Ingenieurbüro Arbeitsgestaltung und Baubiologie Peter Rauch  
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Air-steam-mixture

- Questions and answers -

  1. What is mixture under the relative dampness, under the absolute dampness and under the repletion-degree of a vapor (air) - steam - to be understood?
  2. How dozes humidity the density of moist depend on the air?
  3. Can in a gas (air) - steam-mixture the steam-share wants at big is?
  4. How big are the relative dampness and the repletion-degree in moist air if the steam-share has full-steam-condition?
  5. How dozes ago / its / their relative dampness change with the isobar of warming up of moist air?
  6. The humanely being feels cozy with 20ºC and 60 percent of relative humidity.
    Why is it necessary to moisten the area-air in the winters anuses the ventilation of the rooms in orders to gain the comfort-condition?
  7. The absolute dampness of the Mischluft always is anuses the mixing two moist-airflows between the absolute dampness of the part-streams. Is this therefore applicable to the relative dampness?
  8. One observes the exhalation-air in the cold winters, stand's out so, that she / it is densely invisible at mouth (or nose), then hazily and in some distance of the mouth again invisible becomes. How that is to be explained?
  9. How fog-containing moist air leaves sea de is foggy?
  10. Which meaning has in the h,x-Diagram the edge-standard?
  11. How change when cooling off of at unsaturated vapor (air) - Steam-mixture the relative dampness?
  12. What is under the dew point of a vapor (air) - steam-mixture, to understand?
  13. How dozes it come when cooling off of a vapor (air) - steam-mixture of the reduction of the absolute dampness?
  14. At the isolation of a cold-water pipe, condensation refines. Which cause dozes this appearance have? Does this let itself doze prevent through which measures?
  15. Why is it important that heat-isolations of the air-side (inside warmly normally) get (steam-impermeable cover) a "steam-barrier?"
  16. How do cooling-off-procedures of moist air differ tk for itself with coolness-surface-temperatures > ts and tk < ts (ts dew point-temperature, tk coolness-surface-temperature)?
  17. How dozes depend the dew point-temperature of the total-pressure?
  18. How do the procedures about drying of moist air take place?

1. What is mixture under the relative dampness, under the absolute dampness and under the repletion-degree of a vapor (air) - steam - to be understood?

Answer: Die relative dampness. the relation-hip from existing steam-part-pressure to topmost-possible steam-part-pressure (repletion-pressure) is with given temperature.
The absolute dampness of x is the moisture-masses (steam, therefore fog), that are mixed doubles of dry GA with 1 kg.
The repletion-degree. the relation-hip of existing absolutely is x dampness to ace steam topmost-possible absolutely dampness xs with given temperature.


2. How dozes humidity the density of moist depend on the air?

Answer: Mit increasing humidity (until repletion-condition) removes the density. Dampness air is specifically easier than dry (with seed temperature).


3. Can in a gas (air) - steam-mixture the steam-share wants at big is?

Answer: The steam-share is restricted in a gas-steam-mixture through his / its repletion-condition. The steam-part-pressure cannot become bigger than the repletion-pressure neatly to the given temperature of the mixture.


4. How big are the relative dampness and the repletion-degree in moist air if the steam-share has full-steam-condition?

Answer: Wenn the steam-share in moist air full-steam-condition has, then is the relative dampness. = 1 and the repletion-degree. = 1.


5. How dozes ago / its / their relative dampness change with the isobar of warming up of moist air?

Answer: The relative humidity removes air moist when warming up under constant pressure.


6. The humanely being feels with 20 ºC and 60 percent of relative humidity cozy. Why is it necessary to moisten the area-air in the winters anuses the ventilation of the rooms in orders to gain the comfort-condition?

Answer: In the winters, with low temperatures, the outside-air has a very low absolute dampness. The heating of looks air more relatively dampness for yields very dry with very low air, that is, air. Is consequently to be moistened in orders to gain the comfort-condition. Advantage is taken of this effect to air about elevated humidity out. The area-enclosing surface (embankment, blankets, floor and equipment) hands over a part of the stored moisture again to the area-air (Desorption). Therefore, at additional Luftbefeuchtung is necessary only in few cases.


7. The absolute dampness of the mixed air always is anuses the mixing two moist-airflows between the absolute dampness of the part-streams. Is this therefore applicable to the relative dampness?

Answer: The relative dampness doesn't need to be in contrast to the absolute dampness anuses the mixing two part-streams between the relative dampness of the part-streams. It yields of lake in the h, x-Diagramm, through the situation of the of mixing point.


8. One observes the exhalation-air in the cold winters, stand's out so, that she / it is densely invisible at mouth (or nose), then hazily and in some distance of the mouth again invisible becomes. How that is to be explained?

Answer: The exhalation-air is warmly and relatively moist. It mingles with increasing distance of the 1 mouth with more and more cold and relatively dry outside-air when exhaling. There is therefore mix conditions with the mixing point of the fog-area on that occasion.


9. How fog-containing moist air leaves sea de is foggy?

Answer: The de is foggy of fog-containing air is possible
a, through heating or
b, through to mix of fog-free air so, that the mixing point if into the unsatisfied area.


10. Which meaning has in the h, x-diagram the edge-standard?

Answer: The edge-standard boasts into the direction of the Mix exactlys for moistening (to add of liquid or steam) moist air.


11. How change when cooling off of at unsaturated vapor (air) - Steam-mixture the relative dampness?

Answer: With the isobar of cooling off of at unsaturated vapor (air) - steam-mixture gains the relative dampness.


12. What is under the dew point of a vapor (air) - steam-mixture, to understand?

Answer: The dew point is the temperature, with which when cooling off of a (previously unsatisfied) vapor (air) - Steam-mixture the steam-share repletion-condition reaches, the relative dampness. = 1 becomes. It is the repletion-temperature, that belongs to the steam pressure existing in the mixture.


13. How dozes it come when cooling off of a vapor (air) - steam-mixture of the reduction of the absolute dampness?

Answer: If a GA's (air) becomes - steam-mixture of its dew point cooled off, so a part of the steam turns into liquid. This liquid can remain ace fog in the mixture or can from-thaw (from-rains or at coolness-surfaces knocks down). The moist GA's decreases its absolute dampness if liquid from-thaws.


14. At the isolation of a cold-water pipe, condensation refines. Which cause dozes this appearance have? Does this let itself doze prevent through which measures?

Answer: If dew (condensations) refines at a surface, the temperature of this surface is lower than the dew point-temperature of a touching vapor (air) - steam-mixture. If therefore itself at the isolation-surface of the cold-water pipe. Condensation forms, the surface-temperature of the Dämmschicht reads under the dew point of the surrounding air. The management would have to be heat-insulated better according to that its surface-temperature becomes somewhat higher than the dew point-temperature.


15. Why is it important that heat-isolations of the air-side (inside warmly normally) get (steam-impermeable cover) a "steam-barrier?"

Answer: Es must be prevented that steam diffuse out of the surrounding air into the heat-isolation. This would be liquefied in the isolation because of dew point-underflow. The isolation would be full-sucked with moisture (liquid) soon and through it ineffective.


16. Like lake's cooling-off-procedures of moist air distinguishing with coolness-surface-temperatures of tk > ts and tk < ts (ts dew point-temperature, tk coolness-surface-temperature)

Answer: Lie with refrigeration of moist air the coolness-surface-temperature over the dew point, according to the air is absolutely chilled dampness with more constant.
If the coolness-surface-temperature reads under the dew point, according to the end-thawing of moisture at the coolness-surface occurs. From the coolness-surface, it drips or trick-reads from liquid, and the air decreases its absolute dampness.


17. How dozes depend the dew point-temperature of the total-pressure?

Answer: Higher total-pressure leads to a higher steam-part-pressure with seed area-share of the steam in the mixture and with it a higher dew point-temperature.


18. How do the procedures about drying of moist air take place?

Answer: Unter to dry of moist air understands the decreasing its absolute dampness we. That is possible, for example, through cooling off under the dew point or through condensing and following cooling off of the compressed air under its dew point.

Question-complexes are inferred from practices to the mechanical thermodynamics of Günter Meyer, Erich Schiffner, Fachbuchverlag Leipzig 1986.

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