Patent Application
20240271798
The present invention relates to a heating apparatus with a housing, comprising an apparatus volume enclosed by the housing and having a liquid supply for a liquid flow of a first liquid temperature, a liquid discharge for the liquid flow at a second, higher liquid temperature, a gas inlet for a gas flow, a gas outlet for the gas flow, a heat exchanger between the gas flow and the liquid flow, which is able and configured to enhance a heat-exchanging contact between the liquid flow and the gas flow, and a compressor with a power consumption, which is driven by a drive and is able and configured to bring the gas flow to an increased pressure and an increased temperature upstream of the heat exchanger.
In a heating apparatus of the type described in the preamble mechanical energy is supplied to the gas flow and converted into heat by means of the compressor mechanism. This heat is then relinquished by means of the heat exchanger to the liquid flow, which thereby increases in temperature. This principle is usually referred to as the Brayton cycle, after the American engineer who based his so-called ready motor on this phenomenon. The cycle is sometimes also referred to as Joule cycle after the British physicist James Prescott Joules, and the device is also described as an air cycle heat pump.
The Brayton cycle or Joule cycle is a thermodynamic cycle process which converts heat into mechanical energy under constant pressure. In the apparatus of the type described in the preamble this process is applied in reverse. This is also the case in the hot water apparatus described in Chinese patent application CN 108730763. This apparatus comprises a motor driven compressor in parallel with a turbine-driven compressor, both as final step in a series with an otherwise motor driven compressor. An incoming airflow is brought to an increased temperature by this system of compressors, and the heat generated therein is then relinquished via a heat exchanger to a primary water flow.
Although use is in this known apparatus made of the above stated Brayton operating principle, in the known apparatus this results in a relatively complicated setup involving no fewer than three compressors and a turbine, two compressors of which are moreover provided with a motor drive. Not only is this not very efficient from an energetic viewpoint, this multitude of components furthermore increases the cost price and susceptibility to malfunction of the apparatus, which is therefore not very attractive in economic and operational respect either.
The present invention has for its object, among others, to provide a heating apparatus which has considerably more potential.
In order to achieve the stated object a heating apparatus of the type described in the preamble has the feature according to the invention that upstream of the gas outlet a turbine driven by the gas flow is provided in the gas flow in the apparatus volume, which turbine produces an output capacity which is supplied to the drive of the compressor, and that the compressor comprises a mechanical drive which supplements the power supplied by the turbine up to the power consumed by the compressor. The turbine thus already provides for a part of the necessary power consumed by the compressor. The mechanical drive thereby need provide only the deficit, for instance in the form of a motor drive of the compressor.
The heating apparatus according to the invention is distinguished by a driven turbo-compressor which is formed by the energetic coupling of the turbine to the driven compressor. The turbo-compressor is particularly a centrifugal air compressor with only one moving part in the form of a continuous rotor shaft which mutually connects the rotors of the compressor and turbine. This rotor can be suspended in air foil bearings. Magnetic bearings can optionally also be applied for this purpose. In both cases there is low resistance during operation, and only very limited wear occurs. In addition, such a system is free from oil or other lubricants, and almost no maintenance of mechanical components is needed. The turbo-compressor has a compressor blade wheel on one side and a turbine blade wheel on the other side. The two can be dimensioned and designed as required and be adjusted to each other and to the application and be manufactured accordingly, so that both components preferably perform an efficient compression or expansion at an identical and for each component optimal rotation speed. By making use of the same rotation speed, transmission losses are limited to a minimum. Situated between the compressor and turbine of the turbo-compressor is the drive, for instance in the form of a permanent magnet synchronous (PMS) motor which is suitable for high rotation speeds.
A particular embodiment of the apparatus has for this purpose the feature that the turbine is coupled mechanically to the drive of the compressor. In practice, such a driven turbo-compressor in the apparatus has been found to suffice, which results in a considerable saving in respect of components and a significant increase in both the energy and operational efficiency of the apparatus. In a preferred embodiment the apparatus according to the invention is characterized here in that the mechanical drive of the compressor comprises a drive motor, particularly an electric motor, with a drive shaft, and that an output shaft of the turbine is coupled to the drive shaft of the drive motor. This is a direct coupling between the turbine and that of the compressor. Their individual rotation speeds can be tuned by a suitable transmission ratio of an intermediate transmission. The rotors and blades of the turbine and compressor are however advantageously designed and dimensioned such that both operate at at least substantially the same rotation speed in an at least substantially optimal rotation speed range.
In a further preferred embodiment a heating apparatus according to the invention has the feature that the housing closes the apparatus volume enclosed thereby at least substantially gas-tightly, that the compressor comprises a compressor inlet for the gas flow, and that the compressor inlet receives the gas flow from the gas inlet of the apparatus via the apparatus volume. The enclosed apparatus volume of the housing is thus included in the gas flow which is thereby able to enter into heat-exchanging contact with consumers housed in the same apparatus volume. The motor-driven compressor in particular will thus for instance unavoidably generate heat. This heat can thus advantageously be taken up at least partially by the gas flow before the gas flow is admitted by the compressor.
In this latter respect a particular preferred embodiment of the apparatus according to the invention is characterized in that an electronic control device of the apparatus is provided in the apparatus volume, wherein the control device is placed to enter into heat-exchanging contact with the gas flow upstream of the compressor. As with many other electronics, a control device usually unavoidably dissipates heat. This is thus taken up at least partially by the gas flow. Not only does this heat up the gas flow, which contributes to the energy efficiency of the device; this also results in a cooling which is desirable for many electronics.
A further energy advantage is achieved with a further particular embodiment of the apparatus according to the invention which is characterized in that provided in the apparatus volume between the gas flow taken in at the gas inlet of the apparatus and the gas flow blown out at the outlet is a further heat exchanger, which enhances a heat-exchanging contact between the gas flow taken in and blown out. Any residual heat in the released gas flow can in this way be recovered at least partially by enriching the admitted gas flow therewith.
With a view to residential applications, a further preferred embodiment of the apparatus according to the invention has the feature that the apparatus volume of the housing is enclosed by walls, which walls are acoustically damping. With such an acoustic separation of the apparatus volume relative to the surrounding area the acoustic impact on the environment can be reduced. It is particularly in residential applications that this is an important factor for acceptance of such an apparatus, such as in homes and offices, but it is also more generally advantageous.
In order to also suppress sound which could otherwise still escape via the gas outlet a further embodiment of the apparatus according to the invention is characterized in that the gas outlet is provided with an acoustic damper device. A preferred embodiment has the feature here that the gas outlet comprises the acoustic damper device and the damper device is arranged inside the apparatus volume. In this latter case it is not only an additional acoustic insulation of the walls of the housing that is utilized, but any formation of ice in the gas outlet as a result of the sometimes very low temperatures of the blown-out gas flow is also avoided. As a result of the consumers, conduits and heat exchanger(s) present therein, the apparatus volume will generally provide a frost-free environment in which possible ice formation is able to melt and to be discharged as condensation.
Besides serving as a primary heat supply, via said primary liquid flow, the heating apparatus can if desired also serve to supply heat to a further thermodynamic system. In this respect a further particular embodiment of the apparatus according to the invention has the feature that a further heat exchanger is provided which enhances heat-exchanging contact between the liquid flow and a secondary liquid flow. In order to limit energy losses in the secondary liquid flow, a preferred embodiment of the apparatus according to the invention in this case also has the feature that the housing comprises the further heat exchanger in the apparatus volume and is provided with a supply and a discharge for the secondary liquid flow. Heated tap water can for instance be provided for homes and offices by means of this secondary liquid flow. A further embodiment of the apparatus has for this purpose the feature that the secondary liquid flow feeds a residential tap water system.
Although the apparatus is suitable for various gases in the gas flow and the liquid flow can also have different compositions, a most practical embodiment of the apparatus according to the invention has the feature that the gas flow comprises an ambient airflow which is taken in from an area surrounding the apparatus and is blown out to the surrounding area, particularly an outside airflow. Not only is there usually unlimited immediate availability of such an airflow, air is also harmless to the environment and thus also a responsible choice from an environmental viewpoint.
In respect of the liquid flow, a particularly practical embodiment of the apparatus according to the invention has the feature that the liquid flow comprises a water flow which is carried through a central heating system of a building, particularly of a home. It has been found that, using mainly existing and commercially widely available components, such an apparatus can be realized in economically competitive manner and having a thermal power which is sufficient for an average home, including existing homes. The invention thereby makes a significant contribution to the energy transition wherein gas-fired heating boilers and similar heating apparatuses on the basis of fossil fuel combustion must be phased out as much as possible.
The invention will be further elucidated hereinbelow with reference to an exemplary embodiment and an accompanying drawing.
In the drawing:
It is otherwise noted here that the figures are purely schematic and not always drawn to (the same) scale. Some dimensions in particular may be exaggerated to greater or lesser extent for the sake of clarity. Corresponding parts are designated in the figures with the same reference numeral.
Air inlet 11 carries an admitted airflow via a regenerator W1 to an internal apparatus volume 15 inside the airtight housing 10. Accommodated inside this apparatus volume 15 is a compressor 30 with a compressor inlet 31 which opens freely into the apparatus volume 15. In this embodiment the compressor inlet 31 comprises a trumpet-shaped suction mouthpiece which is shown separately in further detail in
The regenerator W1 comprises an air/air heat exchanger and has a primary air inlet in open connection with the air inlet 11 of the apparatus, and opens with a primary air outlet 12 into apparatus volume 15. The airflow admitted via the regenerator W1 at atmospheric pressure and temperature is thus drawn in by compressor 30 via the apparatus volume at a flow rate in the order of between 1100 and 1200 cubic metres per hour. For this purpose the compressor 30 is driven by a PMS electric motor 40 with a rotation speed in the order of 35000-50000 revolutions per minute. An electric power supply of the electric motor and of the other electric or electronic components in the apparatus are taken from a mains electricity, for which a common single-phase mains current with an alternating voltage of 230 volt or a three-phase power current with an alternating voltage of 400 volt suffices.
The compressor 30 compresses the admitted airflow to an increased pressure in the order of around 2 bar. In this example a compression pressure of about 1.85 bar is realized. The mechanical energy thus supplied in the airflow then translates according to the general gas laws into a temperature increase in the order of 65° C. This hot airflow leaves compressor 30 via a compressor outlet 32. The compressor outlet 32 is connected to a primary inlet 41 of an air/water heat exchanger W2.
On a secondary side a secondary inlet 43 of heat exchanger W2 is coupled to the water supply 13 of the apparatus and receives therefrom a return water flow of the CH system to be heated. A typical return temperature thereof amounts to around 30° C. This temperature rises to between 70° C. and 80° C. by heat exchange with the heated air of the compressor.
The heated CH water is discharged at a secondary outlet 44 of heat exchanger W2 and carried via a three-way valve 60 to a hot water outlet 14 of the apparatus. The heated water can be removed there for supply of the CH system.
The airflow of compressor 30 has lost a large part of its heat content in the heat exchanger W2 and leaves the heat exchanger at a primary outlet 42 at a temperature in the order of between 30° C. and 35° C. The airflow coming from compressor 30 is carried via a secondary side of the regenerator W1 so as to there relinquish a remainder of its heat to the airflow admitted via the inlet 11. The admitted airflow is typically admitted at a temperature in the order of 5° C. and thereby heats up to the order of 20-30° C., and is admitted to the apparatus volume at this temperature.
The flow path of the admitted airflow is configured such that the airflow can enter into heat-exchanging contact with different energy consumers in the apparatus volume, such as particularly the electric motor 40 and a central control unit 100 with power electronics and an inverter of the apparatus. Not only does this provide an air cooling desirable for these components; this also contributes to the energy efficiency of the device in that the inlet airflow of compressor 30 is thus already brought to a higher temperature.
The temperature of the airflow blown out by compressor 30 decreases in the regenerator W1 to the order of between 5 and 10° C. This airflow still has an increased pressure in the order of 1.85 bar (185 kPa) and is carried to the inlet 51 of a turbine 60, and loses its overpressure therein. The mechanical energy released here is coupled to the output drive shaft of the electric motor 40 and thereby contributes to the power consumed by the compressor.
The turbo-compressor 30, 40, 50 is a centrifugal air compressor with only one moving part. This rotor is held in place by means of air foil bearings. Magnetic bearings can optionally also be applied for this purpose. In both cases there is no contact during operation between the rotor and the motor housing, whereby there is a low resistance and only very limited wear occurs. In addition, the system is free from oil and other lubricants, and almost no maintenance of mechanical components is needed. The turbo-compressor 30, 40, 50 has a compressor 30 blade wheel on one side and a turbine 50 blade wheel on the other side. The two are adjusted to each other and to the application as required and manufactured accordingly, so that an efficient compression and expansion takes place at an identical and for each component 30, 50 optimal rotation speed. A mutually differing rotation speed can optionally be imposed on the two blade wheels by a transmission ratio. By making use of the same rotation speed however, transmission losses are thus however limited to a minimum. Situated in the centre of the turbo-compressor is the drive in the form of permanent magnet synchronous (PMS) motor which is suitable for high rotation speeds.
Adiabatic expansion of the air also causes the temperature of the airflow to drop far below freezing point. The airflow leaves turbine 60 at a turbine outlet 52, typically at a temperature in the order of −30° C. to −40° C. At this temperature the airflow is blown out by the apparatus via the air outlet 12. An acoustic damper can optionally be incorporated in air outlet 12 in order to limit the noise impact of the apparatus on the surrounding area. This is preferably provided in the relatively warm apparatus volume 15 in order to prevent freezing and formation of condensation therein.
The heat exchangers W1, W2 are of the plate fin type and have a counterflow orientation. The counterflow orientation provides for higher thermal effectiveness in a compact and weight-saving format. The relative positioning of turbo-compressor (30, 50) relative to heat exchangers (W1, W2) is visible in the figures. The layout was designed with a view to minimizing the number of changes in direction between compressor outlet (32) and a turbine inlet piece (52) in order to achieve the smallest possible pressure drop.
In the shown embodiment a second hot water circuit is also provided. This is a tap water installation which is coupled to the apparatus via the three-way valve 60. This circuit is coupled to the primary water flow 13, 14 of the apparatus via a drinking water/water plate heat exchanger W3. Use is in this embodiment made of a tap water circuit lying wholly outside the apparatus, although one or more components thereof can if desired also be provided in the apparatus (volume). For the purpose of heating the tap water the three-way valve 60 carries the heated water via an inlet 81 and outlet 82 over a primary side of the heat exchanger W3. The heat exchanger W3 receives on its secondary side 83, 84 the tap water which is being carried to a hot water storage tank 80, usually referred to as boiler. Use is in this embodiment made of 50-litre boiler, although a greater or smaller content thereof can be opted for if desired. A water pump 85 in the tap water circuit circulates the tap water over the heat exchanger W3 and the boiler 80, which is thereby held at temperature. The cold mains water admitted at the tap water inlet 81 is supplied at a tap water outlet 82 of the system at a temperature typically in the order of 80° C.
All in all, the invention provides a heating apparatus which, owing to the absence of an internal combustion of fossil fuels, provides a sustainable alternative to common heating apparatuses which are still dependent on the combustion of wood, natural gas or oil. The invention hereby particularly makes a contribution to the energy transition in which fossil fuels must be phased out as much as possible, and which is deemed necessary.
Although the invention has been further elucidated above with reference to only a single exemplary embodiment, it will be apparent that the invention is by no means limited thereto. On the contrary, many variations and embodiments are still possible within the scope of the invention for a person with ordinary skill in the art.
Use is thus made in the embodiment of an air cooling of the electric motor, although a liquid-cooled electric motor or another type of mechanical drive can also be applied for this purpose, particularly a water-cooled (electric) motor, optionally with a return of the primary heat generation flow. If desired, the heat dissipated in such a liquid cooling can also be exchanged with interposing of a secondary closed circuit. The same applies to a cooling of the electronics present in the housing, particularly the power electronics. These can also be cooled by a liquid cooling instead of by an air cooling, wherein the heat taken up in the liquid cooling is likewise fed at least partially back to the airflow directly or with interposing of a secondary circuit.
For the housing use is advantageously made of sound-damping panels. Acoustic metamaterials in particular are suitable for application in a sound-damping casing to be formed therefrom. Such acoustic metamaterials are specifically configured to remove or at least suppress determined frequencies from the sound so that they do not propagate 10 therein, or hardly so. In this way annoying vibrations can be prevented to significant extent from being able to penetrate outside the casing of the apparatus.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2028575 | Jun 2021 | NL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2022/056057 | 6/29/2022 | WO |
