Abstract:
Existing energy recovery systems are used in the fields of air conditioning and ventilation for recovering energy from the outgoing air or external air. Subsequent to an energy recovery system ( 10 ), additional thermal energy is extracted from a used air volume flow AB, which is coming from an air-conditioned room, by another system, which consists of a heat pump ( 3 ), a heat exchanger ( 1 ), another heat exchanger ( 2 ), an accumulator circuit ( 9 ), an energy accumulator ( 9.1 ), and of a mixing valve ( 6 ). The associated supply air volume flow ZU is, when heating, additionally heated by the heat pump ( 3 ) by means of thermal energy from the used air volume flow AB. This results in increasing the energy yield from the used air volume flow AB. The temperature of the supply air is regulated. When cooling, the supply air volume flow ZU is cooled to the desired supply air temperature.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to a method for recovering energy from an air-conditioning and/or ventilation system.  
       BACKGROUND OF THE INVENTION  
       [0002]     Heat recovery systems, systems with recuperative and regenerative heat exchangers, and also systems with an intermediate medium or heat pumps are used in air-conditioning and ventilation technology for recovering energy from the used or outgoing air.  
         [0003]     In the literature, heat recovery systems are described in many forms. Such systems are known in ventilation technology and used frequently. According to the literature, so-called return-heat indices of up to 0.8 can be achieved.  
         [0004]     In the publication “Recknagel, Sprenger, Schramek; Handbook for Heating+Air-conditioning Technology Jan. 02, 2001 edition, Oldenbourg Industrieverlag Munich” on pages 1367ff., various techniques for recovering heat are described. Among other systems, this publication also mentions a system with a heat pump.  
         [0005]     Additional clues on systems for recovering heat in ventilation systems can be found in the publication “Handbook on Air-conditioning Technology, 3rd edition, Verlag C. F. Müller GmbH, Karlsruhe, Vol. 2; Calculation and Regulation” on pages 115ff.  
         [0006]     In conventional heat recovery systems, in which various constructions of heat exchangers are used, the thermal output decreases linearly with the temperature difference between the outgoing air discharged from a ventilation system and the external air fed to the ventilation system. Thus, in the heating case, if the external air temperature increases, the temperature difference between the external air and the used air volume flow to be carried away by means of the ventilation system decreases. Less energy can be absorbed from the used air volume flow and discharged to the external air to be fed as the supply air volume flow. Therefore, the external air must then be reheated with a heater.  
         [0007]     In the cooling case, for the same reason, thus, due to the decrease in the temperature of the external air, only a portion of the energy can be removed from a used air volume flow forming the outgoing air.  
         [0008]     Thus, in the heating case the external air must then be reheated with a heater or, in the cooling case, it must be re-cooled with a cooler.  
         [0009]     It is also known to provide cooling with an integrated cooling device after a heat exchanger or to perform heating with a downstream heat pump after a heat exchanger tube. Both of the mentioned systems can be controlled only conditionally, e.g., turned on and off by multiple contact switching or by means of rpm-controlled compressors. The cooling is sometimes also adapted with a hot-gas bypass control. This method is being used less and less due to the associated loss of energy.  
         [0010]     A sliding control over the entire range of the various outside temperatures is not possible with any of the systems without reducing the so-called output number. Variable volume flows, like those used more and more frequently in modern air-conditioning systems, cannot be cooled or heated with the previously mentioned systems.  
         [0011]     With prior systems, switching from cooling mode to the heating mode and vice versa cannot be controlled effectively, if at all, or only with worse efficiency by means of air mixing.  
         [0012]     From document DE 9218937 U1, a device for shaping the climatic environment in rooms of a building is known. This device has a regenerative heat exchanger between the supply air and used air volume flow. An evaporator of a heat pump is arranged after this heat exchanger. Another regenerative heat exchanger and the condenser of the heat pump are arranged in the used air volume flow. To increase the energy yield, a second external air flow is provided in parallel with the external air flow fed to the building rooms. The compressor and the condenser of the heat pumps are each arranged in different external air flows, so that energy can be transferred from the first external air flow into the second external air flow by means of the heat pumps.  
         [0013]     Furthermore, an air conditioner is known from DE 19500527 A1. This air conditioner has supply air and used air volume flows that are both guided via a heat exchanger. A heat pump is connected after the heat exchanger in the supply air volume flow or in the used air volume flow of the compressor or condenser. The heat pump enables optimum energy recovery only for a certain application. This comes from the design of the output of the heat pump.  
         [0014]     Finally, from DE 19851889 A1, a heat-pump air-conditioning system with energy recycling is also known. In the air-conditioning system, the supply air and the used air are guided by means of a common heat exchanger. Among other things, another heat exchanger coupled to a hot-water accumulator in a first coupling circuit is connected after a first heat exchanger in the supply air. The hot-water accumulator is coupled to the condenser of a heat pump in a second coupling circuit. The compressor of the heat pump can be charged with a partial flow of the used air. Furthermore, another part of the used air is guided via the heat exchanger and another, smaller part of the used air is mixed with the supply air. The air-conditioning system has a complicated shape, can only be poorly controlled, and requires, for the cooling case, an additional cooling unit, which must be connected into the supply air by means of another heat exchanger.  
         [0015]     Consequently, for a conventional ventilation system, the described state of the art produces a not insignificant additional expense in terms of devices for the heating or cooling of the supply air volume flow to be generated.  
       SUMMARY OF THE INVENTION  
       [0016]     Therefore, an object of the invention is to prevent the above mentioned disadvantages of prior systems to significantly increase the yield of the recovered heat with good controllability.  
         [0017]     The invention comprises a combination of one of the known heat recovery systems with a system made up of a heat pump, an accumulator circuit, and a heat exchanger, which is coupled to the accumulator circuit and which is connected after the heat recovery system in the supply air volume flow. Another heat exchanger is arranged after the heat recovery system in the used air volume flow. The two heat exchangers are coupled by means of the heat pump, wherein, also on the side of the supply air treatment, the heat pump is connected to the accumulator circuit, which is provided with an energy accumulator and a mixing valve, by means of another heat exchanger.  
         [0018]     Through the interaction of the mentioned components, it is possible to regulate the heat transfer. Among other things, this is necessary to limit the supply air temperature.  
         [0019]     The temperature in the circulating fluid in the accumulator circuit is set high enough to effect a sufficiently high condensation temperature for the operation of the heat pump. This is calculated according to information from the manufacturer of the compressor under consideration of the temperature of the used air volume flow, the structure of the heat exchanger in this flow, and the evaporation temperature. If a higher temperature is needed in the circulating fluid to reach the average temperature difference in the heat exchanger in the supply air volume flow, then the temperature for reaching the necessary average temperature difference is selected. In this way, an optimum output number of the heat pump is always achieved, but it also guarantees that the heat exchange is possible in the heat exchanger in the supply air volume flow.  
         [0020]     The supply air temperature is controlled by means of the mixing valve, which can be formed, for example, as a 3-port directional control valve with a regulator and a motor. In the heating case, for example, the volume flow of the circulating fluid to the heat exchanger in the supply air volume flow is increased when the supply air temperature falls below the required temperature. In contrast, when the supply air temperature exceeds the required temperature, the volume flow of the circulating fluid to the heat exchanger in the supply air volume flow is decreased.  
         [0021]     If the used air volume flow should become smaller for some reason, then the evaporation temperature decreases, because less heat is delivered. Reduction of the evaporation temperature is determined by means of a pressure sensor before the compressor, alternatively by means of a temperature sensor. If the evaporation temperature falls below a predetermined value, the regulator turns off the compressor. The supply air volume flow is then heated by the thermal energy from the energy accumulator. After the standstill period necessary to stop the compressor has expired, the compressor turns on again.  
         [0022]     If the heat pump is turned off because a maximum temperature in the circulating fluid has been reached, then the supply air volume flow is held at a constant temperature with energy from the energy accumulator controlled by the mixing valve. If the circulating fluid cools down again, the heat pump turns on again in order again to transfer energy from the used air volume flow into the circulating fluid and to the energy accumulator.  
         [0023]     A continuous turning on and off is performed for heat pumps with a compressor. More powerful heat pumps are equipped with several compressors. If several compressors are installed in the heat pump, then the turning on and off of the compressors is performed in sequence. Rpm-controlled models can also be used as the compressors. In this case, the energy accumulator can be dimensioned somewhat smaller, which, however, under some circumstances reduces the output number.  
         [0024]     The energy accumulator is designed in terms of contents to be large enough that the time interval for complete circulation of the fluid volume lasts longer than that necessary for the standstill period of the smallest compressor of the heat pump. To avoid turbulent flow in the energy accumulator, the incoming volume flow of the circulating fluid can be led into the energy accumulator with a nozzle tube. This creates a favorable laminar flow in the energy accumulator.  
         [0025]     The used air volume flow is cooled down for reasons of the largest possible energy gain as much as is necessary for the heat transfer. If icing on the heat exchanger in the used air volume flow is not a restriction or if no icing occurs due to the condition of the used air, then the desired supply air temperature can be achieved after the heat exchanger in the supply air volume flow without additional heaters with a correspondingly powerful heat pump.  
         [0026]     Through the use of the heat pump and the electric power consumption necessary for the operation of the heat pump, it is possible to transfer more energy to the external air than can be removed from the outgoing air.  
         [0027]     With the described invention, in the cooling case, the external air can be cooled for preparing the supply air volume flow. This happens by reversing the refrigeration cycle of the heat pump. Here, the setting of a constant supply air temperature is also possible.  
         [0028]     Among other things, the advantages that can be achieved with the invention consist of the advantageous effects described below:  
         [0029]     1. An extremely large heat recovery is achieved. The transfer power WRG achieved with the heat recovery system is increased by the heat pump system configured in the described combination. It is possible to remove more energy from the used air volume flow than is necessary for the heating of the supply air volume flow. The excess energy can optionally be used also for heating service water, e.g., also for heating after the adiabatic humidification of the supply air volume flow.  
         [0030]     In comparison with other heat recovery systems, due to the controllable heat recovery system, the value of the return heat index can exceed 1, while in other, known heat recovery systems, a maximum economical return heat index of 0.8 is achieved.  
       EXAMPLE  
       [0031]    
       
         
           
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                     IN 
                   
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                     ) 
                   
                 
                 ⁢ 
                 t 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 
                   FO 
                   OUT 
                 
               
               
                 t 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 
                   
                     FO 
                     IN 
                   
                   ⁡ 
                   
                     ( 
                     
                       Previously 
                       ⁢ 
                       
                           
                       
                       ⁢ 
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                 ⁢ 
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                   AU 
                   IN 
                 
               
             
           
         
       
     
         [0032]     The used air volume flow is cooled with an interconnected circulating system, with a return heat index of 0.47, in combination with the heat pump system from 24° C. at 50% relative humidity to 6.8°: 
    h IN =43.2     h OUT =21.6     Δh=21.5    
 
         [0036]     The external air enters at 10° C. at 70% relative humidity. The supply air volume flow is then converted by the treatment into the state of 31° C. at 19% relative humidity: 
    h IN =23.4     h OUT =43.7     Δh=21.5    
 
         [0040]     From this follows for the value of the return heat index:  
       ϕ   =           24   ⁢   °C     -     6.8   ⁢   °C           24   ⁢   °C     -     10   ⁢   °C         =   1.23         
 
         [0041]     2. In the majority of cases, for the heating case an additional heating cycle of the supply air volume flow ZU, with an additional heater, is not necessary.  
         [0042]     3. In most circumstances, in the cooling case, the external air AU can be cooled sufficiently that an additional cooling cycle with an additional cooler is not necessary. The cooler in the ventilation device can be eliminated.  
         [0043]     4. The output received by the supply air ventilator to the shaft becomes smaller, because by eliminating the air cooler, the dynamic pressure difference required until now is eliminated.  
         [0044]     5. The supply air devices become smaller and lighter through the elimination of the air heater.  
         [0045]     6. For cooling the supply air and for the decentralized cooling of the building, in most cases additional refrigerating machines are no longer required.  
         [0046]     7. The invention can be used in a decentralized arrangement or integrated into an air handler in a central arrangement.  
         [0047]     8. The invention can be used in a central arrangement for the parallel operation, for example, of several ventilation systems.  
         [0048]     The invention is described as an example with reference to schematic representation of the systems and methods and is described in more detail below. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0049]     Shown here are:  
         [0050]      FIG. 1  is a schematic of a first variant of the invention with an energy accumulator,  
         [0051]      FIG. 2  is a schematic of a second variant of the invention with two energy accumulators,  
         [0052]      FIG. 3  is a schematic of a first variant of the invention for use in parallel ventilation systems, and  
         [0053]      FIG. 4  is a schematic of a second variant of the invention for use in parallel ventilation systems. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0054]     According to the first embodiment of the invention from  FIG. 1 , a heat exchanger  2  is placed after a heat recovery system  10  in a used air volume flow AB, which becomes outgoing air FO through ventilation-specific handling. The heat recovery system  10  is coupled on the other side to a supply air volume flow ZU, which is obtained from the external air AU through ventilation-specific handling. The heat recovery system  10  can be formed according to one of the known configurations, e.g., as a KVS (interconnected circulating) system, rotary or plate heat exchanger, smooth tube heat exchanger, accumulator mass heat exchanger, or heat exchanger tube. The heat exchanger  2  is coupled to a heat pump  3  and in the heating case acts as an evaporator and in the optional cooling case as a condenser of the heat pump  3 . In the refrigeration cycle of the heat pump  3 , there is another heat exchanger  4 , which is used in the heating case as a condenser, and in the cooling case as an evaporator. Furthermore, in the supply air volume flow ZU, a heat exchanger  1  is arranged after the heat recovery system  10 . The heat exchanger  1  is coupled in an accumulator circuit  9 . The heat exchanger  4  coupled to the heat pump  3  is also coupled in this accumulator circuit  9 . Furthermore, in the accumulator circuit  9  there is an energy accumulator  9 . 1 . The accumulator circuit  9  and the energy accumulator  9 . 1  are filled with a circulating fluid, which stores heat and which is circulated by a pump.  
         [0055]     The circulating fluid for the heat transport between the heat exchanger  1  and the heat exchanger  4  can be water, a water-glycol mixture, or another fluid that is common in refrigeration and air-conditioning technology.  
         [0056]     In the heating case, the temperature of the circulating fluid in the accumulator circuit  9  is selected to be high enough that the minimum required condensation temperature for the heat pump  3  is guaranteed, and also the average temperature difference in the heat exchanger  1  is large enough that the thermal energy can be transferred to the external air AU, which forms the supply air volume flow ZU after the described ventilation-specific handling. In the optional cooling case, the temperature of the circulating fluid in the accumulator circuit  9  is selected to be low enough that the external air AU is cooled in the supply air volume flow ZU to the desired supply air temperature.  
         [0057]     The temperature level of the circulating fluid and thus the regulation of the temperature of the supply air volume flow ZU is set with a mixing valve  6  or alternatively with a hydraulic distributing guide. The mixing valve  6  can be configured as a 3-port directional control valve with regulator and motor.  
         [0058]     To regulate the temperature level of the circulating fluid, the mixing valve  6  is arranged at a juncture of the accumulator circuit  9 , in which two branches A and B of the accumulator circuit  9  are joined. One branch A of the juncture is connected directly to the heat exchanger  1  as a return line. A second branch B is connected to the supply line for the heat exchanger  1  coming from the energy accumulator  9 . 1 . Through adjustments, the mixing valve  6  can now allow different amounts of flow of the circulating fluid through the two branches A and B and thus forms a mixed flow A-B. In this way, the heat throughput on the heat exchanger  1  can be regulated from a maximum level to a minimum level. In the maximum case, the circulating fluid is guided completely through the heat exchanger  1 , and in the minimum case, no circulating fluid is fed to the heat exchanger  1 . The energy accumulator  9 .  1 , which is arranged directly after the heat exchanger  4 , always carries a flow of the total amount of fluid, and in this way receives the amount of heat delivered by the heat pump  3  but not converted by the heat exchanger  1 . Likewise, when turning off the heat pump  3 , the thermal energy is discharged from the energy accumulator  9 . 1  via the heat exchanger  1  to the supply air volume flow ZU.  
         [0059]     If a disruptive formation of ice should appear in the heat exchanger  2 , the temperature of the circulating fluid will rise. For an unacceptable thickness of the ice formation, the refrigeration cycle will become temporarily stopped, so that the heat exchanger  2  is not cooled by the heat pump, and the used air volume flow AB remelts the ice formation. Alternatively, at this point a separate defroster heater could also be used for the heat exchanger  2 . Whether ice has formed can be determined, e.g., by means of a differential pressure sensor  5  on the used air volume flow (AB) before and after the heat exchanger  2 . Alternatively, the ice formation can also be determined by means of the increase of the air pressure in the used air volume flow AB before the heat exchanger  2 .  
         [0060]     The heat pump  3  is turned on and off by means of a temperature sensor generally used in refrigeration technology. If the temperature in the refrigeration cycle of the heat pump  3  is too high, then the compressor is turned off, or for larger, e.g., multi-stage heat pumps, the compressor is turned on or off as a function of temperature. Likewise, the compressor turns off when the temperature in the refrigeration cycle falls below the permissible temperature.  
         [0061]     A possibly necessary additional heat source can output its energy via an optional heat exchanger  16 , which is coupled in the supply line to the heat exchanger  1  into the accumulator cycle  9 . The regulation of the transfer of this thermal energy is performed simply by means of the mixing valve  6 .  
         [0062]     In cases of air-circulation operation, in which heat recovery is not performed, and also in the reheating operation of the ventilation system, the accumulator cycle  9  can be used in an additional way. Here, in a simple manner the PWW (pump warm water) of the heating system, which heats the accumulator cycle  9  via the heat exchanger  16 , can be operated at a lower forward and return temperature. Therefore, in turn, the use of calorific-value technology as a heating system in ventilation technology is enabled. For this purpose, preferably a condensing boiler, which already operates very effectively at low temperatures, is attached to the heat exchanger  16 ; for example, a plate heat exchanger is used.  
         [0063]     The optional function for cooling the external air AU for a cooled supply air volume flow ZU is achieved by switching the refrigeration cycle through known devices on the heat pump  3 .  
         [0064]     For optional humidity control of the supply air volume flow ZU, in the cooling case, another heat exchanger  7  is placed after the heat exchanger  1  in the supply air volume flow ZU. The heat exchanger  7  outputs heat to the supply air volume flow ZU previously cooled down again for dehumidification from the energy available virtually free of the refrigerant. The temperature of the supply air volume flow ZU is here regulated with a mixing valve  8 .  
         [0065]     In the heating case, on the other hand, an optional humidity regulation of the supply air volume flow ZU is coupled to the energy accumulator  9 , and is described in more detail below in the second embodiment.  
         [0066]     To improve the heat dissipation in the cooling case, in the used air volume flow AB there is a device for adiabatic cooling between the heat recovery system  10  and the heat exchanger  2  of the heat pump  3 . Thus, the heat transfer at this point is greatly improved in a simple manner.  
         [0067]     To influence the air handling, air valves can be provided in the channels between the supply air volume flow ZU and the used air volume flow AB in a known way for the supply of mixed air from the used air volume flow AB to the supply air volume flow ZU or for performing an air-circulation operation, as mentioned above. For the use of mixed air, by increasing the air volume flow by means of the air valve, more thermal energy can be taken by the condenser at a lower air temperature. Thus, cold water can also be generated for a possible decentralized cooling arrangement. The cold water can be removed from the energy accumulator  9 . 1 .  
         [0068]     The evaporation and condensation temperature can alternatively also be regulated by means of pressure sensors.  
         [0069]     In the refrigeration cycle, for heating service water at a high temperature level, an additional heater can be installed.  
         [0070]     A second embodiment of the invention is used for improving the transfer of thermal energy for variable volume flows of the supply air and/or used air. Such a system for generating variable volume flows is shown in  FIG. 2 .  
         [0071]     The refinement according to the invention has on the supply air side of the heat pump  3  an arrangement of the accumulator circuit  9  with the heat exchanger  1 , the heat exchanger  4 , and the energy accumulator  9 . 1 , as well as the mixing valve  6  between the branches A and B of the accumulator circuit  9 , as was described in more detail above under  FIG. 1 .  
         [0072]     However, in the arrangement according to  FIG. 2 , the heat exchanger  2  does not carry a flow of refrigerant from the heat pump  3 . Here, the heat exchanger  2  is used as a fluid/air heat exchanger. Another accumulator circuit  12  with an energy accumulator  12 . 1  is allocated to the heat pump  3  on the used air side of the system. The accumulator circuit  12  is coupled to the heat pump by means of a fourth heat exchanger  13 . In this case, the heat exchanger  13  acts selectively as an evaporator or a condenser for the heat pump  3 . Thus, the output of the compressor(s) of the heat pump  3  in the cooling case and in the heating case can be fully utilized. The accumulator circuit  12  and the energy accumulator  12 . 1  are likewise filled with a circulating fluid, which stores heat and which is circulated by a pump. The regulation of the fluid throughput in the accumulator circuit  12  is performed by means of a mixing valve  14 . Branches A and B of the accumulator circuit  12  are allocated to the mixing valve  14 . A branch A is directly connected to the heat exchanger  2  as a return line. A branch B is connected to the supply line coming from the energy accumulator  12 . 1  and leading to the heat exchanger  2 . By setting on the mixing valve  14 , the throughput of the circulating fluid in the accumulator circuit  12  can be regulated from the extreme states with full throughput through the heat exchanger  2  to deactivation of the heat exchanger  2 . The energy accumulator  12 . 1  is arranged directly after the heat exchanger  13  and carries a flow of the entire amount of fluid.  
         [0073]     By means of the circulating fluid, the thermal energy is transferred to the outgoing air FO by means of the heat exchanger  2 . If the differential pressure exceeds a predetermined value due to ice formation on the heat exchanger  2 , at the mixing valve  14 , the flow from branch B is opened to A-B and the thermal energy optionally used by the heat pump  3  is temporarily stored in the accumulator circuit  12 . In this way, the heat exchanger  2  is stopped. After the ice formation in the heat exchanger  2  melts and thus the differential pressure decreases, the mixing valve  14  in the accumulator circuit  12  opens the branch from A to A-B and the thermal energy is further transferred via the heat exchanger  2  to the used air volume flow AB and thus to the outgoing air FO.  
         [0074]     In addition to humidity control for the cooling case (summer) as described in the first embodiment from  FIG. 1 , humidity control for the heating case (winter) can also be provided. For this purpose, in the supply air volume flow ZU, another heat exchanger  11  is arranged. This is connected to the energy accumulator  12 . 1  of the additional accumulator circuit  12  and arranged after a dehumidification device in the supply air volume flow ZU. A mixing valve  15  controls the amount of throughput and thus the final temperature of the supply air volume flow ZU.  
         [0075]     The transferred energy is stored in the energy accumulators  9 . 1  and  12 . 1  and continuously transferred to the external air AU or to the supply air volume flow ZU and to the used air volume flow AB or to the outgoing air FO even if the compressor is stopped.  
         [0076]     In particular, the energy accumulator  9 . 1  can be directly or indirectly connected via the accumulator circuit  9  to additional devices for supplying or discharging heat in order better to utilize its energy capacity.  
         [0077]     A possibly required additional heating source transfers the energy by means of the optional heat exchanger  16  to the accumulator circuit  9 . The regulation of the transfer of this thermal energy is performed with the mixing valve  6 .  
         [0078]     As already described under the first embodiment, the system can be expanded at this point by a heating device according to calorific-value technology. This is then possible if the ventilation system is operated in the air-circulation mode or in the reheating mode at low water temperatures. Here, in a simple way, the pump warm water of the heating system, which heats the accumulator circuit  9  by means of the heat exchanger  16 , can be operated at lower forward and return temperature.  
         [0079]     The invention can also be used in very advantageous ways if a heat pump is used without allocating to this heat pump an additional conventional first heat recovery system in the first recovery stage.  
         [0080]     The described invention can be operated both with one-stage and also with multi-stage heat pumps.  
         [0081]     In the ventilation channels, in addition to the described necessary elements, other elements for air handling, such as filters, sound absorbers, or humidifiers can be used in conventional ways. To increase the output number of the heat pump  3  and for total heat transfer at variable volume flows, the mixture of external air to outgoing air that is typical in air-conditioning technology can also be performed by means of a mixing air valve. Similarly, the system is suitable for air-circulation operation, as already mentioned in more detail above.  
         [0082]     As shown in  FIGS. 3 and 4 , the invention can also be used for the operation of combination systems. Here, a heat pump  3  is connected in a very efficient way to several ventilation systems  17 ,  18  via the accumulator circuit or the accumulator circuits  19  or  20 .  
         [0083]     In  FIG. 3 , an arrangement with two accumulator circuits  19  or  20  is shown for two ventilation systems  17 ,  18 . These ventilation systems  17 ,  18  can be operated independently of each other in the cooling and heating modes. For this purpose, an energy accumulator  19 . 1  or  20 . 1  is used for the cooling mode and an energy accumulator  19 . 1  or  20 . 1  is used for the heating mode.  
         [0084]     In  FIG. 4 , the accumulator circuit  19  is reduced to a single energy accumulator  19 . 1 . This embodiment is then used if the ventilation systems  17 ,  18  are to be used generally only in the heating mode.  
         [0085]     Furthermore, the invention can also be used if the heat pump is operated with an external condenser or evaporator. Therefore, the effect of the heat pump can be supported in an especially advantageous way.  
         [0086]     The invention can be used in connection with air-conditioning and ventilation systems of any order of magnitude, thus also, for example, for auditorium air conditioners or auditorium heaters.  
         [0087]     Finally, the invention is also suitable in a very advantageous way for retrofitting existing systems because the heat pump can be coupled to the accumulator circuit or the accumulator circuits as a unit on existing ventilation systems.  
         [0088]     The invention is not limited to the described embodiments, but instead can also be configured in different ways within the scope of the knowledge of someone skilled in the art.