Patent Application
20250020336
The present invention relates to a method for operating a heat pump having a heating register in a ventilation system. In particular, the method is intended to prevent the heating register of the heat pump from being unintentionally in operation if an outside temperature is above a limit temperature. This makes it possible to avoid unnecessarily high energy consumption and correspondingly high costs.
In order to save costs, heat pumps which are used to heat a building and/or to prepare hot water are generally not designed for the temperatures which are absolutely lowest possible over the year at a particular location. Instead, heat pumps often have an electric heating device, for example a heating register for heating air or a heating rod for heating water, in order to provide additional heating power if the heat pump alone can no longer supply a required heating power. This can be the case in particular at very low outside temperatures. Both air-water heat pumps and air-air heat pumps can operate less efficiently at particularly low outside temperatures.
An electric heating register operates less efficiently than the heat pump and can ideally generate only one kilowatt-hour of thermal energy from one kilowatt-hour of electrical energy. By contrast, the heat pump has a significantly higher efficiency and can generate, for example, 3 to 4 kilowatt-hours of thermal energy from one kilowatt-hour of electrical energy depending on the outside conditions.
Long operation of the heating register is therefore undesirable from economic points of view and should be avoided as far as possible. The heating register should be operated in particular only if the heat pump alone cannot supply sufficient heating power.
On the other hand, long and/or frequent operation of a heating register can provide an indication that the heat pump or another part of a ventilation system having a heat pump is defective and/or requires maintenance. In order to ensure efficient and economic operation of a ventilation system having a heat pump, it is therefore desirable to reliably and rapidly detect long and/or frequent operation of the heating register in order to be able to take corresponding countermeasures.
A heat pump having an additional electric heating element is described, for example, in DE 699 25 389 T2. If the outside temperature is below a limit value, the additional electric heating element is activated in order to heat a supply air of the heat pump.
The present invention is based on the object of overcoming the problems known in the prior art and of specifying a method for operating a heat pump which is improved over the prior art. Furthermore, an improved ventilation system having a heat pump is to be provided. The object is achieved by the method according to claim 1 and by the ventilation system according to claim 7. Further aspects of the invention are the subject matter of the dependent claims, of the following description of the exemplary embodiments and of the drawings.
A heat pump according to the invention for heating air in a ventilation system for a building transfers heat to a fluid heat transfer medium, here in particular air, flowing through one or more ventilation ducts of the ventilation system. The ventilation ducts can be formed for example as a system of pipes or lines through which the heat transfer medium flows. The ventilation system comprises in particular a feed duct via which warm supply air is provided to a room, and a return duct via which exhaust air is discharged from the room. Such a feed duct is also referred to as a supply air duct.
In the ventilation ducts, in particular in the feed duct, a plurality of outlets for discharging the heated air to room air of a room can additionally be arranged. The return duct can have a plurality of openings for drawing in room air as exhaust air. In each case at least one pump or at least one fan for generating an air flow can be arranged in the return duct and/or in the feed duct. Such a return duct is also referred to as an exhaust air duct.
The ventilation system can have at least one ventilation duct for drawing in fresh outside air, which is also referred to as an outside air duct. In addition, the ventilation system can have at least one ventilation duct for discharging used exhaust air, which is also referred to as an exhaust air duct. These ventilation ducts can be flow-connected to an environment of the building via suitable openings.
The ventilation ducts of the ventilation system can be divided into a plurality of subsystems, which can be separated for example according to the heating purpose. Thus, for example, a feed duct of a ventilation duct can branch off into two or more feed ducts starting from the heat pump. A first feed duct can be provided for heating rooms in a first floor of a building. A second feed duct can be provided for heating rooms in a second floor of a building. Correspondingly, a separate feed duct can be provided for each floor of a building. The individual feed ducts can be opened or closed via suitable valves, so that a supply of warm air can be set individually for each floor. In a similar manner, the division can also take place according to dwellings in a floor or according to other criteria.
The ventilation ducts can be supplied with fresh air (outside air) from outside the building via a supply duct or a plurality of supply ducts. The heat pump can then heat the fresh air before it is supplied to the feed duct. Correspondingly, exhaust air can be discharged to the outside via an exhaust air duct or a plurality of exhaust air ducts.
In a preferred embodiment of the invention, one or more supply ducts are coupled via a heat exchanger to one or more feed ducts for supply air, so that no direct air exchange of room air with the outside air takes place via the ventilation system. Correspondingly, one or more exhaust air ducts can be coupled as return ducts via the heat exchanger to one or more exhaust air ducts for exhaust air. The term supply air can be used below for recirculated room air or for freshly supplied outside air or fresh air. The term exhaust air can be used below for room air which is drawn in for recirculation by the ventilation system or which is discharged to the outside as exhaust air.
In an embodiment with a heat exchanger, the heat pump can be arranged such that an evaporator of the heat pump is arranged in the exhaust air duct for exhaust air. In this way, residual heat from the building can be reused for heating and the efficiency of the ventilation system can be increased. A condenser of the heat pump can be arranged in the feed duct for supply air in order to heat the supply air. A heating register can preferably be arranged downstream of the condenser in the flow direction in order to supply additional heat to the supply air, in particular if the heat output of the heat pump is not sufficient to reach a predefined setpoint temperature in the feed duct.
A heating register is understood below to mean a device which can heat air in a ventilation duct and consumes electrical energy for this purpose. For this purpose, the heating register can have, for example, a plurality of fins around which the air to be heated flows. The heating register can be arranged in the ventilation duct upstream or downstream of the compressor of the heat pump in the flow direction.
The ventilation system preferably comprises an outside temperature sensor for acquiring an outside temperature of the building. The heat pump has an electric heating register for transferring heat to the fluid heat transfer medium, here in particular outside air or supply air. The control device is used to control an operating state of the heat pump and of the heating register. The control device is configured to carry out a method according to the invention for operating the heat pump.
The acquisition of an outside temperature can take place in particular by means of an outside temperature sensor. Alternatively, the outside temperature can also be acquired in another manner. For example, the outside temperature can be received via a network from a server or transmitted from another external device to the control device of the heat pump.
If the outside temperature is higher than a limit temperature, an operating time of the electric heating register of the heat pump is acquired, for example by the control device. The limit temperature can be predefined for example depending on a geographical position of the building. The limit temperature can correspond in particular to a design temperature of the heat pump. Usually, the heat pump can be designed such that efficient operation is possible on most days of a year. In order to avoid expensive overdimensioning of the heat pump, the heat pump can be designed such that a loss of efficiency of the heat pump is accepted on the coldest days of a year with a very low outside temperature. If the outside temperature falls below the limit temperature, the electric heating register can provide additional heating power.
The limit temperature is generally a temperature below the zero point and can be variable in particular. For example, the limit temperature can be in a range between −15° C. and −5° C. If the outside temperature is above the limit temperature, operation of the heating register is not intended to take place. If the heating register is nevertheless operated, this can be an indication of a defect or reduced efficiency of the heat pump.
The operating time of the heating register can be acquired for example in seconds, minutes or hours. Operating time of the heating register means an integrated time period during which the heating register is in operation, that is to say consumes electrical energy or converts it into thermal energy. In particular, an operating time per day or per 24 hours is acquired. Furthermore, in each case an operating time per week, per month, per year and/or overall from the start-up of the heat pump and/or from a last maintenance date of the heat pump can also be acquired.
The operating time of the heating register is preferably acquired together with a respective time of the operation of the heating register. Thus, it is possible to evaluate later at which times the heating register is used, and whether there are particular times at which the heating register is particularly frequently in operation. For example, after a night-time reduction, excessively rapid heating can lead to the heating register being switched on in order to assist the heat pump in order to reach a setpoint value.
If the outside temperature is higher than the limit temperature, an energy consumed by the heating register can be acquired, for example by the control device. The energy consumed can also be determined by acquiring the power consumed and the operating time and forming the product.
A first limit value is set for the operating time within a set period of time. For example, a maximum operating time can be set in a set period of time of one day or within 24 hours. The first limit value can in particular be variable and can be set depending on various factors such as for example the season or a heating purpose. For example, a daily maximum operating time of a plurality of minutes or a few hours can be set, in particular in a range from 15 minutes to 2 hours.
A second limit value is set for the energy consumed in the set period of time. It is thus possible in particular to monitor whether the energy consumed on one day or within 24 hours exceeds the second limit value. The aim is to prevent or to detect that the heating register consumes more than a permitted amount of energy. In comparison with monitoring only the operating time alone, undesired operation of the heating register can thus be reliably detected. An exemplary range for the second limit value can be between 1 and 4 kWh per day, in particular the second limit value can be 2 kWh per day.
If the first limit value and/or the second limit value is/are exceeded, a message is output. In particular, it is advantageous if a message is output only if both limit values are exceeded. In certain cases, it may be desirable to tolerate a high power consumption of the heating register over a short period of time. This can be the case, for example, if a large amount of warm air is required for a short time, for example rapid heating of a room. Such a short-term demand for warm air can namely not be met by the heat pump alone under certain circumstances. The abovementioned “short period of time” is in particular no longer than one hour, preferably no longer than half an hour and particularly preferably no longer than 15 minutes. If the heat pump is in an emergency operating state, the output of the message can be dispensed with.
The message can be in particular a warning message in order to alert a user of the heat pump that the heating register is or has been in operation for longer and/or with a higher energy consumption than permitted or desired. A user can also be understood below to mean in particular a person or the like who is tasked with the maintenance of the heat pump or is responsible for the operation of the ventilation system, for example a heating engineer or heating installer.
Furthermore, the message can be any output which can be processed further electronically, for example in order to perform a control intervention. For this purpose, the message can be transmitted via the network to the server or a cloud, for example. The message can comprise in particular a plurality of data relating to the operating state of the heat pump and/or the heating register, with the result that these data can be stored and/or processed further in the server or in the cloud, as described in more detail further below.
The control intervention can be performed or proposed automatically by the control device in response to the message, with the result that it is performed only after confirmation by a user. Alternatively, the message can already comprise the proposal for the control intervention. Thus, a possible problem of the heat pump can advantageously be reported together with a suitable solution for the problem.
The control intervention can include that a night-time reduction is adapted. The night-time reduction can mean that a setpoint temperature (for example of the feed duct) is reduced overnight. The night-time reduction can thus save energy overnight. However, reducing the setpoint temperature(s) to a lesser extent overnight can have the advantage that less operation of the heat pump is sufficient in the morning to reach the setpoint temperature(s) again during the day. Operation of the heating register can then be reduced in particular at low outside temperatures.
The control intervention can include adapting the heating times (or operating times). If, for example, it is detected that the heating register is used for heating in the morning hours in a controlled manner (see night-time reduction), an earlier time for starting a heating process can be set by the heat pump, so that the setpoint temperature(s) can be reached at a predefined time even without (or with less) assistance of the heating register.
The warning message can be output by a control device of the heat pump to a terminal of the user, in particular a mobile terminal such as a smartphone, a tablet, a laptop or another device suitable for this purpose. The terminal can receive the warning message in particular via a network, for example the Internet. The warning message can additionally or instead be displayed via a display device of the control device.
The message or the warning message can advantageously be used to avoid an undesired operating state of the heat pump. In particular, it can be determined on the basis of the warning message that the heating register has exceeded the first and/or the second limit value. Accordingly, suitable countermeasures can then be taken. For example, the warning message can be an indication that the heat pump is operating inefficiently and maintenance of the heat pump should be carried out.
The control device of the heat pump controls and/or controls the heat pump in particular depending on one or more parameters, for example a target flow temperature, the outside temperature and the like. The control device can receive the parameters from an external device, for example via a network. However, the parameters for controlling and/or controlling the heat pump can also be preprogrammed or stored in a local memory device. Furthermore, the heat pump can be controlled by means of a heating curve. In particular for emergency operation, operating parameters are stored in the control device.
The acquired values of the outside temperature and/or the operating time of the heating register and/or the energy consumed by the heating register and/or the first limit value and/or second limit value and/or control parameters of the heat pump can be transmitted from the control device of the heat pump via the network to the cloud and/or the server. This transmission of the values can take place independently of the message described above. The transmission can take place at regular time intervals, for example, with the result that a time series of data becomes available in the server and/or the cloud.
The cloud and/or the server can process the transmitted data and values further and evaluate them in particular depending on the first limit value and the second limit value. In this case, for example, machine learning can also be used, for example in order to detect or predict a decrease in the efficiency of the heat pump at an early stage. Accordingly, the message can also be generated and output by the server.
If the operating time exceeds the first limit value within the set period of time and/or the energy consumed by the heating register in the set period of time exceeds the second limit value, the server can determine optimised control parameters for the operation of the heat pump and of the heating register, and transmit the optimised control parameters via the network to the control device of the heat pump.
The first limit value and/or the second limit value can be set depending on an operating state of the heat pump. In particular, operating states can be defined depending on a heating purpose of the heat pump. For example, a distinction can be made between a first operating state for providing warm air for heating a first room or a first group of rooms (for example a first of a plurality of floors of a building) and a second operating state for providing warm air for heating a second room or a second group (for example a second of a plurality of floors of a building) of rooms.
In the first operating state, as described above, a high power consumption of the heating register can be tolerated over a short period of time. If the heat pump is in the first operating state for a relatively long time, the second limit value can be correspondingly raised.
In the second operating state, the heat pump should be operated primarily without assistance by the heating register. The first limit value and/or the second limit value can thus be reduced in the second operating state.
The first limit value and/or the second limit value can be adapted to the heating purpose by means of a weighting. Correspondingly, the weighting of the limit values can be reduced in the first operating state. In the second operating state, the weighting of the limit values can be correspondingly increased. The weighting can in particular be set such that the message is output earlier if the heating register is used for heating (second operating state).
The weighting can be designed, for example, such that the function reacts more sharply in the second operating state, that is to say in particular from the set limit value (weighting=1), while operation of the heating register can be tolerated rather (weighting>1) in the first operating state, since a high power is necessary in this case for a short time in order to be able to provide sufficiently warm air. In particular in the first operating state, heating of the rooms is therefore more important than avoiding operation of the heating register. In order to make this possible, the permissible runtime (first limit value) or the permissible energy consumption (second limit value) can be increased by multiplying by a weighting factor greater than one.
For example, a weighting factor equal to two can be used. This can be implemented for example such that on the day 30 minutes of operating time (first limit value) of the heating register for operation in the second operating state and one hour of operating time for operation in the first operating state are permitted. Correspondingly, the second limit value can be set such that per day 1 kWh of energy consumption of the heating register for operation in the second operating state and 2 kWh of energy consumption of the heating register for operation in the first operating state are permitted. The weighting with factor two is to be understood here such that the heating register in the first operating state can be operated twice as long or can consume twice as much energy as in the second operating state before suitable countermeasures are taken.
Further advantageous embodiments are described in more detail below on the basis of an exemplary embodiment which is illustrated in the drawings and to which the invention is not restricted, however.
There are shown schematically:
In the following description of a preferred embodiment of the present invention, identical reference signs denote identical or similar components.
The air-water heat pump 1 can use the ambient air of the building as a heat source in order to supply the building with heat. In
During operation, a fan 3 actively draws in outside air and passes it on to a heat exchanger, the evaporator 4. A refrigerant which changes its state of matter already at a low temperature on account of its thermal properties circulates therein. The circulation of the refrigerant is illustrated by dots in
If the refrigerant comes into contact with the supplied “warm” outside air, it heats up until it finally begins to evaporate. Since the temperature of the resulting vapour is still relatively low, the vapour flows on to an electrically driven compressor 5. The latter increases the pressure, as a result of which the temperature also rises. If the refrigerant vapour has reached the desired temperature level, it flows on to the next heat exchanger, the condenser 6. Here, it transfers its heat to a hydraulic line system (illustrated by bold solid lines in
The heat thus obtained can be used for heating or for preparing hot water. Before the cooled refrigerant can be heated and compressed again, it first flows through an expansion valve 8. Here, pressure and temperature fall to the initial level and the circulation can be repeated. The expansion valve 8 can be electronically controllable.
The division of the components between external unit A and internal unit B is not set to that of
Water circulates as a fluid heat transfer medium in the hydraulic lines. In the condenser 6, the water absorbs heat from the refrigerant. A heat transfer from the refrigerant to the heat transfer medium therefore takes place in the condenser. A pump 7 arranged in the heating circuit can generate a desired volume or mass flow of the heat transfer medium. In
An electric heating rod 2 is arranged in the internal unit B, which can function substantially like an electric immersion heater or continuous-flow heater and additionally heats the heat transfer medium as required. A control device 10 (not illustrated in
The internal unit furthermore has a 3-way switching valve 9 at which the feed from the heat pump branches off into two feed lines VL1, VL2. The first feed line VL1 can lead for example into a heating circuit of a heating system (room heating). The second feed line VL2 can be used for example as a hot water line (drinking water heating). Depending on requirements, the ratio of the volume or mass flow of the heat transfer medium between the first feed VL1 and the second feed VL2 can be set via the 3-way switching valve 9.
Via a return RL, the heat transfer medium flows out of the heating system or drinking water lines of the building back to the heat pump 1. The circulation of the refrigerant between the condenser 6 and the evaporator 4 is also referred to as a primary circuit or generator circuit. The circulation of the heat transfer medium with feed and return is also referred to as a secondary circuit or consumer circuit.
In contrast to the air-water heat pump from
A pump or fan 7 draws in outside air or fresh air. The fresh air flows via a heat exchanger W. A complete decoupling of the volume flows of fresh air and room air can hereby be achieved, so that no outside air enters the building. However, the heat exchanger W can also be designed such that room air and outside air are mixed, or that fresh outside air is used directly as supply air for rooms 11, 12.
In particular, a heat transfer from warm exhaust air from a room 11, 12 to fresh outside air takes place at the heat exchanger W. Heat remaining in the exhaust air can be used at the evaporator to heat the refrigerant of the heat pump 2. A heat transfer from the refrigerant to the supply air in the ventilation duct (feed duct) takes place at the condenser 6. An additional heating of the supply air can take place at the heating register 2. The shown arrangement of the heating register 2 in the supply air duct (feed duct), wherein the heating register 2 is connected downstream of the heat exchanger W, is referred to as a reheating register. In addition, a preheating register can be arranged upstream of the heat exchanger W in the supply air duct for outside air, which preheating register can be used to prevent icing of the heat exchanger W.
A further fan 7 is arranged in a ventilation duct or return duct and generates an air flow for discharging exhaust air from a room 11, 12. The exhaust air flows through the heat exchanger W and can transfer heat to the drawn-in outside air. Depending on the design of the heat exchanger W, the exhaust air can be discharged directly to the outside as exhaust air, wherein it flows via the evaporator 4.
A division of the heat pump 1 into external unit and internal unit is not illustrated in
The control device 10 is communicatively connected to a server 20 and a cloud 30 via a network 40. In addition, at least one terminal T, for example a smartphone or a laptop or another device, can be communicatively connected to server 20, cloud 30 and control device 10 via the network 40. For communication via the network 40, the control device 10, the server 20, the cloud 30 and the terminal T each have suitable communication interfaces, the details of which will not be described in more detail.
The heat pump 1 with feed ducts VL1, VL2 and return duct RL and the consumers 11, 12, the control device 10, the server 20, the cloud 30, the network 40, the terminal T and the outside temperature sensor 13 belong to the ventilation system 100, wherein not all components are essential for the operation of the ventilation system 100. For example, the outside temperature can also be transmitted from the server 20 via the network 40 to the control device 10 instead of from an outside temperature sensor 13.
The server 20 and/or the cloud 30 are used as a memory and/or computing device for storing and evaluating data which are acquired and transmitted by the control device 10. In particular, the control device 10 acquires and transmits operating parameters of the heat pump 1 including an operating time and a power consumption of the heating register 2. Furthermore, the control device 10 can receive control parameters from the server 20 or the cloud 30, with the result that a control intervention on the operation of the heat pump can take place.
A method according to the invention for operating the heat pump 1 according to the invention in the ventilation system 100 according to the invention is described below with reference to a flowchart illustrated in
In a first step S1, an outside temperature of the building is acquired. In the second step S2, the acquired outside temperature is compared with a predefined limit temperature. The limit temperature can be predefined for example depending on a geographical location at which the heat pump 1 is operated and/or depending on a device type and a design of the heat pump 1. The limit temperature is generally a temperature below the freezing point. For example, the limit temperature can be in a range between −15° C. and −5° C.
If the outside temperature is higher than the limit temperature (YES in step S2), an operating time of the electric heating register 2 and an energy consumed by the heating register 2 are acquired in the next step S3. The acquisition of the operating time and the energy consumption takes place over a set period of time, which can generally be a plurality of hours or for example one day long. In particular, the set period of time can begin with a heating phase early in the morning and can last 24 hours. In the following, a set period of time of one day (24 hours) is assumed by way of example, which begins at 6:00 in the morning. The acquisition can take place continuously over the set period of time at regular time intervals, for example every minute or even several times per minute. Furthermore, the acquired data can be transmitted from the control device 10 via the network 40 to the server 20 and/or the cloud 30.
In particular, in S1, the acquired values of the outside temperature, the operating time of the heating register 2 and the energy consumed by the heating register 2 (or the current power consumption of the heating register 2) can be transmitted from the control device 10 via the network 40 to the cloud 30 and/or the server 20.
If the outside temperature is lower than the limit temperature (NO in step S2), the method returns to step S1. In this case, the operating time and the energy consumption of the heating register 2 are not monitored according to the method according to the invention. Operation of the heating register 2 can be necessary or desired in this case.
In the next step S3, an evaluation of the operating time and the energy consumption takes place in the set period of time. In particular, in this step, the transmitted operating time data points can be integrated over the set period of time in order to calculate the operating time of an entire day. Correspondingly, the energy consumption can be calculated, wherein, for example, individual transmitted data points which indicate an instantaneous power consumption of the heating register 2 are evaluated in order to calculate a total energy consumption of the heating register in the set period of time.
Steps S2 and S3 and the next steps S4, S5 and S6 can be carried out by the control device 10, the server 20 or the cloud 30. In the following steps S4 and S5, the calculated total values of the operating time and of the energy consumption in the set period of time are compared with respective limit values.
In step S4, it is determined whether the operating time exceeds a first limit value in the set period of time. If this is the case (YES in S4), the method continues with step S5. If the first limit value is not exceeded (NO in S4), the daily operating time of the heating register 2 is in the permitted range and the method returns to the first step S1.
In step S5, it is determined whether the energy consumed by the heating register 2 in the set period of time exceeds a second limit value. If this is the case (YES in S5), the method continues with step S6. If the second limit value is not exceeded (NO in S5), the daily consumed energy of the heating register is in the permitted range and the method returns to the first step S1.
In step S6, a message is generated and output. The message can be for example a warning message which indicates that the operating time of the heating register 2 exceeds the first limit value and/or that the energy consumption of the heating register 2 exceeds the second limit value. The message can additionally indicate whether the heating register 2 is currently in operation.
The message or warning message can be output by the control device 10 or by the server 20 or the cloud 30 to a terminal T of a user of the heat pump 1 communicatively connected to the network 40. Additionally or instead, the message can be output via a display device of the control device 10.
It should be noted that the comparisons with the first limit value and the second limit value in steps S4 and S5 depend on one another in the present example. In other words, both the first limit value and the second limit value must be exceeded (YES in S4 AND S5) before the message is generated and output in S6. However, the method according to the invention is not restricted to this. The method can also be carried out such that exceeding only one of the two limit values (YES in S4 OR YES in S5) can be sufficient to generate and output the message in S6.
If the operating time exceeds the first limit value within the set period of time (YES in S4) and/or the energy consumed by the heating register 2 in the set period of time exceeds the second limit value (YES in S5), in step S6 optimised control parameters for the operation of the heat pump 1 and of the heating register 2 can be determined by the server 20 or the cloud 30, and the optimised control parameters can be transmitted via the network 40 to the control device 10 of the heat pump 1.
The features disclosed in the above description, the claims and the drawings can be of importance both individually and in any combination for the implementation of the invention in its various refinements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 133 511.6 | Dec 2021 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/085283 | 12/12/2022 | WO |
