Condensation

of these articles is concerned with the physical condensation; for the term of the same name in chemistry see condensation reaction

as condensing designates one a changing of a material of the gaseous into the liquid state of aggregation. One calls the procedure condensation and/or. physical condensation, the product as condensate. This process takes place under certain pressure - and temperature conditions, which one calls point of condensation. During the transition the temperature remains constant, all extracted warmth becomes in form of the condensation warmth into the change in status invests. The opposite of the condensation is evaporation or the evaporation.

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] thermodynamic

bases condensation processesthe same basic principle, however nevertheless two fundamental types can be differentiated. Condition is in each case that the gaseous phase is surfeited concerning the respective gas. The basis of the differentiation based on it is determined now by the respective Nukleationsprozess, thusthe way like the liquid particles from the gaseous phase form. If this takes place freely, thus via static meeting of gas particles, one speaks of a homogeneous condensation. Since it is necessary for this that itself sufficiently slow particleswithout further assistance to larger structures together-find, is possible this process only with an extreme supersaturation of usually several hundred per cent. In contrast to it one needs only very small supersaturations with the heterogeneous condensation of often even undera per cent. This form of the condensation takes place at surfaces, thus as a rule on in the gaseous phase floating firm particles, already existing, the condensation nuclei and/or. Aerosol particle. These function regarding the respective gas as a kind Teilchenfänger, whereby inSubstantial ones the radius and the chemical characteristics of the particle determine, how well the gas particles remain sticking to it. Similarly this also to surfaces patikulärer body does not apply, whereby one speaks then of a fitting.

The condensation process is as stated thusby the reciprocal effect between gas and particles determined and can be described therefore also only over micro-physical methods. This conditionally however also a high range at parameters, never all this completely instrumentation to seize leave themselves and therefore also to an accurateComputation from condensation processes contrary run. This can in many cases to an unexpected system performance lead and must therefore with sensitive applications with be considered.

condensation processes of the atmosphere

condensing water vapour at a windowpane

of the condensation comes in case ofthe water of the terrestrial atmosphere as well as the evaporation a separate meaning too, since the phase transition between water vapour and liquid water is a fundamental process of the natural water circulation as well as the weather at all. On macro-physical level here alone already are the turnover quantitiesenormously, there the atmospheric water with approximately 13·10 15 kg a middle period spent of only approximately 10 days possesses, thus also within this period essentially over the condensation one converts. The condensation is the basic process of each education ofliquid precipitation from water vapour as well as the fog - and Wolkenbildung. Over the latent warmth thereby also the heat balance of the earth is crucially along-coined/shaped.

On micro-physical level the condensation processes are however as shown very complex and extract themselves from the accuratePredictableness. It comes out in the atmosphere practically exclusively to the heterogeneous Nukleation, thus in this case of the formation of water droplets from air. The for this necessary supersaturation of air must be differently strong after the dominant in each case conditions,in order to cause a condensation. It can on the one hand by an increase of the absolute air humidity in the course of the evaporation and/or. Sublimation and on the other hand by a reduction of the air temperature to be reached. The cooling, particularly, dominates the adiabatic thus a reduction that maximum dampness, those air capable is to be taken up. If the diameter of the aerosol particles over roughly 1 is large μm, then supersaturations of few tenths per cent are already often sufficient. Further is it meaning whether the surface of the particles hydrophilic or , facilitates those exhibits hydrophobe characteristics the accumulation of water vapour particles and/or. make more difficult. Just as important the concentration of the aerosol particles is natural in the gaseous phase.

The meteorological and climatological aerosol research must thus a whole pallet of factors of influence berücksichten, whereby additionally to that alreadyregarded still different factors like the spatial and temporal occurrence of the aerosol particles in addition come. All these factors must be set thereby in purchase, in order to come to a correct understanding of processes of the precipitation and Wolkenbildung, those again for influence with one anotherhave on the water and radiation balance. This is on qualitative level quite well possible, the quantitative influence of these parameters particularly on global level is however difficult to determine and forms a factor of uncertainty in all climatic models.

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Industrial application

steam power plant

within steam power plants is the condensation of the Abdampfes from the steam turbine at the condenser a substantial Verfahrensabschnitt. With the liquefaction of the Wasserdampfeses ready for a feed water for the steam generator, as well as that is placed carried out thermodynamically necessary step of the withdrawal of the waste heat from the water vapour.

chemical plants

with large chemistry parks is the condensation of water vapour an economic important size, since the power supply for chemical processes takes place in individual enterprises with water vapour. AfterDelivery of the thermal energy is present condensed water, which is collected over ring circuits. This under normal conditions „pure “ water is supplied to the steam generator after quality controls and possible dressing again as so-called feed water for the production of steam. By such a condensate feedback leaveobtain themselves depending upon size of the chemistry park savings in million euro height.

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