EP4617569A1

EP4617569A1 - Tank and heating system

Info

Publication number: EP4617569A1
Application number: EP24162933.6A
Authority: EP
Inventors: Florian ANTOINE; Clement Christmann
Original assignee: BDR Thermea Group BV
Current assignee: BDR Thermea Group BV
Priority date: 2024-03-12
Filing date: 2024-03-12
Publication date: 2025-09-17

Abstract

The present disclosure relates to a (decoupling) tank for accommodating liquid for heating and/or cooling appliances, in particular in a heat pump system and comprises: a tank reservoir for receiving liquid, an upper and a lower region, when the tank is installed on site, wherein the upper and lower regions are located basically opposite to each other, wherein the tank is configured for liquid connection to at least a first primary and a first secondary liquid circuit external to the tank, the tank further comprising at least a first upper inlet port and a first upper outlet port located in the upper region, wherein the first upper inlet port is for liquid connection to the first primary liquid circuit, and the first upper outlet port is for liquid connection to the first secondary liquid circuit, at least a first lower inlet port and a first lower outlet port located in the lower region, wherein the first lower inlet port is for liquid connection to the first secondary liquid circuit, and the first lower outlet port is for liquid connection to the first primary liquid circuit, the tank further comprising heating means, optionally electrical heating means, for heating liquid in the tank, optionally at least in the upper region of the tank, wherein the tank is configured to flow liquid at least in parts, in a first operational state, from the first upper inlet port to the first upper outlet port and from the first lower inlet port to the first lower outlet port; in a second operational state, from the first upper inlet port to the first lower outlet port; and, in a third operational state, from the first lower inlet port to the first upper outlet port, for establishing a liquid flow at a desired liquid temperature in the first primary and/or first secondary liquid circuits.

Description

Technical field

The invention concerns a tank and a (domestic liquid) heating system comprising such tank.

Background

Heating installations (domestic heating systems) such as heat pump systems may comprise a (often so-called decoupling) tank which is used as a separate entity, in particular separate to an indoor unit, to manage the liquid flows in primary and secondary circuits of the heat pump system. More specifically, such tank may allow for mixing of liquid and as pressure balancer between the primary and secondary liquid circuits. Decoupling tanks may have the same geometry as boilers, due to the historic development and requirement to fit in the boiler location when updating the boiler to an indoor unit of a heat pump without having to change the whole system/design. In addition to the components installed in an indoor unit, such decoupling tank may be installed.
Improvements as to the reliability and/or functionality of such tank and an associated indoor unit are desired.

Summary of the invention

The present invention relates to a (decoupling) tank for accommodating liquid for heating and/or cooling appliances, in particular in a domestic heating system, e.g. a heat pump system, and comprises:

a tank reservoir for receiving liquid,
an upper and a lower region, when the tank is installed on site, wherein the upper and lower regions are located basically opposite to each other (seen vertically, i.e. opposite with respect to a vertical direction),
wherein the tank is configured for liquid connection to at least a first primary and a first secondary liquid circuit external to the tank, the tank further comprising
at least a first upper inlet port and a first upper outlet port (both) located in the upper region, wherein the first upper inlet port is for liquid connection to the first primary liquid circuit, and the first upper outlet port is for liquid connection to the first secondary liquid circuit,
at least a first lower inlet port and a first lower outlet port (both) located in the lower region, wherein the first lower inlet port is for liquid connection to the first secondary liquid circuit, and the first lower outlet port is for liquid connection to the first primary liquid circuit,
the tank further comprising heating means, optionally electrical heating means, for heating liquid in the tank, optionally at least in the upper region of the tank,
wherein the tank is configured to flow liquid at least in parts, in a first operational state, from the first upper inlet port to the first upper outlet port and from the first lower inlet port to the first lower outlet port; in a second operational state, from the first upper inlet port to the first lower outlet port; and, in a third operational state, from the first lower inlet port to the first upper outlet port, for establishing a liquid flow at a desired liquid temperature in the first primary and/or first secondary liquid circuits.

The tank of the invention may be seen as combining/integrating a (back-up) heating function (i.e. back-up heater) with a known (decoupling) tank. Specific advantages of the tank including the heating means, i.e. a tank having integrated heating means, may be compactness, reduced costs and reduced thermal and/or pressure loss. This may improve the performance efficiency of the system (due to less heat to produce to compensate for thermal loss and less power consumption of the pump to compensate for pressure loss).
Also, the integrated heating means allows liquid to be heated directly in the tank, where primary and secondary liquid circuits are in liquid communication. It follows that liquid for liquid circuits at both sides may be heated by means of the same heating means in a simple manner. In other words, primary and secondary liquid circuits may easily share a common heating means. In more detail, a heat request may be made on both sides: At the destination side, i.e. the secondary side, a heat request may concern heating of the liquid if not enough heat is provided by the source side. So, the additional heat it is used to heat the liquid and, thus, heat a building or water for a domestic hot water tank. On the primary side (i.e. the source side), a heat request may be made to realize an anti-freeze function to ensure that the liquid does not freeze in the pipe or in the heat exchanger in case of extreme temperature conditions. In case of freezing, there is a risk of damage of the pipe and/or of the heat exchanger, which could lead to failure of the heat pump and even risk or leakage of refrigerant (in particular flammable) in the liquid circuit of an installation site.
Further, as the heating means is integrated in the tank, no decision whether to install the heating means as an individual entity in the primary or the secondary liquid circuit needs to be made. Rather, as the heating means is integrated and not separately provided from the tank, the heating means does not provide "asymmetry" to the installation in that the heater is either in the primary or secondary liquid circuit. This allows for symmetrical installations and, hence, for increased versatility and flexibility. Further, it may be possible to have pipes on both sides installed at the same height and/or to install the identical elements on both sides, such as a temperature sensor and a pressure sensor.
A tank of the invention may in particular be beneficial, if it is relatively large, e.g. accommodating at least 10l or at least 30l. The reason is that a heating element in the tank may, in this case, also be relatively large, in particular as to its heating surface. Due to a large heating surface, the surface heating density may be lower, which may then reduce deposition of lime etc. (because lime deposition is increased with the temperature. By having a lower surface heating density, a lower temperature surface on the immersed heating element is achieved.) Also, a reduced heating surface temperature may allow for specific additives to be added to the liquid, e.g. glycol. A large tank may also allow to use heating means which have a larger heat exchange area, such as a heating belt around the tank. A larger heat exchange area allows to reduce the surface heating density. Also, a large tank may provide enough space for a hydraulic heat exchanger, such as a coil heat exchanger, to be positioned inside the tank. In other words, a hydraulic back-up heater may more easily be possible, as more space for accommodation of a heater inside the tank is available.
The invention may allow for improved thermal impact on liquid flows. The integration of heating means in the tank may render parts redundant (which would otherwise be present in each individual entity) and, hence, allow for removal of parts, such as a three-way valve and/or an air vent and/or two heating means and associated safety means (e.g. thermal safety to ensure that liquid does not vaporize). Also, this allows to reduce piping in a heat pump system, and the distance between further entities which are part of the heat pump system. Specific advantages may be as follows: The consumption of materials used in pipe connections, especially copper may be reduced. The length of piping and angles may be reduced and therefore a reduction in the pressure drop of the hydraulic circuit may be achieved. This may improve the system performance by limiting the power required from the pump. A reduced length of the tubes may reduce associated thermal losses and/or may reduce required thermal insulation around the pipe (which may, more specifically, reduce material consumption, costs and assembly time). The energy performance of the system may therefore be improved. Reducing the length of cables/wires between the different entities of the heat pump system reduces copper consumption and limits the risk of defects, such as cutting, abrasion of the film, bad assembly of the wire etc. Reducing the length of the piping may reduce the number of pipe connections and, hence, the risk of leakage between pipe connections. Reducing the weight of the heat pump system to be installed lowers the energy costs of transport (fewer pipe, less wiring etc...). Also, improved electric connectability and improved hydraulic accessibility may be supported.
The first, second and/or third operational states of the tank may take place at the same time, e.g. by divided liquid flows inside the tank. Hence, operational states are not mutually exclusive, but are combinable.
In general, alternatively, a (decoupling) tank may be referred to as hydraulic separator, buffer tank or mixing tank, or simply as tank. The tank of the invention may also be regarded as a heat pump system tank.
A (decoupling) tank of the invention may allow for mixing of liquid and as pressure balancer between the primary and secondary liquid circuits. Such tank may be seen as making the link between several closed circuits, such as a primary liquid circuit and a secondary liquid circuit. The tank has several connectors to pipes and, hence, pipes at each side. The primary circuit corresponds to and is at the source side (i.e. the side of the heating device, such as the heat pump, where the fluid is heated/cooled by the heating device). The secondary circuit corresponds to and is at the distribution side (i.e. the side of the radiators, floor heaters, domestic water consumption).
There may be one or two primary circuits and/or one or two secondary circuits, or even more corresponding circuits. Each of the primary and secondary circuits have their own circulation flow of liquid and own liquid temperature etc., thus representing actually independent liquid circuits.
By means of a (decoupling) tank between liquid circuits, the liquid flows and, hence, the liquid circuits are (remain) separated and do not conflict with the others. Each circuit may have its "own" flow. However, the tank allows for a balance between the primary and secondary liquid circuits, i.e. the demand and supply flows, so that the circuits may be in communication so as to allow for balanced heat, charge, recirculation etc.
The (decoupling) tank allows for impact on the thermal transfer of heat in the system. For example, a (decoupling) tank allows liquid from the primary circuit to enter the tank and leave the tank into the secondary circuit, as if a "main flow" of liquid crosses the tank as if the tank were a simple, connecting tube. If the liquid flow (in terms of the volumetric flow rate) differs between the primary and the secondary liquid circuits, i.e. at different sides of the (decoupling) tank, a part of the liquid flow entering the tank on one side may exit the tank on the same side, at another pipe at another height. Such liquid paths imply mixing of liquids having different temperatures.
The liquid in the primary and secondary liquid circuit(s) is optionally water-based. More specifically, the liquid may be pure water or water mixed with additives, such as glycol for anti-freeze purposes.
The physical principle underling a tank accommodating liquid at different temperatures is stratification: The coldest liquid will, in theory, be at the lowest level (close to the bottom of the tank) and the hottest liquid will be at the highest level (close to the top of the tank). Such theoretical distribution may be compromised by perturbations, such as flow or a mixing element. Presently, flow differences between inlet(s)/outlet(s), may lead to less "ideal" thermal stratification. Nevertheless, by means of a tank, it is possible to manage different outlet temperatures (for the secondary circuit(s)) with a single inlet tube (providing liquid at a single temperature from the primary circuit). For example, the secondary circuit which requires the highest liquid temperature may be connected to the highest outlet tube, for example for radiators (as the liquid temperature of liquid for radiation heating is higher than the temperature of liquid for floor heating).
The upper region may be regarded as a hot or warm zone of the tank, as it usually comprises the warmer part of the liquid in the tank. The lower region may be regarded as a cold zone of the tank, as it usually comprises the colder part of the liquid in the tank. A continuous decrease of the temperature of the liquid in the tank from top to bottom of the tank, when installed on site, is the usual configuration. As the hottest part of the liquid is in the upper most part of the upper region, the radiator circuit and/or a connection to a heat exchanger of a domestic hot water tank may be connected to the uppermost secondary outlet port. Moderately warm liquid may best be supplied into another secondary liquid circuit from a lower port in the upper region, for floor heating, for example.
The heating means may be configured for electric or hydraulic heating of the liquid. For example, the heater may be removable and may be configured as a cartridge. The heater may be removable from the heater e.g. for maintenance. The heating means may be located within the tank reservoir or outside the tank reservoir. Optionally, heating elements of the heating means are located in the upper region of the tank. This may particularly be preferable as it is desired to heat the liquid in the upper region because this is where hot liquid which will flow in the destination/secondary circuit is pumped/sucked. If liquid in the lower region is heated, liquid which flows back into the source/primary circuit (toward the heating device) would be heated - which is not desired for usual operation.
For example, the heating means may comprise at least one heating element (at least partially) immersed in the liquid inside the tank and in direct contact with the liquid. Alternatively, the heating means may comprise a heating element inside a sheath inside the tank without direct contact with the liquid. In this case, the heating element heats the air inside the sheath and the sheath is in direct contact with the liquid. Further alternatively, the heating means may comprise a heating element positioned outside the tank such as a heating belt. Another alternative may be a hydraulic heat exchanger, such as coil immersed in liquid inside the tank, and connected to another, separate hot liquid circuit, such as a circuit connecting to a boiler.
One or more of the ports may be connected to a "T-pipe" with two pipes connecting to the same port of the tank. In other words, a pipe connected to a port bifurcates into two or more pipes. This may represent an alternative to providing a second upper/lower inlet/outlet port.
Optionally, the tank comprises primary and secondary side regions, which are basically located at opposite sides of the tank (seen horizontally), and the first upper inlet port and the first lower outlet port are located in the primary side region, and the first upper outlet port and the first lower inlet port are located in the secondary side region. If the corresponding ports are located at substantially opposite sides of the tank, liquid flow from one port to the basically opposite the port occurs with least mechanical resistance, substantially corresponding to a straight/direct connection of the corresponding ports via a tube. Also, this may reduce disturbance in the flow, which may lead to less perturbation in connection with the thermal stratification.
Optionally, the first upper inlet port and the first upper outlet port are basically at the same height, and the first lower inlet port and first lower outlet port are basically at another same height. This may further support direct flow from one liquid circuit to another liquid circuit. This may also contribute to less perturbation of the thermal stratification and may allow for symmetrical installations. Compared to ports/pipes not having the same height (i.e. asymmetrical installations), performance or control of the installation is (ideally) not compromised.
Optionally, the tank comprises at least a second upper inlet port and/or a second lower outlet port for liquid connection to a second primary circuit, optionally for liquid connection to a hydraulic heating circuit; and/or a second upper outlet port and/or a second lower inlet port for connection to a second secondary liquid circuit, optionally for liquid connection to a radiator circuit and/or a floor heating circuit. This allows to include further hydraulic entities to the tank, at one or both sides of the tank. Accordingly, the versatility of the tank if further improved. According to this embodiment, in total, the tank may comprise eight ports for connection to primary/secondary circuits, in opposite side regions of four ports each. It is not excluded that third and fourth (or more) additional inlets/outlets at any side are provided.
Further optionally, the second upper inlet port and/or the second upper outlet port are located in the upper region, and/or the second lower outlet port and/or the second lower inlet port are located in the lower region. Further optionally, the second upper outlet port and the second lower inlet port are located in the secondary side region and/or the second upper inlet port and the second lower outlet port are located in the primary side region.
Further optionally, the second upper outlet port and the second lower inlet port are located in the secondary side region and/or the second upper inlet port and the second lower outlet port are located in the primary side region.
Optionally, the ports for connection to the first and/or second primary liquid circuits and the ports for connection to the first and/or second secondary liquid circuits are symmetrical relative to a plane of symmetry including a longitudinal direction of the tank. Alternatively or additionally, the ports in the lower region and the port in the upper region are symmetrical relative to a plane of symmetry including a transverse, in particular radial, direction of the tank. A symmetrical tank allows for greater installation flexibility and versatility for the user. For example, the orientation of inlets/outlets of the tank may be swapped. The user may choose the configuration that is most suitable, thus improving the ergonomics of the installation and thus reducing the risk of improper connections and leakage. This may also allow the length of the connection tubes between the tank of the invention and the remaining heat pump system to be reduced, thus improving the performance of the system and reducing material consumption further. This may be beneficial in terms of less pressure drop, less leakage risk, less thermal loss, and/or less thermal insulation and may in particular lead to less costs, energy consumption, material consumption, and/or risk.
Optionally the tank comprises an air vent, further optionally at a top (cover) of the tank, and/or a drain, further optionally at a basis of the tank, and/or one or more sensors for temperature determination, further optionally for determining the temperature of the liquid in the tank and/or at one or more ports, and/or a pressure sensor and/or a thermostat and/or a safety valve and/or a connector to an expansion vessel and/or a filter for filtering liquid in the tank. For example, a filter may be provided for filtering liquid inside the decoupling tank. The filter may include a mesh with a turbulent flow in order to attach fine particles or may be an integrated magnetic filter. The filter may be configured to be removed for maintenance, e.g. for washing.
Alternatively or additionally, optionally the tank comprises at each of the first upper inlet port and the first upper outlet port; and/or at each of the first lower inlet port and the first lower outlet port, a sensor for temperature determination, optionally for determining the temperature of the liquid in the tank and/or at the respective port. Accordingly, the tank (indoor unit) may support freely choosing the source and destination side.
Optionally, the tank further comprises an insulation layer, further optionally made of Polyurethan foam or expanded plastic foam and/or gas/vacuum insulation, at least partially outside the tank reservoir and/or at least in the upper region of the tank for thermal insulation of the liquid in the tank against the surroundings. As an example, the insulation layer comprises EPS (expanded polystyrene).
The invention is also directed to an indoor unit comprises a (integrated) tank of the invention. In other words, the tank of the invention is integrated in the indoor unit. More specifically, the indoor unit comprises an expansion vessel for adaption of the pressure in the first primary or first secondary liquid circuits, optionally at least partially located below the tank and/or in the housing, when the indoor unit is installed on site, in liquid communication with the liquid in the tank, optionally in liquid communication with a port in the lower region. If the expansion vessel is separate from the tank (not integrated in the tank), this allows for selection of an appropriate expansion vessel for the desired installation, considering e.g. space requirements (wherein factors are the volume of the circuit and the maximum difference temperature). This allows for a modular and versatile indoor unit and may avoid material wastage. Additionally or alternatively, integration of the tank including the heating means in an indoor unit may be expedient during installation, as the indoor unit integrates various entities which may render the need for individual installation of various entities void. This may also be beneficial in terms of potential leakage.
Optionally, the indoor unit further comprises a control unit for control of the indoor unit, the control unit optionally located at least in part in front of, below or above the tank and/or in the housing. Preferably, the control unit is located on the upper region of the tank and/or in an upper section of the indoor unit. This may be beneficial in case of any leakage of liquid of the assembly, as droplets on the control unit may be avoided, which reduces safety and reliability risk.
Optionally, the indoor unit further comprises a user interface, optionally an HMI or display, at least partially located outside the housing for user operation. If the user interface is separate from the tank, the position of the user interface may be selected based on the user's preferences, such as at an ergonomic location.
The invention is also directed to a heating system comprising the tank/indoor unit of the invention. Specifically, the heat pump system of the invention comprises a primary liquid circuit comprising a heating unit, e.g. a heat pump unit, for heating (optionally also for cooling) the liquid of the primary liquid circuit and further comprising a tank of the invention.
The invention refers to any kind of heating system, including at least a ground source (water)- and/or air source-heat pump unit. A heating unit of the heating system (in particular of the heat pump system) may be a split unit or a monobloc unit. The heating unit may be a heat pump, e.g. in an outdoor unit or an indoor unit, for example for a ground source heat pump. The heating system may be configured to heat and/or cool air or water (of a closed loop or of an open loop, such as domestic hot water). The heating system may comprise further heating devices in addition to a heat pump unit. For example, the heating system may be a hybrid system.
The heating system of the invention comprises a tank and/or an indoor unit of the invention, wherein the system further comprises a heating unit, optionally an outdoor unit, for heating and/or cooling of liquid in the first primary liquid circuit, wherein the heating unit is in liquid communication with the first upper inlet port and the first lower outlet port. This allows for efficient piping of the heating system. While the heating system of the invention is preferably a heat pump system, it may alternatively be a heating system having no heat pump, e.g. a system having only one or more boilers.
Optionally, the system comprises a domestic hot water tank in liquid communication with the first primary or second liquid circuit and/or an additional heater, preferably a boiler, for heating of liquid in the tank and in liquid communication with the second primary liquid circuit.
Optionally, the system further comprises a floor circuit and/or a radiator circuit in liquid communication with the first and/or second secondary liquid circuits, i.e. on the destination side.
Optionally, the system further comprises a control unit for receiving signals pertaining to the temperature, pressure and/or flow velocity of liquid entering and/or exiting the tank and for control of the liquid flow in the first or second primary liquid circuit and/or in the first or second secondary liquid circuit.
Detailed embodiments and further advantages and features related to the present invention are described in the following, wherein these examples shall not be regarded as limiting the invention.

Brief description of the drawings

Figs. 1(a) and (b): show a lateral cross-sectional view and a lateral partial cross-sectional view (with the insulation removed), respectively, from different sides of a tank of an embodiment of the invention.
Fig. 2(a): shows a perspective view of a tank of an embodiment of the invention, wherein parts are cut off for the sake of visibility.
Fig. 2(b): shows a lateral cross-sectional view of a tank of an embodiment of the invention.
Fig. 3: shows an indoor unit of an embodiment of the invention, wherein Fig. 3(a) shows a plan view, Fig. 3(b) shows a perspective view, and Fig. 3(c) shows another perspective view.
Fig. 4: schematically reflects different operational states of a tank of an embodiment of the invention.
Fig. 5: schematically shows heating systems of embodiments of the invention, wherein Fig. 5(a), 5(b) and 5(c) refer to different ways of using an indoor unit of an embodiment of the invention.
Fig. 6: schematically shows a prior art heating system.

Detailed description

Figures 1(a) and 1(b) each show a cross-sectional view of a tank 12 of an embodiment of the invention, when the tank 12 is installed on site. The tank 12 is configured for liquid connection to at least a first primary P₁ and a first secondary S₁ liquid circuit external to the tank 12. The tank may accommodate a liquid volume of between 10 and 100 l, in particular between 10 and 50 I, more preferably 20 to 50 I.
The tank 12 comprises a first upper inlet port P_{in, 1} and a first upper outlet port S_{out, 1} located in an upper region U, wherein the first upper inlet port P_{in, 1} is for liquid connection to the first primary liquid circuit P₁, and the first upper outlet port S_{out, 1} is for liquid connection to the first secondary liquid circuit S₁. The tank 12 further comprises a first lower inlet port S_{in, 1} and a first lower outlet port P_{out, 1} located in a lower region L of the tank 12, wherein the first lower inlet port S_{in, 1} is for liquid connection to the first secondary liquid circuit S₁, and the first lower outlet port P_{out, 1} is for liquid connection to the first primary liquid circuit P₁. The upper region U may be seen as the upper half of the tank 12, and the lower region L may be seen as the lower half of the tank 12, in the vertical direction.
The tank 12 comprises a second upper inlet port P_{in, 2} and a second lower outlet port P_{out, 2} for liquid connection to a second primary circuit P₂, for liquid connection to a hydraulic heating circuit; and a second upper outlet port S_{out, 2} and a second lower inlet port S_{in, 2} for connection to a second secondary liquid circuit S₂, for liquid connection to a radiator circuit 10 and/or a floor heating circuit 11. The second upper inlet port P_{in, 2} and the second upper outlet port S_{out, 2} are located in the upper region U, and the second lower outlet port P_{out, 2} and/or the second lower inlet port S_{in, 2} are located in the lower region L. The second upper outlet port S_{out, 2} and the second lower inlet port S_{in, 2} are located in the secondary side region SRs and the second upper inlet port P_{in, 2} and the second lower outlet port P_{out, 2} are located in the primary side region SR_P. The first upper inlet port P_{in, 1} and the first upper outlet port S_{out, 1} are basically at the same height H₁, and the first lower inlet port S_{in, 1} and the first lower outlet port P_{out, 1} are basically at another same height H₂. Also, the second upper inlet port P_{in, 2} and the second upper outlet port S_{out, 2} are basically at the same height, and the second lower inlet port S_{in, 2} and second lower outlet port P_{out, 2} are basically at another same height. The heights of the corresponding first and second inlet/outlet ports differ, so that a respective pair of first upper inlet and outlet ports P_{in, 1} and S_{out, 1}; P_{in, 2} and S_{out, 2}; P_{out, 1} and S_{in, 1}; P_out,2 and S_{in, 2} is each positioned at a same height. While figures 1(a) and 1(b) indicate that the first upper inlet and outlet ports P_{in, 1} and S_{out, 1} are located above the second upper inlet and outlet ports P_{in, 2} and S_{out, 2}, respectively, it is possible that the second upper inlet and outlet ports P_{in, 2} and S_{out, 2} are located above the first upper inlet and outlet ports P_{in, 1} and S_{out, 1}. The same applies in connection with the lower inlet and outlet ports.
The ports P_{in, 1} and P_in,2 may be at the same height or one port may be above the other port. This may apply to all "pairs" of inlet/outlet ports of the tank 12. For example, P_in,1 may be, for example, above P_{in, 2} and P_out,1 may, at the same time, be below P_out,2. The position of ports as to their heights may depend on the temperature requirement and/or efficiency of the system.
The ports for connection to the first and/or second primary liquid circuits P₁, P₂ and the ports for connection to the first and/or second secondary liquid circuits S₁, S₂ are symmetrical relative to a (e.g. vertical) plane of symmetry including a longitudinal direction of the tank 12. The ports in the lower region L and the ports in the upper region U are symmetrical relative to a plane of symmetry including a transverse, in particular radial, direction of the tank 12.
The tank 12 comprises heating means 4, for heating liquid in the tank 12. Figure 1(a) shows electrical heating means 4 having a resistive element in the lower region L of the tank 12. However, it is preferable that the heating means 4 is for heating liquid primarily in the upper region U of the tank.
Tank walls 8 (e.g. enameled) define a tank reservoir 24. The tank 12 comprises an insulation layer 7, preferably made of Polyurethane foam or expanded plastic foam, or have a gas or vacuum insulation. The insulation layer 7 is provided at least partially outside the tank reservoir 24, i.e. outside the tank walls 8, for thermal insulation of the liquid in the tank 12 against the surroundings.
An air vent 2 is located at a top (cover) 9 of the tank 2. A drain 5 is located at a basis of the tank 12. The lower region L of the tank 12 terminates at the bottom 6 of the tank 12. A thermostat 3 is also provided.
As shown in figure 2(a), the tank 12 comprises the tank reservoir 24 for receiving liquid and has an upper U and a lower L region, when the tank 12 is installed on site, wherein the upper U and lower L regions are located basically opposite to each other, in the vertical direction.
The tank 12 comprises primary SR_P and secondary SRs side regions, which are basically located at opposite sides of the tank 12 (in the horizontal direction). The upper inlet ports P_{in, 1} and P_{in, 2} and the lower outlet ports P_out,1 and P_out,2 are located in the primary side region SR_P, and the upper outlet ports S_{out, 1} and S_{out, 2} and the lower inlet ports S_{in, 1} and S_{in, 2} are located in the secondary side region SRs.
Fig. 2(b) shows sensors 22 for temperature determination, wherein temperature sensors for determining the temperature of the liquid at one or more ports may be provided. Figure 2(b) further shows a connection 20 to an expansion valve (not shown) at the lowermost inlet and outlet ports and pressure gauges (safety valves) 21, also at the lowermost inlet and outlet ports. For each of the ports, a connector 23 for connection to corresponding piping is provided. The connectors 23 may in particular be threaded connectors and/or quick coupling connectors so as to allow for reliable mechanical engagement to a corresponding connector at the pipe end (not shown).
In general, ports may be flush with the tank wall 8, or may extend inside the reservoir 24, as reflected in Fig. 1(a). In other words, ports (inlet and outlets) do not need to penetrate inside the tank and may have an opening directly flush with the inner side of the wall 8 of the tank 12. Some ports may be designed in a different way than other ports.
Figures 3(a), 3(b) and 3(c) show an indoor unit 1 of an embodiment of the invention. The indoor unit 1 comprises the tank 12 of the invention, wherein the indoor unit 1 further comprises a housing 25 in which at least the tank 12 is accommodated.
The indoor unit 1 comprises an expansion vessel 13 for adaption of the liquid pressure in the first primary or first secondary liquid circuits, at least partially located below the tank 2 and in the housing 25, when the indoor unit 12 is installed on site. The expansion vessel 13 is via the connection 20 in liquid communication with the liquid in the tank 12, more specifically in liquid communication with the lowermost port in the lower region L of the tank 12.
The indoor unit 1 comprises a control unit 18 for control of the indoor unit 1, i.e. of the liquid flow through the tank 12. The control unit 18 is located at least in part above the tank 12, in the housing 25. The indoor unit 1 further comprises a user interface, e.g. a HMI or a display, at least partially located outside the housing 25 for user operation, here in the upper region U of the tank 12.
Fig. 4 shows various operational states and corresponding liquid paths, at least some of which a tank of an embodiment of the invention may allow for. The liquid paths provide the basis for establishing a liquid flow at a desired volume rate and/or liquid temperature in the primary P₁ and/or secondary S₁ liquid circuits. Arrows indicate fluid flow in the tanks shown in figure 4. Lines with small dots indicate a high temperature liquid flow, larger line indicate a low temperature and dots and lines indicate an intermediate temperature. T_h and T_l indicate a (relatively) high and low temperature of the liquid in the tank 12, respectively. The ports labelled in figure 4(a) apply to all tanks shown in figure 4.
During heating, liquid enters from the primary liquid circuit in the upper region at the primary side region and leaves the tank for the secondary liquid circuit in the upper region at the secondary side region is hot liquid. Liquid entering via the secondary liquid circuit in the lower region at the secondary side region and leaving the tank for the primary liquid circuit in the lower region at the primary side region is cold liquid.
At least, the tank 12 is configured to flow liquid at least in parts, in a first operational state, from the first upper inlet port P_{in, 1} to the first upper outlet port S_{out, 1} and from the first lower inlet port S_{in, 1} to the first lower outlet port P_{out, 1}. This first operational state is reflected in figure 4(a), wherein the volumetric flow rate Q is the same in the first primary liquid circuit (Q_P) and the first secondary liquid circuit (Q_s), i.e. on the primary and secondary sides. This operational state may be seen as a normal heating mode, in which the heat production flow on the source side basically equals the heat requirement flow on the destination side.
Figure 4(b) shows i.a. another (second) operational state in which liquid flows from the first upper inlet port P_{in, 1} to the first lower outlet port P_{out, 1}. Accordingly, a part of the liquid does not enter the secondary liquid circuit but remains in the primary liquid circuit. At the same time, liquid flows from the first upper inlet port P_{in, 1} to the first upper outlet port S_{out, 1} and from the first lower inlet port S_{in, 1} to the first lower outlet port P_{out, 1}, so that the operational state shown in figure 4(a) may be seen as a combination of the first and second operational states. The volumetric flow rate Q_P in the first primary liquid circuit exceeds the volumetric flow rate Q_s of the first secondary liquid circuit. Hence, liquid re-circulates in the primary liquid circuit. This may be seen as a charging mode in which the heat production flow on the source side is above the heat requirement flow on the destination side.
Figure 4(c) shows i.a. another (third) operational state in which liquid flows from the first lower inlet port S_{in, 1} to the first upper outlet port S_{out, 1}. Accordingly, a part of the liquid remains in the secondary liquid circuit and does not flow into the primary liquid circuit. At the same time, liquid flows from the first upper inlet port P_{in, 1} to the first upper outlet port S_{out, 1} and from the first lower inlet port S_{in, 1} to the first lower outlet port P_{out, 1}, so that the operational state shown in figure 4(c) may be seen as a combination of the first and third operational states. The volumetric flow rate Q_P in the first primary liquid circuit is lower than the volumetric flow rate Q_s of the first secondary liquid circuit. Hence, liquid re-circulates in the secondary liquid circuit. Heat stored in the tank and/or generated by the heating means is transferred between S_in,1 and S_out,1 and offers sufficient energy to the secondary liquid circuit.
Figure 4(d) shows another operational state, in which no liquid flows into the secondary liquid circuit. Liquid merely flows within the primary liquid circuit, according to the second operational state. At the same time, liquid in the tank12 is being heated by the heating means 4. The reason for such operation may be de-frosting of the evaporator and/or of piping (not shown) in the primary liquid circuit.
Figure 4(e) shows another operational state, in which no liquid flows into the primary liquid circuit. Liquid merely flows within the secondary liquid circuit, according to the third operational state, while the heating means 4 is switched off. This may correspond to a state in which the heat pump in the primary liquid circuit is not working.
Figure 4(f) shows another operational state, in which no liquid flows into the primary liquid circuit. Liquid merely flows within the secondary liquid circuit, according to the third operational state. At the same time, liquid in the tank is being heated by the heating means. Basically, the temperature is high throughout the tank. This may correspond to a state in which the heat pump (or other heating device) in the primary liquid circuit is not working. Nevertheless, via the heating means 4 in the tank 12, the liquid in the tank 12 is being heated. This may be beneficial during installation of the heating device or in other situations in which the heating device is not working, for example.
Figure 4(g) shows another operational state including the first operation, wherein, in addition to the first primary liquid circuit, a second primary liquid circuit is present. Only a first second primary circuit is present, no second secondary liquid circuit. This may allow for hydraulic back-up heating via the second primary liquid circuit.
Figure 4(h) shows another (first) operational state, in which liquid flows from the first upper inlet port P_{in, 1} to the first upper outlet port S_{out, 1} and from the first lower inlet port S_{in, 1} to the first lower outlet port P_{out, 1}. Liquid entering at the first upper inlet port is cold, so as to provide for a cooling effect by the secondary liquid circuit. Liquid flowing back from the first lower inlet port S_{in, 1} to the first lower outlet port P_{out, 1} is hot, when it flows back into the heat pump unit (not shown). This reflects a cooling operation.
On this basis, the tank 12 may allow for establishing the desired operational mode and, hence, for the desired volumetric flow rate and/or temperature of the liquid. It is noted that the control as to the volumetric flow rate and temperature, e.g. including operation of the heating means, is controlled by the control unit 18. In particular, the control unit 18 controls the various pumps the system, in particular the pumps in the primary and secondary liquid circuits P1, P2; S1, S2, which pumps effect the desired fluid flow. The control of the fluid flow allows to reach the targeted temperature(s), i.e. the heating requirement.
The heat pump system 26 comprises a tank 12 and an indoor unit 1. The heat pump system further comprises an outdoor unit 16, for heating and/or cooling of liquid in the first primary liquid circuit P₁, wherein the heat pump unit 16 is in liquid communication with the first upper inlet port P_{in, 1} and the first lower outlet port P_{out, 1}.
Figures 5(a), (b) and (c) show different heat pump systems 26 of embodiments of the invention. The heat pump system 26 comprises, in the indoor unit 1, a control unit 18 for receiving signals pertaining to the temperature, pressure and/or flow velocity of liquid entering and/or exiting the tank 12 and for control of the liquid flow in the first or second primary liquid circuit and/or in the first or second secondary liquid circuit. In total, eight ports for connection to liquid circuits of the heat pump system 26 are provided, namely four ports at a primary side, and four ports at a secondary side.
While the indoor units 1 as shown in Figure 5 may be wall-hung indoor units, the invention is not limited to such type of indoor units. Also e.g. a floor standing solution, e.g. a stand-alone indoor unit, may be an embodiment of the invention. For example, a standing indoor unit may allow for an even larger tank.
The heat pump system 26 of figure 5(a) comprises a domestic hot water tank 14 at the primary side (alternatively on the secondary side) and in liquid communication with the first primary liquid circuit P₁. The heat pump system 26 comprises a floor heating circuit 11 and a radiator circuit 10 in liquid communication with the first and second secondary liquid circuits S₁, S₂, respectively. In the specific embodiment shown in figure 5(a), the second secondary liquid circuit and the first secondary liquid circuit share a (first) lower inlet port. The outdoor heat pump unit 16 heats the primary liquid and is, hence, part of the primary liquid circuit, which may also be referred to as a source circuit. On the opposite side, in the secondary liquid circuit, which may also be referred to as the destination circuit, heat is consumed for heating of the building.
The heat pump system 26 of figure 5(b) may be seen as a symmetrical switch of the embodiment shown in figure 5(a). More specifically, the secondary and primary liquid circuits are, compared to figure 5(b), provided at the opposite side. This reflects the versatility of the indoor unit 1, in particular if the ports at the tank 12 are symmetrical.
The heat pump system 26 of figure 5(c) is similar to the system shown in figure 5(a) and comprises an additional heater 15, preferably a boiler, for heating of liquid in the tank 12 and which is in liquid communication with the second primary liquid circuit. Also, a difference relative to the embodiment of figure 5(a) is that the floor circuit 11 and the radiator circuit 10 are supplied via different secondary upper outlet ports. The outlet port S_{out, 2} supplies less warm liquid (about 30°C) into the floor heating circuit 11, while the higher outlet port S_{out, 1} supplied very hot water (about 60°C) into the radiator heating circuit 10. In Fig. 5(c), the indoor unit 1 comprises at each of the first upper inlet port P_{in, 1} and the first upper outlet port S_{out, 1}, the first lower inlet port S_{in, 1} and the first lower outlet port P_{out, 1}, a sensor for determining the temperature of the liquid in the tank and/or at the respective port. Also, the indoor unit 1 comprises at each of the second upper inlet port P_{in, 2} and the second upper outlet port S_{out, 2}, the second lower inlet port S_{in, 2} and the second lower outlet port P_{out, 2}, a sensor for determining the temperature of the liquid in the tank and/or at the respective port. Accordingly, the indoor unit 1 may support freely choosing the source and destination side.
As reflected in Fig. 5(a) to 5(c), it may depend on the application and installation, if some of the ports are (not) used and may be closed by the user (closed by a sealing cap for, example). For example, if there is no additional boiler 15 in the installation site, there may be only one primary liquid circuit, so that only one inlet and one outlet at the source side is used. Additionally or alternatively, there may be only one circuit on the distribution side (for example a single type of emitters is installed and connected in serial in the installation site), so that only one inlet and one outlet at the secondary side are used. Additionally or alternatively, if e.g. a T-connection is provided at an inlet/outlet port instead on a pipe, another inlet/outlet port may not be used.
Fig. 6 schematically shows a prior art heating system having an indoor unit 1' not according to an embodiment of the invention. Specifically, such prior art heating systems do not allow for easy inverted (symmetric) installation, i.e. reversal of the indoor unit. If an inverted installation were to be required for spatial reasons (constraints of the site), this may entail additional hydraulic pipes and intricate liquid paths in connection with a prior art indoor unit 1'. Various other advantages are provided by the present invention relative to e.g. the prior art system of Fig. 6, as explained above.
The detailed description of the invention is provided with respect to the embodiments depicted in the drawings. Obvious variations and alternatives may occur to the skilled person, based on the summary of the invention. Variations and alternatives are part of the invention in so far they are covered by the appended claims.

Reference signs

1: indoor unit
2: air vent
3: thermostat
4: (electrical) heating means
5: drain
6: bottom
7: insulation layer
8: tank wall
9: top
10: radiator circuit
11: floor heating circuit
12: (decoupling) tank
13: expansion vessel
14: domestic water tank
15: additional heater, such as boiler (back-up heater)
16: heat pump unit
17: wall
18: control unit
19: HMI (human machine interface)
20: connection to expansion valve
21: pressure gauge (safety valve)
22: sensor for temperature determination
23: connector
24: tank reservoir
25: housing of indoor unit
26: heating system, in particular heat pump system

P1: first primary liquid circuit
S1: first secondary liquid circuit
P2: second primary liquid circuit
S2: second secondary liquid circuit

Pin, 1: first upper inlet port
Pin, 2: second upper inlet port
Sout, 1: first upper outlet port
Sout, 2: second upper outlet port
Sin, 1: first lower inlet port
Sin, 2: second lower inlet port
Pout, 1: first lower outlet port
Pout, 2: second lower outlet port

SRP: primary side region
SRs: secondary side region
L: lower region of tank
U: upper region of tank
H1: first height of ports
H2: second height of ports

Claims

Tank (12) for accommodating liquid for heating and/or cooling appliances, in particular in a domestic heating system (26), the tank (12) comprising
a tank reservoir (24) for receiving liquid,

an upper (U) and a lower (L) region, when the tank (12) is installed on site, wherein the upper (U) and lower (L) regions are located basically opposite to each other,

wherein the tank (12) is configured for liquid connection to at least a first primary (P₁) and a first secondary (S₁) liquid circuit external to the tank (12), the tank further comprising:
at least a first upper inlet port (P_{in, 1}) and a first upper outlet port (S_{out, 1}) located in the upper region (U), wherein the first upper inlet port (P_{in, 1}) is for liquid connection to the first primary liquid circuit (P₁), and the first upper outlet port (S_{out, 1}) is for liquid connection to the first secondary liquid circuit (S₁),

at least a first lower inlet port (S_{in, 1}) and a first lower outlet port (P_{out, 1}) located in the lower region (L), wherein the first lower inlet port (S_{in, 1}) is for liquid connection to the first secondary liquid circuit (S₁), and the first lower outlet port (P_{out, 1}) is for liquid connection to the first primary liquid circuit (P₁),

the tank (12) further comprising heating means (4), optionally electrical heating means, for heating liquid in the tank (12), optionally at least in the upper region (U) of the tank (12),

wherein the tank (12) is configured to flow liquid at least in parts, in a first operational state, from the first upper inlet port (P_{in, 1}) to the first upper outlet port (S_{out, 1}) and from the first lower inlet port (S_{in, 1}) to the first lower outlet port (P_{out, 1}); in a second operational state, from the first upper inlet port (P_{in, 1}) to the first lower outlet port (P_{out, 1}); and, in a third operational state, from the first lower inlet port (S_{in, 1}) to the first upper outlet port (S_{out, 1}), for establishing a liquid flow at a desired liquid temperature in the first primary (P₁) and/or first secondary (S₁) liquid circuits.
Tank (12) of claim 1, wherein the tank (12) further comprises primary (SR_P) and secondary (SRs) side regions, which are basically located at opposite sides of the tank (12), and the first upper inlet port (P_{in, 1}) and the first lower outlet port (P_out,1) are located in the primary side region (SR_P), and the first upper outlet port (S_{out, 1}) and the first lower inlet port (S_{in, 1}) are located in the secondary side region (SRs).
Tank (12) of claim 1 or 2, wherein the first upper inlet port (P_{in, 1}) and the first upper outlet port (S_{out, 1}) are basically at the same height (H₁), and the first lower inlet port (S_{in, 1}) and first lower outlet port (P_{out, 1}) are basically at another same height (H₂).
Tank (12) of any of the preceding claims, further comprising at least
- a second upper inlet port (P_{in, 2}) and/or a second lower outlet port (P_{out, 2}) for liquid connection to a second primary circuit (P₂), optionally for liquid connection to a hydraulic heating circuit, and/or

- a second upper outlet port (S_{out, 2}) and/or a second lower inlet port (S_{in, 2}) for connection to a second secondary liquid circuit (S₂), optionally for liquid connection to a radiator circuit (10) and/or a floor heating circuit (11),

- wherein optionally the second upper inlet port (P_{in, 2}) and/or the second upper outlet port (S_{out, 2}) are located in the upper region (U), and/or

- the second lower outlet port (P_{out, 2}) and/or the second lower inlet port (S_{in, 2}) are located in the lower region (L),

- optionally wherein the second upper outlet port (S_{out, 2}) and the second lower inlet port (S_{in, 2}) are located in the secondary side region (SRs) and/or the second upper inlet port (P_{in, 2}) and the second lower outlet port (P_{out, 2}) are located in the primary side region (SR_P).
Tank (12) of any of the preceding claims, wherein the ports for connection to the first and/or second primary liquid circuits (P₁, P₂) and the ports for connection to the first and/or second secondary liquid circuits (S₁, S₂) are symmetrical relative to a plane of symmetry including a longitudinal direction of the tank (12), and/or the ports in the lower region (L) and the port in the upper region (U) are symmetrical relative to a plane of symmetry including a transverse, in particular radial, direction of the tank (12).
Tank (12) of any of the preceding claims, further comprising an air vent (2), optionally at a top (9) of the tank (12), and/or a drain (5), optionally at a basis of the tank (12), and/or one or more sensors for temperature determination (22), optionally for determining the temperature of the liquid in the tank and/or at one or more ports, and/or a pressure sensor and/or a thermostat and/or a safety valve and/or a connector to an expansion vessel and/or a filter for filtering liquid in the tank (12), and/or
optionally the tank comprising:
a) for or at each of the first upper inlet port (P_{in, 1}) and the first upper outlet port (S_{out, 1}) and/or

b) for or at each of the first lower inlet port (S_{in, 1}) and the first lower outlet port (P_{out, 1}) a sensor for temperature determination (22), optionally for determining the temperature of the liquid in the tank and/or at the respective port.
Tank (12) of any of the preceding claims, further comprising an insulation layer (7), preferably made of Polyurethan foam or expanded plastic foam, at least partially outside the tank reservoir (24) and/or at least in the upper region of the tank (12) for thermal insulation of the liquid in the tank (12) against the surroundings.
Indoor unit (1) of a heat pump system, comprising the tank (12) of any of the preceding claims, wherein the indoor unit (1) further comprises a housing (25) in which at least the tank (12) is accommodated.
Indoor unit (1) of claim 8, further comprising an expansion vessel (13) for adaption of the liquid pressure in the first primary or first secondary liquid circuits, optionally at least partially located below the tank (2) and/or in the housing (25), when the indoor unit (12) is installed on site, in liquid communication with the liquid in the tank (12), optionally in liquid communication with a port in the lower region (L).
Indoor unit (1) of claim 8 or 9, further comprising a control unit (18) for control of the indoor unit (1), the control unit (18) optionally located at least in part in front of, below or above the tank (12) and/or in the housing (25).
Indoor unit (1) of any of the preceding claim 8 to 10, further comprising a user interface, optionally an HMI or display, at least partially located outside the housing (25) for user operation.
Heating system, such as a heat pump system (26), comprising a tank (12) and/or an indoor unit (1) of any of the preceding claims, wherein the system further comprises a heating unit, optionally heat pump unit (16), for heating and/or cooling of liquid in the first primary liquid circuit (P₁), wherein the heating unit (16) is in liquid communication with the first upper inlet port (P_{in, 1}) and the first lower outlet port (P_{out, 1}).
Heating system (26) of claim 12, further comprising a domestic hot water tank (14) in liquid communication with the first primary or second liquid circuit (P₁) and/or an additional heater (15), preferably a boiler, for heating of liquid in the tank (12) and in liquid communication with the second primary liquid circuit (P₂).
Heating system (26) of claim 12 or 13, further comprising a floor circuit (11) and/or a radiator circuit (10) in liquid communication with the first or second secondary liquid circuits (S₁, S2).
Heating system (26) of any of the claims 12 to 14, further comprising a control unit (18) for receiving signals pertaining to the temperature, pressure and/or flow velocity of liquid entering and/or exiting the tank (12) and for control of the liquid flow in the first and/or second primary liquid circuit and/or in the first and/or second secondary liquid circuit.