A METHOD OF OPERATING AN HVAC SYSTEM

Abstract

A method of operating an HVAC system that includes a thermal energy source and a thermal energy transfer device, using a flow regulating device arranged to regulate a flow rate of a fluid between the thermal energy source and the thermal energy transfer device, the method including determining a supply temperature of the fluid, determining a return temperature of the fluid, determining the flow rate of the fluid, and regulating the flow rate of the fluid such as to maintain a target temperature difference between the supply temperature and the return temperature, while ensuring that the return temperature is above a minimum return temperature threshold and the flow rate is above an operational flow rate threshold of the thermal energy transfer device.

Claims

1. A method of operating an HVAC system that comprises a thermal energy source and a thermal energy transfer device, using a flow regulating device arranged to regulate a flow rate of a fluid between the thermal energy source and the thermal energy transfer device, the method comprising: determining a supply temperature of the fluid; determining a return temperature of the fluid; determining the flow rate of the fluid; and regulating the flow rate of the fluid such as to maintain a target temperature difference between the supply temperature and the return temperature, while ensuring that: the return temperature is above a minimum return temperature threshold; and the flow rate is above an operational flow rate threshold of the thermal energy transfer device.

2. The method according to claim 1, further comprising increasing the flow rate if the return temperature is equal to or less than a sum of the minimum return temperature threshold and a temperature safety margin.

3. The method according to claim 2, further comprising closing off the flow regulating device such as to prevent the flow of fluid to and/or from the thermal energy source: if the flow regulating device is fully open and the return temperature is equal to or less than the sum of the minimum return temperature threshold and the temperature safety margin; and/or if the flow regulating device is fully open and the flow rate is equal to or less than a sum of the operational flow rate threshold and the flow safety margin; and/or upon detection of a sudden change of the return temperature, indicative of a malfunction/deactivation of the thermal energy transfer device.

4. The method according to claim 3, further comprising transmitting, by the flow regulating device, a turn-off signal to the thermal energy transfer device if the flow regulating device is fully open and the return temperature is equal to or less than the sum of the minimum return temperature threshold and the temperature safety margin.

5. The method according to claim 3, further comprising transmitting, by the flow regulating device, a turn-off signal to the thermal energy transfer device if the flow regulating device is fully open and the flow rate is equal to or less than the sum of the operational flow rate threshold and the flow safety margin.

6. The method according to claim 1, further comprising increasing the flow rate if the flow rate is equal to or less than the sum of the operational flow rate threshold and a flow safety margin.

7. The method according to claim 1, further comprising: receiving, by the flow regulating device, a signal indicative of a thermal energy demand of the thermal energy transfer device; and regulating the flow rate of the fluid further as a function of the thermal energy demand.

8. The method according to claim 7, further comprising increasing the flow rate at one or more predetermined time intervals, in the presence of thermal energy demand.

9. The method according to claim 1, wherein regulating the flow rate of the fluid such as to maintain a target temperature difference comprises: maintaining a target temperature difference as a function of the supply temperature; or maximizing the temperature difference; or maintain a predefined return temperature range.

10. The method according to claim 1, further comprising: receiving, by the flow regulating device, data indicative of a secondary supply temperature and/or a secondary return temperature of a secondary fluid flowing between the thermal energy transfer device and a thermal energy consumer and regulating the flow rate of the fluid further as a function of the secondary supply temperature and/or the secondary return temperature; and/or receiving, by the flow regulating device, data indicative of an energy consumption of the thermal energy transfer device and regulating the flow rate of the fluid further as a function of the energy consumption of the thermal energy transfer device; and/or receiving, by the flow regulating device, data indicative of one or more internal states(s) of the thermal energy transfer device and regulating the flow rate of the fluid further as a function of the one or more internal states(s) of the thermal energy transfer device.

11. A flow regulating device comprising a valve and/or a damper configured to regulate a flow rate of a fluid between a thermal energy source and a thermal energy transfer device and a processor configured to carry out the method according to claim 1.

12. The flow regulating device according to claim 11, further comprising: a temperature sensor device configured to determine the supply temperature (Ts) of the fluid and a the return temperature of the fluid; and a flow rate sensor device configured to determining the flow rate of the fluid to and/or from the thermal energy source and the thermal energy transfer device.

13. The flow regulating device according to claim 12, wherein the temperature sensor device comprises a first temperature sensor configured to determine the supply temperature of the fluid to the thermal energy source and a second temperature sensor configured to determine the return temperature of the fluid from the thermal energy source.

14. The flow regulating device according to claim 11, further comprising or communicatively connected to a secondary temperature sensor device configured to determine a secondary supply temperature and/or a secondary return temperature of a secondary fluid at a secondary fluid circuit of the thermal energy consumer, the flow regulating device being further configured to determine a thermal energy demand of the thermal energy transfer device based on the secondary supply temperature and/or the secondary return temperature.

15. The flow regulating device according to claim 11, further comprising or communicatively connected to a secondary flow rate sensor device configured to determine a secondary flow rate of a secondary fluid at a secondary fluid circuit of the thermal energy consumer, the flow regulating device being further configured to determine a thermal energy demand of the thermal energy transfer device based on the secondary flow rate.

16. An HVAC system comprising: a thermal energy source; a thermal energy transfer device; and a fluid transportation system comprising: a supply fluid transportation line arranged to transport a fluid from the thermal energy source to the thermal energy transfer device; a return fluid transportation line arranged to transport the fluid from the thermal energy transfer device to the thermal energy source; and a flow regulating device, arranged to regulate a flow rate of the fluid through the fluid transportation system between the thermal energy source and the thermal energy transfer device, wherein the HVAC system is configured to carry out the method according to claim 1.

17. The HVAC system according to claim 16, further comprising a thermal energy consumer fluidly connected with the thermal energy transfer device by a secondary fluid transportation system comprising: a secondary supply fluid transportation line arranged to transport a secondary fluid from the thermal energy transfer device to the thermal energy consumer; and a secondary return fluid transportation line arranged to transport the secondary fluid from the thermal energy consumer to the thermal energy transfer device.

18. The HVAC system according to claim 16, wherein the thermal energy source is configured to supply and/or extract heat to/from the thermal energy transfer device.

19. The HVAC system according to claim 18, wherein the energy transfer device comprises a secondary thermal energy source configured to supplement the thermal energy provided by the thermal energy source.

20. A non-transitory computer readable medium storing thereon instructions which, when executed by a processor of a flow regulating device arranged to regulate a flow rate of a fluid between a thermal energy source and a thermal energy transfer device in an HVAC system, cause the processor of the flow regulating device to carry out the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The herein described disclosure will be more fully understood from the detailed description given herein below and the accompanying drawings which should not be considered limiting to the disclosure described in the appended claims. The drawings which show:

[0044] FIG. 1: a highly schematic block diagram of an embodiment of the HVAC system according to the present disclosure;

[0045] FIG. 2: a highly schematic block diagram of an embodiment of the flow regulating device according to the present disclosure;

[0046] FIG. 3: a highly schematic diagram of an embodiment of the flow regulating device according to the present disclosure, illustrating the installation of the flow regulating device in the fluid transportation system between the thermal energy source and the thermal energy transfer device;

[0047] FIG. 4: a flowchart illustrating steps of an embodiment of the method of operating an HVAC system according to the present disclosure;

[0048] FIG. 5: a flowchart of an embodiment of the method of operating an HVAC system according to the present disclosure, showing substeps of regulating the flow rate of the fluid to maintain a target temperature difference between the supply and return temperatures to/from the thermal energy transfer device;

[0049] FIG. 6: a flowchart of an embodiment of the method of operating an HVAC system according to the present disclosure, showing substeps of a further embodiment of regulating the flow rate of the fluid to maintain a target temperature difference between the supply and return temperatures to/from the thermal energy transfer device; and

[0050] FIG. 7: a flowchart of an embodiment of the method of operating an HVAC system according to the present disclosure, showing substeps of a further embodiment of regulating the flow rate of the fluid to maintain a target temperature difference between the supply and return temperatures to/from the thermal energy transfer device.

DETAILED DESCRIPTION

[0051] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

[0052] FIG. 1 shows a highly schematic block diagram of an embodiment of the HVAC system 1 according to the present disclosure, comprising a thermal energy source 100 and a thermal energy transfer device 200 connected by a fluid transportation system 400. The fluid transportation system 400 comprises a supply fluid transportation line 410 arranged to transport a fluid from the thermal energy source 100 to the thermal energy transfer device 200 and a return fluid transportation line 420 arranged to transport the fluid from the thermal energy transfer device 200 to the thermal energy source 100. A pump/fan 450 may be provided to induce the flow of fluid through the fluid transportation system 400

[0053] The thermal energy source 100 is configured to supply heating and cooling energy to the thermal energy transfer device 200 such as to supply/extract heat to/from the thermal energy transfer device 200. The thermal energy (heating/cooling) is supplied/extracted by means of the fluid flowing through the fluid transportation system 400.

[0054] According to particular embodimentsillustrated on FIG. 1 with dotted lines-the HVAC system 1 comprises a secondary fluid transportation system 500, fluidly connecting the thermal energy transfer device 200 with an energy consumer 300. The secondary fluid transportation system 500 comprises a secondary supply fluid transportation line 510 and a secondary return fluid transportation line 520 for transporting a secondary fluid between the thermal energy transfer device 200 and the thermal energy consumer 300.

[0055] In order to transfer thermal energy (heating/cooling) between the fluid transportation system 400 and the secondary fluid transportation system 500, the thermal energy transfer device 200 comprises a heat exchanger 202, connected to both the fluid transportation system 400 and the secondary fluid transportation system 500 such as to enable thermal transfer therebetween.

[0056] Additionally or alternatively, the thermal energy transfer device 200 comprises a secondary thermal energy source 210 such as a heat pump, a combustion heater, an electric heater or chiller or a combination thereof, configured to supplement the thermal energy provided by the thermal energy source 100.

[0057] FIG. 2 shows a highly schematic block diagram of an embodiment of the flow regulating device 10 according to the present disclosure. The flow regulating device 10 comprises a valve V and/or a damper D configured to regulate the flow rate of the fluid between the thermal energy source 100 and the thermal energy transfer device 200 through the supply fluid transportation line 410 and return fluid transportation line 420 of the fluid transportation system 400. A motor M, in particular an electric motor, is provided to drive the valve V and/or a damper D.

[0058] The flow regulating device 10 further comprises a processing unit 20 configured to operate the HVAC system 1 according to any one of the embodiments of the method disclosed herein. Depending on the embodiment, the processing unit 20 comprises an electronic circuit implemented as programmed processors, including data and program memory, or another programmable logic unit, e.g. an application specific integrated circuit (ASIC).

[0059] Optionally, the flow regulating device 10 further comprises a communication module 26 configured for data communication with a remote computer or external controller, such as a Building Management System BMS. According to embodiments, the communication module of the flow regulating device 10 comprises a radio communication circuit, in particular a Wireless Local Area Network WLAN communication circuit; a Near Field Communication NFC, Ultra Wide Band UWB and/or a Bluetooth Low Energy BLE. According to further embodiments, the communication module of the flow regulating device 10 comprises a wired communication circuit, in particular an Ethernet communication circuit a BACnet, a ModBus and/or an MP-Bus communication circuit.

[0060] Optionally, the flow regulating device 10 further comprises a data store 27 for storing data content comprising configuration data of the flow regulating device 10, and for operationrelated data recorded by the flow regulating device 10.

[0061] The flow regulating device 10, in particular its processing unit 20, motor M, and sensor device(s) 22, 24, is powered by a power supply comprising a power connector and/or an internal energy storage device, such as battery and/or a capacitor. According to particular embodiments, the power connector is connected to the wired communication circuit, the flow regulating device 10 being powered by a data line connection, such as Power over Ethernet POE or Power over Data Line PODL.

[0062] The flow regulating device comprises a flow rate sensor device 24 configured to determining the flow rate of the fluid to and/or from the thermal energy source 100 and the thermal energy transfer device 200 and a temperature sensor device 22 configured to determine a supply temperature Ts of the fluid and a return temperature Tr of the fluid.

[0063] In order to allow operation of the HVAC system 1 in view of the energy demand of the thermal energy transfer device 200, the flow regulating device 10 is communicatively connected to a secondary temperature sensor device 22 configured to determine a secondary supply temperature Ts2 and/or a secondary return temperature Tr2 of the secondary fluid transportation system 500 connecting the thermal energy consumer 300. Furthermore, the flow regulating device 10 is optionally communicatively connected to a secondary flow rate sensor device 24 configured to determine a secondary flow rate 2 of the secondary fluid at the secondary fluid transportation system 500.

[0064] Optionally, according to further embodiments, the flow regulating device 10 is communicatively connected to the thermal energy transfer device 200 using a corresponding interface 28 to receive a signal indicative of a thermal energy demand thereof.

[0065] FIG. 3 shows a highly schematic diagram of an embodiment of the flow regulating device 10, illustrating the installation of the flow regulating device 10 in the fluid transportation system 400 between the thermal energy source 100 and the thermal energy transfer device 200. As shown on this figure, the valve V/damper D of the flow regulating device 10 is arranged on the return fluid transportation line 420 of the fluid transportation system 400. The temperature sensor device 22 comprises a first temperature sensor S1 configured to determine the supply temperature Ts of the fluid to the thermal energy source 100 and a second temperature sensor S2 configured to determine the return temperature Tr of the fluid from the thermal energy source 100.

[0066] According to various embodiments, the flow regulating device 10 may be arranged within a single housing or distributed amongst various housings. In particular, the sensor devices (flow rate sensor device 24, secondary flow rate sensor device 24, the temperature sensor device 22 and/or the secondary temperature sensor device 22) may be arranged in housings separate from the housing accommodating the processing unit 20, the communication module 26, the data store 27 and/or the interface to thermal energy transfer device 28.

[0067] Turning now to FIGS. 4 to 7, embodiments of the method of operating the HVAC system 1 shall be described in detail.

[0068] FIG. 4 shows a flowchart illustrating steps of an embodiment of the method of operating an HVAC system 1 comprising a thermal energy source 100 and a thermal energy transfer device 200. In a first, preparatory step S10, a flow regulating device 10 is arranged between the thermal energy source 100 and the thermal energy transfer device 200 such as to be able to regulate a flow rate of a fluid between the thermal energy source 100 and the thermal energy transfer device 200. According to various embodiments, the flow regulating device 10 regulates the flow rate of the fluid using a valve V/damper D arranged in the supply fluid transportation line 410 and/or the return fluid transportation line 420 of the fluid transportation system 400 connecting the thermal energy source 100 and the thermal energy transfer device 200.

[0069] Thereafter, in steps S20, S30 and S40, supply temperature Ts; return temperature Tr respectively flow rate of the fluid are determined (continuously, pseudo-continuously and/or at intervals during operation of the HVAC system).

[0070] Based on the determined supply temperature Ts; return temperature Tr and flow rate of the fluid, in step S50, the flow rate () of the fluid is controlled such as to maintain a target temperature difference dTt between the supply temperature Ts and the return temperature Tr.

[0071] According to embodiments of the present disclosure, regulating the flow rate () of the fluid such as to maintain a target temperature difference dTt comprises: [0072] Maintaining a target temperature difference dTt as a function of the supply temperature Ts, advantageous in particular in HVAC systems 1 having non-linear thermal energy transfer characteristics. [0073] Maximizing the temperature difference dT, advantageous in particular in HVAC systems 1 wherein minimizing the flow of the fluid is desired, e.g. when the fluid needs to be conveyed over long distances/great differences in elevation and/or in case billing of energy costs is based on volume of supplied fluid. [0074] Maintain a predefined return temperature range, advantageous in particular in HVAC systems 1 where the return temperature should not exceed a set threshold (in addition to ensuring that it is above a minimum return temperature thresholdsee below).

[0075] As shown on the flowchart of FIG. 5, the flow rate () of the fluid is regulated such as to maintain a target temperature difference dTt while ensuringin substep S52 that the return temperature Tr is above a minimum return temperature threshold Trmin and ensuringin substep S54that the flow rate is above an operational flow rate threshold min of the thermal energy transfer device 200. Adherence to these two criteria addresses the aim to ensure that the HVAC system 1 operates optimally, with less interruptions and less prone to errors. Ensuring that the return temperature Tr is above a minimum return temperature threshold Trmin avoids the thermal energy transfer device 200 and/or the fluid transportation system 400 from being damaged due to freezing and/or condensation of the fluid. Ensuring that the flow rate is above an operational flow rate threshold min of the thermal energy transfer device 200 helps avoid unnecessary interruptions in the operation of the HVAC system 1 due to the thermal energy transfer device 200 being forced to shut down due to insufficient flow rate. Furthermore, ensuring that the flow rate is above an operational flow rate threshold min of the thermal energy transfer device 200 prevents unnecessary wear of the thermal energy transfer device 200 due to operation near or below its optimum parameters.

[0076] As illustrated on the flowchart of FIG. 6, in order to prevent the return temperature Tr from dropping below the minimum return temperature threshold Trmin, the method further comprisesin a step S60increasing the flow rate if the return temperature Tr is equal to or less than the sum of the minimum return temperature threshold Trmin and a temperature safety margin Tx. If, despite the flow regulating device 10 being fully open, the return temperature Tr is equal to or less than the sum of the minimum return temperature threshold Trmin and the temperature safety margin Tx, in a step S56, the flow regulating device 10 is closed off, preventing the flow of fluid to and/or from the thermal energy source 100. The flow regulating device 10 is closed off to avoid damage due to the return temperature Tr dropping below the minimum return temperature threshold Trmin. Furthermore, the flow regulating device 10 is closed off, if the flow rate is equal to or less than the sum of the operational flow rate threshold min and the flow safety margin x despite the flow regulating device 10 being fully open.

[0077] Furthermore, if the flow regulating device 10 is fully open and the return temperature Tr is equal to or less than the sum of the minimum return temperature threshold Trmin and the temperature safety margin Tx, in step S58, the flow regulating device 10 transmits a turn-off signal to the thermal energy transfer device 200 to avoid damage due to risk of the return temperature Tr dropping below the minimum return temperature threshold Trmin.

[0078] To avoid the flow rate dropping below the operational flow rate threshold min, in step S60, the flow rate is also increased if the flow rate is equal to or less than the sum of the operational flow rate threshold min and a flow safety margin x. Correspondingly, to avoid damage due to risk of the flow rate below the operational flow rate threshold min, the flow regulating device 10 also transmitsin step S58a turn-off signal to the thermal energy transfer device 200 if the flow regulating device 10 is fully open and the flow rate is equal to or less than the sum of the operational flow rate threshold min and the flow safety margin x.

[0079] As shown on the flowchart of FIG. 7, in order to allow the HVAC system 1 to be operated further as a function of a demand of thermal energy and hence to operate the HVAC system 1 even more efficiently, in step S62, the flow rate is increased at predetermined time interval(s) dt in the presence of thermal energy demand. Hence, if the flow rate has been previously reduced (e.g. to ensure a safe return temperature) or if the flow regulating device 10 has been previously closed off, the flow regulating device 10 makes successive attempts to meet the energy demandwhile meeting the safe conditions of minimum return temperature threshold Trmin and operational flow rate threshold min.

LIST OF REFERENCE NUMERALS

[0080] HVAC system 1 [0081] flow regulating device 10 [0082] temperature sensor device 22 [0083] secondary temperature sensor device 22 [0084] flow rate sensor device 24 [0085] secondary flow rate sensor device 24 [0086] communication module 26 [0087] data store 27 [0088] interface to thermal energy transfer device 28 [0089] thermal energy source 100 [0090] thermal energy transfer device 200 [0091] heat exchanger 202 [0092] secondary thermal energy source 210 [0093] thermal energy consumer 300 [0094] fluid transportation system 400 [0095] pump/fan 450 [0096] supply fluid transportation line 410 [0097] return fluid transportation line 420 [0098] secondary fluid transportation system 500 [0099] secondary supply fluid transportation line 510 [0100] secondary return fluid transportation line 520 [0101] flow rate [0102] secondary flow rate 2 [0103] operational flow rate threshold min [0104] flow safety margin [0105] supply temperature Ts [0106] secondary supply temperature T2s [0107] secondary return temperature T2r [0108] return temperature Tr [0109] target temperature difference dTt [0110] minimum return temperature threshold Trmin [0111] temperature safety margin Tx [0112] secondary supply temperature Ts [0113] secondary return temperature Tr