DD281754A5 - METHOD FOR AIR DEHUMIDIFICATION OF INTERIORS - Google Patents

Abstract

The invention includes a method for dehumidifying indoor air. The invention relates to the use of surface-distributed desiccant to prevent the schaedigenden influx of high relative humidities and condensation phenomena in interior preferably the traffic and transport technology. The process is characterized in that surface-dispersed desiccants with medium-pore adsorbents uniformly distributed on or in a carrier material are used. The desiccants are suitable for lining virtually the entire damp-proofed interior of technical systems. The principle of the method is based on the adsorption and desorption of water by thermal cycling during the use and storage regime. preservatives; Corrosion protection; Moisture protection}

Description

Field of application of the invention The process of air dehumidification of interior spaces is particularly suitable for technical products that are caused by frequent Business interruptions of the risk of condensation phenomena and over long periods of direct or

Indirect influence of the relative humidity of the ambient atmosphere are exposed. These include, in particular, the technology of transport (motor vehicles, aircraft) as well as the most diverse types of technical products in storage and transportation

Transport containers. In particular, the method can be used for the protection of electrical, electronic, micro-and optoelectronic and

laser equipment especially in periods of interruption of the operating regime.

Characterization of the known prior art To protect against direct influences of water (splash water, rain), technical systems are largely hermetized. In general, however, the case occurs that a forced (by temperature changes) or free air exchange

(Wind convection) between interiors of technical systems and the external atmosphere is, so that in principle is assumed to be a moisture hazard isi. Well-known phenomena of such air exchange processes are the

Condensation in cavities and condensation on internal surfaces. These phenomena are particularly observed when interruptions occur in the operating regime. typical Examples are the parking of motor vehicles after the journey as well as the standing of airplanes on airfields. In order to prevent moisture damage under such conditions, methods of air conditioning (ventilation, heating)

known.

These methods are technologically very complicated and require a lot of energy. Another known method is the use of desiccants (mainly silica gel). Here but Condensation phenomena are the result of rapid temperature changes on surfaces

previous application forms of desiccants (bag, cartridge the following disadvantages:

1. The requirement for high abrasion resistance requires the use of finite grain sizes (d> 2 mm). This creates only a relatively small outer surface. The diffusion of water vapor to the grain is much faster than the diffusion on and in the grain.

2. The form of application as Trockenmitte'beutel or dry cartridge does not allow Glei. Like distribution in geometrically complicated spatial systems. Due to the inevitable necessary bed bulk, the outer surface is further reduced compared to the single grain, the diffusion processes are slowed down.

3. Due to the adsorption characteristics of the hitherto commonly used narrow pore silica gels (DDR product, silica gel A) regeneration (desorption c'es water) is possible only above temperatures of 100 ⁰ C. Such silica gels are already saturated to a considerable extent in the range of non-critical relative humidity (= 40% rh).

For practical application, this means that the equilibration between water absorption capacity and the offered moisture is much slower than the change in the relative humidity in the system, in particular caused by temperature fluctuations. Ultimately, this results in the requirement to maintain relative humidities & x50% in the technical system to exclude condensation processes on green, the mentioned temperature fluctuations (change in temperature by 10 K corresponds to a change in relative humidity of about 40%). Relative humidities below 50% occur relatively rarely in the ambient atmosphere. Therefore, due to the ever-present Wasserdampfpartialdruckgefälles between the external environment and dried indoor spaces to a constant diffusion of water vapor, which ultimately leads to the saturation of the desiccant used. Since the ambient conditions fluctuate virtually every hour, the exact prediction of the time of a necessary desiccant change is impossible. A high control and maintenance effort is the result. The increasing proportion of highly sensitive equipment therefore forces us to introduce more effective methods of dehumidification in order to prevent as far as possible the endangerment of the operational readiness and reliability of modern technology due to moisture.

In practice, the problem of preventing the influence of moisture on modern technology would be solved only by placing it in air-conditioned halls or by air conditioning transport or storage containers, which is hardly feasible for economic and technological reasons.

The object of the invention is the preservation of the functional and operational readiness of technical products preferably in, or the traffic engineering and transport technology per se, by a method of dehumidification, which requires no additional work in the production of operational, operational or operational readiness.

Explanation of the essence of the invention The object of the invention is the use of area-distributed desiccant and using thermal Alternating stresses during use and storage regime, within technical equipment subject to humidity Systems such humidities to achieve the damage caused by exposure to moisture for extended periods of time and any Avoid condensation phenomena as far as possible. The problem is solved by the use of surface ·· / desiccant desiccants, through which virtually the entire

moisture-prone interiors can be lined technically sr systems. As a desiccant are medium pores

Adsorbents used, which are fixed in or on ei.iem Trägerr laterial. Aufftillig on medium-porous adsorbents is a steeper Anstip-j of the adsorption isotherms in the range of relative humidities of 40-80%. In this Boreich have low Changes in the relative humidity result in large changes in the adsorption capacity. Assuming the operation of technical products, this is almost always associated with a heat development. In relative

closed sections containing mainly moisture-endangered equipment means one

Temperature increase lowering the relative humidity. On Gn ·,, d of the large outer surfaces of the areal distributed Adsorbent adjusts very quickly the corresponding Adsorp.ionsgleichgewicht by a release of Water vapor is characterized from the adsorbent. Associated with the warming is simultaneously a Volumonausdeh.iung the enclosed atmosphere. This means, at

not complete hermetization, a release of warmed air with an absolutely higher water vapor content to the outside

The atmosphere. This water vapor desorption practically provides a self-regeneration effect of the area-distributed Desiccant under operating conditions. When using narrow-pored desiccant (narrow pore silica gels, zeolites) such desorption processes are only at very much

low humidity (RH: s20%) possible. However, such humidities rarely occur when heated within technical systems.

Practically the other way round, the processes take place during business interruptions, combined with a cooling down inside

technical systems.

Similar to the cycle "operation-interruption-operation" is due to daily temperature fluctuation and the Global radiation of the sun the cycle "day-night-day". In principle, the same volume and moisture exchange processes take place here. Thus, also can be interior spaces

technical systems, which are parked outdoors, effective against moisture damage, especially against

Condensation phenomena, protect. embodiments Use of flat distributed desiccants In airplanes over a tent period of about Vi year The table below shows the pervasive value of the relative humidity in periods of various types Weather character. The choice of devices was made according to geometrical and radiation laws Aspects. table

date Lukei Luke 2 Luke 3 weathering (1987) rel. rel. rel. character Humidity% Humidity% Humidity% 22.6. 50 53 74 sunny 24.6. 51 55 58 easy cloudy 25.6. 48 65 60 easy to cool 26.6. 85 77 74 continuous rain 29.6. 74 81 82 temporarily rain 30.6. 47 64 70 sunny and warm 18.8. 78 82 87 shower 20.8. 81 88 74 rain 21.8. 73 79 76 fog 24.8. 82 78 78 Rain, windy 21.9. 74 69 64 slightly cloudy 24.9. 77 72 67 cloudy 30.9. 75 71 66 slightly cloudy 1.10. 75 62 67 Early morning fog, overcast 2.10. 76 72 67 changeable 5.10. 77 73 67 slightly cloudy

Average values of relative humidity in the experimental period

64 71 73

± 11 ± 11 ± 10

During the trial period, only 1 failure of the electronic and microelectronic equipment could be detected by humidity influences.

2. Use of flat-distributed desiccant in transport containers

Transport containers are characterized by relatively good Hermetjsierung. This means that a Luftkonvektlon by Wind influences from the outside is negligible. Air and moisture exchange are caused by volume expansion and

realized contraction of the trapped air volume.

Calculated and measured values (the table below ) represent the absolute maximum value of the relative humidity

(r) F.max) per day and its monthly mean (r. F. max) C ¹ T.

table Month calculated values readings

r.F.max (%) r.F.max (%) r.F. max (%) r.F.max (%)

69

68

64

63

64

64 57

62 53

62 55

64 67

67 59

72 63

71

Regression approach: r.F. max = 22.55% + 0.52X%

Jan. 64 Febr. 62 March 56 April 55 May 56 June 56 July 54 Aug. 54 Sept. 56 October 6J Nov. 65 December 65

Correlation coefficient r = 0.82

The results of the table clearly show that certain average values of the relative humidity occur corresponding to the individual months. The calculated values were obtained by a regression analysis on the basis of the monthly average values of individual climatic variables (TGL 27217):

- temperature fluctuation per day T (K)

- Daily average temperature T ("C)

- mean value of relative humidity r.F. (%)

- global radiation of the sun Q (kJ / cm ² )

By the use of area-distributed desiccant thus parked technical systems can effectively protect against the harmful influence of high relative humidity. A prediction of the degree of humidity hazard is thus also possible for other climatic zones.

3. Use of surface-dispersed desiccant in the interior of motor vehicles

In the colder months fogging the inner surfaces of viewing windows in motor vehicles, especially cars, an unpleasant Impairment of the all-round view of the driver. In particularly unfavorable weather conditions even the freezing of the viewing window on the inside. such Effects can be prevented as much as possible by using surface-spread desiccants. The principle here is the lining of decorative surfaces with area-distributed desiccants. Previously used decorative fabrics

(Artificial leather) can be replaced by area-distributed desiccant in the form of filled polyurethane foam.

Especially in cars decoratively designed area distributed desiccant for lining the sky, the parcel shelf, the Inner sides of doors or directly used for the design of protective covers. This gives you a relatively large Water vapor absorption capacity in the entire vehicle. If you use the properties of area-distributed desiccant during operation of the car as follows:

Regeneration of the area-distributed desiccants by heating while driving,

- ventilation of the motor vehicle before switching off the engine (replacement of the warm indoor air of high absolute humidity with cooler outside air of lower absolute humidity),

Closing the openings to the outside,

achieved during the Absteilens reduced relative humidity inside the car. Especially in the winter months you can prevent such a freezing of the insides of the windows as much as possible.

At the beginning of the journey is due to the lowered inside air humidity, as well as the remaining capacity of the area distributed desiccant, fogging the viewing window largely excluded.

Claims (3)

1. A process for dehumidifying indoor spaces, which are exposed to naturally and / or artificially generated thermal cycling, characterized in that medium-porous adsorbents are used, which are evenly distributed on or in a carrier material. 2. The method according to claim 1, characterized in that the maximum of the pore radius distribution is between 1.0 and 10 nm. 3. The method according to claim 1, characterized in that the particle size of the adsorbents is preferably less than 100 microns.