WO2013023764A1

WO2013023764A1 - Ventilation system having a coolable pcm heat exchanger and method for operating the ventilation system

Info

Publication number: WO2013023764A1
Application number: PCT/EP2012/003402
Authority: WO
Inventors: Thomas Pollmeier
Original assignee: Thomas Pollmeier
Priority date: 2011-08-12
Filing date: 2012-08-09
Publication date: 2013-02-21
Also published as: DE102011110039A1; EP2742295A1

Abstract

The invention relates to a ventilation system (2) for a building having an air suction opening (4), an air guide duct (6) adjacent to said opening, in which duct a heat exchanger (16) containing a phase exchange material is located, a ventilator (10), and an air outlet opening (8) arranged at the end of the air guide duct (6), characterized in that the ventilation system (2) has a system for supplying a liquid, having at least one port opening (20) from which the liquid that exits from the port opening (20) reaches the surface of the heat exchanger (16).

Description

Ventilation system with coolable PCM heat exchanger and method for

Operating the ventilation system

The present invention relates to a ventilation system for a building with an air intake, an adjoining air duct, in which a heat exchanger is disposed with a phase change material therein, a fan and an air outlet opening arranged at the end of the air duct and a method for operating a such a ventilation system.

From the prior art, it is known to use heat exchangers with therein phase change materials to buffer temperature peaks in the ventilation of buildings. An example of this can be found in the document DE 203 14 018 U1. Phase change materials need during the phase change, for example from solid to liquid considerable amounts of energy that are released again in the reverse phase change. If the supplied air is too warm during the day, it can be cooled above the heat exchanger, which absorbs heat energy. If cool air is introduced during the night, the energy absorbed and stored in the heat exchanger during the day can be used to heat the air, which is too cool.

The temperatures at which a phase change occurs can be accurately adjusted by selecting and designing the phase change material. For example, if a building is to be maintained at a constant temperature of 22 ° C, and the outdoor air supplied for ventilation is at a temperature of, for example, 30 ° C by day, the outside air may be passed along the heat exchanger to cool it and the heat exchanger during the phase

CONFIRMATION COPY change energy. If the phase change in the phase change material used in the heat exchanger, for example, at 23 ° C, and the phase change material at the beginning of the air cooling, for example, a temperature of 19 ° C, the outside air can be used to heat the phase change material, for example, to 26 ° C, During the phase change by 23 ° C much energy is needed for the phase change. The stored energy in the heat exchanger can later be used to heat up to 17 ° C cold outside air at night to 22 ° C by corresponding amounts of heat are released during the phase change back from the heat exchanger. The heat energy exchanged during the respective heating and cooling processes is taken from the air in each case, without primary energy being consumed.

The time-shifted energy exchange via the phase change material is used in the building ventilation system to cut heat peaks and to use the energy gained during the phase change later for the air heating. However, a problem arises when the temperature of the supplied air does not cool below the value at which the phase change occurs over an extended period of time. The phase change material, for example, remains at a temperature level at which it retains its liquid state of aggregation. After passing through the phase change, above the phase change temperature only comparatively small amounts of energy are taken up via the heat exchanger and released again. The buffer effect is thus no longer usable at higher continuous temperatures above the phase change temperature.

It is known from document DE 20 2007 015 938 U1 to use an additional air-conditioning device in order to cool the phase-change material of a heat exchanger at times of higher temperatures so far that its temperature falls below the phase change temperature and thus again usable for energy storage purposes. However, the use of an additional air conditioning unit is expensive and consumes significant amounts of primary energy. The desired energy saving effect is thereby significantly reduced.

Accordingly, it is the object of the present invention to provide a ventilation system in which an air cooling by means of the heat exchanger also remains possible if the permanent temperatures of the supply air over a longer period of time above the temperature level of the phase change of the phase change material used.

The object is achieved for a generic ventilation system in that the ventilation system has a system for supplying liquid with at least one orifice, from which the liquid emerging from the orifice reaches the surface of the heat exchanger.

The system for liquid supply has a supply line with which a liquid can be conveyed into the region of the heat exchanger and can be applied by the latter to the surface of the heat exchanger or heat exchangers. From the surface of the heat exchanger, the liquid can then evaporate. Evaporation results in adiabatic cooling of the heat exchanger, but also in the air guided along the surface of the heat exchanger. In this way, the heat exchanger can still be used for air cooling, even if the phase change material located in the heat exchanger has already taken a required amount of energy for the phase change and the temperature level of the fresh air supplied does not allow a renewed phase change. If water is used as liquid according to a preferred embodiment of the invention, this is generally available in buildings, it is relatively inexpensive and there is no need to use primary energy in order to exploit the adiabatic cooling effect can. Normally, the water can be recirculated so that only the evaporated water is consumed and the excess water is collected and reused in a cycle. But excess water can also be easily disposed of, for example via the sewer system.

Depending on which quantities of liquid reach the heat exchanger and which temperature the liquid reaching the heat exchanger has, it is possible to cool the heat exchanger itself and also the phase change material located therein. In this case, the heat exchanger can even be cooled so far that it exceeds the temperature threshold at which a phase change of the phase change material located in the heat exchanger occurs. After falling below the temperature threshold, the heat exchanger can be used again to cool incoming fresh air and to save the energy released during a renewed phase change. This process can be repeated as often as desired with the aid of the liquid supplied, although the temperature level of the fresh air supplied is above the temperature threshold relevant for the phase change. The heat energy repeatedly accumulated in the heat exchanger heat energy is dissipated via the liquid, which evaporates partially or completely in the air flow flowing along the heat exchanger and thereby consumes energy and partially or completely heated runs and thereby dissipates energy from the heat exchanger. A separate air conditioning unit is not required. The ability to change its temperature via the liquid supplied to the heat exchanger, of course, also works if you want to heat the heat exchanger. It suffices to wet the heat exchanger for a sufficiently long time with a liquid whose temperature is higher than the temperature threshold at which the phase change material in the heat exchanger changes the temperature. If this temperature threshold, for example, at 23 °, a phase change can be brought about by the correspondingly long supply of sufficient quantities of lukewarm liquid with, for example, 26-30 ° C. Due to the low temperature level of the liquid used to heat the heat exchanger for heating purposes, the energy losses of the liquid to the environment, which are generated during heating to heat the liquid and transport it, remain low. These low flow temperatures can be obtained by environmentally friendly techniques such as solar modules or soil probes (geothermal) or waste heat from sewage, exhaust air, manure or manure, so that no or at least less primary energy must be used for heating with the heat exchanger according to the invention.

The present invention is particularly suitable for use in the air conditioning of agricultural stables, but also of industrial plants. The rearing and keeping of livestock in stables requires a healthy stable climate, which ensures good housing conditions for kept in the stable livestock. For this purpose, the stable must be supplied with a certain volume of fresh air per unit of time with an air temperature adapted to the age of the animal in order to ensure oxygen consumption, pollution of the air inside the house and the dissipation of heat loads arising in the house. The basis for the planning of closed livestock houses, where the air exchange is preferably carried out by fans, is the DIN 18910 "heat protection of closed stables - Thermal Insulation and Ventilation - Planning and Calculation Principles "(2004) .The ventilation system must be designed so that the calculated air mass flow can be conveyed with certainty and thus ensure that sufficient heat can be dissipated at high outside temperatures The use of phase change materials according to the invention has decisive advantages here: If a heat exchanger with phase change materials is installed in a stable building, it is not necessary to provide additional expensive refrigerators or to increase the air delivery capacity for the particularly hot times with correspondingly increased air flow rates. Instead, the heat exchanger is able to continue to cool air flowing along the heat exchanger due to the liquid supplied, even if the phase change material has already absorbed energy through a phase change Cooling capacity of provided with the phase change material heat exchanger can be dispensed with additional cooling devices and additional fan power completely, or the corresponding devices can be at least smaller.

A particular difficulty with agricultural stables is that the stables are often not kept at a constant temperature level, but this varies considerably over a few months, depending on the age of the animals. In chickens, but also in the rearing of other young animals, it is necessary to initially maintain elevated room temperatures of, for example, 30 ° C, which then decrease with increasing age of the animals. Because of these comparatively extremely changing setpoint temperatures, the economical use of heat exchangers with phase change materials has hitherto not been considered, since they were always designed for a specific target temperature level and the desired energy savings differed therefrom. the temperature levels have not been fully achievable. Due to the larger use of the heat exchanger with phase change materials due to the invention with greater cooling and heating options, these can now be used economically in stables, even if different setpoint temperatures are set in a short time sequence.

The heat exchanger with a phase change material is designed to be suitable for the purposes of the invention. Corresponding heat exchangers with phase change material may for example consist of a single or a plurality of flat plates, at which the supplied air can flow along or between which. Inside the plate or plates is the phase change material. The envelope is usually made of a material that easily absorbs heat and gives off and has a high heat transfer coefficient. The heat output of the heat exchanger is determined by the number of plates used, the rate of heat conversion and the energy capacity of the phase change material used. Thus, if in the description of a heat exchanger is mentioned, this may mean that this heat exchanger is only a single plate module or has a significant number of plates, which together give a heat exchanger, or there are used in a ventilation system several heat exchangers in a modular manner, which have one or more plates. Instead of plates, it is also possible to use lattices or rods or other three-dimensional structures having internal cavities which are filled with a phase change material and which are flowed around in the form of heat by the introduced supply air for purposes of energy exchange. According to one embodiment of the invention, the mouth opening is arranged in the upper region of the heat exchanger and the liquid drips by gravity from the mouth opening to the heat exchanger and / or the mouth opening is designed as a liquid distribution element, for example as a spray nozzle or atomizer, from which the liquid as a spray and / or as a spray, for example, from small droplets emerges. The arrangement of one or more orifices in the upper region, the gravity can be used to distribute the liquid as possible over the entire surface of the heat exchanger and run. Of course, when selecting the position of the orifice, the flow conditions of the air passing through the heat exchanger must be taken into account. In particular, when the liquid is to be distributed via spray nozzles in the heat exchanger, the droplets forming the spray mist can be easily entrained by the air flow, after which they can precipitate on the surface of the heat exchanger. It is therefore not necessary to always arrange the orifices exactly above a heat exchanger, these may in particular also be arranged upstream of the air flowing along the heat exchanger. With strong air flows in a heat exchanger, it is possible with a spray of droplets to convey the liquid droplets against gravity and / or in the horizontal direction. In order to achieve optimal wetting of the surface of the heat exchanger with the liquid, the proposed options can also be combined with each other.

According to one embodiment of the invention, a collecting trough for collecting the liquid dripping from the heat exchanger is arranged below the heat exchanger and the collecting trough has a drain, from which the collected liquid via a line to a collecting container and / or the system to Fluids sigkeitszuführung is zulädbar. Through the collecting container, it is possible to circulate the unevaporated portion of the liquid which has been applied to the heat exchanger. The circulation of the liquid makes optimum use of this, unnecessary wastewater does not accumulate and unnecessary collection capacities are avoided. The collected liquid can be directly fed back into the system for liquid supply, which is inexpensive to produce with a feed pump and a corresponding connecting pipe, or the collected liquid is first passed into a sump, from where it is pumped out later and again in the system for Liquid supply is initiated.

The separate collection container offers the opportunity to check the degree of contamination of the liquid in circulation and to estimate the remaining available amount of liquid. From the collection container, liquid samples can be drawn which can be examined for germ load or the like, or disinfectant or fragrance tablets are thrown into the collection container, through which the liquid is conditioned for the intended use. The sump can be additionally cooled or heated as needed, as needed. The sump can be placed above ground level or underground, inside the building or outside.

According to one embodiment of the invention, the collecting container is designed as a floor tank built into the ground. As a floor tank surrounding the ground tank surrounding earth space can be used as a cooling or heating means. At appropriate depths, the soil keeps temperatures relatively constant throughout the year. Waste heat, which is introduced into the bottom tank via the liquid, can be passed on to the surrounding soil via the outer walls of the bottom tank. are given. As a result, the liquid cools down and can be used for a renewed cooling cycle. The cooling effect of the surrounding soil makes the use of additional cooling devices superfluous. In a floor tank, the liquid can also be well protected against frost, so that sets a temperature-compensating effect even in the cold season. The use of a floor tank is an additional means of buffering heat and cold spikes without the need for separate equipment or primary energy.

According to one embodiment of the invention, the liquid emerging from the mouth opening has a temperature which is lower than the temperature at which a phase change occurs in the phase change material used in the heat exchanger. When using a liquid with such a low temperature, it is possible to bring about a phase change of the phase change material used in the heat exchanger only over the liquid used and supplied and make the heat exchanger so operational again to considerable amounts of heat from the through the Heat exchanger to absorb incoming supply air. Fresh water often has a correspondingly low temperature. The fresh water leaves the water pipes because of their installation deep in the ground even in warmer outside temperatures comparatively cold. Additional cooling of the fresh water is eliminated in such cases, this can be passed directly to the heat exchanger for cooling purposes, resulting in a renewed energy savings. A suitable temperature for cooling can also be adjusted when existing hot water from the sump such a quantity of fresh water from the supply line is added that sets a desired set temperature. The excess fresh water used, because it is hardly contaminated by the trickling, for example, even for impregnation purposes of the animals standing in the stable or for industrial processes in a workshop.

According to one embodiment of the invention, the air duct on a bypass, through which the air flow flows away from the heat exchanger, and in the air duct control valves are arranged, through which the air flow depending on the position of the control valves only on the heat exchanger along, only by the bypass or by both paths is guided. The bypass can be used alone if, for example, the heat exchanger is not needed to cool or heat the incoming fresh air. The bypass can be used in addition to the air duct through the heat exchanger, for example, if increased air flow rates are to be driven, which are not feasible with one of the two paths alone or only a partial cooling is needed. The bypass can be shut down if, for example, only air flows are to be introduced into the building, which have passed through the heat exchanger and are cooled or heated accordingly. The desired use of the bypass and the path over the heat exchanger can be adjusted via a corresponding position of the control valves, which can be done manually, motorized, remote-controlled or automated via a controller.

According to one embodiment of the invention, the ventilation system has a controller for automatically influencing the air flow with actuators connected to the control and the inflow of liquid to at least one orifice is controllable via a valve and / or via a pump depending on sensor data, which also at the controller is connected. As sensor data, the temperatures and the flow velocities of the incoming and outgoing air, the transported air volume, the interior temperature in the building de, the temperature of the phase change material in the heat exchanger, the temperature of the delivered liquid, the temperature of the liquid in the sump and in the liquid supply line determined and fed to the controller for evaluation purposes. The actuators are, for example, actuators for adjusting the control valves, but also of the fan or fans. By adjusting the speed of operation of the fans and the flow paths through the dampers, the controller can precisely set where the airflow should travel at which speed through the ventilation system. The flow rate and the residence time of an amount of air in the heat exchanger has a significant influence on the amount of energy exchanged between the air flowing through and the surfaces of the heat exchanger and what actual temperatures are set for the fresh air after leaving the heat exchanger. If the controller is to ensure or at least support a specific setpoint temperature in the interior of the building by means of the corresponding automated setting of the corresponding manipulated variables, it is advantageous if the controller can set the corresponding manipulated variables directly. This is readily possible via the actuation of the actuators. The controller may also regulate, via the valve and / or the pump, the inflow of liquid to the heat exchanger, thereby affecting the temperature of the air flowing out of the ventilation system.

According to one embodiment of the invention, the controller is controlled by software so that it preferably withdraws liquid from the sump in a liquid feed mode and when the liquid removed from the sump is too warm, the liquid to be withdrawn from the sump is dirty and / or or there is not enough fluid in the sump, via actuation of a valve from a liquid supply fed additional liquid from the liquid supply line into the liquid supply and / or the collecting container. The liquid feed mode is thus regulated so that it first tries to cover the liquid requirement exclusively from the collecting container. Only when the controller recognizes via sensor data that the liquid supply from the reservoir is not sufficient to meet the desired desired parameters of the supply air as the desired temperature and / or the desired flow rate, measures are introduced by the liquid supply by liquid quantities from an additional Supply line is supplemented and refilled. As a trigger factors for a supplementation and replenishment are here too high temperature, too high pollution and a low supply amount mentioned, but it can also be defined in addition to other triggering criteria.

According to one embodiment of the invention, upstream of the air flow in front of the heat exchanger in the ventilation system, a filter element is arranged, which preferably has a germ-reducing equipment. The filter element is to prevent rapid soiling of the heat exchanger. Although a filter element, depending on the fineness of the pores, the flow velocity of the air flowing therethrough and thus significantly reduce the flow rate. However, prefiltering of the air is nevertheless expedient, since otherwise the suspended particles not filtered out of the air are deposited on the surface of the heat exchanger and are taken from there by the circulating liquid in the circulation. So the circulating liquid would pollute quickly. As far as the particles accumulating in the liquid and the surfaces of organic origin, they can also form a breeding ground for fungi and bacteria, which are registered on the air flowing past the surfaces in the air of the building. By pre-filtering the incoming supply air is the pollution process at least delayed, thereby reducing the overall maintenance and reliability of the plant. By a germ-reducing equipment of the filter element and the risk is reduced that corresponding germs can multiply in the filter element.

According to one embodiment of the invention downstream of the air flow behind the heat exchanger, an air conveyor unit such as a fan is arranged. The arrangement of the delivery unit behind the heat exchanger results in a suction air flow, which flows through the heat exchanger and / or the bypass. By dividing the fan power of the air conveyor unit on the heat exchanger and / or the bypass on the suction side and the blow-off in the building on the pressure side, there is a good distribution of the flow rates and air flow rates.

The object is achieved for a generic method for operating the ventilation system in that the ventilation system has a system for supplying liquid with at least one orifice and by switching on the system for liquid supply from the orifice exiting liquid to the surface of the heat exchanger can be conducted. For this method, the advantages already described above for the ventilation system arise accordingly.

According to one embodiment of the method, the ventilation system has a controller for automatically influencing the air flow with actuators connected to the controller and the controller controls the inflow of liquid to at least one mouth opening via a valve in response to sensor data, which is also connected to the controller. According to a further embodiment of the method, the controller is controlled by software so that it preferably takes liquid in a liquid feed mode from the sump and then, if the liquid removed from the sump is too warm, the liquid to be removed from the sump is dirty and / or insufficient liquid is present in the collecting container, dosed via the actuation of a valve from a liquid supply line additional liquid from the liquid supply line into the liquid supply.

Also for these two procedural embodiments, the advantages already described for the appropriately equipped ventilation system result in a corresponding manner.

It is expressly understood that the preferred embodiments described above can each be combined with each other, but also in any combination with the subject of the main claim, as far as this is not excluded by technical constraints.

The invention will now be described with reference to an embodiment. Show it:

Fig. 1: a schematic view of the ventilation system, and Fig. 2: the ventilation system of Fig. 1 with additional control. In Fig. 1, a ventilation system 2 is shown in a schematic cross-sectional view. The ventilation system 2 has an air intake 4, an upper air duct 6, a lower air duct 6 and an air outlet 8. At the rear end of the air ducts 6 seen in the flow direction of the air flow is the fan 10, which is an example of an air conveyor.

In the upper and lower air duct 6 are each two control valves 12, which are selectively adjustable between a closed position and an open position. While in Fig. 1 arranged in the upper air duct 6 two control valves 12 are shown in a closed position, the two arranged in the lower air duct 6 control valves 12 are in their open position. The upper air duct 6 is separated from the lower air duct 6 by a wall and forms for the air flowing through a bypass 14, in which no heat exchangers 16 are arranged. In the lower air duct 6, a number of heat exchangers 16 are arranged. Since the control flaps 12 associated with the lower air duct 6 are in their open position, an air flow is sucked through the air intake 4 in the lower air duct 6 during operation of the fan 10, the air flow flows through the spaces between the heat exchangers 16, then reaches the fan 10th Are the control valves 12 in the lower air duct 6 closed and opened in the upper air duct 6, the air flow through the upper air duct 6. Are all the control valves 12 is opened, the air flow through both air ducts 6 can flow , Also intermediate positions of the control valves 12 are possible to control the respective flow velocities and mixing ratios. During the flow of the air flow through the portion of the air duct 6 in which the heat exchangers 16 are arranged, heat energy can be exchanged between the heat exchangers 16 and the air flowing along the heat exchangers 16 via the surfaces of the heat exchangers 16. In this case, the temperatures of the air and the heat exchanger 16 are equal to each other. The heat exchangers 16 are configured in the embodiment as flat plates, which are aligned transversely to the air flow and spaced from each other and arranged. The heat exchangers 16 contain in their interior a phase change material which changes state of aggregation at a suitable temperature, preferably between solid and liquid, since the volume of the space changes only slightly. The heat exchanger 16 may be the embodiment differently dense, less dense, upright, horizontal or otherwise arranged in the lower air duct 6 and take other spatial forms as plates. In order to achieve a high degree of heat exchange, the largest possible surface of the heat exchanger in relation to the phase change material contained in it is advantageous.

The system for liquid supply has a supply line 18, with which a liquid in the region of the heat exchanger 16 is conveyed. At the supply line 18 are a number of orifices 20, from which the liquid is conveyed to the surface of the heat exchanger 16. The mouth openings 20 are shown in Fig. 1 as black dots. From the orifices 20, the liquid can be dropped and / or sprayed onto the surfaces of the heat exchangers 16, both on the upwardly facing surfaces and on the downwardly facing surfaces, with the latter in particular offering a spray of the liquid. The liquid can be fed by a pump 22 into the supply line 18. In the embodiment in Fig. 1st divides the supply line 18 in two strands, which supply the front and the rear part of the lower air duct 6 with liquid.

In the supply line 18 also opens a liquid supply line 24, via which in addition to the pump 22 also liquid in the supply line 18 can be fed. The liquid supply line 24 may be, for example, a normal water supply line.

Below the heat exchangers 16 is a collecting trough 26 into which liquid which has not evaporated on the surface of the heat exchanger 16 can drip. From the sump 26, the collected liquid passes through a drain 28 into a sump 30. From there, the pump 22 can feed the liquid back into the supply line 18 when the valve 32 is open.

The ventilation system 2 has a controller 34, as shown in Fig. 2 in the embodiment with the fan 10, the control valves 12, the pump 22, the valve 32 for opening and closing the supply line 18 and the valve 36 for opening and closing the Liquid supply line 24 is connected. The controller 34 has appropriate software to automatically run the control operations required to operate the ventilation system. Thus, the controller 34 can turn the fan 10 on and off, pivot the control valves 12 to their open and closed positions as needed, turn the pump 22 on and off to deliver fluid into the supply line 18, open and close the valve 32, to block or release the inlet of the liquid to the pump 22 from the sump 30, and open or close the valve 36 to allow the supply of fresh water from the liquid supply line 24 into the supply line 18. Depending on the design of the controller 34 and the associated closed actuators, it is possible that the controller 34 not only switches black and white, but can also set intermediate positions, for example, to adjust different fluid pressures in the supply line 18, etc. Also, more valves may be present to control the inlet of the liquid in more detail to be able to, for example, liquid supply only in the front or only in the rear region of the air duct 6, and the like. Not shown in detail are connectable to the controller 34 sensors with which control-relevant parameters can be determined and transmitted to the controller 34.

In the air intake opening 4 there is a filter element 40, with which coarse or even finer dirt particles can be filtered out of the air stream flowing into the air intake opening 4.

The invention is not limited to the above embodiment. The subject description is only to illustrate the invention with reference to an embodiment. It is not difficult for a person skilled in the art to adapt the exemplary embodiment to a specific application in a manner which seems suitable to him.

Claims

claims

1. ventilation system (2) for a building with an air intake opening (4), an adjoining air duct (6) in which a heat exchanger (16) is arranged with a phase change material therein, a fan (10) and one at the end of Air duct (6) arranged air outlet opening (8), characterized in that the ventilation system (2) has a system for supplying liquid with at least one orifice (20), from which from the mouth opening (20) exiting liquid on the surface of the heat exchanger ( 16).

2. Ventilation system (2) according to claim 1, characterized in that the mouth opening (20) in the upper region of the heat exchanger (16) is arranged and the liquid by gravity from the mouth opening (20) dripping onto the heat exchanger (16) and / or the Mouth opening (20) is designed as a liquid distribution element, from which the liquid emerges as a spray and / or spray.

3. Ventilation system (2) according to claim 1 or 2, characterized in that below the heat exchanger (16) a collecting trough (26) for collecting the heat exchanger (16) dripping liquid is arranged and the collecting trough (26) has a drain (28). has, from which the collected liquid via a line to a collecting container (30) and / or the system for liquid supply is zuleitbar.

4. ventilation system (2) according to claim 3, characterized in that the collecting container (30) is designed as a built-in soil floor tank.

5. Ventilation system (2) according to one of the preceding claims, characterized in that the liquid emerging from the outlet opening (20) has a temperature which is lower than the temperature at which a phase change occurs in the phase change material used in the heat exchanger (16) ,

6. Ventilation system (2) according to one of the preceding claims, characterized in that the air duct (6) has a bypass (14) through which the air flow from the heat exchanger (16) flows away, and in the air duct (6) control valves (12) are arranged, through which the air flow, depending on the position of the control valves (12) only along the heat exchanger (16) along, only through the bypass (14) or through both paths.

7. Ventilation system (2) according to any one of the preceding claims, characterized in that the ventilation system (2) has a controller (34) for automatically influencing the air flow to the controller (34) connected actuators and the inflow of liquid to at least one mouth opening (20) via a valve (32) and / or a pump (22) in response to sensor data is controlled, which is also connected to the controller (34).

8. Ventilation system (2) according to claim 7, characterized in that the controller (34) via a software is regulated so that it preferably takes liquid in a liquid supply mode from the collection container (30) and when the liquid withdrawn from the sump (30) is too warm, the liquid to be withdrawn from the sump (30) is dirty, and / or there is insufficient liquid in the sump (30) to actuate a valve (36) from a liquid supply line (24) additional liquid from the liquid supply line (24) in the liquid supply and / or the collecting container (30) metered.

9. Ventilation system (2) according to one of the preceding claims, characterized in that upstream of the air flow in front of the heat exchanger (16) in the ventilation system (2), a filter element (38) is arranged, which preferably has a germ-reducing equipment.

10. Ventilation system (2) according to one of the preceding claims, characterized in that downstream of the air flow behind the heat exchanger (16) an air conveyor unit is arranged.

11. A method for operating a ventilation system (2) for a building with an air intake, an adjoining air duct (6) in which a heat exchanger (16) is arranged with a phase change material therein, a fan (10) and one at the end the air duct (6) arranged air outlet opening (8), characterized in that the ventilation system (2) has a system for supplying liquid with at least one orifice (20) and by switching the system for liquid supply from the mouth opening (20) leaking liquid on the surface of the heat exchanger (16) is conductive.

12. The method according to claim 11, characterized in that the ventilation system (2) has a controller (34) for automatically influencing the air flow to the controller (34) connected actuators and the controller (34) the inflow of liquid for at least an orifice (20) via a valve (32) in response to sensor data controls, which is also connected to the controller (34).

13. The method according to claim 12, characterized in that the controller (34) via a software is regulated so that it preferably takes liquid in a Flüssigkeitszuführungs- mode from the collecting container (30) and then when the from the collecting container (30). withdrawn liquid is too warm, the liquid to be removed from the collecting container (30) is polluted and / or in the collecting container (30) is not enough liquid, via the operation of a valve (36) from a liquid supply line (24) additional liquid from the Liquid supply line (24) metered into the liquid supply.