Process for improved energy recovery in supply and exhaust air heat exchangers of closed-loop heat exchanger systems for air conditioning and ventilation systems

Abstract

Method for controlling the operation of supply and exhaust air heat exchangers of closed-loop systems for air conditioning and ventilation systems, comprising: Supplying at least one supply air flow and / or at least one exhaust air flow of an air conditioning or ventilation system to one or more heat exchangers through which a medium flows; Measuring a temperature difference, ΔT value, between a flow and a return temperature of the medium for each of the heat exchangers; Adjusting the media flow through the associated heat exchanger in such a way that the ΔT value for the associated heat exchanger is regulated to a setpoint.

Description

Field of the InventionThe invention relates to a method, a device and a control system for operating inlet and outlet air heat exchangers of circulating composite systems for air conditioning and ventilation systems.BACKGROUND OF THE INVENTIONIn order to achieve good energy efficiency of an air conditioning system or ventilation system, a circuit composite system with heat exchangers in the inflow and outflow air stream is provided, which are connected to one another via a hydraulic circuit and by means of which heat can be extracted from the exhaust air in the case of heating and supplied to the inflow air or heat can be extracted from the inflow air in the case of cooling and supplied to the exhaust air. In conventional systems, for example, the temperatures and delivery quantities on the air side and media side are measured at inlet and outlet air heat exchangers in order to adapt the flow of the medium circulating in the heat exchangers to the mass flow on the air side in a continuously regulated manner. However, this requires a relatively high outlay, since a relatively large number of sensors are required and since the regulation of the medium flow through the heat exchanger or exchangers has to be adapted and optimized for each specific use and each individual system as a function of the numerous measurement values.Object of the InventionIt is an object of the present invention to provide a method and a system whereby efficient recovery of the heat of the exhaust air or heat emission of the supply air ("recovery" of the cold of the exhaust air) can be ensured, and which can be used in different air conditioners and ventilation systems each having one or more separate heat exchangers for the exhaust air and supply air.Overview of the InventionAccording to the invention, a method is provided in which one or more heat exchangers are each connected to an exhaust air stream or a plurality of exhaust air streams and one or more heat exchangers are connected to an intake air stream or a plurality of intake air streams of an air conditioning or ventilation installation. For each heat exchanger, the temperature difference ΔT between the supply and return temperature of the heat exchanger is determined and the medium flow through the associated heat exchanger is adjusted in such a way that the ΔT value for the associated heat exchanger is regulated to a setpoint value.In one embodiment, wherein, for example, a respective heat exchanger is provided in the inlet air stream and a heat exchanger is provided in the outlet air stream, the medium flow rate through the heat exchangers can be adjusted by adjusting a rotational speed of at least one speed-regulated pump.In other embodiments, wherein, for example, more than one heat exchanger is arranged in an inlet air stream or a plurality of inlet air streams, and / or more than one heat exchanger is arranged in an outlet air stream or a plurality of outlet air streams, each heat exchanger can be assigned a delta-T control valve, by means of which the flow through the associated heat exchanger is adjusted in such a way that the value of the temperature difference ΔT is controlled to a setpoint value which is either fixed in advance or can be dynamically scaled. As a result, efficient energy recovery is achieved in a particularly simple manner, merely by temperature measurements at the heat exchangers.By controlling the at least one speed-controlled pump, a demand-based differential pressure control can be implemented to save energy in the integrated circuit system. In addition, this control achieves automatic hydraulic balancing.The flow rate of the medium circulating in the heat exchangers, such as a water / glycol mixture, can be controlled in such a way that the heat exchangers are each operated with an optimum degree of heat transfer.According to some embodiments, the method may further comprise determining and regulating the delta-T control valve having the widest valve opening degree in each of the inlet and outlet air lines, and adjusting the increase in pressure by one or more speed controlled pumps so that the power consumption of the system is reduced to the minimum necessary.For example, in the case of too low a ΔT value of a heat exchanger, the flow rate of the medium can be lowered, and in the case of too high a ΔT value of a heat exchanger, the flow rate of the medium can be increased in order to optimize the heat transfer of this heat exchanger in each case.According to some embodiments, an automatic determination of an operating state of the air conditioning and ventilation system may be performed based on the measured ΔT values, wherein the operating state comprises a heating or cooling operating state. Here, ΔT command values for the determined operation state may be transmitted to the respective delta-T control valves of the heat exchangers in the inflow air and the outflow air, and the control of the opening degree may be performed for each delta-T control valve using the transmitted command value. The method can thus be automatically set to different operating states and the energy recovery can be automatically adapted to whether the air conditioning and ventilation system is in a heating or cooling operating state.The automatic determination of the operating state of the air conditioning and ventilation system can thereby comprise determining for each heat exchanger on the basis of the ΔT values whether it is in a neutral operating state, in a heating operating state or in a cooling operating state; and determining in which operating state the majority of the heat exchangers are located, wherein heat exchangers which are in a neutral operating state are not taken into account in this case. The operating state of the air conditioning and ventilation system can be set as the operating state of the majority of the heat exchangers. If there are equal numbers of heat exchangers in the heating and cooling operating states, the operating state is set corresponding to the heat exchanger having the ΔT value with the greatest amount. As a result, in any operating situation, even if, for example, individual heat exchangers and individual components of the air conditioning and ventilation system are not in operation, an operating state can be determined and the ΔT setpoint values can be automatically adjusted on the basis of the determined operating state.In addition to energy recovery, the supply air can be temperature-controlled at the one or more supply air heat exchangers by feeding in heat or cold. In this case, the ΔT setpoint value for the respective inlet air heat exchangers can be adjusted accordingly in order to prevent fed energy from being fed via the return to the exhaust air heat exchangers.Since the flow rates are controlled via the valves and the pressure increase via the valve position is controlled for an optimum degree of energy recovery, no additional hydraulic adjustment of the system is necessary.Further, according to some embodiments, it may be determined whether a ΔT value of a heat exchanger is less than a set minimum value over a certain period of time, and if so, the delta-T control valve of that heat exchanger may be fully closed because the heat exchanger does not contribute to energy recovery.Herein, the delta-T closed control valve of the heat exchanger may be opened after a predetermined period of time, and the determination of whether the ΔT value of a heat exchanger is less than a set minimum value over a certain period of time may be repeated after the delta-T control valve is opened to determine whether the heat exchanger is meanwhile contributing to energy recovery. Instead of being triggered at predetermined periods of time, this repetition can also be triggered, for example, by an energy recovery operation being interrupted briefly and restarted by a superordinate building automation system if a room air technology device which is coupled to the heat exchanger is switched on, or if no heat exchanger has a sufficiently large ΔT value in the inflow or outflow of air.According to a further embodiment, the present invention also provides a method for dehumidifying cold recovery (EKR) of the supply air of an air conditioning and ventilation system, wherein a plurality of heat exchangers are each arranged in a supply air stream, the supply air is cooled by a first dehumidifying heat exchanger in order to reduce the moisture content of the supply air, and thermal energy is fed back to the supply air by means of a downstream heat exchanger. In this case, both heat exchangers are connected via a common medium circuit, and the medium flow through the dehumidifying heat exchanger and the downstream heat exchanger is regulated in such a way that a ΔT value between a feed temperature and a return temperature of the medium is regulated for each of these heat exchangers to an EKR setpoint value. Therefore, even in an EKR operation, the energy recovery by means of the EKR heat exchangers can be optimized by the temperature measurements of the respective feed and return temperatures without the need for measurements of the feed air temperature, the feed air flow or the like.The invention furthermore provides a device for regulating the operation of inlet and outlet air heat exchangers of circulating systems for air conditioning and ventilation systems, a circulating system station and a machine-readable storage medium which contains instructions which, when they are executed in a processor of a control unit of a circulating system for air conditioning and ventilation systems, are suitable for carrying out the method described above.Brief Overview of the DrawingsFIG. 1 shows an example of a circulatory composite system in an air conditioning and ventilation system, wherein energy recovery can be carried out according to an embodiment of the present invention. FIG. 2 shows an example of a circulatory composite system in a variant with an air supply heat exchanger and an air exhaust heat exchanger. FIG. 3 shows an example of a cycle composite system in a variant with any number of inlet air and outlet air heat exchangers. FIG. 4 is a schematic diagram of the control method for the respective delta-T control valves according to an embodiment of the present invention. FIG. 5 shows a functional diagram of the method according to an embodiment of the invention.Detailed Description of EmbodimentsIn the following detailed description, exemplary embodiments and variations of the present invention will be described with reference to the accompanying drawings. This is merely for understanding the present invention, and the invention is not limited to a specific embodiment, as a matter of course. Features of different embodiments can be combined with one another in each case, even if this is not explicitly stated in the individual case.FIG. 1 shows a circulatory composite system (KVS) station 10 for a not-shown air conditioning and ventilation system, for example for a building, an industrial system, a hospital or the like. In the closed-circuit composite system (KVS) 10 shown in FIG. 1, a medium, such as a water-glycol mixture, is conducted through one or more exhaust air heat exchangers 11 and through one or more supply air heat exchangers 12 in each case in order to extract heat or cold from the exhaust air and feed this to the supply air. It should be noted here that the exhaust air heat exchangers and the supply air heat exchangers are designed as separate devices, so that the respective supply air and exhaust air streams can also be designed to be spatially separate and contamination of the supply air by germs or pollutants possibly contained in the exhaust air can be prevented. For the temperature control and dehumidifying of the supply air, a cooler 13 and / or a reheater 14 can optionally also be provided in the supply air flow, as shown in FIG. 1. At the exhaust air heat exchangers 11 and the supply air heat exchangers 12, two temperature sensors 15 are provided in each case, which measure a flow temperature and a return temperature of the medium. From these measured temperatures, a temperature difference, ΔT value, is determined.Optional temperature sensors can furthermore be provided in the supply air stream, which measure the temperature of the supply air which passes through the cooler 13 and the reheater 14. With the aid of these measured temperatures, an air-supply temperature control with dehumidification cooling recovery is realized.For the purpose of tempering the medium, a heat / cold feed module 16 can be provided.During operation, the medium is pumped by means of one or more pumps 18 in each case through the exhaust air heat exchanger or exchangers 11 and the supply air heat exchanger or exchangers 12, a pressure compensation container 17 being provided. The flow of the medium through the exhaust air heat exchanger or exchangers 11 and the supply air heat exchanger or exchangers 12 is controlled by delta-T control valves 19 in accordance with the determined ΔT values, as will be explained in detail below with reference to some examples. In the exemplary embodiment shown here, the delta-T control valves 19 are designed as pressure-independent control valves (PICV valves) 19, but other types of control valves can also be used. By means of a power control valve 20, the heat transfer between inlet and outlet air heat exchangers can be controlled centrally in part-load operation.By means of the ΔT values, an operating state (for example heating operation or cooling operation) can first be determined. According to the operating state determined, setpoint values for ΔT for the delta-T control valves of the inlet air and outlet air heat exchangers 11, 12 can then be set.The operation of the heat exchangers 13 and 14 for dehumidifying cold recovery of the supply air can also be optimized according to one embodiment in that the temperature difference, ΔT value, between the feed temperature and the return temperature is also determined for these heat exchangers. The medium flow through the heat exchangers 13 and 14 can thus be adjusted in such a way that the respective ΔT value is regulated to an EKR setpoint value for the respective EKR heat exchangers. This control of the medium flow rate can be effected by regulating the rotational speed of a pump and / or by regulating the degree of opening of delta-T control valves of the EKR heat exchangers.According to an exemplary embodiment, upon an energy / heat recovery (WG) release, the KVS starts in the last stored operating state. In the first operation or after a longer standstill time, a neutral operating state (N) is set. The automatic operating state recognition of the heating or cooling operation (H / K) is then carried out according to the ΔT values determined at each heat exchanger 11, 12 and functions according to the majority principle. For each heat exchanger, an operating state is determined from the ΔT value, as indicated in Table 1 below, and then it is counted in which operating state the majority of the heat exchangers are located. Heat exchangers which are in the neutral (N) operating state are not authorized to match. At 50 / 50 inconsistency, the ΔT value with the most significant excursion gains the mode selection and regions whether the system is to be in H or K mode. Table 1 Table 1Heating (H)ΔT>=5KWRG requirement to an adjustable setpoint value, for example 75%, by heat input. With input >0% WG request internal=100% heating.Neutral (N)Abs(ΔT)<5KΔT Set Values Do not ChangeCooling (K)ΔT>=5KWRG requirement to, for example, 75% by cold feed. With input >0% WRG request internal=100% cooling.Dehumidification Cold Recovery (EKR)EKR activeEKR requirement of the air conditioning and ventilation system to, for example, 75% by feeding in heat. EKR takes priority over WRGIn the case of an input of energy by means of the heat / cold input module 16 during a WG operation, two control circuits-one for the heating operation and one for the cooling operation-have the task of regulating the WG requirement to, for example, 75%. Only one of these control circuits is always active per operating state (H / K) and acts on the respective input of heating or cooling power. The more energy is fed in, the closer the temperature of the medium moves to the flow of the air-intake heat exchanger and thus the air-intake temperature to the desired value, whereby the WG requirement falls again. Without feeding, two ΔT setpoints per air-to-air delta-T control valve are needed (one setpoint for heating operating condition, one for cooling operating condition). An additional ΔT setpoint value is required for each feed. In the case of H and K feeding, four ΔT setpoint values (H; H2 / K; K2) are therefore required. When fed, the absolute ΔT setpoint for the air-supply heat exchanger or exchangers 12 is greater than the ΔT setpoint without feed. This is intended to prevent energy fed in from being fed to the exhaust air heat exchangers 11 via the return. In order to avoid that medium heated or cooled by the feeding arrives at the return of the air-intake heat exchangers 12 and flows to the exhaust-air heat exchangers 11, as a result of which the energy fed in would be lost, the medium flow through the air-intake heat exchangers 12 is regulated in such a way that the return temperature of the air-intake heat exchangers 12 is kept at a meaningful difference from the return temperature of the exhaust-air heat exchanger medium by throttling the feeding (heating mode: T air-intake medium<T air-exhaust medium; cooling mode: T air-intake medium>T air-exhaust medium). The function of this control loop can be switched off.In order to prevent an input from unintentionally affecting the operating state detection, it can be provided that the switching over of the operating state (H / N / K) takes place only after a time in the minute range has elapsed following a cold or heat input.As listed in Table 1 above, the operating conditions also include the dehumidification refrigeration recovery (EKR) operating condition. In this case, the supply air is cooled by the dehumidifying heat exchanger 13 in order to reduce the moisture content of the supply air by steam contained in the supply air condensing out during cooling, and thermal energy is then supplied again to the supply air by means of the downstream heat exchanger 14, wherein the two heat exchangers 13, 14 are connected via a common media circuit. Since EKR is a particularly energy-efficient method for dehumidifying and pretempering the supply air stream, in this example the EKR is operated with priority before the energy recovery.The EKR request functions as a request for post-heating. The EKR delta-T control valve is enabled starting from an EKR requirement of 10% and disabled again at 0% (reheater isolation). The pumps 18 regulate the pressure increase in EKR operation, as well as in WRG operation. The setpoint value of the pressure increase is limited even more deeply by way of the EKR requirement upward and by way of the widest opening of the EKR and delta-T control valves. The widest opening of the delta-T control valves is also maintained at 75%, for example, during EKR operation by means of the continuous adaptation of the pressure increase. In the case of EKR, the WRG requirement plays no part in the setpoint value for the pressure increase.The WG delta-T control valve disconnects the exhaust air heat exchangers 11 if the return temperature of the inlet air heat exchangers 12 measured in the KVS station 10 is lower than the return temperature of the exhaust air heat exchangers 11, the exhaust air heat exchangers 11 thereby being de-released and fully closing. This state can be temporarily cleared cyclically and rechecked. This check is based on that of the automatic detection of the operation of the inlet air and outlet air heat exchangers 11, 12 and is simultaneously started.In cooling operation, it may furthermore be expedient to carry out adiabatic cooling of the exhaust air stream. If the calculated wet bulb temperature upstream of the humidifier is at least 2K below the exhaust air temperature measured there, it is expedient to release an exhaust air humidifier for adiabatic cooling. For the dehumidifying operation, if the calculated wet bulb temperature upstream of the humidifier is at least 2K below the exhaust air temperature measured there, the release of the exhaust air humidifier for adiabatic cooling is expedient if it is a further 2K below the return temperature measured in the KVS station 10 to the exhaust air heat exchangers 11.Furthermore, in the case of the KVS station 10 shown in FIG. 1, it is possible to integrate measures for frost protection. Frost formation can be prevented when the supply medium to the exhaust air heat exchanger 11 has a temperature of not more than 2K below the dew point temperature of the exhaust air. This can be achieved by a frost protection valve 21. If the measured values moisture and temperature of the exhaust air for dew point calculation are not transmitted from the higher-order air conditioning or ventilation system or a central control unit to the KVS station, then 0° C. can be assumed as dew point temperature.As a further optional addition to the method described above, an automatic detection of the operation of inlet air and outlet air heat exchangers 11, 12 can be carried out. In this case, all delta-T control valves 19 are initially enabled for delta-T control when WG is enabled. If the ΔT value of a delta-T control valve 19 remains at almost zero (e.g. ±2 K) over a certain period or is even with a sign with opposite sense, the heat exchanger concerned contributes nothing to the WG or its use and the corresponding room air technology device on the supply air side or exhaust air side is presumably not active. The delta-T control valve 19 is then de-energized thereby fully closing it.This state can be temporarily canceled cyclically per delta-T control valve 19 and rechecked if, for example, one or more of the following conditions are fulfilled:• When WRG release is temporarily withdrawn and re-granted. In this case, the WG can easily continue to run over a run-on for bridging (e.g. release pulse 1 second and run-on 2 seconds). This is a particularly simple way of carrying out cyclic checks as to whether the heat exchangers contribute to the WG in each case;• when a room air-conditioning apparatus is turned off or on;• When Exhaust Air Humidifiers are switched on or off for adiabatic cooling; when the WG requirement has changed by, for example, at least ± 5% since the last test (all delta-T control valves 19 release and reassess).• If the WRG requirement is >=95% (all delta T control valves enable and reassess).• If no heat exchanger in the feed air stream has any more meaningful temperature difference of Abs(ΔT)>2K. In this case, all delta T control valves of the inlet air heat exchangers may be released and revaluated;• If no heat exchanger in the exhaust air flow has any more meaningful temperature difference of Abs(ΔT)>2K. In this case, all delta T control valves of the exhaust air heat exchangers can be released and revaluated.All the options listed above can be parameterized and dialed or deselected. If none of the options are selected, the delta-T control valves maintain the WG release without further restrictions.If (one) humidifier for adiabatic cooling is(s) present, the air conditioning or ventilation system can release it for cooling (early before the test), if appropriate. The automatic operating state recognition system takes into account the cooling potential thereby present during the test.In general, as input variables for a method according to one embodiment, for example, a digital signal for WG release, an optional analog WG request in the case of external temperature control or external temperature setpoint specification in the case of temperature control by the KVS station 10, an optional analog EKR request in the case of external temperature control, an analog temperature setpoint which can be obtained at the same input as WG request and is optional in the case of temperature control by the KVS station 10, an optional analog value of the exhaust air temperature for dew point determination and / or an optional analog value for exhaust air humidity can be received at the KVS station 10. In particular, the temperature and moisture values can also be measured at the KVS station 10 with the respectively required sensors.FIG. 2 shows an example of the operation of a KVS station 10 with an air-supply heat exchanger 12 and an air-discharge heat exchanger 11. In this case, ΔT setpoint values for different operating states are stored in a memory 22, as explained above.For example, in this embodiment, energy recovery can be carried out in such a way that, after the KVS station has been released, one of the pumps 18 starts from a WG request of 10% (switch-off hysteresis-10%). Between 0% to 10% WG request, the WG power valve 20 opens from 0% to 100%. The WG requirement is used to interpolate the differential pressure setpoint value of the pumps linearly between minimum and maximum. The differential pressure is limited (throttled) upward by a control circuit which controls the delta-T between the forward and return of the exhaust air heat exchanger 11. As a result, the pump rotational speed is optimized according to requirements, which reduces the average energy requirement.FIG. 3 shows an example of the operation of a KVS station 10 with any number of inlet air heat exchangers 12 and outlet air heat exchangers 11, wherein, in contrast to the embodiment shown in FIG. 2, the medium flow through the respective heat exchangers 11, 12 is adjusted by regulating the degree of opening of the delta-T regulating valves 19. During operation for energy recovery, the delta-T control valves 19 are enabled for control operation as soon as the associated air conditioning and ventilation system is in operation. The individual ΔT set point is communicated to each delta-T control valve 19 in the KVS station 10. The ΔT setpoint values for the heating and cooling case are stored in the memory 22 of the KVS station 10. A control device of the KVS station automatically distinguishes the heating and cooling cases by comparing the supply and return temperatures. In the case of heating, the ΔT setpoint for the delta-T control valves 19 is positive in the exhaust air and negative for the delta-T control valve, which represents the WG power valve in the KVS station 10.The delta-T setpoint values for heating and cooling cases can be calculated in the planning process for each delta-T control valve 19 and be specified as fixed values. The same applies to the minimum and nominal flow rates per valve, which can be configured individually for each plant during startup. Within these limits, the respective delta-T control valve 19 can run in a continuously regulated manner independently in order to maintain the temperature difference ΔT at its setpoint value.After the KVS station has been released, one of the pumps 18 starts from a WG request of, for example, 10% (switch-off hysteresis -5%). Between 0% to 10% WG request, the WG power valve opens from 0% to 100%. The differential pressure setpoint value of the pumps is interpolated linearly between minimum and maximum via the WG request, as is schematically shown in FIG. 4. In FIG. 4, y Xx corresponds to position feedback of the respective delta-T control valve 19, x Fmax corresponds to maximum position feedback of all delta-T control valves as a controlled variable of the pilot regulator; w F corresponds to the setpoint value of the pilot regulator in bar; y F corresponds to the control signal of the pilot regulator; P Min corresponds to a lower scaling limit value for the pilot regulator control signal in bar; P Max corresponds to an upper scaling limit value for the pilot regulator control signal in bar; w N corresponds to the setpoint value of the secondary regulator in bar; x N corresponds to a measured value of the differential pressure as a controlled variable of the secondary regulator in bar; y N control signal of the secondary regulator.The differential pressure is limited (throttled) upward by a control circuit which limits the greatest valve opening of the delta-T control valves 19 (maximum of yz max and ya max= x Fmax) downward to, for example, 75%. As a result, the pump rotational speed is optimized according to requirements, which reduces the average energy requirement.In the event of a thermal imbalance between inlet and outlet air heat exchangers, at least one delta-T control valve 19 opens into inlet or outlet air in the direction of 100%. In order to promote automatic hydraulic balancing in this scenario and thus optimize the WG performance, the air side with the widest valve opening requires more medium flow than the opposite air side. This is achieved with an additional control circuit which is responsible for limiting the maximum valve opening of the inlet and outlet air heat exchangers to, for example, 85% opening. The control signal of this control circuit acts on the opening of the anti-frost valve 21 when the valve concerned is on the exhaust air side and on the bypass via the WG power valve 20 when it is on the intake air side. The frost protection valve 21 has priority. While the frost protection valve 21 is opened, the bypass of the WG power valve 20 remains closed. It cannot occur that the bypass of the WG power valve 20 and the frost protection valve 21 are simultaneously opened.According to one embodiment, the software for implementing the method described above can be constructed in a layered model, wherein in a first phase the hydraulic control is carried out by achieving an energy-efficient pump operation and an efficient use of the energy fed in, as described above, by delta-T management and optionally by feeding heat and / or cold to the medium. In a second phase, the air temperature control takes place, which comprises an exhaust air and / or supply air temperature control and optionally adiabatic cooling and / or dehumidification cooling recovery. In a third phase, optimization functions are then implemented, which enable, for example, a more rapid settling of the control circuits by calculated starting and limit values for control signals.FIG. 5 shows a simplified functional plan of a method according to an embodiment. As described above, it is understood that the delta control valves are opened to an opening degree of at least, for example, 75% (S1), and the pump speed is adjusted accordingly to obtain a target value for the differential pressure (S2). From a comparison of the exhaust air and supply air temperatures with corresponding setpoint values (S 3), a WG request can be generated (S 4) which can be received as an analog signal (such as a percentage value) and can also be taken into account in the pressure regulation by means of the speed-regulated pump.Furthermore, hydraulic balancing is automatically carried out (S 5), wherein the flow through the heat exchangers can be balanced via the power valve 20. A frost protection control (S6) prevents frost formation by controlled opening of the frost protection valve 21.Finally, external feeds of heat or cold can also be taken into account (S 7, S 8), wherein the WG requirement is adapted accordingly in order to efficiently use the fed energy.

Claims

A method for controlling the operation of inlet and outlet air heat exchangers of circulating composite systems for air conditioning and ventilation systems, comprising: supplying at least one inlet air stream and / or at least one outlet air stream of an air conditioning or ventilation system to one or more heat exchangers through which a medium flows; measuring a temperature difference, ΔT value, between a supply and a return temperature of the medium for each of the heat exchangers; adjusting the medium flow through the associated heat exchanger such that the ΔT value for the associated heat exchanger is controlled to a setpoint value.Method according to Claim 1, wherein the medium flow rate through the heat exchangers is adjusted by adjusting a rotational speed or the rotational speeds of at least one speed-regulated pump.The method of any of claims 1 or 2, wherein adjusting the flow rate of media through the heat exchanger is performed by controlling an opening degree of a delta-T control valve for each of the heat exchangers.Method according to one of claims 1 to 3, further comprising: determining and regulating the delta-T regulating valve, which has the widest valve opening degree in each case in the inlet and outlet air line, adapting the pressure increase by one or more speed-regulated pumps, so that the power consumption of the system is reduced to the necessary minimum.The method of any one of claims 1 to 4, further comprising: in the case of a ΔT value of a heat exchanger being too low compared to the set point, decreasing the opening degree of the associated delta-T control valve to decrease the flow rate of the medium through the heat exchanger, and in the case of a ΔT value of the heat exchanger being too high compared to the set point, increasing the opening degree of the associated delta-T control valve to increase the flow rate of the medium through the heat exchanger.The method of any of claims 1 to 5, further comprising: automatically determining an operating state of the air conditioning and ventilation system based on the measured ΔT values, wherein the operating state comprises a heating or cooling operating state; transmitting set values for the determined operating state to the respective delta T control valves of the heat exchangers in the inlet air and outlet air streams; performing the control of the opening degree for each delta T control valve using the transmitted set value.The method of claim 6, wherein automatically determining the operating state of the air conditioning and ventilation system comprises: determining, for each heat exchanger based on the ΔT values, whether it is in a neutral operating state, in a heating operating state or in a cooling operating state; and determining in which operating state the majority of the heat exchangers are located, wherein heat exchangers that are in a neutral operating state are not considered, and wherein the operating state of the air conditioning and ventilation system is set as the operating state of the majority of the heat exchangers should equal numbers of heat exchangers be in the heating and cooling operating states, the operating state is set corresponding to the heat exchanger having the ΔT value having the largest amount.The method according to any one of claims 1 to 7, further comprising: feeding heat or cold for tempering the feed air to the one or more of the heat exchangers in the feed air stream.The method of claim 8, further comprising: adjusting the set point for the ΔT value of the one or more of the heat exchangers in the feed air stream into which heated or cooled medium is fed to prevent fed energy from being fed via the return to the exhaust air heat exchangers.The method of any one of claims 1 to 9, further comprising: determining whether a ΔT value of a heat exchanger is less than a set minimum value over a certain period of time, and if so, fully closing the delta T control valve of the heat exchanger.The method of claim 10, comprising: opening the delta-T closed control valve of the heat exchanger after a predetermined period of time; repeating the determination of whether the ΔT value of a heat exchanger is less than a set minimum value over a certain period of time; and if so, repeating fully closing the delta-T control valve of the heat exchanger.Method according to one of claims 1 to 11, wherein: a plurality of heat exchangers are each arranged in an inlet air stream, the inlet air is cooled by a first dehumidifying heat exchanger in order to reduce the moisture content of the inlet air, and thermal energy is fed back to the inlet air by means of a downstream heat exchanger, wherein the two heat exchangers are connected via a common media circuit, and wherein the media flow rate through the dehumidifying heat exchanger and the downstream heat exchanger is regulated in such a way that a ΔT value between a feed temperature and a return temperature of the medium for each of these heat exchangers is regulated to an EKR setpoint valueAn apparatus for controlling the operation of inlet and outlet air heat exchangers of circulating composite systems for air conditioning and ventilation systems, comprising: sensors for measuring a temperature difference, ΔT value, between a supply and a return temperature of the medium for each of the inlet and outlet air heat exchangers; a controller for adjusting the medium flow rate through the associated heat exchanger such that the ΔT value for the associated heat exchanger is controlled to a setpoint value, wherein the adjusting of the medium flow rate comprises a speed control of at least one pump and / or controlling an opening degree of a delta-T control valve for each of the heat exchangers.A circulating composite system station for an air conditioning and ventilation system, comprising: one or more heat exchangers in at least one inlet air stream of the air conditioning or ventilation system and one or more heat exchangers in at least one outlet air stream of the air conditioning and ventilation system, wherein a medium flows through the inlet air heat exchangers and the outlet air heat exchangers; sensors for measuring a temperature difference, ΔT value, between a supply and a return temperature of the medium for each of the heat exchangers; a controller for adjusting the flow of media through the associated heat exchanger such that the ΔT value for the associated heat exchanger is controlled to a set point, wherein adjusting the flow of media comprises a speed control of at least one pump and / or controlling an opening degree of a delta T control valve for each of the heat exchangers.A machine readable storage medium containing instructions which, when executed in a processor of a controller of a cycle integrated system for air conditioning and ventilation systems, are adapted to carry out the method according to any one of claims 1 to 12.

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