WO2019008544A2

WO2019008544A2 - Heating system comprising a plurality of radiant heating panels

Info

Publication number: WO2019008544A2
Application number: PCT/IB2018/054990
Authority: WO
Inventors: Carlo Alberto Zenobi
Original assignee: Carlo Alberto Zenobi
Priority date: 2017-07-07
Filing date: 2018-07-06
Publication date: 2019-01-10
Also published as: WO2019008544A3

Abstract

A heating system comprising a plurality of radiant heating panels (1) and a plurality of room thermostats (21), each of which is associated with a respective heating panel (1) and has a control unit (28) for calculating a reference panel temperature (TPR) as a function of a desired room temperature (TAD). Each heating panel (1) has a front plate (8) which favours thermal radiation, an electric heating film (9) arranged behind and in contact with the front plate (8), a vacuum hollow space (10) arranged behind the electric heating film (9), and a power supply unit (17) for adjusting the supply of power to the heating film (9) as a function of the reference panel temperature (TPR). The heating system (20) has a coordination unit (24) for calculating individual maximum power values (Pmax) of the heating panels (1) as a function of a total maximum power value (PmaxT) that can be used by the heating system (20).

Description

"HEATING SYSTEM COMPRISING A PLURALITY OF RADIANT HEATING

PANELS"

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Italian Patent

Application No. 102017000076910 filed on July 7, 2017 and Italian Patent Application No. 102017000076925 filed on July 7, 2017, the disclosure of which is incorporated by reference .

TECHNICAL FIELD

The present invention relates to a heating system comprising a plurality of radiant heating panels.

In particular, the present invention finds advantageous, but not exclusive, application in the heating of rooms of residential buildings, to which the following description will make explicit reference without thereby losing generality.

BACKGROUND ART

Radiant heating panels, otherwise known as infrared panels, are known, which transmit heat in the environments in which they are placed by using the principle of thermal radiation. A radiant heating panel typically comprises a front face adapted to face the room to be heated, a rear face that can be fixed to a wall of the room, a radiating plate, which defines at least part of said front face and is made of a high-emissivity material, for example metal, so as to favour thermal radiation, and an electric heating film, which is arranged behind the plate and in contact with the latter so as to heat it, and a relatively thick insulating plate arranged between the heating film and the rear face so as to limit the thermal radiation towards the wall.

Despite the presence of the insulating plate, a really large part (up to 40%) of the thermal radiation is dispersed into the wall on which the radiant heating panel is mounted and this is highly undesirable if the wall is an external wall of a building.

A heating system exclusively comprising radiant heating panels normally has a discontinuous consumption with absorption peaks, especially when first ignited after a prolonged shutdown period, such that the rated power of a standard household electrical supply (3 kW) is frequently exceeded, with consequent disconnection of the electric energy meter.

For these reasons, heating systems exclusively based on radiant heating panels have always been considered as not very energy-efficient and by no means suitable to be installed in a normal home that has a standard electricity supply .

DISCLOSURE OF INVENTION

The object of the present invention is to provide a heating system comprising a plurality of radiant heating panels, which system is free from the drawbacks described above and at the same time easy and inexpensive to manufacture. Further object of the present invention is to provide a radiant heating panel for the above-mentioned heating system, which panel has a better energy efficiency and at the same time is easy and inexpensive to manufacture.

In accordance with the present invention, a heating system and a radiant heating panel are provided as defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings, which illustrate a non-limiting embodiment thereof, in which:

- Figures 1 and 2 show a front view and a rear view, respectively, of a radiant heating panel;

- Figure 3 shows a cross-sectional view of the panel in figures 1 and 2 along the plane A-A indicated in Figure 2;

- Figure 4 shows a portion of the cross-section of Figure 3 in greater detail;

- Figure 5 is a schematic view of a heating system comprising a plurality of panels, such as the one illustrated in figures 1 to 4, and a plurality of room thermostats;

- Figure 6 shows a block diagram of each of the room thermostats of the heating system in Figure 5; - Figure 7 shows a block diagram of a power supply and control unit on board the panel of figures 1 to 4;

- Figure 8 shows a block diagram of a coordination unit of the heating system in Figure 5; and

- Figure 9 shows a flow chart relating to part of the operation of the coordination unit of Figure 8.

BEST MODE FOR CARRYING OUT THE INVENTION

In Figures 1 and 2, reference numeral 1 generally designates, as a whole, a radiant heating panel for heating a room (not shown) . The panel 1 comprises a front face 2 adapted to face the room and a rear face 3 that is fixable to any surface of the room, for example that of a wall or a ceiling. On the rear face 3 there is a plurality of supports 4 to facilitate the fixing to the surface of the room.

With reference to figures 1 to 3, the panel comprises a parallelepiped-shaped box-like frame 5 made in one piece and closed on all sides except for a rear opening 6, which extends over most of the rear face 3 and is closed by a plate 7 comprising the supports 4. The rear opening 6 is necessary for the assembly of internal parts of the panel 1 described below .

The front face 2 is completely defined by a plate 8 of the frame 5. The plate 8 is made of a first material exhibiting high emissivity, preferably higher than 0.85, to allow high thermal radiation towards the room. Preferably, said first material is glass or metal, in particular aluminium. Aluminium combines high emissivity with low specific weight.

According to one embodiment, not shown, the frame 5 comprises a front opening which extends over most of the front face 4, and the plate 8 closes said front opening. In this way, it is possible to select a material for the plate 8, which is different from that of the frame 5.

With particular reference to Figure 3, the panel 1 comprises at its inside an electric heating film 9, which is arranged behind the plate 8 and in contact with the latter so as to heat it. The panel 1 also comprises a vacuum hollow space 10, which is arranged between the heating film 9 and the rear face 3. The vacuum hollow space 10 extends parallel to the plate 8 and preferably along an area substantially equal to that of the plate 8. The vacuum hollow space 10 prevents heat transmission by conduction or convection towards the rear face 3, according to the known Dewar principle used, for example, in the so-called Dewar Vessel.

Advantageously, the vacuum hollow space 10 is defined inside a hermetically sealed box-like body 11 arranged between the heating film 9 and the rear face 3. The box-like body 11 is made of a second material having a thermal conductivity of less than 10 W/m K. Advantageously, the second material is glass or polycarbonate. Figure 4 shows, in greater detail, a portion of the cross-section of Figure 3 near a support 4. With reference to figures 3 and 4, the box-like body 11 comprises two walls

12 and 13 parallel to each other and made of the second material, between which the vacuum hollow space 10 is defined. The two walls 12 and 13 are preferably joined by means of a peripheral frame 14 (Figure 3) of the box-like body 11.

With reference to Figure 4, advantageously, the panel 1 comprises a coating 15, which adheres to the inner side of at least the wall 13, i.e. the one closer to the rear face 3, and is made of a third material capable of reflecting thermal radiation. The coating 15 serves to minimize heat transmission by radiation towards the rear face 3. In fact, the vacuum hollow space 10 does not prevent heat transmission by radiation. Preferably, said third material is mirror- polished aluminium with very low roughness. In particular, the coating 15 consists of a polished aluminium sheet.

According to further embodiments, not shown, the coating 15 extends over the inner side of both walls 12 and

13 or extends over the entire inner surface of the vacuum hollow space 10.

With reference to figures 3 and 4, the panel 1 comprises a heat storage panel 16, which is arranged between the vacuum hollow space 10 and the heating film 9. The heat storage panel 16 comprises a Phase Change Material (PCM) to increase the overall thermal inertia of the panel 1. Advantageously, the heat storage panel 16 is in contact, on one side, with the box-like body 11 defining the vacuum hollow space 10 and, on the other side, with the heating film 9.

With reference again to Figure 3, the panel 1 comprises an on-board power supply and control unit 17, which is preferably arranged inside the frame 5, is connectable to an AC electric network (not shown in Figure 4), and is adapted to adjust the supply of power to the heating film 9.

In the example of figures 1-3, the front face 2 has a substantially flat and square shape. However, for the purposes of the present invention, the shape of the front face 2, as well as that of the frame 5, is not limiting and is substantially dictated by aesthetic reasons and by the type of surface (wall or ceiling) to which the panel 1 is to be fixed.

According to embodiments not shown, the box-like frame 5 is structured to be fixed on, or embedded in a floor, or to be used as a tile for flooring or wall coverings.

In Figure 5, reference numeral 20 generally designates, as a whole, a heating system comprising a plurality of panels 1 and a plurality of room thermostats 21, each of which is associated with a respective panel 1. The power supply and control units 17 of the panels 1 are connected to the AC electric network, indicated by the numeral 22, downstream of a normal electric energy meter 23.

The room thermostats 21 are configured to provide the respective panels 1 with parameters for adjusting the power supplied to the respective heating films 10, and the heating system 20 comprises a coordination unit 24 to manage the maximum power that can be used by the various panels 1. Advantageously, the heating system 20 also comprises a power analyser 25 connected immediately downstream of the electric energy meter 23 so as to measure its instantaneous active power PAac, and the coordination unit 24 is configured to manage the maximum power that can be used by the various panels 1 as a function of the measured instantaneous active power PAac.

Each panel 1, each thermostat 21, the coordination unit

24, and the power analyser 25 comprise a respective communication module 26 to allow the coordination unit 24 to communicate with each panel 1, with each thermostat 21, and with the power analyser 25, and each panel 1 to communicate with the respective thermostat 21. Preferably, the communication module 26 is wireless, for example it comprises an ISM frequency band radio frequency transceiver.

With reference to Figure 6, each thermostat 21 comprises a man-machine interface 27 of a known type, for example comprising a liquid crystal display (LCD) and a plurality of keys, to allow a user to set a desired room temperature TAD, and a control unit 28, which comprises a very low consumption microcontroller and is configured to calculate a reference panel temperature TPR as a function of the desired room temperature TAD and transmit the TPR temperature to the power supply and control unit 17 of the respective panel 1 through the respective communication module 26.

Advantageously, each thermostat 21 comprises a temperature sensor 29 for providing a signal indicative of the room temperature to the control unit 28, which processes this signal to obtain a measured room temperature TAM. The control unit 28 is configured to calculate the TPR temperature as a function of the measured temperature TAM and the desired temperature TAD.

Advantageously, each thermostat 21 comprises an energy collecting system 40 comprising one or more photovoltaic cells exposed to the ambient light and coupled to a supercapacitor, also called a supercap. Each thermostat further comprises a primary lithium button battery (not shown) in case of long-term lightless periods.

The power supply and control unit 17 of each panel 1 is adapted to adjust the power supplied to the respective heating film 9 as a function of the TPR temperature.

With particular reference to Figure 7, the power supply and control unit 17 of each panel 1 comprises a control unit 30 comprising a microcontroller, one or more temperature sensors 31, for example consisting of thermistors mounted in contact with the inner surface of the plate 8 for providing signals indicative of the temperature of the plate 8 to the control unit 30, which processes these signals to obtain a measured panel temperature TPM, a power supply connector 32 for connection to the electric network 22, through the electric energy meter 23, and a power stage 33, which is AC powered through the power supply connector 32 and adapted to supply electric power to the heating film 9. The control unit 30 is configured to control the power stage 33 so as to adjust the power supplied to the heating film 9 as a function of the TPR and TPM temperatures.

Preferably, the communication module 26 is integrated into the control unit 30.

The power supply and control unit 17 comprises a safety thermostat 34 circuitally arranged in series between the power stage 33 and the heating film 9 to prevent the latter from reaching such high temperatures as to be dangerous for the user.

The power supply and control unit 17 comprises a power supply unit 35, preferably a flyback power supply unit, which receives AC voltage from the power supply connector 32 and is adapted to deliver DC voltage for supplying power to the electronic devices of the unit 17 itself, such as for example the control unit 30 and the communication module 26. The AC inputs of the power stage 33 and the power supply unit 35 are connected to the power supply connector 32 via a fuse 36.

Furthermore, the power supply and control unit 17 comprises an expansion connector 37, which is directly connected to the power supply connector 34 and can be connected to a similar expansion connector of another panel 1 for electrically connecting several panels 1 to each other.

In accordance with a first embodiment of the power supply and control unit 17, the power stage 33 comprises a static relay, preferably with thyristors, supplied with the AC voltage of the electric network 22, and the control unit 30 is configured to control the static relay according to a Burst Fire mode.

In accordance with a second embodiment of the power supply and control unit 17, the power stage 33 comprises an AC/DC switching converter supplied with the AC voltage of the electric network 22 so as to deliver a PWM modulated output voltage, and the control unit 30 is configured to control the AC/DC switching converter so as to adjust the duty cycle of said output voltage.

With reference to Figure 8, the coordination unit 24 comprises, in addition to the respective communication module 26, a control unit 38 and a second communication module 39, preferably consisting of an Ethernet module or a WIFI module, for communicating with a remote processing and monitoring unit, for example a personal computer, a tablet computer, or a smartphone .

The control unit 38 is configured to calculate individual maximum power values Pmax, each representing the maximum electric power that can be used by a respective panel 1, as a function of a total maximum power value PmaxT, which represents the maximum electric power that can be used by the heating system 20. The control unit 38 is configured to determine the total maximum power value PmaxT as a function of the measured instantaneous active power PAac and of a rated network power PNac associated with the electric energy meter 23.

Figure 9 is a flow chart of a part of the algorithm implemented by the control unit 38, which determines the total maximum power value PmaxT. With reference to Figure 9, the total maximum power value PmaxT is set, and normally kept at a predetermined total rated power value PnomT of the heating system 20 (step 100 of Figure 9), preferably equal to the sum of the rated power values of the panels 1 of the system 20 itself.

The control unit 38 periodically receives the measurements of the instantaneous active power PAac from the power analyser 25 through the corresponding communication modules 26 to check if the PAac power is less than or equal to the rated network power PNac (step 101) . When the instantaneous active power PAac exceeds the rated network power PNac (NO output of step 101) , the deviation ΔΡ of the instantaneous active power PAac relative to the rated network power PNac is then calculated (step 102) and the total maximum power value PmaxT is reduced to a value that is equal to the difference between the total rated power value PnomT and the deviation ΔΡ (step 103) .

The total maximum power value PmaxT remains at the reduced value until the instantaneous active power PAac remains less than or equal to the difference between the rated network power PNac and the deviation ΔΡ (step 104) . When the instantaneous active power PAac exceeds the difference between the rated network power PNac and the deviation ΔΡ, the total maximum power value PmaxT is then returned to the total rated power value PnomT.

The control unit 38 is configured to recalculate the individual maximum power values Pmax each time the total maximum power value PmaxT is changed. Advantageously, the individual maximum value Pmax of each panel 1 is calculated as a function of the total maximum power value PmaxT and of the ratio between the rated power Pnom of the panel 1 and the total rated power value PnomT.

The control unit 38 is configured to control the respective communication module 26 so as to send the individual maximum power values Pmax to the respective panels 1 each time they are recalculated.

With reference again to Figure 7, the control unit 30 of each panel 1 receives the respective individual maximum power value Pmax via the respective communication module 26. The control unit 30 is electrically coupled to the power stage 33 in a known way, so as to measure the electric power absorbed by the power stage 33, and configured to control the power stage 33 so that the absorbed electric power does not exceed the respective individual maximum power value Pmax .

According to one embodiment, not shown, the heating system 20 does not include the power analyser 25, and the control unit 38 of the coordination unit 24 exhibits a simplified operation, i.e. it does not include all those processing steps that are used to change the total maximum power value PmaxT relative to the total rated power value PnomT .

The main advantage of the heating system 20 described above is that of optimizing electricity consumption, thus reducing the likelihood of disconnections of the electric energy meter 23, especially in the embodiment comprising the power analyser 25.

Moreover, the communication module 39 on board the coordination unit 24, and the communication modules 26 on board the various components of the heating system, which provide a communication interface inside the heating system 20, allow the entire heating system 20 to be monitored and configured remotely. For example, the room temperatures TAD can be set on the thermostats 21 via smartphone .

Claims

C L A I M S

1. A heating system comprising a plurality of radiant heating panels (1), each comprising an electric heating film (9) and power supply and control means (17) connectable to an AC electric network (22) and adapted to adjust the supply of power to the electric heating film (9), a plurality of room thermostats (21), each associated with a respective radiant heating panel (1), and being characterized in that each room thermostat (21) comprises first control means (28), which are configured to calculate a reference panel temperature (TPR) as a function of a desired room temperature (TAD) and the power supply and control means (17) of each radiant heating panel (1) are configured to adjust the supply of power to the respective heating film (9) as a function of the reference panel temperature (TPR) ; and in that it comprises a coordination unit (24), which comprises second control means (38) configured to calculate individual maximum power values (Pmax) , each representing the maximum electric power that can be used by a respective radiant heating panel (1), as a function of a total maximum power value (PmaxT) , which represents the electric power that can be used by the heating system (20) .

2. The heating system according to claim 1, wherein each room thermostat (21) comprises first temperature sensor means (29) to acquire a measured room temperature (TAM) and said first control means (28) are configured to calculate said reference panel temperature (TPR) as a function of the measured room temperature (TAM) and of said desired room temperature (TAD) .

3. The heating system according to claim 1 or 2, wherein each radiant heating panel (1) comprises a plate (8), which is in contact with said heating film (9) and adapted to radiate heat, and said power supply and control means (17) of each radiant heating panel (1) comprise second temperature sensor means (31) in contact with said plate (8) so as to obtain a measured panel temperature (TPM) , an AC-supplied power stage (33) to supply electric power to the respective heating film (9), and third control means (30), which are configured to control the power stage (33) as a function of the measured panel temperature (TPM) and of said reference panel temperature (TPR) .

4. The heating system according to any of the claims from 1 to 3, wherein said power supply and control means (17) of each radiant heating panel (1) comprise an AC- supplied power stage (33) to supply electric power to the respective heating film (9) and third control means (30), which are coupled to the power stage (33) so as to measure the electric power absorbed by the power stage (33) and configured to control the power stage (33) in such a way that the absorbed electric power does not exceed the respective individual maximum power value (Pmax) .

5. The heating system according to any of the claims from 1 to 4 and comprising a power analyser (25) , which is connected downstream of an electric energy meter (23) of said AC electric network (22) so as to measure the instantaneous active power (PAac) supplied by the electric energy meter (23); said second control means (38) being configured to determine said total maximum power value (PmaxT) as a function of the measured instantaneous active power (PAac) and of a rated network power (PNac) .

6. The heating system according to claim 5, wherein said coordination unit (24) is configured to normally keep said total maximum power value (PmaxT) at a predetermined total rated power value (PnomT) of the heating system (20) and reduce it to a value that is equal to the difference between the total rated power value (PnomT) and an excess deviation (ΔΡ) of the instantaneous active power (PAac) relative to said rated network power (PNac) , from when the instantaneous active power (PAac) exceeds the rated power (PNac) up to when the instantaneous active power (PAac) remains higher than the difference between the rated network power (PNac) and said excess deviation (ΔΡ) , which is calculated in the moment in which the instantaneous active power (PAac) exceeds the rated power (PNac) .

7. The system according to any of the claims from 1 to 6, wherein said power supply and control means (17) of each radiant heating panel (1) comprise a power stage (33) to supply electric power to the respective heating film (9); the power stage (33) comprising a static relay, preferably with thyristors, which can be supplied with the AC voltage of said electric network (22), and said third control means (30) being configured to control the static relay according to a Burst Fire mode.

8. The system according to any of the claims from 1 to 6, wherein said power supply and control means (17) of each radiant heating panel (1) comprise a power stage (33) to supply electric power to the respective heating film (9); the power stage (33) comprising an AC/DC switching converter, which can be supplied with the AC voltage of said electric network (22) so as to deliver a PWM modulated output voltage, and said third control means (30) being configured to control the AC/DC switching converter so as to adjust the duty cycle of said output voltage.

9. The heating system according to any of the claims from 1 to 8, wherein each radiant heating panel (1), each room thermostat (21) and the coordination unit (24) comprise respective first communication means (26), preferably wireless communication means, to allow the coordination unit (24) to communicate with each radiant heating panel (1) and each room thermostat (21), and each radiant heating panel (1) to communicate with the respective room thermostat (21) .

10. The heating system according to claims 6 and 7, wherein said power analyser (25) comprises respective first communication means (26) to communicate with said coordination unit (24) .

11. The heating system according to any of the claims from 1 to 10, wherein said coordination unit (24) comprises second communication means (39) to communicate with a remote processing and monitoring unit.

12. A radiant heating panel to heat a room, comprising a front face (2) adapted to face the room, a rear face (3) fixable to a surface of said room, a plate (8), which defines at least part of said front face (2) and comprises a first material favouring thermal radiation, an electric heating film (9), which is arranged behind said plate (8) and in contact with the latter so as to heat it, and being characterized in that it comprises a vacuum hollow space (10), which is arranged between the electric heating film (9) and the rear face (3) .

13. The radiant heating panel according to claim 12, wherein said vacuum hollow space (10) extends parallel to said plate (8) and preferably along an area that is substantially equal to that of said plate (8) .

14. The radiant heating panel according to claim 12 or 13 comprising a box-like body (11), which defines said vacuum hollow space (10) and is at least partly made of a second material having a thermal conductivity of less than 10 W/m K.

15. The radiant heating panel according to claim 14, wherein said box-like body (11) comprises two walls (12, 13), which are parallel to one another and made of said second material, and preferably a peripheral frame (14) to join said two walls (12, 13), said vacuum hollow space (10) being defined between said two walls (12, 13) .

16. The radiant heating panel according to claim 15 comprising a coating (15), which adheres to the inner side of at least the one wall (13) of said two walls (12, 13) that is closer to said rear face (3) and is made of a third material capable of reflecting thermal radiation.

17. The radiant heating panel according to any of the claims from 12 to 16 and comprising a heat storage panel (16), which is arranged between said vacuum hollow space (10) and said electric heating film (9) .

18. The radiant heating panel according to claim 17, wherein said heat storage panel (16) comprises a phase change material to increase the thermal inertia of the radiant heating panel (1) .

19. The radiant heating panel according to claim 17 or 18 comprising a box-like body (11), which defines said vacuum hollow space (10) ; said heat storage panel (16) being in contact, on one side, with said box-like body (11) and, on the other side, with said electric heating film (9) .

20. The radiant heating panel according to any of the claims from 12 to 19 comprising power supply and control means (17), which can be connected to an AC electric network (22) and are adapted to adjust the supply of power to said electric heating film (9) .

21. A heating system comprising at least one radiant heating panel (1) according to claim 20, at least one room thermostat (21), which is interfaced with said power supply and control means (17) so as to transmit a temperature reference value (TPR) to them, and a coordination unit (24), which is interfaced so as to communicate with said power supply and control means (17) and with said room thermostat (21) .

22. The heating system according to any one of claims 1 to 11, wherein each panel of said plurality of radiant heating panels (1) is according to any one of claims 12 to 19.