Patent Grant
11754325
The water vapor is provided through the suction line 12 to a compressor/liquefier system 14 comprising a turbo-machine such as a radial compressor, e.g. In the form of a turbo compressor, designated with 16 in
The turbo-machine is coupled with a liquefier 18 configured to liquefy the compressed working vapor. Through liquefying, the energy contained in the working vapor is provided to the liquefier 18 in order to be provided to a heating system through the advance flow line 20a. The working liquid then flows back into the liquefier through the return flow line 20b.
According to the above-stated example, it is advantageous to extract the heat (energy) absorbed by the energy-rich water vapor directly through the colder heating water, the heat being absorbed by the heating water so that it heats up. Here, so much energy is extracted from the vapor that it is condensed and also takes part it heating circuit.
DE 4431887 A1 discloses a heat pump system with a lightweight, large-volume high-performance centrifugal compressor. Vapor leaving a second-stage compressor has a saturation temperature that exceeds the ambient temperature or that of available cooling water, which allows for heat dissipation. The compressed vapor is transferred by the second-stage compressor into the condenser unit consisting of a bulk layer that is provided within a cooling water spray unit on a top side, which is fed by a water circulation pump. The compressed water vapor rises in the condenser through the bulk layer where it comes into direct counter-flow contact with the cooling water that flows downwards. The vapor condenses and the latent heat of the condensation absorbed by the cooling water is ejected to the atmosphere via the condensate and the cooling water that are together removed from the system. The condenser is continuously flushed with non-condensable gases through a pipeline by means of a vacuum pump.
WO 2014072239 A1 discloses a liquefier having a condensation zone for a condensing vapor to be condensed in a working liquid. The condensation zone is configured as a volume zone and has a lateral boundary between the upper end of the condensation zone and the lower end. Furthermore, the liquefier includes a vapor introduction zone extending along the lateral end of the condensation zone and configured to supply vapor to be condensed laterally over the lateral boundary into the condensation zone. With this, without increasing the volume of the liquefier, the actual condensation becomes a volume condensation since the vapor to be liquefied is not only introduced frontally from one side into a condensation volume, or into the condensation zone, but laterally and advantageously from all sides. This not only ensures that the condensation volume provided is increased at the same external dimensions as compared to a direct counter-flow condensation, but that the efficiency of the condenser is simultaneously improved since the vapor to be liquefied in the condensation zone comprises a flow direction transverse to the flow direction of the condensation liquid.
A general problem with heat pumps is the fact that moving parts and in particular fast moving parts need to be cooled. Here, the compressor motor and especially the motor shaft are particularly problematic. Particularly for heat pumps which use radial impellers as compressors, which are operated very quickly in order to achieve a small design, e.g. in regions larger than 50,000 revolutions per minute, shaft temperatures may reach values that are problematic since they may lead to destruction of the components.
A further generally problematic disadvantage of heat pumps using a compressor motor with a radial impeller is that the activity of the radial impeller and the guide space arranged downstream causes the working vapor to overheat considerably. Overheated working vapor and in particular overheated water vapor, when using water as the working medium, has a higher viscosity and therefore a greater flow resistance than saturated vapor.
In principle, overheated working medium vapor is to first reduce its overheating in order to be able to then condense particularly well and efficiently. However, efficient condensation is particularly important in order to achieve a heat pump which, on the one hand, creates high performance values for heating or cooling, depending on the use of the heat pump. In addition, a heat pump should take up as little space as possible, placing limitations on the size of the condenser. The smaller the condenser is dimensioned, the smaller the “footprint” or the volume or space occupied by the heat pump will be. It is therefore of great importance to achieve highly-efficient condensation in the condenser of a heat pump. Only then, a heat pump having good efficiency and not having too large of a volume or footprint may be created.
According to an embodiment, a heat pump may have: an evaporator for evaporating a working liquid; a liquefier for condensing a compressed working vapor; a compressor motor with a suction mouth having attached thereto a radial impeller to convey a working vapor evaporated in the evaporator through the suction mouth; a guide space arranged to guide a working vapor conveyed by the radial impeller into the condenser; and a cooling device for cooling the guide space or the suction mouth with a liquid, wherein the cooling device is configured to guide the liquid onto an outside of the guide space or of the suction mouth, wherein the outside is not in contact with the working vapor, and wherein an inside of the guide space or of the suction mouth is in contact with the working vapor.
Another embodiment may have a method for pumping heat with an evaporator for evaporating a working liquid: a liquefier for condensing a compressed working vapor; a compressor motor with a suction mouth having attached thereto a radial impeller to convey a working vapor evaporated in the evaporator through the suction mouth; and a guide space arranged to guide a working vapor conveyed by the radial impeller into the condenser, having the steps of: cooling the guide space or the suction mouth with a liquid, wherein the liquid is guided onto an outside of the guide space or of the suction mouth, wherein the outside is not in contact with the working vapor and wherein an inside of the guide space or of the suction mouth is in contact with the working vapor.
Another embodiment may have a method for manufacturing a heat pump with an evaporator for evaporating a working liquid; a liquefier for condensing a compressed working vapor; a compressor motor with a suction mouth having attached thereto a radial impeller to convey a working vapor evaporated in the evaporator through the suction mouth; and a guide space arranged to guide a working vapor conveyed by the radial impeller into the condenser, having the steps of: attaching a cooling device for cooling the guide space or the suction mouth with a liquid, wherein the cooling device is arranged to guide the liquid onto an outside of the guide space or of the suction mouth, wherein the outside is not in contact with the working vapor and wherein an inside of the guide space or of the suction mouth is in contact with the working vapor.
The present invention is based on the finding that cooling of the guide space and/or the suction mouth with a liquid is employed in order to avoid a reduced condenser efficiency due to an overheated working medium vapor. With this, the temperature of the guide space and/or the suction mouth is brought and maintained as close as possible to the saturation pressure temperature of the pressure prevailing in the liquefier. Thus, energy/heat from the vapor flow is coupled in via the material, or wall, of the suction mouth or the guide space. If water is used as the working liquid, which is the case in embodiments, the water brought to the suction mouth or guide space starts to boil and therefore releases its energy. The guide space and/or the suction mouth are therefore kept very close to the saturated vapor temperature of the vapor pressure that is first sucked in by the radial impeller via the suction mouth element and is fed into the contacting space from there. The working vapor is then compressed in the guide space to its intended liquefier, or condenser, pressure. Cooling the guide space and/or the suction mouth therefore prevents the working medium vapor from overheating too much. When entering the condenser, the working medium vapor therefore no longer has to reduce its overheating in order to be able to condense easily. Instead, the working medium vapor may directly condense in the condenser without further loses with respect to time or volume or running distance. With this, an efficient condenser may be achieved even if the condenser volume is made smaller compared to an embodiment that would not have employed a corresponding guide space/suction mouth cooling.
In embodiments of the present invention, the guide space is configured of a thermally well-conducting material. In this way, the guide space extracts energy from the vapor flowing past it and transfers it directly to the cooling water that flows around the guide space or the suction mouth. With this, the guide space is kept even better at the saturated vapor temperature of the vapor pressure. On the other hand, liquefaction in the guide space is prevented due to the remaining thermal resistance of the material of the guide space, as the overheating is not fully reduced, but only to a large extent. However, this remaining overheating ensures that condensation does not already take place in the guide space but only in the liquefier where it takes place particularly efficiently.
In embodiments of the present invention, the cooling liquid for the guide space is previously guided through a motor ball bearing and/or through an open motor cooling that is advantageously used. Through the open motor cooling, the cooling liquid is again cooled down through partial evaporation back to the saturated vapor temperature. In the cascade of the ball bearing cooling and the motor cooling, the cooling liquid releases the energy absorbed through the ball bearing cooling already in the motor cooling. Thus, an optimally tempered liquid medium is provided for the open guide space cooling.
In implementations, the upper part of the outside of the guide space is first filled with liquid. In such a one-sided guide space cooling, the working liquid would then simply overflow, which is unproblematic or even desired, since the working liquid then simply flows into the condenser, into which, in embodiments of the present invention, working liquid is introduced in any case in the form of a “shower”. In further embodiments, the cooling liquid is further guided from the upper guide space cooling, i.e. the cooling of the top side of the guide space, into an additional lower guide space cooling and/or suction mouth cooling. At the end of the guide space there is an open area with an overflow. Through evaporation, the working liquid constantly cools itself down to the saturated vapor temperature. The remaining working liquid also overflows and simply flows into the condenser volume in order to be further processed accordingly. Alternatively, however, the working liquid may also be a working liquid that is not the working liquid of the heat pump, especially since the working liquid does not necessarily have to come into contact with the compressed working vapor according to the implementation.
The present invention is further advantageous in that thermal component loads are further reduced by the guide space cooling and/or the suction mouth cooling, which typically take up relatively large surfaces in a heat pump, being arranged close to the compressor. Due to the liquid cooling used, which advantageously takes place at the pressure level prevailing in the condenser, a highly-efficient evaporation cooling is achieved. Through this evaporation cooling, the entire compressor may be kept close to the saturated vapor temperature. In embodiments, motor losses, bearing losses and overheating in the compression are essentially reduced through evaporation in order to achieve not only a highly efficient heat pump, but also a heat pump that is safe and stable in operation.
Further aspects and advantages of embodiments are presented in the following.
The heat pump according to a further aspect includes a special convective shaft cooling. This heat pump comprises a condenser having a condenser housing, a compressor motor attached to the condenser housing and having a rotor and a stator, wherein the rotor comprises a motor shaft having a radial impeller attached thereto which extends into an evaporator zone, and a guide space configured to receive vapor compressed by the radial impeller and to guide the same into the condenser. In addition, the heat pump comprises a motor housing surrounding the compressor motor and advantageously configured to maintain a pressure that is at least the same as the pressure in the condenser. However, a pressure that is larger than the pressure behind the radial impeller is also sufficient. In certain implementations, this pressure is set to a pressure that is in the middle between the condenser pressure and the evaporator pressure. In addition, a vapor feed is provided in the motor housing in order to feed vapor in the motor housing to a motor gap between the stator and the motor shaft. Furthermore, the motor is configured such that a further gap extends from the motor gap between the stator and the motor shaft along the radial impeller to the guide space.
This results in a relatively high pressure in the motor housing, being higher than the mean pressure from the condenser and the evaporator and advantageously the same as or higher than the condenser pressure, while a lower pressure is present in the wider gap that extends along the radial impeller to the guide space. This pressure, which is the same as the mean pressure from the condenser and the evaporator, prevails due to the fact that the radial impeller creates a high pressure area in front of the radial impeller and a low pressure or vacuum area behind the radial impeller when compressing the vapor from the evaporator. In particular, the high pressure area in front of the radial impeller is still smaller than the high pressure in the condenser and the low pressure “behind” the radial impeller, so to speak, is still smaller than the high pressure at the exit of the radial impeller. The high condenser pressure is only present at the exit of the guide space.
This pressure gradient, which is “coupled” to the motor gap, ensures that working vapor is pulled from the motor housing through the vapor feed along the motor gap and the further gap into the condenser. This pressure is at the temperature level of the condenser working medium or above. However, this is especially advantageous since this avoids all condensation problems that would support corrosion etc. within the motor and in particular within the motor shaft.
In this aspect, the coldest working liquid available in the evaporator is therefore not used for the convective shaft cooling. The cold vapor in the evaporator is not used either. Instead, for the convective shaft cooling, the vapor present in the heat pump at condenser temperature is used. Due to the convective nature, this still provides sufficient shaft cooling, i.e. a significant and especially adjustable amount of vapor flows around the motor shaft due to the vapor feed and the motor gap and the further gap. At the same time, the fact that this vapor is relatively warm in contrast to the vapor in the evaporator ensures that there is no condensation along the motor shaft in the motor gap and/or the further gap. Instead, a temperature that is higher than the coldest temperature is created here. Condensation takes place at the lowest temperature in a volume and does therefore not take place within the motor gap and the further gap since they are surrounded by warm vapor.
This ensures a sufficient convective shaft cooling. This prevents excessive temperatures in the motor shaft and the associated wear and tear. In addition, condensation in the motor, e.g. when the heat pump is at a standstill, is effectively prevented. This also effectively eliminates all operational safety problems and corrosion problems that would be associated with such a condensation. According to the aspect of convective shaft cooling, the present invention leads to a significantly reliable heat pump.
In a further aspect that relates to a heat pump with motor cooling, the heat pump includes a condenser having a condenser housing, a compressor motor attached to the condenser housing and having a rotor and a stator. The rotor includes a motor shaft having attached thereto a compressor motor for compressing a working medium vapor. Furthermore, the compressor motor has a motor wall. The heat pump includes a motor housing surrounding the compressor motor and advantageously configured to maintain a pressure that is at least the same as the pressure in the condenser, and having a working liquid inlet for guiding a liquid working medium from the condenser to the motor wall in order to cool the motor. However, the pressure in the motor housing may here also be significantly lower since the heat dissipation from the motor housing takes place through boiling, or evaporation. The thermal energy at the motor wall is therefore mainly transported away through the vapor from the motor wall, wherein this heated vapor is then dissipated, e.g. into the condenser. Alternatively, the vapor from the motor cooling may also be brought into the evaporator or to the outside. However, guiding the heated vapor into the condenser is advantageous. In this aspect of the invention, in contrast to water cooling where a motor is cooled by water flowing past it, cooling takes place by evaporation so that the heat energy to be transported away is carried off by the provided vapor dissipation. One advantage is that less liquid is needed for cooling and that the vapor may be simply guided away, e.g. automatically into the condenser, where the vapor condenses again and therefore transfers the thermal output of the motor to the condenser liquid.
Thus, the motor housing is configured, during operation of the heat pump, to form a vapor space in which the working medium is located due to bubble boiling or evaporation. The motor housing is further configured to lead away the vapor from the vapor space in the motor housing through a vapor discharge. It is advantageously led away into the condenser so that the vapor discharge is achieved by a gas-permeable connection between the condenser and the motor housing.
The motor housing is advantageously further configured, during operation of the heat pump, to maintain a maximum level of liquid working medium in the motor housing, and to further form a vapor space above the maximum level. The motor housing is further configured to guide working mediums above the maximum level into the condenser. This implementation makes it possible to keep the cooling very robust through vapor generation, as the level of working liquid ensures that there is enough working liquid on the motor wall for bubble boiling. Alternatively, instead of the level of working liquid constantly maintained, a working liquid may be sprayed onto the motor wall. The sprayed liquid is then dosed in such a way that it evaporates when contacting the motor wall, thereby achieving the cooling capacity for the motor.
The motor is therefore effectively cooled on its motor wall with liquid working medium. However, this liquid working medium is not the cold working medium from the evaporator, but the warm working medium from the condenser. Using the warm working medium from the condenser nevertheless provides sufficient motor cooling. At the same time, however, it ensures that the motor is not cooled too much and in particular that it is not cooled to the point where it is a coldest part in the condenser, or on the condenser housing. This would lead to condensation of working medium vapor on the outside of the motor housing, e.g., when the motor is not running but also during operation, which would lead to corrosion and other problems. Instead, it is ensured that the motor is well cooled but is at the same time the warmest part of the heat pump so that condensation, which takes place at the coldest “end”, does not occur at the compressor motor.
Preferably, the liquid working medium in the motor housing is kept at almost the same pressure as the condenser. This means that the working medium that cools the motor is close to its boiling point, as this working medium is a condenser working medium and is at a similar temperature as in the condenser. If the motor wall is now heated due to friction caused by motor operation, the thermal energy is transferred to the liquid working medium. Due to the fact that the liquid working medium is close to its boiling point, bubble boiling now starts in the motor housing in the liquid working medium that fills the motor housing up to a maximum level.
This bubble boiling enables an extremely efficient cooling due to the very strong mixing of the volume of liquid working medium in the motor housing. This boiling-assisted cooling may also be significantly assisted by a advantageously provided convection element, so that a very efficient motor cooling with a relatively small volume or no standing volume of liquid medium is eventually achieved, which, in addition, does not need to be controlled further because it is self-controlling. In this way, efficient motor cooling is achieved with a low technical effort, which in turn significantly contributes to an operational reliability of the heat pump.
Embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which:
This “entangled” or interlocking arrangement of the condenser and the evaporator, characterized in that the condenser bottom is connected to the evaporator bottom, provides a particularly high efficiency of a heat pump and therefore allows a particularly compact design of a heat pump. Regarding the size, the dimensioning of the heat pump, e.g. in a cylindrical shape, is such that the condenser wall 114 represents a cylinder with a diameter of between 30 and 90 cm and a height of between 40 and 100 cm. However, the dimensioning may be chosen according to the performance class of the heat pump, but advantageously in the above dimensions. This results in a very compact design which may be manufactured easily and cheaply since the number of interfaces, especially for the evaporator space that is almost at vacuum, may be reduced easily if the evaporator bottom is designed according to embodiments of the present invention in such a way that it includes all liquid inlets and outlets and that liquid inlets and outlets are therefore not necessary from the side or from above.
It should also be noted that the operating direction of the heat pump is such as is shown in
The “entangled” arrangement in which the evaporator is almost fully or fully arranged within the condenser enables a very efficient implementation of the heat pump with an optimal use of space. Since the condenser space extends to the evaporator bottom, the condenser space is formed within the entire “height” of the heat pump or at least within a significant portion of the heat pump. At the same time, however, the evaporator space is also as large as possible because it also extends almost over the entire height of the heat pump. Through the entangled arrangement, in contrast to an arrangement in which the evaporator is arranged below the condenser, the space is used in a most efficient manner. On the one hand, this enables a particularly efficient operation of the heat pump, and on the other hand, a particularly space-efficient and compact design, since both the evaporator and the liquefier extend across the entire height. This reduces the “thickness” of the evaporator space and also of the liquefier space. However, it has been found that reducing the “thickness” of the evaporator space tapering inside of the condenser is unproblematic since the main evaporation takes place in the lower area, where the evaporator space fills almost the entire volume available. On the other hand, the reduction of the thickness of the condenser space is not critical, especially in the lower area, i.e. where the evaporator space fills almost the entire available space, because the main condensation takes place at the top, i.e. where the evaporator space is already relatively thin, leaving sufficient space for the condenser space. The entangled arrangement is therefore ideal in that each functional space is given the large volume where said functional space needs the large volume. The evaporator space has the large volume at the bottom, whereas the condenser space has the large volume at the top. Nevertheless, even the corresponding small volume which remains where the other functional space has the large volume for the respective functional space contributes to an increased efficiency compared to a heat pump in which the two functional elements are arranged one above the other, as is the case in WO 2014072239 A1, for example.
In embodiments, the compressor is arranged at the top side of the condenser space such that the compressed vapor is deflected through the compressor on the one hand and is at the same time fed into an edge gap of the condenser space. This achieves condensation with particularly high efficiency since this achieves a cross-flow direction of the vapor with respect to a descending condensation liquid. This condensation with a cross-flow is particularly effective in the upper area, where the evaporator space is large, and in the lower area, where the condenser space is small in favor of the evaporator space, it no longer requires a particularly large area to still allow condensation of vapor particles that have penetrated up to this area.
An evaporator bottom that is connected to the condenser bottom is advantageously configured in such a way that it accommodates the condenser inlet and condenser outlet as well as the evaporator inlet and the evaporator outlet, wherein passages for sensors may also be provided in the evaporator or in the condenser. This makes it possible that lines are not necessary for the condenser inlet and the condenser outlet through the evaporator, which is almost under vacuum. This makes the entire heat pump less prone to failure since any passage through the evaporator would be a possibility for leakage. For this purpose, the condenser bottom is provided with a respective recess at locations where condenser inlets/outlets are located so that no condenser inlets/outlets run in the evaporator space defined by the condenser bottom.
The condenser space is limited by a condenser wall that is also attachable to the evaporator bottom. Thus, the evaporator bottom has an interface both for the condenser wall and for the condenser bottom and additionally has all liquid feeds both for the evaporator and the condenser.
In certain implementations, the evaporator bottom is configured to comprise connecting ports for the individual feeds, having a cross-section that differs from a cross-section of the opening on the other side of the evaporator bottom. The shape of the individual connecting ports is then configured such that the shape, or cross-sectional shape, changes across the length of the connecting port, however, the pipe diameter, which is important for the flow speed, remains approximately the same within a tolerance of ±10%. This prevents water flowing through the connection port from starting to cavitate. Through the good flow conditions obtained through shaping the connecting ports, it is ensured that the corresponding pipes/lines may be as short as possible, which in turn contributes to a compact design of the entire heat pump.
In a special implementation of the evaporator bottom, a condenser inlet is divided into a two-part or multi-part flow almost in the form of “spectacles”. This makes it possible to feed the condenser liquid into the condenser at its upper portion at two or more points simultaneously. This results in a strong and, at the same time, particularly uniform condenser flow from top to bottom, which enables highly efficient condensation of the vapor that is also introduced into the condenser from above.
Another smaller-dimensioned feed for condenser water may be also provided in the evaporator bottom in order to connect a hose that provides cooling liquid to the compressor motor of the heat pump, wherein it is not the cold liquid provided to the evaporator that is used for cooling but the warmer liquid provided to the condenser which, however, is still cool enough to cool the motor of the heat pump in typical operating situations.
The evaporator bottom is characterized by its combination functionality. On the one hand, it ensures that condenser inlet lines do not have to be passed through the evaporator, which is under very low pressure. On the other hand, it represents an interface to the outside, advantageously having a circular shape since a circular shape leaves as much evaporator surface as possible. All inlet lines and outlet lines lead through an evaporator floor and from there to either the evaporator space or the condenser space. Manufacturing the evaporator bottom using plastic injection molding is particular advantageous since the advantageous, relatively complex shapes of the inlet/outlet ports may be easily and inexpensively carried out using plastic injection molding. On the other hand, due to the design of the evaporator bottom as an well-accessible component, it is easily possible to produce the evaporator bottom with sufficient structural stability, so that it may easily withstand the low evaporator pressure in particular.
In the present invention, the same reference numerals refer to identical or similar elements, wherein, if they come up again, not all the reference numerals are repeated in all of the drawings.
The heat pump includes an evaporator 90 for evaporating working liquid. In addition, the heat pump includes a condenser or liquefier 114 for condensing evaporated and compressed working liquid.
The heat pump further includes a compressor motor having a radial impeller 110, 304 coupled to a suction mouth 92 to convey working vapor evaporated in the evaporator 90 through the suction mouth. In addition, the heat pump includes a guide space 302 arranged to guide working vapor conveyed by the radial impeller into the condenser 114. The working vapor evaporated in the evaporator 90 is schematically indicated with 314, and the working vapor 112 conveyed into the guide space and arriving in a compressed manner in the condenser 114 is schematically illustrated at 112.
According to the invention, the heat pump includes a cooling device 420 configured to cool the guide space 302 or the suction mouth 92 or the guide space 302 and the suction mouth 92 with a liquid. To this end, the cooling device 420 includes a liquid line 421 to the suction mouth 92 and/or a liquid line 422 to the guide space 302. Alternatively, only a single liquid line may be present to supply the guide space and the suction mouth. e.g., sequentially one after the another with cooling liquid. The cooling device is further configured to guide the liquid advantageously via lines 421, 422 or sequentially via one line to an outside of the guide space 302 or of the suction mouth 92, wherein the outside is not in contact with the working vapor 314, 112, whereas the inside of the guide space 302 or of the suction mouth 92 is in contact with this working vapor 314 and 112, respectively.
Preferably, water is used as the working liquid and in particular condenser water, i.e. a working liquid that is the same as the working liquid of the heat pump. Thus, the vapor of the liquid is the same vapor as the working medium vapor 314, 112 so that an open concept is obtained. Alternatively, a closed concept using a cooling liquid may be employed, where the cooling liquid is treated separately from the working liquid. Then, the cooling device 120 would be configured to have a return flow line of the cooling liquid, wherein the returned heated cooling liquid is to be cooled separately in order to then provide a cooled cooling liquid to the guide space or the suction mouth. However, an open guide space/suction mouth cooling is advantageous due to the simplicity of the design.
The motor further includes a motor housing 300 surrounding the compressor motor and advantageously configured to maintain a pressure that is at least the same as the pressure in the condenser. Alternatively, the motor housing is configured to maintain a pressure that is higher than a mean pressure of the evaporator and the condenser, or that is higher than the pressure in the further gap 313 between the radial impeller and the guide space 302, or that is higher than or the same as the pressure in the condenser. The motor housing is configured such that a pressure drop occurs from the motor housing along the motor shaft towards the guide space, through which a working vapor is pulled through the motor gap and the further gap past the motor shaft in order to cool the shaft.
The area in the motor housing with the needed pressure is illustrated in
In the inventive arrangement, there is a relatively high pressure p3 in the condenser. On the other hand, there is a medium pressure p2 in the guide path or guide space 302. Besides the evaporator, the lowest pressure is behind the radial impeller, where the radial impeller is fixed to the moto shaft. i.e. in the further gap 313. There is a pressure p4 in the motor housing 300 that is either the same as the pressure p3 or larger than the pressure p3. Through this, there is a pressure gradient from the motor housing to the end of the further gap. This pressure gradient causes a vapor flow through the vapor feed into the motor gap and the further gap up to the guide path 302. This vapor flow takes working vapor from the motor housing past the motor shaft into the condenser. This vapor flow provides a convective shaft cooling of the motor shaft through the motor gap 311 and the further gap 313 that connects to the motor gap 311. Thus, the impeller sucks vapor downwards past the motor shaft. This vapor is drawn into the motor gap via the vapor feed, which is typically implemented as specially implemented drill holes.
At this point, it should be generally pointed out that the two aspects of convective shaft cooling on the one hand and motor cooling on the other hand are also used separately. For example, a motor cooling without a special separate convective shaft cooling already leads to a considerably increased operational reliability. Furthermore, a convective motor shaft cooling without the additional motor cooling also leads to an increased operational reliability of the heat pump. However, as shown in
The embodiment shown in
The motor housing defines a separate space which, however, represents almost the same pressure area as the condenser. Due to the motor being heated and the energy therefore emitted at the motor wall 309, this supports bubble boiling in the liquid volume 328, which in turn results in a particularly efficient distribution of the working liquid in the volume 328 and therefore a particularly good cooling with a small volume of cooling liquid. It also ensures that the cooling is carried out with the working liquid that is at the most favorable temperature, i.e. the hottest temperature in the heat pump. This ensures that all condensation problems, which occur on cold surfaces, are eliminated for the motor wall and the motor shaft and the areas in the motor gap 311 and the further gap 313. In the embodiment shown in
The drilled holes 320 for the vapor feed lines supply will typically be configured in an array that can be regularly or irregularly arranged. Individual drilled holes have a diameter of no more than 5 mm and may be at a minimum size of about 1 mm.
In particular, the lines 422 may be implemented as channels that are configured in a fixed manner or as flexible lines such as hose elements.
In addition, the guide space includes a recessed area 372 that is configured to collect liquid and that is illustrated in its cross-section in
The projection 382 is located at the end of the cooling channel, projecting far enough that a certain level is formed. Excessive working liquid runs over this projection downwards into the condenser, or in to the condenser volume.
It should be noted that
In addition, a grid 209 is arranged, configured to support a filling body, which is not shown in
The liquefier of
In addition, a vapor provider is provided that, as is shown in
What is not shown in
For the sake of illustration, reference is made to
The upper area of the heat pump of
In addition,
The heat pump with a convective shaft cooling advantageously has a vapor feed that is configured such that a vapor flow through the motor gap and the further gap does not pass through a bearing portion configured to support the motor shaft with respect to the stator. The bearing portion 343, including two ball bearings in the present case, is sealed from the motor gap, e.g. by O-rings 351. With this, as is illustrated by the path 310, the working vapor can only enter into an area within the motor wall 309 from the vapor feed, flow from there into a free space towards the bottom and reach along the rotor 307 through the motor gap 311 into the further gap 313. The advantage of this is that vapor does not flow around the ball bearings, so that a bearing lubrication remains in the sealed ball bearings and is not drawn out through the motor gap. Furthermore, this also ensures that the ball bearing is not moistened, but remains in the defined state during installation.
In another embodiment, the motor housing is attached on top of the condenser housing 114 in the operation position of the heat pumps so that the stator is located above the radial impeller and the vapor flow 310 extends through the motor gap and the further gap from top to bottom.
Furthermore, the heat pump includes the bearing portion 343 configured to support the motor shaft with respect to the stator. In addition, the bearing portion is arranged such that the rotor 307 and the stator 308 are arranged between the bearing portion and the radial impeller 304. This has the advantage that the bearing portion 343 may be arranged in the vapor area within the motor housing and that the rotor/stator, where the largest heat loss occurs, may be arranged underneath the maximum liquid level 322 (
The motor housing further includes the working medium inlet 330 in order to guide liquid working medium from the condenser to a wall of the compressor motor in order to cool the motor.
By means of bubble boiling due to the working medium in contact with the motor wall 309 in particular in the lower area where the fresh working medium inlet 366 ends, there is a convection zone 367 within the volume of working liquid 328. In particular, boiling bubbles are pulled from the bottom to the top through the bubble boiling. This leads to a continuous “stirring”, wherein hot working liquid is brought from the bottom to the top. The energy due to the bubble boiling is then transferred into the vapor bubble that then lands in the vapor volume 323 above the liquid volume 328. The pressure arising there is immediately brought into the condenser through the overflow 324, the overflow continuation and the drain 342. This results in a permanent heat transfer from the motor to the condenser, which is mainly due to the transfer of vapor and not to the transfer of heated liquid.
This means that the heat, which is actually the waste heat from the motor, is advantageously transferred by the vapor discharge to exactly where it should go, namely into the condenser water to be heated. In this way, the entire motor heat is retained in the system, which is particularly advantageous for heat pump heating applications. However, the heat transfer from the motor to the condenser is also favorable for cooling applications of the heat pump since the condenser is typically coupled to an efficient heat dissipation. e.g. in the form of a heat exchanger or a direct heat dissipation in the area to be heated. This means that there is no need to provide a separate motor waste heat device, but the heat dissipation from the condenser to the outside, which already exists form the heat pump, is “used” to a certain extent by the motor cooling.
The motor housing is further configured to maintain the maximum level of the liquid working medium and to create the vapor space 323 above the level of the liquid working medium during operation of the heat pump. The vapor feed is further configured to communicate with the vapor space so that the vapor in the vapor space is guided through the motor gap and the further gap in
In the heat pump shown in
In the embodiment shown in
As is further shown in
To secure the motor in case of a bearing problem, the emergency bearing 344 is provided, configured to secure the motor shaft 306 between the rotor 370 and the radial impeller 304. In particular, the further gap 313 extends through a bearing gap of the emergency bearing or advantageously through drilled holes that are introduced in the emergency bearing on purpose. In an implementation, the emergency bearing is provided with a multitude of drilled holes so that the emergency bearing itself represents a lowest possible flow resistance for the vapor flow 10 for the purpose of the convective vapor cooling.
Preferably, the shaft is made of aluminum and has a fixing portion 395 that is fork-like in its cross section and represents a holder for the radial impeller 304 if the radial impeller 304 and the motor shaft are not configured integrally, but using two elements. If the radial impeller 304 is configured integrally with the motor shaft 306, the impeller holding portion 395 is not present, but the radial impeller 304 is directly connected to the motor shaft. As can be seen in
Furthermore, the motor housing 300 of
Preferably, the bearing portion 346 is further arranged above the maximum liquid level so that no liquid working medium may reach into the bearing portion even if the motor wall 309 is not sealed. On the other hand, the area of the motor that at least partially includes the rotor and the stator is below the maximum level since the largest heat loss that may be transported away in an ideal manner by the convective bubble boiling occurs in the bearing area, but also between the rotor and the stator.
In addition,
The course of the cooling liquid therefore extends via the feed line 422, 324, 377, 376 onto the upper outer side 372 of the guide space 302. From there, the liquid flows via the outlet line 378 from the outside of the guide space 302 to the outside of the suction mouth 92. From there, the liquid flows via the cooling channel 379 along the outside of the suction mouth to the lower outside of the guide space and along the lower outside of the guide space to the overflow 382 and from there down into the condenser.
According to the invention, this achieves that, after compression, the strong overheating of the water vapor otherwise occurring in the uncooled guide space is avoided. Part of the pressure build-up takes place in the guide space, where overheating is also reduced by the cooling, increasing the efficiency and the process quality of the compression process. Overheated water vapor has a higher viscosity and therefore a higher flow resistance and saturated vapor. Overheated water vapor is to therefore first reduce its overheating so that it may easily condense. Preferably, the guide space 302 and the suction mouth 92 are formed from a material with a good thermal conductivity, such as metal. The heat from the vapor flow may then be reduced particularly well, although good results may also be achieved with poorer heat-conducting materials. By reducing the overheating of the vapor flow, the flow resistance is reduced and the condensability of compressed vapor is improved.
In order to keep the temperature of the guide space as close as possible to the saturated vapor temperature of the pressure prevailing in the condenser, the guide space is made of metal and surrounded by liquid, such as water, which performs a pressure compensation with the liquefier. If energy/heat from the vapor flow is coupled in, the surrounding water begins to boil and releases the energy again. This keeps the guide space very close to the saturated vapor temperature of the vapor pressure. Liquefaction in the guide space is prevented by the remaining thermal resistance of the materials and the resulting low overheating.
The cooling water for the guide space is passed through the bearings and also the open motor cooling beforehand. Due to the open motor cooling, the water cools down again to the saturated water temperature by partial evaporation and is available for the open guide space cooling. At first, the upper part of the guide space is filled with water. With a one-sided guide space cooling, the water would simply overflow, as is the case in the embodiment shown in
In addition to the advantages mentioned above, the reduced stress of thermal components is another advantage. Through the evaporation cooling, the entire compressor may be kept near the saturated vapor temperature despite losses. Through the evaporation, motor losses, bearing losses and losses in the compression are reduced.
While this invention has been described in terms of several embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations and equivalents as fall within the true spirit and scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 215 085.8 | Aug 2017 | DE | national |
This application is a continuation of copending International Application No. PCT/EP2018/072548, filed Aug. 21, 2018, which is incorporated herein by reference in its entirety, and additionally claims priority from German Application No. DE 10 2017 215 085.8, filed Aug. 29, 2017, which is incorporated herein by reference in its entirety.
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| Number | Date | Country | |
|---|---|---|---|
| 20200200447 A1 | Jun 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2018/072548 | Aug 2018 | US |
| Child | 16793260 | US |
