. Method for operating a heating system (1) for a building (G), the heating system (1) comprising: a primary circuit in which a first fluid heat transfer medium circulates; a secondary circuit in which a second fluid heat transfer medium circulates; a heat exchanger (7) which transfers heat between a flow (VP) of the primary circuit and a flow (VS) of the secondary circuit and between a return (RP) of the primary circuit and a return (RS) of the secondary circuit; a first heat sink (4) arranged in the primary circuit and which absorbs heat from the first fluid heat transfer medium; a second heat sink (5) arranged in the secondary circuit, which absorbs heat from the second fluid heat transfer medium, the method comprising: Operating a fuel cell (2) arranged in the primary circuit to generate electrical current and providing the heat generated thereby to the first heat sink (4) or the second heat sink (5); Operating a switching valve (9) for switching between a first state in which the heat of the fuel cell (2) is supplied to the first heat sink (4) and a second state in which the heat of the fuel cell (2) is supplied to the second heat sink (5 ) is supplied; Measuring a return temperature in the return (RS) of the secondary circuit; Controlling the heating system (1), the switching valve (9) being switched to the first state or the second state depending on the measured return temperature of the secondary circuit; Specifying a limit value for the return temperature in the secondary circuit; Comparing the measured return temperature in the secondary circuit with the limit value; and switching the changeover valve (9) to the first state if the return temperature in the secondary circuit is equal to or greater than the limit value; or Switching the changeover valve (9) to the second state if the return temperature in the secondary circuit is less than the limit value; Measuring a volume flow in the secondary circuit; and Determining the limit value depending on the measured volume flow in the secondary circuit and/or depending on the performance of the heat exchanger (7). Procedure according to Claim 6 , further comprising: measuring an actual temperature in a heat storage as a first heat sink (4); and/or measuring a flow temperature in the secondary circuit. Procedure according to Claim 7 , further comprising: specifying a target temperature in the heat storage; and switching the switching valve (9) depending on the measured actual temperature in the heat storage and/or the target temperature in the heat storage; and/or specifying a target temperature in the flow (VS) of the secondary circuit; and switching the changeover valve (9) depending on the measured flow temperature in the secondary circuit and/or the target temperature in the flow (VS) of the secondary circuit. Procedure according to one of the Claims 6 until 8th , further comprising: operating a second heat generator (3) in the primary circuit; Specifying a target temperature in the flow (VS) of the secondary circuit; and controlling the second heat generator (3) depending on the measured actual temperature and/or the target temperature in the heat storage; and/or controlling the second heat generator (3) depending on the measured flow temperature and/or the target temperature in the flow (VS) of the secondary circuit.

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