DEHUMIDIFICATION
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PRACTICAL KNOWLEDGE GUIDE DEHUMIDIFICATION EVERYTHING YOU NEED TO KNOW!

HUMIDITY -ABSOLUTE OR RELATIVE DEHUMIDIFICATION PRACTICAL INFORMATION ON THE DIFFERENT SYSTEMS AND THEIR APPLICATION POSSIBILITIES 000 +’• -C Water vapour content of the air: At a temperature of 25 °C, one cubic metre of air can absorb max. 23 g of water; this would correspond to a humidity level of 100 %. If the air cools down to 10 °C due to contact with cold surfaces, it can only absorb 9.4 g. The excessive moisture then condenses to water on the cooler surfaces. An ideal room climate is not only the basis of comfort but also a prerequisite for the value retention of humidity-sensitive...

THEORY FIRST, PRACTICE SECOND A basic knowledge of the subject of humidity is rather helpful for keeping your rooms ideally dry. The air cannot absorb an unlimited amount of water. There is a saturation limit, i.e. a maximum amount of water vapour that can be absorbed by the air in absolute terms. This is the absolute humidity, given in grams of water per cubic metre of air. We have to admit that this is quite a complex matter - and it becomes even more complicated in view of the fact that corrosion, rotting and mould formation are only promoted by the relative humidity, and never by the...

DEW POINT VERSUS HYGROSCOPY The figure above shows the content of a typical refill pouch for passive dehumidification by means of granules. These disposable pouches usually contain highly hygroscopic salts such as calcium chloride serving as a drying agent that can withdraw moisture from the room air by desiccation. In direct comparison with electrical dehumidification units with hot air regeneration, the cost-benefit ratio of such solutions is extremely poor. DEHUMIDIFICATION METHODS TWO TECHNIQUES – ONE OBJECTIVE: A CONTROLLED REDUCTION OF EXCESSIVE HUMIDITY Before going into the details...

Room climate limits of the different methods Water vapour content of the air (g/kg) CONDENSATION As already shown in the saturation curve on page 3, the water absorption capacity of the air solely depends on its temperature. The lower the temperature, the less water can be bound by the air. But what happens if the air enriched with water cools down abruptly, for example due to contact with a colder surface? In this case, the saturation limit of 100 % RH is exceeded and the air can no longer bind the excessive moisture, which consequently condenses on the cold surface and turns into water....

Refrigeration drying live: the room air that is taken in is cooled to below its dew point at the dehumidifier’s cold evaporator and water condenses on the fins and refrigerant line. TECHNICAL DIFFERENCES AND FUNCTIONAL PRINCIPLE CONDENSER DRYERS WITH COMPRESSOR TECHNOLOGY Since most dehumidification tasks at home are carried out at temperatures between 12 and 25 °C, and thanks to its excellent ratio of price, performance and energy efficiency, this refrigerant dryer is among the most frequently used dehumidifiers in the private sector and building industry. Compressor-operated condenser...

Functional principle of a compression refrigeration dryer SOLENOID VALVE* Refrigerant circuit CONDENSER (HEATING ELEMENT) EXPANSION VALVE Refrigerant circuit hot gas defrosting* EVAPORATOR (COOLING ELEMENT) * Solenoid valve and bypass line only available in compression refrigeration dryers with integrated hot gas automatic defrost system COLLECTION CONTAINER TYPES OF DEFROSTING IN COMPRESSION REFRIGERATION DRYERS AIR CIRCULATION DEFROSTING With this method, defrosting usually takes place electronically in a time- or sensor-controlled manner by means of air circulation, which is why it is...

Exemplary comparison showing the size of a typical Peltier element as used in the small electric dehumidifiers. The illustration on the right shows an open electric dehumidifier with a Peltier element behind a screwed off refrigeration unit. CONDENSER DRYERS WITH PELTIER TECHNOLOGY ALSO KNOWN AS ELECTRIC OR SEMICONDUCTOR DEHUMIDIFIERS Just like in compressor-operated condenser dryers, a cold surface must be generated inside this type of dehumidifier. The temperature of this surface must lie below the dew point of the air so that water can condense on it. Peltier dehumidifiers, however, do not...

vi i i’ii *,» V4* t» >» |Vv^ig Detailed view of the desiccant wheel of the comfort desiccant dehumidifier TTR 57 E. The rotor is coated with silica gel, a desiccant with a very large hygroscopic surface. In professional industrial desiccant dehumidifiers, each gram of this desiccant has a surface of more than 700 square metres. This means that less than 10 grams have a surface as large as an entire football pitch. §S&- DESICCANT DEHUMIDIFIERS INDUSTRIAL DEVICES WITH MOIST AIR DISCHARGE Professional desiccant dehumidifiers are mostly used in the commercial and industrial sector, where large...

DEHUMIDIFIER SELECTION – WHICH PROCEDURE FOR WHICH PURPOSE? SELECTION FACTOR ROOM TEMPERATURE The average air temperature in the room to be kept dry is the most important decision criterion for selecting a suitable dehumidifier. High performance below 8 °C In unheated basements, weekend homes or cooler rooms with an average room temperature below 8 °C during the wintertime, we recommend using a desiccant dehumidifier. Their functional principle makes it possible to keep environments permanently and effectively dry even at low temperatures. Even if the temperature occasionally rises to 12 °C,...

- impossible; □ possible; ■ recommended; 4 commercial types only, comfort dehumidifiers are not suited LAST BUT NOT LEAST: INFILTRATION What sounds like a term from a spy novel does not refer to the infiltration of hostile subjects, but of damp ambient air. For with regard to dehumidifier capacity calculation, "infiltration" refers to the external ingress of additional moisture into the room to be dehumidified. Therefore, the infiltration factor plays an important role when calculating the dehumidification capacity required. After all, not only the air inside the room contains humidity....