I. Overview
Since humidity control has become one of the important indicators of HVAC and comfortable home environment. The application of humidity control in different fields is becoming more and more extensive. And our standard for evaluating human comfort is not limited to temperature. It also highlights the importance of humidity for physical comfort.
The humidity we often say generally refers to relative humidity. The actual relative humidity is only a way of quantifying the humidity of the air. Using percentage quantification makes it easier for everyone to judge the level. However, relative humidity only has a specific meaning below a specific temperature.
II. The human body's comfortable temperature and humidity
According to the national standard <<Code for Design of Heating, Ventilation and Air Conditioning for Civil Buildings>>"GB50736-2012”, the human body's best temperature and humidity value is 24℃,55%RH, where the relative humidity of 55% is only comfortable under the premise of 24℃. In this case, we have to introduce a concept "moisture content". The moisture content represents the mass of water vapor contained in each kg of dry air, in g/kg. Therefore, the moisture content is the basis for judging the humidity of the air.
At
this time, we can check the working condition 24℃ through the calculation
software, the moisture content of the air at 55%RH is:
After
consulting,we learned that the moisture content is 10.2g/kg. If the air
moisture content is higher than 10.2g/kg, it is not conducive to the
evaporation of human sweat and heat dissipation, and lower than 10.2g/kg will
cause excessive evaporation of skin moisture and cause dry skin.
III. Long-term storage conditions of red wine
Red
wine is no exception. Its storage is directly related to temperature and
humidity. The best temperature for long-term storage of red wine is 12-18℃,
humidity is 60-70%. Constant temperature is to ensure that red wine does not
deteriorate. Constant humidity mainly determines the air humidity level and
will not adversely affect the cork stopper of the wine bottle. Low air humidity
will cause moisture loss in the soft plug, dry and cracked cork, and poor
sealing. On the contrary, too high air moisture content can cause mildew on the
cork.
IV. Argument
If
the temperature and humidity of the wine cellar is controlled at 14℃, 70%RH,
then we can query the working condition of 14℃ through the calculation software,
the moisture content of the air at 70%RH is:
From
the above sheet, we can see the moisture content is 6.95g/kg, which is much
lower than 10.2g/kg. In fact, this moisture content is already close to a dry
state. Therefore, the moisture content of the wine cellar space is preferably
higher than 6.95g/kg and less than 10.2g/kg.
V. Case from custom feedback
Our
customers sometimes encounter situations where the relative humidity is as high
as 90% when the cellar temperature is 12°C. In fact, there is no need to worry.
Because we can check the enthalpy-wet diagram
It
can be seen by checking the enthalpy diagram that even if the relative humidity
is as high as 90% under the condition of 12℃, the moisture content is only
7.85g/kg. It is still far below 10.2g/kg. The high relative humidity at 12°C is
just because the dry air at this temperature has a low capacity to hold water
vapor, so the moisture content of 7.85g/kg accounts for a high proportion of
the maximum. It does not mean that the current air is humid and easy to mold.
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