CN108626924B

CN108626924B - Method for operating a heat pump system

Info

Publication number: CN108626924B
Application number: CN201810220390.1A
Authority: CN
Inventors: 米谷博
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2017-03-24
Filing date: 2018-03-16
Publication date: 2021-03-30
Anticipated expiration: 2038-03-16
Also published as: EP3379158B1; EP3379158A1; CN108626924A

Abstract

Method for operating a heat pump system. The invention relates to a method for operating a heat pump system, wherein the operation of the heat pump is controlled taking into account the operating state of a media mover, such as a fan. An operating state of the media mover is determined based on the measurement of the thermodynamic quantity.

Description

Method for operating a heat pump system

Technical Field

The present invention relates to a method for operating a heat pump system, wherein the operation of the heat pump is controlled taking into account the operating state of a media mover, such as a fan. An operating state of the media mover is determined based on the measurement of the thermodynamic quantity.

Background

In a common heat pump system, the capacity control of the heating/cooling emitter and the control of the heat source are separated. Therefore, the operating state of the emitter is generally unknown to the heat source or heat pump supplying heat to the emitter. In the case of a fan line unit as an example of a transmitter, such a unit has two thermostats, one of which is an air temperature thermostat that measures the room temperature and the other is a water temperature thermostat or, more generally, a heat conveyance medium temperature thermostat that prevents the supply of cold air for heating and hot air for cooling. Furthermore, heat pump systems typically have a room temperature sensor that is spaced some distance from the transmitter and read by the controller of the heat pump system.

The air temperature thermostat operates to activate the fan when the air temperature falls to a lower threshold value and to deactivate the fan when the air temperature rises to an upper threshold value in the case of a heating operation, and vice versa in a cooling operation.

The water temperature thermostat (heat transfer medium temperature thermostat) operates to activate the fan when the water flow temperature or the heat transfer medium flow temperature rises above a threshold in the case of heating and falls below a threshold in the case of cooling.

The heat transfer efficiency of the fan line unit, which is the heat transfer efficiency between the heat conveyance medium and the space to be heated or cooled, is very low when the fan is stopped. This results in an increase in the power consumption of the heat pump.

The energy efficiency of the heat pump is higher at lower temperatures of the water flow temperature or the heat transfer medium flow temperature in the case of heating and at higher temperatures in the case of cooling. When the fan has been stopped, the water flow temperature or the heat transporting medium flow temperature must be raised in the case of heating to supply the same heat supply amount, and the temperature is lowered in the case of cooling to remove the same heat removal amount. This results in a lower energy efficiency of the heat pump.

Generally, because the air temperature thermostat of the fan line unit detects an air temperature closer to the fan line unit, it detects an increase or decrease of the room temperature to a target value earlier than the room thermostat read out by the heat pump controller. Therefore, for example, in the case of heating, when the air temperature thermostat of the fan line unit detects that the room temperature rises to a target value, the room temperature detected by the thermostat of the heat pump (which thermostat is read out by the controller) remains below the threshold for stopping the heat pump. Similarly, in the case of operation to cool a room, the room temperature detected by the thermostat of the heat pump will still be above the threshold for stopping the heat pump.

Hereinafter, the problems of the conventional heat pump system will be described with respect to the heating operation. However, the problem exists in a similar manner for the cooling operation.

Fig. 2 shows the general behavior of a conventionally controlled heat pump system. Fig. 2 shows the room temperature with the passage of time in the first graph, the flow temperature of the heat transportable medium with the passage of time in the second graph, the fan operation with the passage of time in the third graph, and the heat pump operation with the passage of time in the lowest graph. In the uppermost diagram, the upper and lower threshold values for fan operation are represented as dashed lines. Further, the target room temperature is indicated as a dashed line between the upper and lower threshold values of the fan operation. The vertical dashed lines indicate corresponding points in time in the first, second and third graphs.

1. At the beginning, the room temperature rises due to the heating operation. At point 1, the air temperature thermostat detects that the room temperature has reached an upper threshold and stops the fan. However, the heat pump is still running.

2. As the fan is stopped, the room temperature gradually decreases because the heat transfer efficiency of the fan line unit decreases. In response, the controller of the heat pump raises the target stream temperature to increase the heating heat.

3. The room temperature rises again as a result of the increase in the target flow temperature of the heat conveyance medium. However, because the room temperature is always kept above the threshold for restarting the fan, the fan will never restart. Therefore, the heat pump efficiency is permanently lower than in the case of fan operation.

The temperature of the water stream, which provides sufficient heat to maintain room temperature, varies from ambient temperature and the target room temperature. At low heat loads, the target stream temperature may be lower.

Fig. 3 shows a conventional operation behavior of a general water temperature thermostat in a conventional control method. The uppermost graph of fig. 3 shows the room temperature with the passage of time, the middle graph of fig. 3 shows the supply flow temperature of the heat transportable medium with the passage of time, and the lowermost graph shows the fan operation with the passage of time.

1. When the heat load is small, the flow temperature required for supplying sufficient heat is below a threshold value if the fan can remain running.

2. However, due to the above-described control, the fan is never operated, and the controller of the heat pump raises the target flow temperature of the heat conveyance medium to a value (solid line) higher than the temperature (lower broken line) that would be sufficient to supply sufficient heat if the fan was operated. Thus, in the conventional control, the room temperature can be maintained without the fan operating, however, the efficiency of the heat pump is lower than when the fan is operating.

Disclosure of Invention

The problem to be solved by the invention is therefore to improve the efficiency of a heat pump system having a heat pump and a heat emitter with a medium mover, such as a fan, wherein the heat pump and the heat emitter are controlled independently of each other.

The invention relates to a method for operating a heat pump system. The heat pump system may be used for heating or cooling a medium. The inventive concept is applicable to both cases, however, it will be described separately here.

The heat pump system operating in the method according to the invention comprises a heat pump and a heat emitter. The heat emitter comprises a heat exchanger configured to exchange heat between a heat conveyance medium and a medium to be heated. The heat emitter also includes at least one media mover for effecting flow of the media through the heat exchanger. The media mover may be, for example, a fan or an array of fans. However, other suitable means for achieving a flow of the medium to be heated or cooled through the heat exchanger may equally be employed.

Throughout the present invention, the heat conveyance medium may be, for example, water, and the medium to be heated or cooled may be, for example, air in a room to be heated or cooled. The temperature of the medium to be heated or cooled may be, for example, room temperature. If reference is made to a medium, this means a medium that is to be heated or cooled. If a heat transport medium is mentioned, this means a medium flowing between the heat pump and the heat emitter.

In a common heat pump system, the heat pump and the heat emitter are controlled separately. The operation of the media mover is typically stopped when the temperature of the media to be heated, as measured by the thermostat at the transmitter, reaches an upper threshold, which shall be referred to herein as an upper media mover threshold. The operation of the media mover is typically initiated when the temperature of the media to be heated measured at the transmitter reaches a lower threshold, which shall be referred to herein as a lower media mover threshold. Typically, the temperature of the medium upon which the medium mover is stopped or started is measured by a thermostat installed at the heat emitter.

In a common heat pump system, the heat pump is controlled to increase the temperature of the heat conveyance medium if the temperature of the medium to be heated is lower than the target medium temperature. Typically, the temperature upon which the heat pump is controlled is measured by a thermostat that is different from the temperature upon which the media mover is stopped or started.

It should be noted that, in general, the thermostat for measuring the temperature of the medium to be heated on which the control of the heat pump is based is located at a greater distance from the heat emitter than the thermostat for controlling the temperature on which the control for stopping or starting the medium mover is based.

In this case, the heat pump controller is typically unaware of the operational state of the media mover. According to the invention, at least one thermodynamic quantity in the heat pump system is measured in a step referred to herein as a thermodynamic quantity measurement step. According to the invention, the thermodynamic quantity comprises at least one of a measured temperature of the medium to be heated, preferably measured by a thermostat for controlling the heat pump, and/or a measured return temperature of the heat conveyance medium and/or a measured heat of supply.

The measured temperature of the at least one medium to be heated is preferably measured by a temperature sensor on which the control heat pump is based. The temperature may be, for example, the room temperature of the room to be heated.

The return temperature of the heat conveyance medium is typically the temperature that the heat conveyance medium has after flowing out of the heat emitter. The measured heating heat is for example typically the amount of heat exchanged in the heat emitter for a certain amount of time.

The method for operating a heat pump system includes a determination step in which it is determined whether the medium mover is operating based on the thermodynamic quantity measured in the thermodynamic quantity measurement step. In the case where the temperature of the medium to be heated, for example, the room temperature, is lower than the target medium temperature, the heat pump is controlled to stop raising the temperature of the heat transportable medium when it is determined in the determination step that the medium mover is not operating. This will allow the temperature of the media to be heated to reach the lower media mover threshold, causing the media mover to be activated. It is ensured that the heat pump system does not operate permanently in the above-described inefficient state in which the heat pump increases the temperature of the heat conveyance medium while stopping the medium mover. Thus, the efficiency of the heat pump system is improved compared to the prior art.

In an advantageous embodiment of the invention, the measurement of the thermodynamic quantity obtained in the thermodynamic quantity measurement step can be used to determine the rate of change of the thermodynamic quantity over time. The media mover may then be determined to have stopped in the determining step if the thermodynamic quantity decreases at a rate of change over time that is below a first rate of change threshold or increases at a rate of change over time that is above the first rate of change threshold. This embodiment is based on the following understanding: for example, when the fan is stopped, the room temperature is lowered and the heating heat is rapidly reduced, and for example, if the fan is stopped, the return temperature is rapidly increased.

In a preferred embodiment, the rate of change of the thermodynamic quantity over time may be determined based on the results of the thermodynamic quantity measurement step. The media mover may then be determined to be operating in the determining step if the thermodynamic quantity increases at a rate of change over time that is above a second rate of change threshold or decreases at a rate of change over time that is below a second rate of change threshold. This embodiment uses the following understanding: when the media mover is operating, the room temperature rises and the heating heat rapidly increases, while if the media mover is operating, the reflow temperature rapidly decreases.

In a preferred embodiment of the present invention, the temperature of the heat transportable medium may be measured, and the medium mover is controlled not to operate when the temperature of the heat transportable medium is below a transport medium threshold. This step ensures that the heat conveyance medium has a sufficient temperature to actually heat the room when the medium mover is operated. As long as the temperature of the heat conveyance medium is too low, the medium mover should preferably not be operated.

In an advantageous embodiment of the invention, the heat pump may be stopped when it is detected that the medium mover is not operating. Furthermore, the heat pump may be activated when the temperature of the medium to be heated, e.g. the room temperature, reaches a lower threshold value, which will be referred to herein as a lower heat pump threshold value. This avoids the following situation: while the heat pump operates at room temperature high enough, the media mover does not operate.

In a preferred embodiment of the invention, the heat pump may be controlled to lower the temperature of the heat transfer medium if the temperature of the medium to be heated is higher than the target medium temperature. This further increases the efficiency of the heat pump, since the heat supplied by the heat pump is reduced if the temperature of the medium to be heated is already above the target medium temperature.

The invention also relates to a method for operating a heat pump system for cooling a medium. Again, this medium will also be referred to as medium to be cooled. Again, the heat pump system comprises a heat pump and an emitter, also referred to herein as a cooling emitter. The cooling radiator can be technically identical to the heat radiator, however, acting as a heat sink for the surrounding medium to be cooled.

According to the invention, the cooling emitter comprises a heat exchanger for exchanging heat between a heat conveyance medium and a medium to be cooled. The heat conveyance medium may flow between the heat pump and the cooling emitter, preferably in a closed loop.

The cooling radiator according to the invention also comprises at least one medium mover for effecting a flow of the medium to be cooled through the heat exchanger. Any of the matters set forth above with respect to the structure of the heat emitter, the heat conveyance medium and the heat pump are also valid here with respect to the method for cooling the medium.

Common heat pump systems are controlled such that operation of the media mover is stopped when the temperature of the media to be cooled, as measured by the thermostat of the transmitter, reaches a lower media mover threshold. On the other hand, operation of the media mover is initiated when the temperature of the media to be cooled, as measured by the thermostat of the emitter, reaches an upper media mover threshold. Further, in general, if the temperature of the medium to be cooled is higher than the target medium temperature, the heat pump is controlled to lower the temperature of the heat transfer medium.

And, in the case of cooling the medium to be cooled, the thermodynamic quantity in the heat pump system is measured in the thermodynamic quantity measurement step. As in the case of heating, the thermodynamic quantity may be a measured temperature of the medium to be cooled and/or a measured return temperature of the heat conveyance medium and/or a measured heat removal quantity, the measured temperature of the medium to be cooled preferably being measured by the following thermostat: the thermostat is located farther from the transmitter than the thermostat of the transmitter is located from the transmitter.

Based on the measured thermodynamic quantity, it may then be determined in the determining step whether the media mover is operating.

If the temperature of the medium to be cooled is now higher than the target medium temperature, the heat pump according to the invention is controlled to stop reducing the temperature of the heat transfer medium when it is determined in the determining step that the medium mover is not operating. Similarly, as in the case of heating, this would allow the temperature of the media to be cooled to reach the upper media mover threshold, causing the media mover to be activated. Thus, it is avoided that the medium to be cooled is kept below the upper medium mover threshold by excessive operation of the heat pump in case the medium mover is not operated. Thus, the efficiency of the heat pump system is improved.

In a preferred embodiment, the rate of change of the thermodynamic quantity over time may be determined based on the result of the thermodynamic quantity measurement step, and the medium mover may be determined to have stopped in the determination step if the thermodynamic quantity increases at a rate of change over time that is above a first rate of change threshold or decreases at a rate of change over time that is below a first rate of change threshold. It is assumed that the increase or decrease of the thermodynamic quantity is dependent here on the thermodynamic quantity, as in the case of heating. If the media mover is stopped, the temperature of the media to be cooled will increase. On the other hand, if the media mover is not operating, the measured return temperature will drop and the measured amount of heat removed will decrease.

In a preferred embodiment of the present invention, a time-wise rate of change of the thermodynamic quantity measured in the thermodynamic quantity measurement step may be determined, and if the thermodynamic quantity falls at a time-wise rate of change below a second rate of change threshold or rises at a time-wise rate of change above a second rate of change threshold, it may be determined in the determination step that the medium mover is operating. Again, whether the thermodynamic quantity falls or rises while the media mover is operating depends on the thermodynamic quantity selected. While the media mover is operating, the temperature of the media to be cooled will drop. On the other hand, if the medium mover is operating, the measured return temperature of the heat conveyance medium will increase, and the measured heat removal amount will increase.

In an advantageous embodiment, the temperature of the heat transportable medium may be measured and the medium mover is not operated when the temperature of the heat transportable medium is higher than or equal to a transport medium threshold. This ensures that the medium mover operates only when the temperature of the heat conveyance medium is low enough to actually achieve cooling of the medium to be cooled.

In a preferred embodiment of the invention, the heat pump may be stopped upon detection that the media mover is not operating, and may be started when the temperature of the media to be cooled reaches an upper heat pump threshold.

In a preferred embodiment of the invention, the heat pump may be controlled to increase the temperature of the heat conveyance medium if the temperature of the medium to be cooled is lower than the target medium temperature. This further increases the efficiency of the heat pump, since the amount of heat removed by the heat pump is reduced if the temperature of the medium to be cooled is already below the target medium temperature.

In all embodiments of the present invention, it is preferable that the thermodynamic quantity measurement step is repeatedly performed at predetermined time intervals in the heating operation as well as in the cooling operation. This allows the heat pump system to operate continuously with optimized efficiency.

Drawings

In the following, the invention shall be described by way of example with reference to the accompanying drawings. Features illustrated in the examples may also be implemented separately from the examples and may be combined between different examples. Like reference numerals designate identical or corresponding features.

An example configuration of a system in which the method according to the invention may be implemented is shown in fig. 1;

the operational behavior of a prior art method for operating a heat pump system is shown in FIG. 2;

the water temperature thermostat and fan operation behavior of the existing control method is shown in fig. 3;

the operational behavior of an exemplary embodiment of a method for operating a heat pump system according to the present invention is illustrated in fig. 4;

the water temperature thermostat and fan operation behavior of an example embodiment of a method for operating a heat pump system according to the invention is shown in fig. 5;

an example flow chart for calculating the target stream temperature is shown in FIG. 6;

an example dependency between the target stream temperature and the outdoor temperature is shown in fig. 7;

an example process for checking for permission to change the temperature target is shown in FIG. 8; and

different options for detecting whether to stop or run the fan are shown in fig. 9A and 9B.

Detailed Description

Fig. 1 shows an example of a heat pump system adapted to heat or cool a medium, such as air in a room. The heat pump system shown in fig. 1 includes a heat pump 1, and a heat emitter 2a, a heat emitter 2b, and a heat emitter 2 c. The

heat emitters

2a, 2b, 2c are in this example fan line units comprising a heat exchanger for exchanging heat between a heat conveyance medium and a medium to be heated or cooled. The

heat emitters

2a, 2b, 2c are always referred to herein as heat emitters, regardless of whether they transfer heat from the heat conveyance medium to the medium or from the medium to the heat conveyance medium. Furthermore, the

heat emitters

2a, 2b, 2c each comprise at least one medium mover, such as a fan, for effecting a flow of the medium through the heat exchanger. The

fan line units

2a, 2b, and 2c each include an air temperature thermostat 3a, an air temperature thermostat 3b, an air temperature thermostat 3c, and a water temperature thermostat.

The room temperature sensor or room temperature thermostat 4, which is positioned at a greater distance from the heat exchangers of the fan line unit 2a, the fan line unit 2b, the fan line unit 2c than the temperature sensor 3a, the temperature sensor 3b, the temperature sensor 3c, measures the room temperature, which is the temperature of the medium to be heated or cooled.

The heat pump 1 and the fan line unit 2a, the fan line unit 2b, the fan line unit 2c are connected to each other by a heat conveyance medium circuit 5, which heat conveyance medium circuit 5 may be, for example, a water loop.

The heat pump 1 comprises an evaporator 6 and a condenser 7 in case of heating or a condenser 6 and an evaporator 7 in case of cooling. A compressor 9 is provided between the

evaporators

6, 7 and the

condensers

7, 6, and an expansion valve 8 is provided between the

evaporators

6, 7 and the

condensers

7, 6 on the opposite side. An expansion valve 8,

evaporators

6, 7, a compressor 9 and

condensers

7, 6 are provided together in the refrigerant circuit. The condenser or evaporator 7 comprises a heat exchanger for exchanging heat between the refrigerant circuit 10 and the heat conveyance medium circuit 5. In the heat conveyance medium circuit 5, the heat conveyance medium, such as water, flows from the heat exchanger in the element 7 to the fan line unit 2a, the fan line unit 2b, the fan line unit 2c, and from the fan line unit 2a, the fan line unit 2b, the fan line unit 2c back to the heat exchanger in the element 7. The flow of the heat conveyance medium is effected by a circulation pump 11 arranged in the heat conveyance medium circuit 5.

In the example shown in fig. 1, an optional vessel 12 is shown, the contents of which may be heated by a heat transfer medium flowing in line 13 within the vessel 12. The heat conveyance medium may branch off from the heat conveyance medium circuit 5 via a three-way valve 14. The duct for feeding the line 13 in the container 12 bypasses the fan line unit 2a, the fan line unit 2b, the fan line unit 2 c.

The heat conveyance medium circuit 5 comprises a heat conveyance medium temperature sensor 15, which heat conveyance medium temperature sensor 15 is positioned immediately before the inlet to the heat pump 1, whereby the return temperature of the heat conveyance medium can be measured by means of this sensor 15. The example system shown in fig. 1 further comprises a heat conveyance medium sensor 16, by means of which sensor the temperature of the supplied heat conveyance medium leaving the heat pump can be measured, which heat conveyance medium sensor 16 is positioned immediately after the outlet of the heat conveyance medium of the heat pump 1. Optionally, the heat conveyance medium circuit 5 further comprises a flow sensor, which is located in the heat conveyance medium circuit 5, by means of which sensor the flow of the heat conveyance medium can be measured. Such a flow sensor 19 may be used to calculate the amount of heat supplied or removed.

The method for operating the heat pump system is controlled by the controller 17. The controller 17 receives temperature measurements from the room temperature sensor 4, optionally the supply flow temperature sensor 16, the return flow temperature sensor 15, and optionally from an ambient temperature sensor 18 located in the heat pump unit. Optionally, the controller 17 also receives the flow measurement from the flow sensor 19. The controller 17 controls the heat pump unit and the circulation pump 11 based on the measurement results from these sensors.

Fig. 4 shows the operational behavior of the method for operating a heat pump system according to the invention. Fig. 4 shows the behavior of heating a room. In the case of cooling a room, the operation is similar, but with inverted lower and upper thresholds.

The top graph shows air temperature over time, the second graph shows target stream temperature over time, the third graph shows fan operation over time, and the lowest graph shows heat pump operation over time.

At the beginning, the fan and the heat pump are operating, so the air temperature shown in the uppermost figure rises. When the air temperature reaches the target room temperature indicated as the middle dashed line in the uppermost diagram of fig. 4, the controller lowers the target stream temperature as shown in the second diagram. With the fan still operating, the air temperature rises further until the upper media mover threshold, indicated as the uppermost dashed horizontal line in the first graph of FIG. 4, is reached. When the threshold is reached, the fan stops operating as shown in the third diagram. The vertical dashed lines indicate corresponding points in time. In response, the air temperature drops rapidly, which causes an increase in the target stream temperature. However, according to the present invention, it is determined that the fan has stopped based on the behavior of the air temperature. Thus, the increase in the temperature of the heat conveyance medium shown in the second diagram is stopped. This causes the air temperature to drop further until the lower media mover threshold, indicated as the lowest dashed horizontal line in the first graph of fig. 4, is reached. As can be seen in the third graph, an air temperature that reaches the lower medium mover threshold causes the fan to be activated. Therefore, the air temperature or room temperature shown in the first graph starts to increase again, but the target stream temperature has not changed. A rapid rise in air temperature may be detected according to the method of the invention and may indicate that the fan is operating. Then, because the air temperature is still below the target room temperature in fig. 4, the target stream temperature is allowed to change again and increase further at the time indicated by the rightmost vertical dashed line. As soon as the air temperature reaches the target room temperature, the increase of the target stream temperature is stopped and the target stream temperature is maintained constant. The air temperature in the room is further increased, which results in restarting the fan operation. If the air temperature is already above the target room temperature when the fan operation is detected, the target flow temperature is lowered as soon as the target flow temperature is allowed to be changed. As the air temperature reaches the uppermost media mover threshold, the fan is stopped again, and the operating cycle is restarted as described above from the point at which the fan was stopped.

In this example, the heat pump is always operating and the target stream temperature is regulated.

Fig. 5 shows an example of operation where the heat pump may be stopped. The uppermost graph of fig. 5 shows air or room temperature, the second shows supply flow temperature, the third shows fan operation, and the lowest shows heat pump operation.

At the beginning, since the heat pump is operated and the fan is operated in the case of operating with additional heating due to the target stream temperature higher than the supply stream temperature, the room temperature rises as shown in the uppermost diagram, and the heating heat is sufficient to maintain the room temperature to keep the fan running. If the room temperature reaches the threshold for stopping the fan as indicated by the uppermost dotted horizontal line in the first diagram of fig. 5, the fan is stopped at the leftmost vertical dotted line. Therefore, the air temperature rapidly drops between the leftmost vertical dashed line and the second vertical dashed line. A rapid drop in the room temperature indicates according to the invention that the fan has stopped, thus stopping the heat pump operation at the second vertical dashed line.

Therefore, the room temperature further decreases until reaching the lower limit heat pump threshold indicated as the lowermost dotted horizontal line in the first graph of fig. 5. At this time, the heat pump is started. However, since the fan is still stopped, the room temperature does not rise. Thus, the fan is restarted after the supply flow temperature reaches the flow temperature threshold for fan restart. Thus, the room temperature was increased again. When the room temperature reaches the threshold for stopping the fan (the uppermost dashed horizontal line in the first diagram of fig. 5), the cycle starts again.

FIG. 6 illustrates an example flow chart for calculating a target stream temperature. The controller may determine the target stream temperature based on the flow chart shown in fig. 6 at a specific control interval, such as one minute. At the beginning, in step S61, it is checked whether the timer is equal to a permitted check interval that is longer than a control interval in which a change in the thermodynamic quantity can be detected. If the timer is equal to the permission check interval, step S62 is performed, and in step S62, the permission status, which indicates whether the target stream temperature is to be changed, is checked. If step S61 determines that the timer is not equal to the permission check interval, step S62 is bypassed.

It is then checked in step S63 whether or not it is permitted to change the target stream temperature based on the permission status determined in S62. If no change to the target stream temperature is permitted, the method ends and restarts at a later time.

However, if it is permitted to change the target stream temperature in step S63, the target stream temperature is calculated in step S64. The calculation of the target stream temperature may use, for example, the characteristics shown in fig. 7, fig. 7 showing the stream temperature as a function of the outdoor temperature. For this calculation, the target stream temperature may be adjusted to be increased if the air temperature is below the target room temperature, or may be adjusted to be decreased if the air temperature is above the target room temperature. Either one of the above-described first calculation method using variation with outdoor temperature or the above-described second calculation method using variation with deviation between air temperature and target room temperature or a combination method of both calculation methods may be used.

It is then determined in step S65 whether the target stream temperature is below the threshold value of the water temperature thermostat shown in the second diagram of fig. 5.

If so, then step S66 is performed and in step S66 the target stream temperature is set to the threshold value of the water temperature thermostat. If the determination is negative in step S65, the target stream temperature is set to the calculated value in step S67. The flow then ends and may proceed again at a later point in time.

Fig. 8 is a flowchart showing how the permission status of changing the target stream temperature is checked in step S62 in fig. 6. Examples assume that the thermodynamic quantity to be measured is room temperature or the temperature of the medium to be heated or cooled. In a first step S81, the temperature change rate α is calculated as α ═ Δ Ta/Δ Ta, where Δ Ta is the temperature change (e.g., -1 ℃ after the fan is stopped) and Δ Ta is the calculation interval (e.g., 10 minutes).

It is then determined in step S82 whether α is equal to or below a first rate of change threshold (negative in sign, e.g., -0.1 ℃/min). If the situation is affirmative, the change of the target stream temperature is stopped in step S83. If not, it is determined in step S84 whether α is equal to or greater than a second rate of change threshold (positive in sign, e.g., +0.1 deg.C/min). If the situation is positive, the target stream temperature is permitted to be changed in step S85. If the situation is not affirmative, the current permission state is maintained (S86).

In the case of cooling, the positive/negative sign of these thresholds and the inequalities in steps 82 and 84 are reversed.

The determination of whether to stop or operate the fan may be based on different thermodynamic quantities in the heat pump system as measured.

First, as already mentioned above, room temperature may be used as the thermodynamic quantity. The rate of change α in room temperature by time is calculated as Δ Ta/Δ Ta, where Δ Ta is a temperature change (e.g., -1 ℃ after the fan is stopped and +1 ℃ after the fan is restarted), and Δ Ta is a calculation interval (e.g., 10 minutes).

Fig. 9A shows the room temperature with the passage of time. Here, Δ Ta is exemplified by a vertical arrow, and Δ Ta is depicted as a horizontal arrow.

Another thermodynamic quantity that may be used to determine whether the fan has been stopped or running may be the return temperature, which is the temperature of the heat conveyance medium after having passed through the heat emitter. Again, one may consider the rate of change of the return temperature β ═ Δ Tb/Δ Tb, where Δ Tb is the change in the return temperature (e.g., +1 ℃ after fan stop and-1 ℃ after fan restart), and Δ Tb is the calculation interval (e.g., 3 minutes). A graphical representation of this approach is shown at (2) in fig. 9B. If β is used instead of α in fig. 8, the signs of the first and second rate of change thresholds and the inequalities of S82 and S84 are opposite. And in the case of cooling, the positive/negative signs of these thresholds and the direction of the inequalities in steps 82 and 84 are opposite to those in the case of heating.

A further possibility for detecting whether the fan has stopped or is running thermodynamic quantities may be a reduction in the heating heat that occurs if the fan stops. Here, the difference Δ Q of the heating heat amount is calculated as

ΔQ＝Q(t)–Q(t-Δtc)

Q(t)＝ρCp Fw/60*(Tsup–Tret)

Where q (t) is the heating heat (e.g., in kW), ρ is the density of the water, Cp is the specific heat, Fw is the flow rate in L/min, Tsup is the supply stream temperature, Tret is the reflux temperature, and Δ tc is the calculation interval (e.g., 3 minutes). The behavior of the reflow temperature is shown in fig. 9B. The supply stream temperature is depicted as a constant horizontal line. The reflux temperature is lower in the case of heating operation and is depicted as the lower curve in fig. 9B. The decrease in the amount of heat supplied is indicated by arrow (3), and the change in the return temperature described above is indicated by arrow (2), where the horizontal arrow is the calculation interval Δ Tb and the vertical arrow is the temperature change Δ Tb.

Claims

1. A method for operating a heat pump system for heating a medium,

the heat pump system includes a heat pump and a heat emitter,

the heat emitter comprises a heat exchanger for exchanging heat between a heat conveyance medium and a medium to be heated,

the heat emitter further comprising at least one media mover for effecting flow of the medium to be heated through the heat exchanger,

wherein,

stopping operation of the media mover when the temperature of the media to be heated reaches an upper media mover threshold,

initiating operation of the media mover when the temperature of the media to be heated reaches a lower media mover threshold,

controlling the heat pump to increase the temperature of the heat conveyance medium if the temperature of the medium to be heated is lower than a target medium temperature,

wherein in a thermodynamic quantity measuring step at least one thermodynamic quantity in the heat pump system is measured, wherein the thermodynamic quantity comprises at least one of a measured temperature of the medium to be heated and/or a measured return temperature of the heat conveyance medium and/or a measured heat supply quantity,

determining in the determining step whether the media mover is operating based on the thermodynamic quantity,

wherein in a case where the temperature of the medium to be heated is lower than the target medium temperature, the heat pump is controlled to stop increasing the temperature of the heat transportable medium when it is determined in the determining step that the medium mover is not operating.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein a rate of change of the thermodynamic quantity over time is determined, and wherein the medium mover is determined to have stopped in the determining step if the thermodynamic quantity decreases and the rate of change of the thermodynamic quantity over time is below a first rate of change threshold or the thermodynamic quantity increases and the rate of change of the thermodynamic quantity over time is above a first rate of change threshold.

3. The method of any one of claim 1 to claim 2,

wherein a rate of change of the thermodynamic quantity over time is determined, and wherein the medium mover is determined to be operating in the determining step if the thermodynamic quantity increases and the rate of change of the thermodynamic quantity over time is above a second rate of change threshold or the thermodynamic quantity decreases and the rate of change of the thermodynamic quantity over time is below a second rate of change threshold.

4. The method of any one of claim 1 to claim 2,

wherein a temperature of the heat transportable medium is measured and the medium mover is not operated when the temperature of the heat transportable medium is lower than or equal to a transport medium threshold.

5. The method of any one of claim 1 to claim 2,

wherein the heat pump is stopped when it is detected that the media mover is not operating, and wherein the heat pump is started when the temperature of the media to be heated reaches a lower heat pump threshold.

6. The method of any one of claim 1 to claim 2,

wherein if the temperature of the medium to be heated is higher than the target medium temperature, the heat pump is controlled to decrease the temperature of the heat transportable medium.

7. The method of any one of claim 1 to claim 2,

wherein the medium mover is activated when the heat pump is operated and the temperature of the medium to be heated drops.

8. The method of any one of claim 1 to claim 2,

wherein the medium mover is activated when the heat pump is operated and the temperature of the medium to be heated is increased.

9. The method of any one of claim 1 to claim 2,

wherein the thermodynamic quantity measurement step is repeatedly performed at predetermined time intervals.

10. A method for operating a heat pump system for cooling a medium,

the heat pump system includes a heat pump and a cooling radiator,

the cooling radiator comprises a heat exchanger for exchanging heat between a heat conveyance medium and a medium to be cooled,

the cooling radiator further comprising at least one medium mover for effecting flow of the medium to be cooled through the heat exchanger,

wherein,

stopping operation of the media mover when the temperature of the media to be cooled reaches a lower media mover threshold,

initiating operation of the media mover when the temperature of the media to be cooled reaches an upper media mover threshold,

controlling the heat pump to reduce the temperature of the heat conveyance medium if the temperature of the medium to be cooled is higher than a target medium temperature,

wherein in a thermodynamic quantity measurement step at least one thermodynamic quantity in the heat pump system is measured, wherein the thermodynamic quantity comprises at least one of a measured temperature of the medium to be cooled and/or a measured return temperature of the heat conveyance medium and/or a measured heat removal quantity,

wherein, in a case where the temperature of the medium to be cooled is higher than the target medium temperature, the heat pump is controlled to stop decreasing the temperature of the heat transporting medium when it is determined in the determining step that the medium mover is not operating.

11. The method of claim 10, wherein the first and second light sources are selected from the group consisting of,

wherein a rate of change of the thermodynamic quantity over time is determined, and wherein in the determining step, it is determined that the medium mover has stopped if the thermodynamic quantity increases and the rate of change of the thermodynamic quantity over time is above a first rate of change threshold or the thermodynamic quantity decreases and the rate of change of the thermodynamic quantity over time is below a first rate of change threshold.

12. The method of any one of claims 10 to 11,

wherein a rate of change of the thermodynamic quantity over time is determined, and wherein the medium mover is determined to be operating in the determining step if the thermodynamic quantity decreases and the rate of change of the thermodynamic quantity over time is below a second rate of change threshold or the thermodynamic quantity increases and the rate of change of the thermodynamic quantity over time is above a second rate of change threshold.

13. The method of any one of claims 10 to 11,

wherein a temperature of the heat transportable medium is measured and the medium mover is not operated when the temperature of the heat transportable medium is greater than or equal to a transport medium threshold.

14. The method of any one of claims 10 to 11,

wherein the heat pump is stopped when it is detected that the media mover is not operating, and wherein the heat pump is started when the temperature of the media to be cooled reaches an upper heat pump threshold.

15. The method of any one of claims 10 to 11,

wherein the heat pump is controlled to increase the temperature of the heat conveyance medium if the temperature of the medium to be cooled is lower than the target medium temperature.

16. The method of any one of claims 10 to 11,

wherein the medium mover is activated when the heat pump is operating and the temperature of the medium to be cooled is increasing.

17. The method of any one of claims 10 to 11,