EP3265732B1 - Method for drying of constructions - Google Patents

Description

The present invention relates to a method for drying buildings, in which an accessible building layer is heated in several iterations during a heating phase by means of an infrared heater directed at it, and then moisture from deeper building layers is drawn in during a rest phase.

Such a device is already from the DE 698 06 000 T3 previously known. There an infrared heater is provided, which is mounted in a housing and is placed with this housing at a point on the floor to be dried. This floor area, insofar as it lies below the infrared heater, is then periodically irradiated, while the air that is located inside the housing and is heated by the infrared heater over time and the moisture-absorbing air driven out of the building is removed with the aid of a suction device.

It is already known in this context that drying of a material to be dried is best carried out in such a way that it is first heated and the associated expulsion of moisture takes place for a certain time and then the irradiation with heat is exposed for a period of rest. During the rest period, the temperature in the building can equalize and the moisture can also be evenly distributed. The process is then repeated, so that the moisture that has then been drawn in is again removed in the second step until, in the end, more or less all of the moisture has been removed from the structure.

The above-mentioned document gives the ratio of radiation time to interruption time as "approximately 2: 4". This means that the radiation time and the interruption time are chosen more or less arbitrarily, which may represent a suitable solution for the building material in question on which the development of the invention was based. The user will therefore first of all set up the device and then decide on a setting for the radiation time and the interruption time based on his feeling. However, since the irradiation becomes ineffective after the moisture has been expelled in the front, irradiated areas and the moisture otherwise receded deeper into the structure, it remains open whether in this way, due to the arbitrary settings of the user, excessive irradiation and thus too high power consumption and possibly also too long a period of use and thus a certain ineffectiveness.

Building drying is essentially about drying the more or less soaked parts of the building as quickly as possible and with as little energy as possible. In this respect, it seems sensible to optimize existing processes in order to achieve greater effectiveness.

In addition to the infrared radiators outlined above, which represent the closest prior art, air dehumidifiers, adsorption dryers and fan heaters are also known, which regularly only process the medium of the air to be dried and thus only indirectly reach the surface of the material concerned. The so-called core moisture is not eliminated in this way, or only to a small extent, because a residue of residual moisture remains, which is unavoidable due to the insufficient energy expenditure on the drying wall. Due to flow blockages, especially in corners, for example in bay windows, etc., the air remains moist in these cases and the effect is reduced even further at these points. Larger and, above all, targeted energy inputs are required in order to achieve this core moisture and thus to bring about complete, ideal drying.

If the core moisture is not removed, the wall loses a large part of its actual function, namely protection against wind and weather. A wet or at least partially wet wall insulates much worse than a dry wall. A further complicating factor is that the drying can usually be carried out after the damage has occurred after removing wallpaper, wood paneling, plaster, etc. and the wall is thus in an ideal condition before the damage is removed. If, on the other hand, the drying is not carried out completely and the protective coverings are put back in place, then some of the core moisture that is still present can slowly pull in, especially in the case of time-shifted ideal conditions such as dry and warm air in the interior, thus leading to mold formation and damage to the protective cladding from the inside.

This is further exacerbated by the new EnEV ordinances, which represent a structural obligation to install comprehensive external insulation and thus prevent core moisture from escaping to the outside. Most insulation materials represent a barrier that is impermeable to moisture and which, in the absence of this, could escape to the outside, but is not penetrated in this way. The fact that drying can now only be carried out from the inside without the support of outside weather conditions is an additional challenge that today's methods are unable to cope with.

EP 0 997 378 A1 discloses a method for drying buildings, in which an accessible wall first experiences a number of heating phases by an infrared radiator and then, in a resting phase, moisture can be drawn in from a deeper layer of the wall. The warm-up phases and rest phases are specified.

US 2014/302446 A1 discloses a method of curing a curable material. The hardening is initiated by hardening parameters. The curing parameters are based on the material data of the material. Temperature values are periodically recorded during the curing process. The curing of the material is controlled based on the curing parameters and the measured temperature values.

Against this background, the present invention is based on the object of creating a method for drying buildings which works much more efficiently and thereby achieves better drying both in a shorter time and with less energy consumption.

This object is achieved by a method for drying buildings according to the features of claim 1. Further, useful embodiments of such a method can be found in the subclaims.

According to the invention it is provided that an infrared radiator is aimed at an accessible building layer and this is first heated for a heating phase. During a resting phase, the moisture can then pull in from deeper building layers. The infrared heater is equipped with a control unit, which in turn is data-linked to a database. The database contains material-specific data records which, depending on the material selected, specify at least one heating time during which the infrared radiator should irradiate the building layer and at least one rest period during which the building layer should not be irradiated. By simply selecting the selected material by the control device, an exactly ideal irradiation can be carried out, which interrupts the irradiation at the moment when the energy input only remains can have a disproportionately small effect on the building layer to be dried.

After heating the upper layer and switching off the heat source, the moisture can easily escape on the side facing the infrared heater. The wall surface also cools there, because the further heat input is temporarily stopped and the evaporation cold on the surface ensures a heat difference directed from the inside to the outside, which supports the drawing in of the moisture. However, the time that the respective building material needs to heat an effective layer varies and depends on the material. The ideal value of the heating time provides the best drying times with the lowest possible energy input and thus sets the basis for the best trailing effects. It is also necessary to choose a suitable rest period. The determination of these times and, if necessary, the intensity of the respective energy input is the subject of continuous research and empirical values from which the aforementioned database is fed.

If you know the length of the heating-up time and the ideal intensity for a material, the next step is to determine the correct rest time in which the moisture from the inside of the material can follow. Due to the solid barriers, porosities and capillary effects, each type of material has different times in which it allows the moisture from the inside to move into the drier, accessible building layer to the outside. The dry outer layer absorbs the moisture from the inside in a similar way as a sponge absorbs water, whereby the moisture and the temperature throughout the material strive to spread evenly.

In addition to a thermal conductance, which is already known in the literature, a moisture conductance that has yet to be determined is important, which is the subject of current research and is not yet widely available. While there is usually faster heat transfer with a larger difference in temperature, other limitations apply to moisture transfer, such as the solid barriers that have to be overcome are. These values are currently being determined in practical tests and added to the database mentioned above.

The control device of the infrared heater now essentially takes over the heating time and the rest time stored there from the database and will irradiate an accessible building layer while observing these times.

In addition, the material-specific data record can also be assigned a nominal power consumption with which the infrared heater is operated during the heating time. Accordingly, the control unit will specify a corresponding target power consumption and limit the heating power accordingly for the infrared heater as required. In addition to such a limited, permanent irradiation with a specified value of the power used, the surface temperature of the accessible building layer can with some advantage also be recorded with the help of a temperature sensor of the infrared heater, so that not only the emitted power is in the foreground, but rather the power that also arrives in the structure. As a result, a predetermined temperature of the accessible building layer can be aimed for, so that in the end a control is set up in the control device that maintains the desired temperature on the surface of the accessible building layer over time.

If it proves to be useful not to maintain a constant power consumption or a constant target temperature over time, a target temperature profile can also be specified in the material-specific data record, which provides for an adjustment of the target temperature over time. Here, the control device will adapt to the target temperature curve in question over time and switch the infrared heater on and off in such a way that the surface temperature of the accessible building layer follows the target temperature curve.

In the course of an initial determination of the required heating and rest times, the accessible building layer can be irradiated with a defined Performance characteristics of an irradiation,
a measurement of the temperature profile on the surface is carried out permanently with the aid of a temperature sensor. Since the temperature develops characteristically with a fixed input power of the infrared heater in different building materials, a conclusion about the material used can be drawn from such a temperature profile, so that the selection of the material-specific data set automatically by the system, in particular by the Control unit, can be done. This anticipates an arbitrary selection of a material data record by a user, so that operating errors can be avoided at this point.

Accordingly, it is also possible to design the prescribed method in such a way that the information that initially came from the database is determined directly in the control unit or an evaluation device provided for this purpose on the basis of predetermined arithmetic operations after such a test measurement. In the case of such a configuration, the various process operations as described above can optionally be followed, that is to say a fixed setpoint power consumption, temperature control or temperature profile control can be used.

In the case of the infrared radiator used, the heated air will be discharged with some advantage, the heated air being discharged by convection or with the aid of a flow machine. The convection can be increased, for example, in that the infrared radiator is positioned at an angle opposite the accessible building layer, so that an upper edge of the infrared radiator is closer to the accessible building layer than a lower edge. In this case, there will be a chimney effect which accelerates the heated air upwards and thus quickly removes it from the heated area. The discharged air can be guided along an air guiding device, which additionally has a cooling device, so that the moisture from the air will at least partially condense on the cooled air guiding device. The resulting condensate can then be collected in a collecting tank and thus removed from the system.

The invention described above is illustrated in the following on the basis of an exemplary embodiment Figure 1 explained in more detail. This shows a diagram of the drying process according to the present invention, the elapsing time being plotted on the longitudinal axis, the relative humidity 3, the moisture loss 4 of the wall and the energy radiation 5 hitting the wall via the infrared heater on the vertical axis. The energy radiation 5 swings quickly to a value after switching on and maintains this for as long as the infrared radiator is switched on. In the heating-up phase 1, the energy radiation 5 increases linearly and will remain constant at zero again in the subsequent rest phase 2. During a first heating phase 1 it can be determined that, on the one hand, the moisture 4 contained in the wall initially drops sharply in order to remain approximately constant in a first rest phase 2. This is repeated again in the second heating phase 1. In the third heating phase, an inversion point is reached and it can be seen that from here on the moisture mainly emerges from the wall in the rest phases 2, but remains constant in the heating phases 1. This is due to the fact that after the wall to be dried was initially heated, the moisture bound on the surface has escaped and only the deeper-seated moisture remains in the wall. After the superficial drying, this will move out of the wall, especially in the resting phase 2, when the moisture no longer evades the acting heat. The relative humidity 3 between the wall and the panel represents a characteristic curve, the course of which depends on the nature of the wall. Based on the data of a material-specific data set or their determination by the control unit, the end of the heating phase 1 and the duration of the resting phase 2 are each selected so that a given, material-dependent ideal value of the relative humidity 3 is achieved with as little power as possible in the shortest possible time.

A method for drying buildings is thus described above, in which a material-specific heating time and a material-specific rest time are specified in order to achieve the most effective drying possible with the aid of an infrared heater.

REFERENCE LIST

1.

Heating phase

2.

Resting phase

3.

relative humidity

4th

Moisture loss

5.

Energy radiation

6th

time

Claims (8)

1. A method for drying structures, in which in several iterations first during a heating phase (1) an accessible structure layer is heated by means of an infrared radiator directed towards it, and then during a rest phase (2) moisture is drawn from deeper structure layers, characterized in that the infrared radiator is associated with a control device which is data-connected to a database and which, on the basis of a selection of a material-specific data set from the database, prescribes at least one heating time within which the infrared radiator is to irradiate the building layer and at least one rest time during which the building layer is not to be irradiated, and that the selection of the material-specific data set is carried out in that, in a preceding step, the accessible building layer is irradiated with a defined power characteristic by using an infrared radiator, and a measurement of the temperature progression at the surface of the accessible building layer is carried out by means of a temperature sensor, an evaluation device records the ratio of power and temperature over time and selects the material-specific data set on the basis of this progression and/or parameters derived therefrom.
2. The method according to claim 1, characterized in that the evaluation device additionally comprises a target power consumption with which the infrared radiator is operated during the heating time.
3. The method according to claim 1, characterized in that the evaluation device additionally comprises a target temperature of the accessible building layer and the control device switches the infrared radiator on and off during the heating phase (1) for the heating time in such a way that a surface temperature of the accessible building layer recorded by means of a temperature sensor follows the target temperature.
4. The method according to claim 1, characterized in that the evaluation device comprises a target temperature progression at the accessible building layer over time, wherein the control device records a surface temperature of the accessible building layer by means of a temperature sensor and switches the infrared radiator on and off in such a way that the surface temperature of the accessible building layer follows the target temperature progression.
5. The method according to any of the preceding claims, characterized in that air located between the infrared radiator and the accessible layer of the structure is discharged.
6. The method according to claim 5, characterized in that the air is discharged by means of a flow machine.
7. The method according to claim 5, characterized in that the infrared radiator is positioned obliquely with respect to the accessible building layer in such a way that an upper edge of the infrared radiator lies closer to the accessible building layer than a lower edge, and the air is thereby discharged by means of the chimney effect.
8. The method according to one of the claims 5 to 7, characterized in that the discharged air is deflected and cooled by using an air deflector device, wherein any condensate produced is collected in a collecting container.

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