WO2020036487A1

WO2020036487A1 - Heat pump system using thermo-electric element

Info

Publication number: WO2020036487A1
Application number: PCT/NL2019/050528
Authority: WO
Inventors: Gerard Joseph LOUPPEN; Jan Johannes Adrianus MAAT
Original assignee: Ecodynamisch Management B.V.
Priority date: 2018-08-13
Filing date: 2019-08-13
Publication date: 2020-02-20
Also published as: EP3837477A1; NL2021459B1

Abstract

A heat pump system (1) with a primary fluid part (2) having a (low temperature) fluid input connector (3) and a (high temperature) fluid output connector (4), and an array of channels (5) connecting the fluid input connector (3) and the fluid output connector (4). A convertor (6) is present in heat energy transfer connection with the array of channels (5), as well as a heat sink (7) in heat energy transfer connection with the convertor (6). A thermo-electric heat transfer element (8) is positioned between the heat sink (7) and the convertor (6). The heat pump system (1) can be utilized in a central heating system and/or for hot tap water supply.

Description

Heat pump system using thermo-electric element Field of the invention

The present invention relates to a heat pump system, more specifically a heat pump system useable in a central heating system and/or a hot tap water supply system.

Background art

US patent publication US2018/0080689 disclosed thermo-electric heat pump systems, especially suited for use in a container for storing or transporting temperature sensitive goods. A stack of Peltier elements is in thermal connection with a capacitance spacer block (used as heat sink) and controls temperature of a storage area.

Summary of the invention

The present invention seeks to provide a heat pump system with a high efficiency, especially when used to heat up water in a fluid circuit of a central heating system or a hot tap water supply system.

According to the present invention, a heat pump system is provided comprising a primary fluid part having a fluid input connector and a fluid output connector, and an array of channels connecting the fluid input connector and the fluid output connector, a convertor in heat energy transfer connection with the array of channels, a heat sink in heat energy transfer connection with the convertor, further comprising a thermo-electric heat transfer element positioned between the heat sink and the convertor. This provides a very efficient heat transfer mechanism during operation to a fluid flowing in the primary fluid part.

Short description of drawings

The present invention will be discussed in more detail below, with reference to the attached drawings, in which

Fig. 1 shows a perspective view of an exemplary embodiment of the heat pump system according to the present invention embodiment;

Fig. 2 shows a cross sectional view of the heat pump system embodiment shown in Fig. 1 along the lines ll-ll;

Fig. 3 shows a cross sectional view of an alternative embodiment of the heat pump system shown in Fig. 2;

Fig. 4 shows a block diagram of an exemplary embodiment of a control unit operatively powering components of the heat pump system;

Fig. 5 shows a perspective view of a further exemplary embodiment of the heat pump system according to the present invention;

Fig. 6 shows an exploded view of three adjacent converters as applied in the embodiment of Fig. 5; and

Fig. 7 shows a perspective view of a cross section through a converter according to a specific exemplary embodiment. Description of embodiments

The present invention embodiments provide for an efficient system for providing a heated medium which can e.g. be used for a central heating system or a hot water supply. The present invention embodiments use a combination of components which obviate any moving parts or other components which are susceptible to wear or degradation over time. This allows to provide a heating/cooling system for a house, optionally also providing (hot) tap water, which is environmentally friendly, energy efficient, silent during operation, and easy to maintain.

An exemplary embodiment of the present invention heat pump system 1 is shown in the perspective view of Fig. 1 , and Fig. 2 shows a cross sectional view of the heat pump system 1 embodiment shown in Fig. 1 along the lines ll-ll.

The heat pump system 1 as shown in Fig. 1 and 2 comprises a primary fluid part 2 having a (e.g. low temperature) fluid input connector 3 and a (e.g. high temperature) fluid output connector 4, and an array of channels 5 connecting the fluid input connector 3 and the fluid output connector 4. A convertor 6 is present in heat energy transfer connection with the array of channels 5, as well as a heat sink 7 in heat energy transfer connection with the convertor 6. Furthermore, the heat pump system 1 comprises a thermo-electric heat transfer element 8 positioned between the heat sink 7 and the convertor 6. When a fluid source is connected to the fluid input connector 3, the heat pump system 1 can be operated to either cool or heat the fluid in the primary fluid part 2, e.g. for heating a house as part of a central heating system.

The thermo-electric heat transfer element 8 uses the physical effect of thermo-electric cooling (TEC) to displace thermal energy form one of its sides to the other side. Thermo-electric cooling is e.g. implemented as a solid-state method of heat transfer through dissimilar semiconductor materials. Like conventional refrigeration counterparts, thermo-electric cooling systems obey the basic laws of thermodynamics. However, the actual physical phenomenon responsible for cooling is different, i.e. the three main working parts in a thermo-electric refrigeration system are a cold junction, a heat sink, and a DC power source. Two dissimilar semiconductors replace the refrigerant in both liquid and vapour form of a conventional refrigeration system. A cold sink (equivalent to the evaporator surface) becomes cold through absorption of energy by the electrons as they pass from one semiconductor to the other, instead of energy absorption by the refrigerant as it changes from liquid to vapour. A DC power source pumps the electrons from one semiconductor to the other, and the heat sink (equivalent to the condenser surface) discharges the accumulated heat energy from the system. Therefore, the thermo-electric cooling system refrigerates without refrigerant and without the use of mechanical devices. It is noted that the transport of thermal energy can also be used in the‘opposite’ direction, i.e. for heating purposes.

The person skilled in the art will be familiar with the specific types of semiconductor materials and structures to be used for implementation of the thermo-electric heat transfer elements 8 in the embodiments of the present invention heat pump system. One of possible implementations, is wherein the thermo-electric heat transfer element 8 comprises one or more Peltier elements. In an exemplary implementation of a Peltier element, two (ceramic) isolation plates are present with bars of semiconducting material in between and a specific electrical connection scheme between the bars, i.e. oppositely doped and series connected. When a current source is connected, a current will flow, wherein electrons can only pass through the semiconducting material in one direction. As a result energy is transported in one direction as well, wherein the side of the Peltier element where the electrons originate will become colder, and the side to which the electrons move, will become warmer, or in otherwords, heat energy is pumped ortransferred from one side of the Peltier element to the other.

In the exemplary embodiment shown in Fig. 1 and 2, the heat pump system 1 further comprises a secondary fluid part 20 having a secondary fluid input connector 23 and a secondary fluid output connector 24, and a secondary array of channels 25 connecting the secondary fluid input connector 23 and the secondary fluid output connector 24. The convertor 6 is in heat energy transfer connection with the secondary array of channels 25. As an exemplary operational use, the secondary fluid input connector 23 of the secondary fluid part 20 is connected to a tap water source, in order to provide hot tap water from the secondary fluid output connector 24.

The primary and secondary fluid part 2, 20 may be alternatively present, or in combination in embodiments of the heat pump system 1 , depending on the specific required use of the heat pump system 1 . E.g. in a further aspect of the present invention, a central heating system is provided which comprises a heat pump system 1 according to any one of the embodiments described herein, wherein the primary fluid part 2 is connected to a heating fluid circuit, e.g. radiators of a central heating system, or a floor (and/or wall) central heating system). The present invention heat pump system 1 is thus only used for room heating in this embodiment.

The embodiments wherein the secondary fluid part 20 is provided in addition to the primary fluid part 2 can be advantageously applied in a further aspect of the present invention, i.e. a central heating system comprising a heat pump system 1 according to any one of the present invention embodiments, wherein the primary fluid part 2 is connected to a heating fluid circuit, and wherein the secondary fluid part 20 is connected to a hot water supply circuit. In this exemplary embodiment, the heat pump system 1 is used for both room heating and for providing hot tap water.

In an even further aspect of the present invention, a hot water supply system comprising a heat pump system 1 according to any one of the present invention embodiments having a primary fluid part 2 only, wherein the primary fluid part 2 is connected to a hot water supply circuit. In this exemplary embodiment, the heat pump system having a single (primary) fluid part 2 can be used for providing hot tap water.

In the embodiments shown in Fig. 1 and 2, the heat pump system 1 further comprises a second heat sink 7’ in heat energy transfer connection with the convertor 6, and a second thermoelectric heat transfer element 8’ positioned between the second heat sink 7’ and the convertor 6. This mirrored arrangement allows to use a single convertor 6 with the array of channels, and a dual provision of the heat sink 7, 7’ and thermo-electric heat transfer element 8, 8’, resulting in an even further improved efficiency.

The arrangement shown in Fig. 1 and 2 comprises a top cover plate 15, bottom cover plate 16 and two side plates 17, 18, allowing to provide a compact and easy to handle heat pump system I with input and output connections to the primary and secondary fluid parts 2, 20 conveniently located at the front side of the heat pump system 1 .

Also shown in the perspective view of Fig. 1 is that the primary fluid part 2 comprises the primary fluid input connection 3 and primary output fluid connection 4, as well as an input manifold

I I connecting the primary fluid input connection 3 to the array of channels 5, and an output manifold 12 connecting the array of channels 5 to the primary fluid output connection 4. Similarly, the secondary fluid part 20 comprises the secondary fluid input connection 23 and secondary output fluid connection 24, as well as an input manifold 21 connecting the secondary fluid input connection 23 to the secondary array of channels 25, and a secondary output manifold 22 connecting the secondary array of channels 25 to the secondary fluid output connection 24.

Furthermore, in the embodiment shown in Fig. 1 and 2 a tensioning assembly 14 is present for providing tension between the heat sink 7; T and the convertor 6. The tensioning assembly 14 in this embodiment comprises two plates 14, 14’ in contact with the respective heat sinks 7, 7’, and with the respective heat transfer elements 8, 8’, in combination with tensioning attachments 14a and tensioning springs 14b. This allows to effectively compress each stack of heat thermo-electric heat transfer elements 8, 8’ and convertor 6 for good physical contact and thermal energy conduction from the heat sinks 7, 7’ to the array of channels 5 in convertor 6.

The present invention embodiments of the heat pump system 1 have the advantages that no moving parts are present, which enables for a very low noise operation, and also allows for a long life time as almost no wear and tear will arise during operation. The heat pump system 1 is also scalable. As shown in the exemplary embodiment of Fig. 1 and 2, the system has six convertors 6, with associated dual heat transfer elements 8, 8’ on side surfaces thereof, but it will be apparent that fewer or more convertors 6 may be implemented. Similarly, the number of channels in the array of channels 5 (and in the secondary array of channels 25) can vary depending on capacity desired from the exemplary embodiment shown (thirteen channels in the array of channels 5, and six channels in the secondary array of channels 25). Also, the capacity and characteristics of the thermo-electric heat transfer elements 8, 8’, 28 can be selected depending on the actual intended use.

As shown in the embodiment of Fig. 1 and 2, the array of channels 5 comprises a plurality of pipes, e.g. made of copper to obtain a good thermal energy transfer from the convertor 6 to the fluid flowing in the pipes. Other materials with a high thermal energy conductivity may also be used. Alternatively, the array of channels 5 comprises a plurality of elongated bores in the convertor 6. When selecting proper material of the convertor 6, and in combination with proper sealing in the primary fluid part 2, this can provide a very efficient thermal energy transfer. It is noted that the cross section of the array of channels 5 is shown as being circular, but alternative cross sectional shapes may also be provided, including but not limited to ellipse, square, rectangular, triangular, hexagonal. It is noted that similar alternative embodiments may be provided in the secondary fluid part 20 in an analogue manner.

Fig. 7 shows a perspective view of a cross section through a converter 6 according to a specific exemplary embodiment. In this embodiment, the convertor 6 comprises a plurality of meandering channel parts forming the array of channels, allowing to have a larger surface of the channel 5 to be in contact with the convertor 6, and also to have a more turbulent flow of the fluid enhancing heat exchange as well. This embodiment of the convertor 6 may be manufactured as a combination of two halve parts (as shown in the embodiment of Fig. 7), in which the meandering channel 5 is cut our, e.g. using milling or casting techniques using aluminium or copper as base material for the convertor 6. Furthermore, in this embodiment of the converter 6, a predetermined number of raised surfaces 6a are provided, which allow to further enhance heat transfer with directly adjacent elements of the heat pump system 1 .

As shown in Fig. 1 and 2, this embodiment of the heat pump system 1 further comprises a secondary convertor part 26 in heat energy transfer connection with the convertor 6. The secondary convertor part 26 including bores for accommodating the secondary array of channels 25, and is e.g. implemented as a combination of two halve parts 26a, 26b for easy installing. A bottom part 26a can be first attached to the top surface of convertor 6, then the secondary array of channels 25 can be provided (e.g. in the form of pipes between secondary input manifold 21 and secondary output manifold 22, positioned in semicircle grooves of the bottom part 26a, and then a top part 26b can be attached to the bottom part 26a.

With respect to material used for the various components of the heat pump system 1 , various selections can be made in view of trade off of efficiency and costs. E.g. the material of the convertor 6 (and if present secondary convertor part 26) may be copper, but any high thermal conducting material will also be possible, such as silver, gold or aluminium. As mentioned above, the thermal heat transfer elements 8, 8’ can be Peltier elements, of which the major surface area can be matched with the side surfaces of the convertor 6.

In embodiments where both a primary and secondary fluid part 2, 20 are present, the characteristics of both can be adapted depending on the actual use of the heat pump assembly 1 . E.g. if the secondary fluid part 20 is applied to provide hot tap water, and the primary fluid part 2 for central heating, in a further embodiment, an inner diameter of channels of the secondary array of channels 25 is smaller than an inner diameter of channels of the array of channels 5. This will increase flow of fluid within the secondary system, allowing a lower flow speed and thus a higher thermal energy transfer. As an example, the inner diameter of the secondary array of channels 25 is 6 mm (plus 0.5mm wall thickness), and the inner diameter of the (primary) array of channels 5 is 10 mm.

In the cross sectional view of Fig. 3, an alternative embodiment is shown of the heat pump system 1 of Fig. 1 and 2, wherein the secondary fluid part 20 is provided with a separate (secondary) thermo-electric heat transfer element 28. The secondary thermo-electric heat transfer element 28 is provided in heat transfer connection between the convertor 6 and the second array of channels 25. Similar to the embodiment above, the secondary thermo-electric heat transfer element 28 may be implemented as a Peltier element, with appropriate dimensions and characteristics specific for the use to heat up water in the secondary array of channels 25 to high temperatures. E.g. in a further embodiment, a power capacity of the secondary thermo-electric heat transfer element 28 is higher than a power capacity of the thermo-electric heat transfer element 8. The heat pump system 1 may have additional features further enhancing efficiency of the heat pump system, which may be applied in addition to, or as alternative for, some of the features described above with reference to the embodiments shown in Fig. 1 -3.

E.g. multiple sections of fluid parts 2, 20 may be applied, of which the function can be controlled by properly controlling the flow from/to the fluid parts 2, 20 (i.e. array of channels 5, 25), and by properly controlling the associated thermo-electric heat transfer elements 8, 28. In an exemplary embodiment, six fluid parts 2, 20 (sections l-VI) are provided in a symmetric structure. Sections l-ll provide heat for a floor heating system, and sections lll-IV provide heat for warm water supply. The sections V-VI may either provide heat to the floor heating system or to the warm water supply, depending an actual demand. The change in function can e.g. be implemented by reversing the current supply to the associated electro-thermal heat transfer elements 8, 28.

In a further embodiment, the heat pump system 1 further comprises reflection material surrounding the convertor 6. This reflection material may be implemented as a reflecting layer on the inside of the heat pump system 1 , and has the effect that also heat energy generated by the heat transfer element 8 is reflected, and received by the convertor 6 and transferred to the array of channels 5. By separating cold and warm areas in the heat pump system using this reflection material, it is possible to retain energy inside and guide it effectively to the array of channels 5.

The reflection material in a further embodiment comprises one or more layers of polyethylene material (with isolation functionality) with a metal layer (e.g. aluminium) deposited on each of the one or more layers of polyethylene material (having a reflection functionality). The combination of reflection material and isolating layers in between provide for a very efficient separation of cold and warm areas in the heating pump system 1 .

Fig. 5 shows a perspective view of a further exemplary embodiment of the heat pump system 1 according to the present invention, having three adjacent convertors 6. The three adjacently positioned convertors 6 are surrounded by heat sinks 7 on four sides to provide an efficient heat energy exchange with the environment of the heat pump system. As shown, the heat sinks 7 are provided as contact plates with outwardly extending fins, which can be easily manufactured from e.g. aluminium material). In the exemplary embodiments shown, each convertor 6 has a primary fluid input connection 3 (connected to the channels 5 inside the convertor 6), the primary fluid output connections 4 then being positioned on the opposite sides of the associated convertor 6. It will be apparent that the primary fluid input and output connections 3, 4 can be interchanged, and/or interconnected by manifolds to obtain predetermined flow patterns of the channels 5 inside the convertors 6.

Fig. 6 shows an exploded view of three adjacent converters 6 as applied in the embodiment of Fig. 5, more clearly showing the further elements 8a and 9 of the heat pump system 1 positioned in between the adjacent convertors 6. In this particular exemplary embodiment, the convertor 6 is provided with raised surfaces 6a which are used for heat exchange/transfer between the convertor 6 and the direct surrounding elements of the heat pump system 1 .

In the embodiment shown, an isolation plate 9 is positioned in between the convertor 6 and a heat transfer element support plate 8a. The isolation plate 9 is e.g. made from the reflection material as described above, i.e. having a heat reflection and/or isolation functionality. Openings or apertures are provided in the isolation plate 9 aligned with the raised surfaces 6a of the convertor 6 and with the heat transfer elements 8 positioned in/on the heat transfer element support plate 8a. This allows a heat transfer contact between each convertor 6 and one of the heat sinks 7, or between adjacent convertors 6. This configuration is furthermore advantageous in allowing easy assembly of the heat pump system 1 , by enabling easy alignment of the respective elements of the heat pump system 1 .

The isolation plate 9 is e.g. provided as a sandwich structure, having a thin (e.g. 1 mm thick) plastic plate, a layer of reflective material (e.g. 10mm thick) and a further thin (e.g. 1 mm thick) plastic plate. This allows easy handling and processing during manufacture and assembly of the heat pump system 1 .

To further enhance the efficiency of the heat pump system 1 , heat energy retention material is positioned around channels 5 of the array of channels 5 in a further embodiment. The heat energy retention material is e.g. a moulding material (which can be easily applied in the spaces between the channels 5), or additionally or alternatively, is a stone like material having a high heat retention capacity.

In an even further embodiment, the heat sink 7 comprises a predetermined volume of a heat sink material. This allows to provide a large heating capacity for the heat pump system 1 . The heat sink material may comprises one or more of a solid (e.g. rock, concrete block, dirt, magnesium carbonate, etc.), a liquid (e.g. water), or a gas (e.g. air). A solid material has the benefit of being a high density material with the ability to accumulate heat energy and (delayed) provision of heat energy in a very efficient manner.

The heat pump system 1 has been tested and applied in a combined central heating system and hot tap water supply system, and it was found that it can operate at a very high efficiency, which expressed in the Coefficient of Performance (COP, i.e. ratio of delivered energy and used energy input) has been shown to be between 4 and 9 in some embodiments, and even up to 10 in the exemplary embodiment shown in Fig. 5-7.

Fig. 4 shows a block diagram of an exemplary embodiment of a control unit 30 operatively powering components of the heat pump system 1 when used in a central heating system embodiment or hot water supply system embodiment as described above.

The control unit 30 has two control sub-units 31 , 32, of which the power control unit 31 is connected to the thermo-electric heat transfer elements 8, 8’ and 28 (if present) of one of the heat pump system 1 embodiments described above. In one embodiment, the control unit 30 comprises a current controlled power supply 31 connected to the thermo-electric heat transfer element 8, 8’, 28. Current control has the benefit of allowing a precise control of energy input to the thermo-electric heat transfer elements 8, 8’, 28, depending on actual heating demand.

Furthermore, application of a current controlled power supply 31 has the advantage of being able to work with a power supply 31 having a low internal resistance (order of 0.1 W), improving efficiency, and allows to use a transformer without a mechanical ventilation, improving sound performance (more silent). Furthermore, as the control unit 30 using such a power supply 31 can be positioned onto the heatsink(s) 7, the heat energy generated by the control unit 30 and/or power supply 31 can even be effectively used (even further increasing the COP).

The control unit 30 may also be arranged to be connected to individual ones of the heat transfer elements 8; 8’; 28 present in the heat pump system 1 . Depending on the specific configuration of convertors 6 and associated fluid channels 5, the transfer of heat energy from/to the fluid flowing in the fluid channels 5 via the convertors 6 to the heat sinks 7 can then be optimized. E.g. a higher heat transfer can be set for a heat transfer element 8 positioned directly in contact with a heat sink 7 as compared to a heat transfer element 8 positioned in between two adjacent convertors 6 (see the embodiment of Fig. 5). In an even further embodiment, the heat pump system 1 is provided with temperature sensors close to or in the channels 5 to allow implementation of a feedback control loop in the control unit 30.

It is noted that for supplying heated fluid to a floor heating system, in general the supply temperature is e.g. about 36°C, and the return temperature e.g. about 28°C. The actual temperature of the floor should not be too high (about 22°C) in order to remain sufficiently comfortable. Sensing can be applied to detect when the return temperature rises above 28°C, and the energy to be delivered by the heat pump system 1 can be scaled down. In a further exemplary embodiment, the control unit 30 is arranged to control the energy delivery based on the temperature difference of the fluid between output and input to the heating system, allowing to provide a heat pump system 1 with a high COP. By controlling the energy provision of the heat pump system 1 in this manner, also the efficiency of the thermos-electric heat transfer elements 8, 28 can be optimized, as it allows to prevent excess heat energy provided to end up in the heat sinks 7.

Furthermore, the control unit 30 in the exemplary embodiment shown, may be used in conjunction with the external system wherein the present invention heat pump system 1 is applied, such as a central heating system or a hot water supply system. To that end, as shown in the embodiment of Fig.4, the control unit 30 comprises a pump control unit 32 connected to a central heating pump 33 and/or a tap water supply pump 34. In addition, or alternatively, the pump control unit 32 may be connected to one or more valve units for controlling flow in the primary fluid part 2 and secondary fluid part 20. The control unit 30 may be further arranged to apply a suitable control algorithm for the associated function, e.g. a clock thermostat function of a central heating system, wherein the heat pump system 1 components and additional components are actively controlled.

The present invention has been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims.

Claims

1 . A heat pump system (1) comprising

a primary fluid part (2) having a fluid input connector (3) and a fluid output connector (4), and an array of channels (5) connecting the fluid input connector (3) and the fluid output connector (4), a convertor (6) in heat energy transfer connection with the array of channels (5),

a heat sink (7) in heat energy transfer connection with the convertor (6),

further comprising a thermo-electric heat transfer element (8) positioned between the heat sink (7) and the convertor (6).

2. The heat pump system (1) according to claim 1 , wherein the heat pump system (1) comprises a plurality of heat sinks (7, 7’) in heat energy transfer connection with the convertor (6), and a plurality of thermo-electric heat transfer elements (8, 8’) positioned between the plurality of heat sinks (7, 7’) and the convertor (6).

3. The heat pump system (1) according to claim 1 or 2, wherein the thermo-electric heat transfer element (8) comprises one or more Peltier elements.

4. The heat pump system (1) according to claim 1 , 2 or 3, further comprising reflection material surrounding the convertor (6).

5. The heat pump system (1 ) according to claim 4, wherein the reflection material comprises one or more layers of polyethylene material with a metal layer deposited on each of the one or more layers of polyethylene material.

6. The heat pump system (1) according to any one of claims 1 -5, further comprising heat energy retention material positioned around channels (5) of the array of channels (5).

7. The heat pump system (1) according to any one of claims 1 -6, wherein the heat sink (7) comprises a predetermined volume of a heat sink material.

8. The heat pump system (1) according to claim 7, wherein the heat sink material comprises one or more of a solid, a liquid, or a gas.

9. The heat pump system (1) according to any one of claims 1 -8, wherein the array of channels

(5) comprises a plurality of pipes.

10. The heat pump system (1) according to any one of claims 1 -8, wherein the array of channels (5) comprises a plurality of elongated bores in the convertor (6).

1 1 . The heat pump system (1) according to any one of claims 1 -8, wherein the array of channels (5) comprises a plurality of meandering channel parts.

12. The heat pump system (1) according to any one of claims 1 -1 1 , further comprising a current controlled power supply (31) connected to the thermo-electric heat transfer element (8).

13. The heat pump system (1) according to any one of claims 1 -12, further comprising a tensioning assembly (14) for providing tension between the heat sink (7) and the convertor (6).

14. The heat pump system (1) according to any one of claims 1 -13, wherein the heat pump system (1) further comprises

a secondary fluid part (20) having a secondary fluid input connector (23) and a secondary fluid output connector (24), and a secondary array of channels (25) connecting the secondary fluid input connector (23) and the secondary fluid output connector (24),

wherein the convertor (6) is in heat energy transfer connection with the secondary array of channels (25).

15. The heat pump system (1) according to claim 14, further comprising a secondary convertor part (26) in heat energy transfer connection with the convertor (6).

16. The heat pump system (1) according to claim 14 or 15, wherein an inner diameter of channels of the secondary array of channels (25) is smaller than an inner diameter of channels of the array of channels (5).

17. The heat pump system (1) according to claim 14, 15 or 16, wherein a secondary thermoelectric heat transfer element (28) is provided in heat energy transfer connection between the convertor (6) and the second array of channels (25).

18. The heat pump system (1) according to claim 17, wherein a power capacity of the secondary thermo-electric heat transfer element (28) is higher than a power capacity of the thermoelectric heat transfer element (8).

19. The heat pump system (1) according to any one of claims 2-18, further comprising a control unit (30) connected to the plurality of thermo-electric heat transfer elements (8; 8’; 28), the control unit (30) being arranged to individually control each of the plurality of thermo-electric heat transfer elements (8; 8’; 28).

20. Central heating system comprising a heat pump system (1) according to any one of claims 1 -13 or 19, wherein the primary fluid part (2) is connected to a heating fluid circuit. 21 Central heating system comprising a heat pump system (1 ) according to any one of claims 14-19, wherein the primary fluid part (2) is connected to a heating fluid circuit, and wherein the secondary fluid part (20) is connected to a hot water supply circuit. 22. Hot water supply system comprising a heat pump system (1) according to any one of claims

1 -13 or 19, wherein the primary fluid part (2) is connected to a hot water supply circuit.

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