METHOD AND SYSTEM FOR CONTROLLING A VALVE IN AN HVAC SYSTEM

Abstract

For controlling opening (B2) of a valve in an HVAC system to regulate the fluid flow through a thermal energy exchanger and adjust power transfer of the thermal energy exchanger, a control system sets (S6) a control signal for the valve to different setpoints and records (S1) a plurality of data points. Each data point includes for a certain setpoint operating data values related to the power transfer effectuated by the thermal energy exchanger with the control signal set to the certain setpoint. The control system determines (S2) a fitting curve for the data points and determines (S3) a transformation which transforms the fitting curve into a transformed curve having a given target shape. The control system controls (B2) the opening of the valve by transforming (S5) the setpoint to a transformed setpoint, using the transformation, and setting (S6) the control signal for the valve to the transformed setpoint.

Claims

1. A method of controlling power transfer ({dot over (Q)}) of a thermal energy exchanger of an HVAC system, the method comprising: controlling (B2) by a control system the opening of a valve in the HVAC system to adjust a flow (Φ) of a fluid through the thermal energy exchanger by setting a control signal for the valve responsive to different setpoints (C); recording in the control system a plurality of data points (D*), each of the data points (D) including for a certain setpoint (C.sub.D) operating data values related to the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger with the control signal for the valve set responsive to the certain setpoint (C.sub.D); determining by the control system of a fitting curve (p.sub.F) which fits the plurality of data points (D*); determining by the control system of a transformation which transforms the fitting curve (p.sub.F) into a transformed curve (p.sub.T) having a given target shape; and controlling by the control system the opening of the valve by transforming the setpoint (C.sub.F) to a transformed setpoint (C.sub.T), using the transformation, and setting the control signal for the valve based on the transformed setpoint (C.sub.T).

2. The method of claim 1, wherein determining the transformation comprises the control system determining a linearization transformation which transforms the fitted curve (p.sub.F) into a linearized curve (p.sub.T).

3. The method of claim 1 wherein recording the plurality of data points (D*) comprises the control system determining the operating data values with the control signal for the valve set responsive to the certain setpoint (C.sub.D) and the operating data values including at least one of: the flow (Φ) of the fluid, a temperature difference (ΔT) between an inlet temperature (T.sub.in) of the fluid entering the thermal energy exchanger and an outlet temperature (T.sub.out) of the fluid exiting the thermal energy exchanger, and the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger.

4. Thee method of claim 1, wherein recording the plurality of data points (D*) comprises the control system determining the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger with the control signal for the valve set responsive to the certain setpoint (C.sub.D); wherein determining the fitting curve (p.sub.F) comprises the control system determining a power transfer curve (p.sub.F) which fits the plurality of data points (D*), the power transfer curve (p.sub.F) indicating power transfer ({dot over (Q)}) as a function of setpoint (C); wherein determining the transformation comprises the control system determining a linearization transformation which transforms the power transfer curve (p.sub.F) into a linearized power transfer curve (p.sub.T); and wherein controlling the opening of the valve comprises the control system transforming the setpoint (C.sub.F) to the transformed setpoint (C.sub.T), using the linearization transformation.

5. The method of claim 4, wherein determining the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger comprises the control system measuring the flow (Φ) of the fluid, an inlet temperature (T.sub.in) of the fluid entering the thermal energy exchanger, and an outlet temperature (T.sub.out) of the fluid exiting the thermal energy exchanger.

6. Thee method of claim 1 wherein the control system performs on an ongoing basis the recording of the data points (D*), the determining of the fitting curve (p.sub.F), and the determining of the transformation, for an iterative adjustment of a power transfer characteristics of the thermal energy exchanger in the HVAC system (10).

7. The method of claim 1 wherein the method comprises: the control system performing a learning phase, the learning phase comprising the recording of the data points (D*), the determining of the fitting curve (p.sub.F), and the determining of the transformation; and the control system performing subsequent to the learning phase, while no longer recording at least some operating data values, a regulating phase, the regulating phase comprising the controlling of the opening of the valve by transforming the setpoint (C.sub.F) to a transformed setpoint (C.sub.T), using the transformation determined in the learning phase, and setting the control signal for the valve responsive to the transformed setpoint (C.sub.T).

8. The method of claim 7, wherein the learning phase further comprises connecting at least one measurement device for measuring the operating data values related to the power transfer ({dot over (Q)}.sub.D), prior to the recording of the data points (D*), and disconnecting the measurement device prior to the regulating phase.

9. A control system for controlling power transfer ({dot over (Q)}) of a thermal energy exchanger of an HVAC system, the control system comprising at least one processor configured to: control the opening of a valve in the HVAC system to adjust a flow (Φ) of a fluid through the thermal energy exchanger by setting a control signal for the valve responsive to different setpoints (C); record in the control system a plurality of data points (D*), each of the data points (D) including for a certain setpoint (C.sub.D) operating data values related to the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger with the control signal for the valve set responsive to the certain setpoint (C.sub.D); determine a fitting curve (p.sub.F) which fits the plurality of data points (D*); determine a transformation which transforms the fitting curve (p.sub.F) into a transformed curve (p.sub.r) having a given target shape; and control the opening of the valve by transforming the setpoint (C.sub.F) to a transformed setpoint (C.sub.T), using the transformation, and setting the control signal for the valve based on the transformed setpoint (C.sub.T).

10. The control system of claim 9, wherein the processor is further configured to determine the transformation by determining a linearization transformation which transforms the fitted curve (p.sub.F) into a linearized curve (p.sub.T).

11. The control system (40) of claim 9, wherein the processor is further configured to record the plurality of data points (D) by determining the operating data values with the control signal for the valve set responsive to the certain setpoint (C.sub.D) and the operating data values including at least one of: the flow (Φ) of the fluid, a temperature difference (ΔT) between an inlet temperature (T.sub.in) of the fluid entering the thermal energy exchanger and an outlet temperature (T.sub.out) of the fluid exiting the thermal energy exchanger, and the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger.

12. The control system of claim 11, wherein the processor is further configured: to record the plurality of data points (D*) by determining the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger with the control signal for the valve set responsive to the certain setpoint (C.sub.D); to determine the fitting curve (p.sub.F) by determining a power transfer curve (p.sub.F) which fits the plurality of data points (D*), the power transfer curve (p.sub.F) indicating power transfer ({dot over (Q)}) as a function of setpoint (C); to determine the transformation by determining a linearization transformation which transforms the power transfer curve (p.sub.F) into a linearized power transfer curve (p.sub.T); and to control the opening of the valve by transforming the setpoint (C.sub.F) to the transformed setpoint (C.sub.T), using the linearization transformation.

13. The control system of claim 12, wherein the processor is further configured to determine the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger by measuring the flow (Φ) of the fluid, an inlet temperature (T.sub.in) of the fluid entering the thermal energy exchanger, and an outlet temperature (T.sub.out) of the fluid exiting the thermal energy exchanger.

14. The control system (40) of claim 9, wherein the processor is further configured to record the data points (D*), determine the fitting curve (p.sub.F), and determine the transformation on an ongoing basis, for an iterative adjustment of a power transfer characteristics of the thermal energy exchanger in the HVAC system.

15. The control system (40) of claim 9, wherein the processor is further configured: to perform a learning phase, the learning phase comprising the processor recording the data points (D*), determining the fitting curve (p.sub.F), and determining the transformation; and to perform a regulating phase subsequent to the learning phase, while no longer recording at least some operating data values, the regulating phase comprising the processor controlling the opening of the valve by transforming the setpoint (C.sub.F) to a transformed setpoint (C.sub.T), using the transformation determined in the learning phase, and setting the control signal for the valve to the transformed setpoint (C.sub.T).

16. The control system of claim 15, wherein the processor is further configured to perform the learning phase by connecting at least one measurement device for measuring the operating data values related to the power transfer ({dot over (Q)}.sub.D), prior to recording the data points (D*), and disconnecting the measurement device prior to performing the regulating phase.

17. A computer program product comprising a non-transient computer-readable medium having stored thereon computer program code configured to control a processor of a control system for controlling power transfer ({dot over (Q)}) of a thermal energy exchanger of an HVAC system, the computer program code configured to control the processor such that the processor performs the following steps: controlling the opening of a valve in the HVAC system to adjust a flow (Φ) of a fluid through the thermal energy exchanger by setting a control signal for the valve responsive to different setpoints (C); recording a plurality of data points (D*), each of the data points (D) including for a certain setpoint (C.sub.D) operating data values related to the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger with the control signal for the valve set responsive to the certain setpoint (C.sub.D); determining a fitting curve (p.sub.F) which fits the plurality of data points (D*); determining a transformation which transforms the fitting curve (p.sub.F) into a transformed curve (p.sub.T) having a given target shape; and controlling the opening of the valve by transforming the setpoint (C.sub.F) to a transformed setpoint (C.sub.T), using the transformation, and setting the control signal for the valve based on the transformed setpoint (C.sub.T).

18. The computer program product of claim 17, wherein the computer program code is further configured to control the processor such that the processor determines the transformation by determining a linearization transformation which transforms the fitted curve (p.sub.F) into a linearized curve (p.sub.T).

19. The computer program product of claim 17, wherein the computer program code is further configured to control the processor such that the recording of the plurality of data points (D*) comprises the processor determining the operating data values with the control signal for the valve set responsive to the certain setpoint (C.sub.D) and the operating data values including at least one of: the flow (Φ) of the fluid, a temperature difference (ΔT) between an inlet temperature (T.sub.in) of the fluid entering the thermal energy exchanger and an outlet temperature (T.sub.out) of the fluid exiting the thermal energy exchanger, and the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger.

20. The computer program product of claim 17, wherein the computer program code is further configured to control the processor such that: the recording the plurality of data points (D*) comprises the control system determining the power transfer ({dot over (Q)}.sub.D) effectuated by the thermal energy exchanger with the control signal for the valve set responsive to the certain setpoint (C.sub.D); the determining the fitting curve (p.sub.F) comprises the control system determining a power transfer curve (p.sub.F) which fits the plurality of data points (D*), the power transfer curve (p.sub.F) indicating power transfer ({dot over (Q)}) as a function of setpoint (C); the determining the transformation comprises the control system determining a linearization transformation which transforms the power transfer curve (p.sub.F) into a linearized power transfer curve (p.sub.T); and the controlling the opening of the valve comprises the control system transforming the setpoint (C.sub.F) to the transformed setpoint (C.sub.T), using the linearization transformation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be explained in more detail, by way of example, with reference to the drawings in which:

[0026] FIG. 1: shows a block diagram illustrating schematically an HVAC system, comprising a thermal energy exchanger and a thermal transfer fluid transport system with a flow regulator system.

[0027] FIG. 2: shows a block diagram illustrating schematically an HVAC system connected via a communication network to a remote computer system.

[0028] FIG. 3: shows a block diagram illustrating schematically an HVAC system comprising a controller that is connected via a communication network to a local computer system.

[0029] FIG. 4: shows a block diagram illustrating schematically an HVAC system comprising a computer system with a controller.

[0030] FIGS. 5 and 5a: show graphs illustrating a plurality of data points, each data point indicating for a certain setpoint operating data values, related to the power transfer effectuated by the thermal energy exchanger, a fitting curve which fits the data points, and a transformed curve having a target shape.

[0031] FIG. 6: shows a flow diagram illustrating an exemplary sequence of steps for determining a transformation for transforming a fitting curve to a transformed curve having a target shape, and for controlling the power transfer of a thermal energy exchanger of an HVAC system by setting the control signal for a valve based on a transformed setpoint which is obtained through the transformation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] In FIGS. 1-4, reference numeral 10 refers to an HVAC system (Heating, Ventilation, Air Conditioning, and Cooling). As illustrated in FIG. 1, the HVAC system 10 comprises a thermal energy exchanger 1, e.g. a heat exchanger for heating or a cooling device for cooling. As further illustrated in FIG. 1, the HVAC system 10 comprises a fluid transport system 2 for moving a (thermal transfer) fluid, e.g. water or a refrigerant, through the thermal energy exchanger 1. As indicated schematically in FIG. 1, the fluid transport system 2 comprises fluid transport lines 200 (conduits, pipes), for conducting a flow of fluid through the thermal energy exchanger 1, a flow regulator system 20 and a pump 25, for driving and controlling the flow of the fluid through the thermal energy exchanger 1. As further illustrated in FIG. 1, the flow regulator system 20 comprises a (motorized) valve 21 with an actuator 24, a controller 22, and a flow sensor 23. The HVAC system 10 further comprises a temperature sensor 11, for determining the temperature of the fluid entering the thermal energy exchanger 1, and a temperature sensor 12 for determining the temperature of the fluid exiting the thermal energy exchanger 1. The sensors further comprise a communication module configured for wireless and/or wired data communication with the computer system 4 and/or the controller 22.

[0033] As illustrated in FIGS. 1-4, the HVAC system 10 comprises or is at least connected via a communication network 5 to a computer system 4. Depending on the embodiment, the computer system 4 comprises one or more operational computers with one or more programmable processors and a data storage system connected to the processor(s). As indicated schematically in FIGS. 1 and 4 by reference numeral 40, the computer system 4 and the controller 22 constitute a control system, particularly a computerized HVAC control system. In the embodiment of FIG. 2, the HVAC system 10 and one or more of its controllers 22 are connected via communication network 5 to a remote computer system 4, e.g. a cloud-based computer system connected to the HVAC system 10 via the Internet. In the embodiment of FIG. 3, the computer system 4 is a part of the HVAC system 10 and is connected via a communication network 5, such as a LAN (Local Area Network) or WLAN (Wireless Local Area Network), to one or more controllers 22 of the HVAC system 10. In the embodiment of FIG. 4, the computer system 4 is a part of the HVAC system 10 and the controller 22 is part of the computer system 4 or the controller 22 constitutes the computer system 4, respectively. The controller 22 includes an electronic circuit, e.g. a programmable processor, an application specific integrated circuit (ASIC), or another logic unit. The controller 22 further comprises a communication module configured for wireless and/or wired data communication with the computer system 4, the temperature sensors 11, 12, the flow sensor 23, and the valve 21 or its actuator, respectively, to control the flow of fluid. The controller 22 and the computer system 4 are configured (programmed) to perform various functions described later in more detail. Depending on the embodiment the communication network 5 includes fixed communication networks or busses and/or mobile communication networks, e.g. WLAN, GSM (Global System for Mobile Communications), UMTS (Universal Mobile Telephone System), or other mobile radio networks.

[0034] The controller 22 is configured to control the opening of the valve 21 in response to a setpoint C received from a building control system or a user terminal, for example, for adjusting the flow Φ of the fluid through the thermal energy exchanger 1. For that purpose the controller 22 generates a control signal for the valve 21 or its actuator 24, respectively, based and depending on the received setpoint C. Depending on a selected or set control mode, the controller 22 generates the control signal using one or more operating data values related to the power transfer {dot over (Q)}.sub.D effectuated by the thermal energy exchanger 1 23 to obtain the target defined by the received setpoint C. For example, in a flow based control mode, illustrated in FIG. 5, the controller 22 generates the control signal using the current flow Φ measured by the flow sensor 23 to obtain the target defined by the received setpoint C. In an energy or power based control mode, the controller 22 generates the control signal further using the temperature of the fluid entering the thermal energy exchanger 1 and the temperature of the fluid exiting the thermal energy exchanger 1 measured by the temperature sensors 11 and 12, respectively, in addition to the current flow Φ to obtain the target defined by the received setpoint C. In a position based control mode, illustrated in FIG. 5a and executed, for example, if the flow sensor 23 is defective or not available, the controller 22 generates the control signal using the current valve position of the valve 21, as provided by the valve 21 or actuator 24, for example, to obtain the target defined by the received setpoint C.

[0035] In the following paragraphs, described with reference to FIG. 6 are possible sequences of steps performed by the control system 40, the computer system 4, and/or controller 22, respectively, for controlling the power transfer {dot over (Q)} of the thermal energy exchanger 1 by adjusting the opening (i.e. the orifice) of the valve 21 to regulate the flow Φ of the fluid through the thermal energy exchanger 1, responsive to a received setpoint C.

[0036] Block B1 relates to a learning phase and comprises steps S1, S2, and S3 for determining a transformation for transforming a fitting curve p.sub.F to a transformed curve p.sub.T with a target shape, e.g. as illustrated in FIGS. 5 and 5a a linearization transformation for transforming the fitting curve p.sub.F to a transformed curve p.sub.T with a linear shape, i.e. a linearized curve p.sub.T. Block B2 relates to a regulating phase and comprises steps S4, S5, and S6 for controlling the power transfer {dot over (Q)} of the thermal energy exchanger 1 by adjusting the opening of the valve 21 by setting the control signal for the valve 21 based on a transformed setpoint C.sub.T, in adherence with the determined transformation, as will be described below in more detail.

[0037] In step S1, the control system 40, i.e. the computer system 4 or the controller 22, respectively, records a plurality of data points D*. Each data point D of the plurality of data points D* is related to the power transfer {dot over (Q)}.sub.D effectuated by the thermal energy exchanger 1 with the control signal for the valve 21 set responsive to a certain setpoint C.sub.D, as illustrated schematically in FIGS. 5 and 5a. Specifically, each data point D includes a setpoint C.sub.D and measured operating data values related to the power transfer {dot over (Q)}.sub.D={dot over (Q)}(C.sub.D) effectuated by the thermal energy exchanger 1 when the control signal for the valve 21 is set in response and adherence to the respective setpoint C.sub.D. Depending on the embodiment and/or configuration, the operating data values related to the effectuated power transfer {dot over (Q)}.sub.D which are recorded with a data point D include the flow Φ of the fluid, the temperature difference ΔT between the current inlet temperature Tin of the fluid entering the thermal energy exchanger 1 and the current outlet temperature Tout of the fluid exiting the thermal energy exchanger 1, the actual power transfer {dot over (Q)}.sub.D effectuated by the thermal energy exchanger 1, and/or the current position of the valve 21 or its actuator 24, respectively.

[0038] Depending on the embodiment or configuration, the (measured) operating data values for the data points D* are read from sensors, e.g. flow sensor 23, temperature sensor 11, and temperature sensor 12, by the computer system 4 or the controller 22, or reported by the sensors to the computer system 4 or the controller 22. Alternatively, the operating data values are collected by the controller 22 and later reported to the computer system 4. Any data point D*, D represents operating data values measured by the control system 40 at a particular point in time (time stamp).

[0039] In step S2, the control system 40, i.e. the computer system 4 or the controller 22, respectively, determines a fitting curve p.sub.F which fits the plurality of data points D* recorded in step S1. The fitting curve p.sub.F. has a best fit with the plurality of data points D*, as illustrated schematically in FIGS. 5 and 5a. In an embodiment, the fitting curve p.sub.F, is a power transfer curve p.sub.F which fits the plurality of data points D* and indicates the power transfer {dot over (Q)}=p.sub.F(C) as a function of setpoint C. The fitting curve p.sub.F, is determined from the plurality of data points D* using a spline or polynomial method, for example, which are well known to the person skilled in the art.

[0040] In step S3, the control system 40, i.e. the computer system 4 or the controller 22, respectively, determines a transformation which transforms the fitting curve p.sub.F into a transformed curve p.sub.r having a given target shape. In an embodiment, the target shape is a linear target shape, and the transformation is a linearization transformation which transforms the fitting curve p.sub.F into a linearized curve p.sub.r. In an embodiment the linearization transformation transforms the power transfer curve p.sub.F into a linearized power transfer curve p.sub.r. One skilled in the art will understand, that any other target shape of the transformed curve p.sub.T can be obtained through a respective transformation of the fitting curve p.sub.F. As illustrated in FIGS. 5, 5a, through the transformation, any point F on the fitting curve p.sub.F , resulting in an energy transfer {dot over (Q)}.sub.F =p.sub.F(C.sub.F) at setpoint C.sub.F, is mapped to a corresponding point F.sub.T on the transformed curve p.sub.T, such that the energy transfer {dot over (Q)}.sub.Tp.sub.T(C.sub.F), obtained with the setpoint C.sub.F on the transformed curve p.sub.T, is equal to the energy transfer {dot over (Q)}.sub.T=p.sub.F(C.sub.T), obtained on the fitting curve p.sub.F with a transformed setpoint C.sub.T. In other words, a transformation of the fitting curve p.sub.F into the transformed curve p.sub.T is achieved by transforming a setpoint C.sub.F into a transformed setpoint C.sub.T=T(C.sub.F) such that the energy transfer {dot over (Q)}.sub.T=p.sub.T(C.sub.F), obtained with the setpoint C.sub.F on the transformed curve p.sub.T, is equal to the energy transfer {dot over (Q)}.sub.T=p.sub.F(C.sub.T), obtained on the fitting curve p.sub.F with the transformed setpoint C.sub.T:

Q.sub.T=p.sub.T(C.sub.F)=p.sub.F(C.sub.T)

C.sub.T=T(C.sub.F)=p.sub.F.sup.−1(p.sub.T(C.sub.F))

Whereby p.sub.F.sup.−1({dot over (Q)}.sub.F)=C.sub.F is an inverse function which determines the setpoint C.sub.F required to obtain a given energy transfer {dot over (Q)}.sub.F on the fitting curve p.sub.F. In plain words, the transformed setpoint C.sub.T of a given setpoint C.sub.F is obtained by determining the energy transfer {dot over (Q)}.sub.T=p.sub.T(C.sub.F) for the given setpoint C.sub.F using the transformed curve P.sub.T, and then determining the setpoint required to achieve the same energy transfer {dot over (Q)}.sub.T using the fitting curve p.sub.F. In an embodiment, the transformation C.sub.T=T(C.sub.F) is implemented by generating and storing a mapping table which maps any setpoint C.sub.F to a transformed setpoint C.sub.T, for the underlying fitting curve p.sub.F and transformed curve p.sub.T.

[0041] In an embodiment, the control system 40, i.e. the computer system 4 or the controller 22, respectively, performs a normalization step which generates normalized data points and/or a normalized fitting curve. The normalization of the data points D* or the fitting curve p.sub.F is executed using normalization variables which are either data values included in the data points D* or fixed parameter values. Through the normalization step, data redundancy is reduced and data independency is increased. In the present context, the normalization reduces measured operational data of the data points D* to a single function or curve through mathematical transformation of the data.

[0042] As indicated schematically in FIG. 6 by step S10, the control system 40, i.e. the computer system 4 or the controller 22, respectively, performs the steps of the learning phase B1, i.e. the recording of the data points D* and the determining of the fitting curve p.sub.F and transformation C.sub.T=T(C.sub.F), on an ongoing basis, e.g. continuously or periodically. Thereby, the power transfer characteristics {dot over (Q)}(C) of the thermal energy exchanger 1 is adjusted iteratively, making it possible to adapt to (gradual or abrupt) changes in the HVAC system 10 or its environment. One skilled in the art will appreciate, however, that in scenarios with moderate fluctuation of the operating data values in the HVAC system 10, the steps S1, S2, S3 can be executed during a temporarily limited learning phase B1, e.g. using one or more measurement devices with sensors which are connected to the HVAC system 10 only temporarily during the learning phase B1 (“clamp on devices”), for recording the plurality of data points D*, D related to the power transfer {dot over (Q)}.sub.D effectuated by the thermal energy exchanger 1 for a variety of setpoints C.sub.D. Thus, in such a scenario, the steps S4, S5, S6 of the subsequent regulating phase B2 are executed once the learning phase B1 is complete, e.g. when the measurement equipment has been removed and the transformation has been determined. The regulating phase B2 is also executable when the measurement devices and/or its sensors are defective; for example, the position based control mode is executable based on the previously learned fitting curve p.sub.F and transformation C.sub.T=T(C.sub.F).

[0043] In step S4, the control system 40, i.e. the computer system 4 or the controller 22, respectively, receives a setpoint C.sub.F for a targeted power transfer and responsive setting of the control signal of the valve 21, e.g. from a building control system or a user terminal.

[0044] In step S5, the control system 40, i.e. the computer system 4 or the controller 22, s respectively, uses the transformation (determined in the learning phase B1) to calculate a transformed setpoint C.sub.T=T(C.sub.F) from the received setpoint C.sub.F.

[0045] In step S6, the control system 40, i.e. the computer system 4 or the controller 22, respectively, generates the control signal of the valve 21 responsive to and in adherence with the transformed setpoint C.sub.T (e.g. in flow based, power based, energy based, or position based control mode). Consequently, the opening (i.e. the orifice) of the valve 21 is adjusted by its actuator 24 in accordance with the transformed setpoint C.sub.T used to generate the control signal of the valve 21. Accordingly, the power transfer characteristics {dot over (Q)}(C) of the thermal energy exchanger 1 is regulated or transformed, respectively, to a target characteristics {dot over (Q)}(C) having a target shape, e.g. a linear power transfer characteristics {dot over (Q)}(C)=p.sub.T(C).

[0046] As indicated schematically in FIG. 6 by step S20, the control system 40, i.e. the computer system 4 or the controller 22, receives setpoints C or respective commands on an ongoing basis, as submitted by a building control system or a user terminal.

[0047] It should be noted that, in the description, the sequence of the steps has been presented in a specific order, one skilled in the art will understand, however, that the order of at least some of the steps could be altered, without deviating from the scope of the invention.