and electricity production
diagram of Mollier or psychrometric diagram
- It makes it possible to simplify calculations at the time of problem
involved in the air-conditioning or with processes having parameters in
connection with humidity of air.
- On X-coordinate is reproduced the temperatures.
- moisture (in gram of water per
Kilogramme of air) is announced on y-axis (right-hand side) Knowing that
moisture represents part of the pressure of air called partial pressure,
It is represented on y-axis (right-hand side)
- The saturated vapour pressure is the
pressure in correspondence with a temperature for a quantity of gram
water/kg to air given, in such way that air cannot contain more
eau(correspondent to 100% of moisture). Beyond, of condensation
materializes in the form of droplet.
- It is possible to arrive to 100% of
moisture, either by bringing the partial pressure to the saturated
vapour pressure, or by cooling air until at the dewpoint (temperature of
saturation) Plus air will be cooled below the dewpoint plus air will be
dehumidified. If one divides the saturated vapour pressure of half, one
decreases his relative humidity by 2 (50%). It is thus possible for us
to trace lines of relative humidity.
- we consider that water Enthalpie. The
heat of evaporation will be withdrawn from the mixture without changing
enthalpy (until to 100% of moisture) total. An application consists in
cooling air by water vaporization. air measures water jusqu?au pressure
not saturation thanks to a contribution of latent heat. The temperature
limits reached to 100% is called wet temperature or wet bulb.
- In reality, dehumidification and fall in
temperature do not occur in two times. To know from when
dehumidification occurs a new parameter was set up: If one wishes to
decrease the temperature and moisture, the delta of enthalpy
corresponding to the delta of temperature is called the requirement in
significant refrigerating power, the delta of enthalpy corresponding to
the delta of moisture is called the requirement in latent refrigerating
The significant power divided by the refrigerating total power reveals
the cosine of an angle which represents the slope by which
dehumidification occurs. This slope is called significant factor of heat (SHF
= sensitive heat factor)