Typical fields of usage of heat pumps are cooling of a region to be cooled and/or heating of a region to be heated. For that purpose, a heat pump, typically consisting of an evaporator, a compressor, a liquefier and a throttle, includes an evaporator side on the one hand and a liquefier side on the other hand. Depending on the implementation, a heat pump is coupled to a heat exchanger on the evaporator side and/or a heat exchanger on the liquefier side.
If the heat pump is used as cooling unit, the region to be cooled is the “useful side”. The region to be cooled can, for example, be an interior space, such as a computer room or another room to be cooled or to be air-conditioned. Then, the region to be heated is, for example, the outside wall of a building or a top side of a roof and another region to which the exhaust heat is to be directed. If, however, the heat pump is used as a heater, the region to be heated is, so to speak, the “useful side” and the region to be cooled would, for example, be ground earth, ground water or the same.
For a general heat pump application, it is problematic that the configuration does not consider that the environmental temperature of the region to be heated varies heavily, when the same is outdoors, for example. Therefore, it can be the case that temperatures of −20° C. in winter and temperatures of more than 30° C. in summer prevail. When considering, for example, an application where a computer room is air-conditioned, it would be sufficient to no longer air-condition the computer room but merely “open the windows” for the case that the outside temperature is, for example, within the range or below the set temperature of the region to be cooled. However, this is problematic since computer rooms do not necessarily have windows, and even when such cooling is considered, it is quite difficult to control that a uniform temperature is achieved in the room. If there are any windows at all, cold zones may be formed close to the windows, for example, while warm zones may be formed further away from the windows or behind certain computer racks that might then not be sufficiently cooled. On the other hand, it is problematic that the fact that outside temperatures can vary heavily and are frequently within ranges where cooling is usually not needed is not used in a heat pump configuration. For that reason, a configuration as generally used is configured for the worst-case situation, e.g., for a very hot summer day although, on average, such a hot summer day is a rare event, at least in Germany, and most of the time of the year temperatures prevail where the needed cooling capacities are far below the assumed worst-case situation.
DE 10 2012 208 174 B4 shows a heat pump and a method for pumping heat in the free cooling mode. The heat pump includes an evaporator having an evaporator inlet and an evaporator outlet, a compressor for compressing operating liquid evaporated in the evaporator and a liquefier for liquefying evaporating liquid compressed in the compressor. Further, the liquefier has a liquefier inlet and a liquefier outlet. In the free cooling mode, the evaporator inlet is connected to a return from a region to be heated. Above that, the liquefier inlet is connected to a return from a region to be cooled. Further, a switch means is provided to separate the evaporator inlet from the return from the region to be heated and to connect the return from the region to be cooled to the evaporator inlet and to further separate the liquefier inlet from the return of the region to be cooled and, additionally, to connect the return from the region to be heated to a liquefier inlet. Thereby, switching from the free cooling mode to the normal mode and back to the free cooling mode can be performed. Thus, it is efficiently considered that outside temperatures are frequently within ranges far below the maximum temperatures when the heat pump is not operated in the classical configuration but in the configuration where the return from the region to be heated is connected to the evaporator inlet and the return from the region to be cooled is connected to the liquefier inlet.
In this free cooling mode, the fact is used that the return temperature from the region to be heated already reaches the order of the temperature normally provided to the evaporator. Above that, the fact is used that the return from the region to be cooled is already within such temperature regions that can be provided to the liquefier of the heat pump. This has the effect that the temperature difference that the heat pump normally has to achieve between the evaporator outlet and the liquefier outlet decreases rapidly compared to the normal mode. Since the temperature difference to be achieved by a heat pump is incorporated in the consumed drive power for the compressor in a squared manner, this results in an efficiency increase of the heat pump compared to a normal configuration without free cooling mode.
Depending on the application, it can happen that the flexibility of the free cooling mode, where the liquefier inlets/outlets are actually switched and hence both the evaporator cycle as well as the condenser cycle is fluidically switched back and forth, is reduced. Above that, switching from the condenser cycle at high pressure to the evaporator cycle at low pressure and vice versa is needed, which can be problematic depending on the embodiment.
U.S. Pat. No. 4,495,777 discloses a load distribution system for a closed cooling system.
US 2006/0010893 A1 discloses a cooling system with a low capacity control.
According to an embodiment, a heat pump arrangement may have: a heat pump device; an evaporator cycle interface for inputting liquid to be cooled into the heat pump device and for outputting cooled liquid out of the heat pump device; a condenser cycle interface for inputting liquid to be heated into the heat pump device and for outputting heated liquid out of the heat pump device; a controllable heat exchanger for controllably coupling the evaporator cycle interface and the condenser cycle interface; and a control for controlling the controllable heat exchanger in dependence on an evaporator cycle temperature in the evaporator cycle interface or a condenser cycle temperature in the condenser cycle interface, wherein the controllable heat exchanger includes a heat exchanger unit with terminals and two fluidically separated paths and at least one control element, wherein at least one terminal of the heat exchanger unit is coupled to at least one terminal of the at least one control element in order to effect, reduce or prevent flow through one of the paths of the heat exchanger unit in dependence on a setting of the control element, and wherein the at least one control element is configured as two-way switch or as mixer.
According to another embodiment, a heat pump system may have: a region to be cooled; a region to be heated; an inventive heat pump arrangement, wherein the evaporator cycle interface of the heat pump system is coupled to the region to be cooled, wherein the condenser cycle interface is coupled to the region to be heated.
According to another embodiment, a method for producing a heat pump arrangement with a heat pump device may have the steps of: inputting liquid to be cooled into the heat pump device and outputting cooled liquid out of the heat pump device; inputting liquid to be heated into the heat pump device and outputting heated liquid out of the heat pump device; coupling liquid cooled by a heat sink in a controllable and thermal manner to the liquid to be cooled via a controllable heat exchanger in dependence on an evaporator cycle temperature including a temperature of the liquid to be cooled or the cooled liquid or in dependence on a condenser cycle temperature including a temperature of the liquid to be heated or the heated liquid or the liquid cooled by the heat sink, wherein the controllable heat exchanger includes a heat exchanger unit with terminals and two fluidically separated paths and at least one control element, wherein at least one terminal of the heat exchanger unit is coupled to at least one terminal of the at least one control element in order to effect, reduce or prevent flow through one of the paths of the heat exchanger unit in dependence on a setting of the control element, and wherein the at least one control element is configured as two-way switch or as mixer.
An inventive heat pump arrangement includes a heat pump device and an evaporator cycle interface for inputting liquid to be cooled into the heat pump device and for outputting cooled liquid out of the heat pump device. Further, the heat pump arrangement includes a condenser cycle interface for inputting liquid to be heated into the heat pump device and for outputting heated liquid out of the heat pump device. Above that, a controllable heat exchanger is provided for controllably coupling the evaporator cycle interface and the condenser cycle interface. Further, a control is provided for controlling the controllable heat exchanger in dependence on an evaporator cycle temperature in the evaporator cycle interface or in dependence on a condenser cycle temperature in the condenser cycle interface. Further, depending on the implementation, an evaporator cycle temperature sensor for detecting the evaporator cycle temperature or a condenser cycle temperature sensor for detecting the condenser cycle temperature or both sensors are present. In the latter case, the control is configured to control the controllable heat exchanger based on a difference of the evaporator cycle temperature and the condenser cycle temperature or based on a comparison of the temperatures in order to actually controllably couple the output side, i.e., the condenser cycle, and the input side, i.e., the evaporator cycle. According to the invention, however, no liquid coupling of the condenser cycle interface and the evaporator cycle interface takes place. Instead, merely thermal coupling of the output side and the input side takes place via the heat exchanger such that the operating liquid in the condenser cycle interface is thermally coupled to the operating liquid of the evaporator cycle interface but not directly fluidically coupled.
Thereby, it is ensured that control elements existing in the controllable heat exchanger in addition to a common heat exchanger with two separate liquid paths only have to switch in the same pressure region, i.e., only in the condenser cycle interface or the evaporator cycle interface but do not establish a fluidic short circuit between the two interfaces.
In embodiments, the control element is configured to effect, reduce or suppress flow through one of the paths in dependence on a setting of the control element. In the case of effecting the flow or suppressing the flow, the control element is configured as two-way control element having a switched-on and a switched-off state. In the case of reducing the flow through one of the two paths, the control element is configured as mixer in order to pass one part of the operating liquid via the controllable heat exchanger and another part past the controllable heat exchanger, depending on the implementation.
In one embodiment, the controllable heat exchanger comprises a heat exchange unit with terminals and two fluidically separate paths and at least one control element, wherein at least one terminal of the heat exchanger unit is coupled to at least one terminal of the at least one control element in order to effect, reduce or prevent flow through one of the paths of the heat exchanger unit in dependence on a setting of the control element. Further, the at least one control element is configured as two-way switch or as mixer.
In a further embodiment, the at least one control element is configured as passive two-way switch in order to effect or prevent the flow through one of the paths of the heat exchanger unit in dependence on the setting of the passive two-way switch, or the same is configured as passive mixer in order to reduce the flow through one of the paths of the heat exchanger unit in dependence on the setting of the mixer. Here, passive means that the two-way switch or the mixer does not include any own pump. In further embodiments, the passive elements also include no valves.
The controllable heat exchanger is incorporated such that one path of the heat exchanger is continuously flowed-through and that the other path can be switched on or off, or in the case of using a mixer, can be throttled with regard to an on-state. Depending on the implementation, power electronics to be cooled are arranged on the controllable heat exchanger or at least in thermal effective contact, due to the fact that the controllable heat exchanger is flowed-through from at least one side. In this implementation, where the controllable heat exchanger is simultaneously used as heat sink, i.e., as cooling for needed electronic parts, such as for a frequency converter of the compressor engine, coupling takes place such that the condenser cycle interface continuously flows through a path of the controllable heat exchanger. Thereby, the exhaust heat of the electronic components is moved directly into the heat dissipation means typically provided for the heat pump arrangement such as a recooler on the roof or on a shadow side of the building, even when free cooling is not activated and the other path of the heat exchanger unit is not flowed-through.
The present invention is advantageous in that the input side and the output side, i.e., the evaporator cycle and the condenser cycle can be thermally coupled by the controllable heat exchanger but are not fluidically coupled. Thereby, it is obtained that different operating liquids can be used in the condenser cycle on the one hand and in the evaporator cycle on the other hand. Above that, the requirements for the control element of the controllable heat exchanger are reduced compared to switching liquids with regard to the input side and the output side since the same pressures prevail and the pressure difference from the input side of the heat pump arrangement, i.e., the evaporator cycle and the output side of the heat pump arrangement, i.e., the condenser cycle, cannot reach the one and same switch element.
Above that, coupling of the two interfaces with the controllable heat exchanger provides more flexibility in that not only a free cooling mode can be implemented where the operating liquid flowing back from the heat exchanger is used in order to directly cool the liquid to be cooled but that vice versa also a controlled short circuit of the heat pump arrangement can be obtained, which can be useful when excessive clocking with switch-on and switch-off events would take place without the heat pump. Such a situation can occur, for example, when the system is in partial load operation. If the system needs high pressure increase when the cooling capacity is too low, which can be the case, for example with partial power in the data center and at high environmental temperatures, this would cause too large a volume flow and hence too large a mass flow. This would result in clocking the heat pump arrangement with alternating on-off-on states. By implementing the controllable heat exchanger by means of a controllable mixer, a controllable power short circuit between cold and cooling water can be provided which improves the partial load behavior and effectively prevents clocking.
Therefore, the heat pump arrangement according to the present invention has, on the one hand, increased flexibility regarding the connection of different liquids in the condenser cycle on the one hand and the evaporator cycle on the other hand. Above that, thermal coupling enables usage of simpler and more cost effective control elements instead of the actual fluidic coupling of the two sides. Finally, based on thermal coupling, not only a free cooling mode can be used for increasing the efficiency of the heat pump but at the same time a controllable power short circuit can be used for improving the partial load behavior of the system or also for implementing other modes of the system, such as service modes.
Embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which:
Thus, depending on the implementation, the controllable heat exchanger comprises a heat exchanger unit having four terminals and two fluidically separate paths, wherein at least one terminal is coupled to a control element, such as a two-way control element and in dependence on a setting of the control element, flow through one of the paths is effected, reduced or suppressed.
Thus, the control element, such as 720, 730, 740, 750, 760 is configured to effect a flow through a path when the condenser cycle temperature is in a predetermined ratio to the evaporator cycle temperature or is less than a predetermined condenser cycle threshold.
Depending on the implementation, the controllable heat exchanger 700 is configured such that one path of the controllable heat exchanger is continuously flowed-through independent of the control and another path of the controllable heat exchanger can be switched on or off or can be throttled by the control with respect to an on-state.
Depending on the implementation, as will be discussed below, the controllable heat exchanger 700 includes a heat exchanger unit, namely the heat exchanger unit 710 of
Above that, the condenser cycle interface 300 is coupled to a second path of the heat exchanger element, such that the liquid to be heated leaves the second path and the heated liquid enters the second path after cooling in a heat sink.
A respective implementation where the controllable element is coupled to the first path of the heat exchanger unit 710 is shown in
Here,
It should further be noted that the condenser cycle interface 300 in
In the embodiment shown in
Above that, the second path of the heat exchanger unit is also connected to the input 230 of the heat pump device 100 for liquid to be cooled via a further connecting line 235.
As shown in
While
Therefore, in the embodiment shown in
If, however, it is determined that the evaporator cycle temperature TWK is lower than the condenser cycle temperature TWW, as determined by sensors 310 or 210, the control element is switched into the position of
Although the control element 720, 730, 740, 750 is illustrated as two-way switches in
Thereby, for example, an operating liquid having a temperature of 20° C. is heated to 24° C. by the effect of the heat exchanger unit 710. Thus, an overall achieved temperature of 21° C. results at the branch point or at the combination point where the output 712 of the first path is connected to the line for the liquid to be cooled 230. Thus, by implementing the control element 760 as a mixer, in a configuration as shown in
Similar implementations for the mixer can also be provided for the control elements 740, 750 of
Further, it should be noted that in the heat pump device 100 not only such a stage as illustrated in
Further,
Since in one embodiment the heat exchanger unit 710 is continuously flowed-through by the condenser cycle or by the evaporator cycle, cooling takes place at all times. The temperatures in the condenser cycle which can be above 20° C. are sufficient as cooling temperatures for the electronic arrangement. Therefore, it is advantageous to couple the heat exchanger unit 710 to the condenser cycle interface such that the heat exchanger unit 710 or a second path of the same is flowed-through by the condenser cycle. Thereby, the exhaust heat of the control electronics enters the condenser cycle directly and hence into the exhaust heat apparatus without having to be “pumped” first from the evaporator cycle into the condenser cycle.
In particular in a cold temperature range where an exemplary air temperature is lower than 10° C. and wherein the sensor values are such that TWK is higher than TWW, free cooling is active. Further, the controllable heat exchanger is flowed-through from both sides, i.e., the same is active. Above that, as exemplarily shown in
In a medium cold temperature range, which is, for example, between 10° C. and 16° C., free cooling is also active. Above that, the compressor is also active and regulation of the temperature fed into the data center or the region to be cooled can take place in that the speed of the radial wheel in the compressor is controlled. If higher cooling capacity is needed, the speed is increased. If, however, lower cooling capacity is needed, the speed of the radial wheel is reduced.
In a normal operating mode which is activated in a warm temperature range, where the temperatures are, for example more than 16° C., it is typically determined that the temperature TWK is lower than the temperature TWW. Then, the controllable heat exchanger 710 is deactivated, i.e., switched to inactive and cooling capacity control can take place again via the speed of the radial wheel. In this mode, i.e., in the warm temperature range, no free cooling is active.
As a special mode where a mixer as described with reference to
Thus, according to the invention, the special mode with controllable short circuit is activated, which is detected, for example, by a specific clocking frequency. If a too high clocking frequency is determined, the controllable short circuit is activated, therefore a typically smaller part, i.e., a part less than 50% of the flow amount is fed into the respective first or second path of the heat exchanger unit and combined again with the other (typically greater) portion at the output of the heat exchanger unit. This mixer effect that has been illustrated in
In embodiments of free cooling plus, a heat exchanger and a three-way switch are installed. This three-way switch can be incorporated on the cold water side or the warm water side and is to enable or disable the flow through the heat exchanger. Depending on the implementation, pumps PV 240 or PK 340 might be present or not. Above that, additional heat exchanges can be used, for example at the output of pump PV 240 or at the output of pump PK 340, although these heat exchanges are not illustrated in
In specific alternative embodiments, it is advantageous that the control, i.e., whether the heat transfer is flowed-through or not, merely depends on the temperatures TWW and TWK, namely when the temperature TWW is lower than TWK, the heat exchanger unit is flowed-through. If the temperature in the evaporator is higher than the flow temperature on the cold water side or customer side, the compressor has to work. If, however, the temperatures in the free cooling mode are below the requested customer temperature, here 16° C., the fan on the roof and the finally the pumps can be throttled.
In an embodiment of the present invention, a throttle is used for free-cooling plus that already safely operates without pressure difference or starting from a small pressure difference less than 10 mbar up to the maximum pressure stroke. Then, it is ensured that the cooling means balance is compensated from the liquefier to the evaporator when respective liquid compensation functionality is needed. This is in contrast to known cooling systems having electronic throttles that only operate at pressure differences of several bar.
Above that, it is advantageous to use a flow machine as a compressor such that the needed pressure difference and the power, for example the mass flow, can be exactly controlled via the speed. Further, water is used as cooling means, wherein small pressure differences of less than 100 mbar are possible across the entire operating range and wherein further a self-regulating throttle can be incorporated due to the extreme volume differences between vapor and liquid. In order to be able to work with so-called chemical cooling means, i.e., cooling means differing from water, it is advantageous to use a switchable throttle bypass instead of the passive self-regulating throttle as illustrated in
As has already been illustrated and has been explained based on
One branch flows continuously through the heat exchanger unit in the controllable heat exchanger. Therefore, the heat exchanger is perfectly suitable for cooling capacity electronics. If the mixer is brought to the cold water side, the electronics introduces its losses directly into the cooling water side, i.e., into the condenser cycle. This has the advantage that the heat pump device does not have to provide the power loss first to the exhaust heat side by compressor work. The rectifiers for the frequency converter circuits are arranged on the heat exchanger unit, i.e., in thermal operative connection with the controllable heat exchanger.
A method for producing a heat pump arrangement having a heat pump device comprises the following steps:
Inputting liquid to the cooled into the heat pump device and outputting cooled liquid out of the heat pump device;
Inputting liquid to be heated into the heat pump device and outputting heated liquid out of the heat pump device; and
Coupling a liquid cooled by a heat sink in a controllable and thermal manner to the liquid to be cooled via a controllable heat exchanger in dependence on an evaporator cycle temperature having a temperature of the liquid to be cooled or the cooled liquid or in dependence on a condenser cycle temperature having a temperature of the liquid to be heated or the heated liquid or the liquid cooled by the heat sink.
Although specific elements have been described as apparatus elements, it should be noted that this description is equally to be considered as the description of steps of a method and vice versa.
Further, it should be noted that a control, for example, effected by the element 400 in
While this invention has been described in terms of several advantageous 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 |
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10 2017 212 131.9 | Jul 2017 | DE | national |
This application is a continuation of copending International Application No. PCT/EP2018/069166, filed Jul. 13, 2018, which is incorporated herein by reference in its entirety, and additionally claims priority from German Application No. 10 2017 212 131.9, filed Jul. 14, 2017, which is also incorporated herein by reference in its entirety. The present invention relates to heat pump applications and in particular to heat pump applications usable for cooling, for heating or for other purposes where heat has to be pumped from one level to another level.
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Number | Date | Country |
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Number | Date | Country | |
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20200141615 A1 | May 2020 | US |
Number | Date | Country | |
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Parent | PCT/EP2018/069166 | Jul 2018 | US |
Child | 16737321 | US |