EP4635255A1

EP4635255A1 - Heating device and a heating system comprising such heating device

Info

Publication number: EP4635255A1
Application number: EP23720224.7A
Authority: EP
Inventors: Radim KOCHWASSER; Alena Alaia; Milan BURANSKY; Martin BUBENIK
Original assignee: Mss Projekt SRO
Current assignee: Mss Projekt SRO
Priority date: 2023-04-17
Filing date: 2023-04-17
Publication date: 2025-10-22
Also published as: WO2024217606A1

Abstract

Heating device comprising a non-magnetic material intended for heating and an induction heating coil for heating the material, where this non-magnetic material is stored in the magnetic field of this induction heating coil, where this non-magnetic material is short-circuited by itself.

Description

Heating device and a heating system comprising such heating device

Background of the Invention

The invention concerns the heating device and a heating system comprising such a heating device.

State of the art

A heat pump process has three phases, at first heat is obtained from the surrounding air, then this heat is increased and finally used, for example, to heat the house or domestic water.

The first stage is ensured by evaporator 1 , which circulates the coolant in the pipeline covered by lamellas 5, where the temperature of the coolant is always lower than the temperature of the surrounding air. In the other words, the coolant receives heat from the surroundings and heats up. In the next stage, the coolant is compressed by compressor 2, which significantly increases its temperature. In this way, hot gas is created, and in the third phase the gas is led to a heat exchanger 3, where it transfers the heat to the secondary circuit, which distributes it around a house. Subsequently, the cooled coolant passes in the form of a liquid through an expansion nozzle or a capillary, where it is turned into a gas again, for which it consumes the heat of vaporization, which is cooled sharply below the ambient temperature. The coolant is subsequently heated in the evaporator 1 by receiving heat from its surroundings, and entire process continues. The design of the heat pump is presented in Fig. 1 .

However, energy withdrawal results in formation of frost on the evaporator 1 , which reduces efficiency and increases the energy demand for the operation.

Currently, this icing is removed, for example, by changing the coolant flow mode in certain cycles, using a four-way valve, and the coolant is compressed in the evaporator 1. It is heated by the compressing coolant, the ice is melted and the resulting water drains away. However, disadvantage of this method is, that for this reverse operation, the heat pump consumes energy from, for example, the heated object.

Another way is preheating method. In such a case, the heat for defrosting of the evaporator 1 is taken from a heating system, when it is necessary, by change of the meaning of the circuit function, to heat the entire part of the circuit. Even for this phase of the heat pump's operation, it is necessary to take the necessary energy from the heating system, which will cool it down. Circuits with a small amount of water, low- energy houses, etc., are particularly sensitive to this phase, as the energy consumption of the house will increase due to the operation of the direct heating element, which significantly worsens the overall energy balance of the operation. This is the main reason why use of, for example, a direct heater is immediately rejected. Another disadvantage of the method is long defrosting time, as the device is essentially out of order during defrosting. The defrosting process can take several tens of minutes under certain adverse conditions. In addition, sudden changes in pressure during reversal in the cooling circuit can significantly shorten the life of an engine of a compressor, check valves, solenoid valves, four-way valves and other components.

An interesting option for the heating is an induction heating device. Such possibilities are listed in several books, but they are completely unsuitable for solving our problem.

The document EP0462544 describes an induction heating device, which comprises a cylindrical source of magnetic induction in a form of an induction coil, outside of which a tubular heating body made of an electrically conductive material, intended for a flow of a heated liquid, short-circuited by shorting clamp, is placed in its magnetic field. The mentioned device is used to transfer of a magnetic flux by use of magnetic core to the heating device. Although the document mentions the use of a short-circuited non-magnetic tube wrapped around the outer surface of the coil, it does not serve to dissipate heat here. The heat is not removed by the water in the pipe. The hot water is generated by induction, therefore, it cannot dissipate heat, quite the opposite. If it does not flow, the coil will be heated. In addition, due to the fact that the device works with a low frequency of 50Hz, it needs a magnetic core and thus completely excludes use of similar devices for evaporators. Another disadvantage is that during its long-term use, there is loss of power caused by loss of the magnetic properties of the core due to its overheating, when it may even melt.

The document JPS56146824 describes a device intended for heating a magnetic material inserted in a coil, where its heating is the goal of this device. Therefore it is the opposite way of use, where the core is required.

The document LIS2011180531 presents a coil, where a tubular body is inserted, but the document also mentions the necessity of presence of a magnetic material. This material is heated by the coil and enables heating of a substance, which flows through the tube. So the tube is used for completely different reason than the one we solve with our modification. In addition, it also heats up in the same way as the core of the above mentioned document EP0462544. In principle, further cooling of the magnetic elements is not possible there, because it is the heat of these magnetic materials that causes the heating of the liquid passing through the pipe, and lowering its temperature would thus result in lowering the temperature of the heated liquid as well, which leads to the same problem, which we want to solve in the document EP0462544.

A combination of the documents EP0462544 and the document LIS2011180531 does not solve the problem either, for the reason that the device according to the EP document does not allow operation without presence of a magnetic core. Therefore, if the core will be replaced by tube, as stated in the US document, the result will be not only change of the design of the core, i.e. from a solid shape to a tube shape, but also a significant deterioration of its output. Its core size is crucial there and any variant of a hollow core is thus ruled out.

The state of the art is also an induction heating device comprising a source of magnetic induction, where in a magnetic field a tubular heating element intended for the flow of heated liquid is placed, which is however made of an electrically conductive non-magnetic material, which seemingly contradicts the principle of induction heating. In order to be able to heat non-magnetic material by induction, it was found out, that it needs to be supplemented by shorting clamp. This also eliminates need for a magnetic core. However, the disadvantage of such heating device is the necessity of the short- circuiting terminal, which is danger to its surroundings, because it transmits unwanted heat, causes tension and vibrations, and may cause an electric shock to an operator in case of improper handling. If these clamps are loosen during its use, it would be very difficult to find the cause of the malfunction. Furthermore, it cannot be said that it is a universal solution, since these devices are already professionally assembled during its production, while in our case we need to solve the problems on already assembled or mass-produced devices, where mounting of the shorting terminals would require expert knowledge, disassembly of the previous structure and subsequent assembly of the equipment, and thus other associated costs. Another problem is also power and dimensions of the induction devices used to now, which drive away an expert in the technical field from its use to heat such parts as, for example slats of an evaporator. Another problem is need to comply with the parameters of the heated house regarding to its low energy demands or passivity. Because another device is necessary, experts will not be pleased to use such technology. The aim of the invention is to present such solution, where above mentioned disadvantages of the state of the art are eliminated.

Feature of the invention

The above mentioned disadvantages are considerably eliminated by heating device comprising a non-magnetic material intended for heating and an induction heating coil for heating it, where this non-magnetic material is stored in the magnetic field of this induction heating coil, where this non-magnetic material is short-circuited by itself.

In an advantageous embodiment the heating device is an evaporator 1 of a heat pump, comprising an induction heating coil 6, tubes 4 intended for passing of the heated coolant, and slats 5, where the non-magnetic material designated for heating is the slats 5.

In another advantageous embodiment the heating device is an evaporator 1 of a heat pump, comprising an induction heating coil 6, tubes 4 intended for passing of the heated coolant, and slats 5, where a non-magnetic material designed to be heated is at least part of at least one tube 4.

In another advantageous embodiment induction coil 6 is located on the outside of the evaporator 1 in front of the slats 5, and its surface covers 50-90% of the surface of the slats 5.

In another advantageous embodiment the induction coil 6 is fitted 2 to 3 cm from the slats 5.

In another advantageous embodiment the induction coil 6 is located inside the evaporator 1 between the slats 5 and the tubes 4.

In another advantageous embodiment that the induction coil 6 is located around the circumference of the evaporator 1 .

The above mentioned disadvantages are considerably eliminated by heating system characterized in that it comprises a heating device according to one of the claims, a measuring device for determining the temperature of the heated material, data linked to a control unit for switching the induction coil 6 with regards to the determined temperature of the heated coolant.

Description of the drawings The invention will be further explained by use of drawings, in which Fig. 1 represents the circuit diagram of a heating pump according to the state of the art and Fig. 2 represents the profile of the evaporator equipped by heating equipment according to the invention.

Preferred embodiments of the invention

The heating device according to the invention comprises an evaporator 1 of a heat pump presented in Fig. 2, which comprises an induction coil 6, which is positioned relative to the evaporator 1 in such a way, that its magnetic field is within the reach of the structural elements of the evaporator 1 , e.g. the slats 5 of the evaporator 1 and/or tubes 4 intended for passing of a heated coolant, which are intended for heating.

The evaporator 1 is a standard outdoor heat pump exchanger, see the above mentioned description in the state of the art, which comprises the parallel fitted tubes 4 intended for passing of a heated coolant, which are connected to each other by pipe elbows, thus forming one tube passing through the inner part of the evaporator 1 , the slats 5 covering these tubes 4 before access from the outside and a fan not shown in the picture, intended for blowing these slats 5, and which blows outwards from the evaporator 1 .

Instead of an evaporator 1 , the presented technology can also be used for heating of another non-magnetic heated devices or materials, which allow the creation of eddy currents and thus their heating. Not all of them require existence of the shorting terminal to create eddy currents, as they are self-shorting, i.e. they are shorted by themselves. For example, a non-magnetic tubular spiral can be used, where the ends of which are directly connected to each other, which forms a non-magnetic grid, which by the very definition of the term "grid" it is also itself connected, and so on.

In the other words, if the non-magnetic material is self-shortened, the shortening terminals are not necessary, but it is possible to have both of the solution or only one of them.

Turn on of the induction coil 6 is carried out by control unit, which switches it according to predefined change of pressure in the circuit, if drop of coolant temperature appear, etc., and which also controls, for example, the operation of the fan, which fully starts, when defrosting is in progress, which blows the slats 5 and thus remove the rest of the water condensation out of the evaporator 1 . The measurement of the above- mentioned parameters, is carried out by standard measuring devices, known from the state of the art, which transmit the measured values to the control unit intended for its evaluation.

According to the exemplary embodiment shown in Fig. 2, the induction coil 6 is placed in front of the slats 5 of the evaporator 1 , for example in such way, that it basically copies some slats 5, i.e. it is parallel to them, while overlapping 50-90% of the area given by the slats 5. This percentage distribution depends on the types of the evaporator 1 and the power of the induction coils 6.

Such solution could not be designed without earlier complex calculations and performed tests for determination of necessary dimensions of the induction coil, whose small dimensions enable the proper function of the evaporator 1. Previously, it was assumed, that such small dimensions are insufficient and that the standard used coils would make the use of the evaporator impossible - the air passing between the slats 5 would be significantly worst and clogging could also occur.

In an exemplary embodiment, the induction coil 6 in front of the slats 5 is mounted on supports 8 at a distance from the slats 5, preferably 2-3 cm.

In another preferred embodiment, the induction coil 6 is located inside the evaporators 1 , i.e. between the slats 5 and the tubes 4, on the connecting metal knees of the tubes 4, which close the loop of the evaporator 1 , or around the perimeter of the evaporator 1 .

Due to density and arrangement of the grid of the evaporator 1 , where the grid means the shape of the mutual arrangement of the slats 5 and the tubes 4, which are perpendicular to each other, not too much power of the induction device is needed. Calculations and measurements showed, that power up to 1000W is sufficient for approx. 1 m² of the evaporator.

The principle is as follows: The inductive transfer of energy from the induction coil 6 causes immediately heating of the slats 5 and tubes 4 of the evaporator 1 . The defrosting efficiency can be increased by subsequently switched fan of the evaporator 1 , according to a predetermined algorithm, which results in rapid cleaning of the evaporator 1 from water, without need to cool the heated space, and with minimal costs.

The above mentioned solution is a result of a long-term experimental work performed by the inventor, who discovered, that contrary to the current assumption, that only surfaces made of magnetic material can be heated by induction, nonmagnetic surfaces can also be heated. The evaporator of a heat pump is already short- circuited based on its structural necessity, as well as its slats, and the application of such technology is therefore possible.

Even so, the use of induction for defrosting of the evaporator would not be completely obvious for experts, since it is de facto the use of an additional direct heater, which, due to its use exclusively in high cold, was assumed necessity to have excessive outputs, even in the case of induction, which would completely suppress the importance of heat pumps, which are installed in houses precisely for reasons of reduction of energy demand. Another expected problem is extreme humidity and temperature conditions, which could have a bad effect on safeness of an operator and life of a used equipment, also because the induction coil 6 heats the entire surface of the evaporator 1 and the entire connected circuit including the compressor, the exchanger, etc. This meaning was found incorrect.

Because of the performed test and experiments it was found out, that the induction coil 6 connected in this way is not dangerous for the operator or for other devices. Furthermore, the power of the induction coil 6, which is necessary for sufficient heating of the required parts of the evaporator 1 and thus for its defrosting were measured. For example, it was found out, that a frozen evaporator 1 with an output 2,5 kW, equipped with an induction coil 6 fitted in front of the slats 5, which covers 50% of their surface, with output 700 W, the tubes 4 were defrosted (from temperature of - 21 °C to the final temperature 13,4°C) in 1 min and 40 s. This is a proof, that the use of such a device does not significantly increase the energy demand of the used device, or of the building where the device is used, as the total power required for this defrosting was 19,43 W.

Claims

1 . Heating device comprising a non-magnetic material intended for heating and an induction heating coil for heating the material, where this non-magnetic material is stored in the magnetic field of this induction heating coil, characterized in, that this non-magnetic material is short-circuited by itself.

2. Heating device according to the claim 1 , characterized in, that the heating device is an evaporator (1 ) of a heat pump, comprising an induction heating coil (6), tubes (4) intended for passing of the heated coolant, and slats (5), where the non-magnetic material designated for heating is the slats (5).

3. Heating device according to the claim 1 , characterized in, that the heating device is an evaporator (1 ) of a heat pump, comprising an induction heating coil (6), tubes (4) intended for passing of the heated coolant, and slats (5), where a non-magnetic material designed to be heated is at least part of at least one tube (4).

4. Heating device according to the claim 2 or 3, characterized in, that the induction coil (6) is located on the outside of the evaporator (1 ) in front of the slats (5), and its surface covers 50-90% of the surface of the slats (5).

5. Heating device according to the claim 4, characterized in, that the induction coil (6) is fitted from 2 to 3 cm from the slats (5).

6. Heating device according to one of the claims 2 to 3, characterized in, that the induction coil (6) is located inside the evaporator (1 ) between the slats (5) and the tubes (4).

7. Heating device according to one of the claims 2 to 3, characterized in, that the induction coil (6) is located around the circumference of the evaporator (1 ). Heating system characterized in, that it comprises a heating device according to one of the claims 1 to 7, a measuring device for determining the temperature of the heated material, data linked to a control unit for switching the induction coil (6) with regards to the determined temperature of the heated coolant.