The vapor pressure or vapor pressure is a physical heater battery property of substances (and more

The adiabatic transformation The adiabatic expansion of the vapor in the Mollier diagram The isobaric transformation The vapor pressure of water The isothermal transformation The transformation isochoric enthalpy and internal energy of the water vapor density: The density of the water side considerations The transformation isoenthalpic steam
The vapor pressure or vapor pressure is a physical heater battery property of substances (and more generally of mixtures of substances) that depends heater battery on the temperature. It is defined as the pressure of the vapor in equilibrium with its condensed phase at a specified temperature. The following graph is related to water.
The image shows that the vapor pressure of water increases with temperature. One very important thing to note is that the graph stops at around 370 C, more precisely at 373.9 C. This value is characteristic of the water and has the name of the critical temperature. It constitutes the maximum heater battery temperature at which the liquid phase can exist. Beyond this temperature, the liquid phase is no longer accessible. The graph shown in the above is also representative of the isochoric transformation of a system where both are present simultaneously, the liquid phase that the vapor phase. It should now be clear why the danger of heat a sealed container (isochoric heating) containing liquid water. Above 100 C, further temperature increases are rapidly rise the pressure inside to extremely high values and the container could easily explode. Very instructive is the comparison with the transformation at constant volume of an ideal gas. In this case in fact the relation between pressure and temperature is derived directly from the 'equation of state of ideal gas and is as follows P = n * R * T / V where P is the pressure heater battery expressed in Pa n is the amount of gas expressed moles R is the gas constant, and that is 8.314 J mol -1 K -1 T is the temperature expressed in KV is the volume in m 3 As for isochoric transformation n, R and V are constant, the previous relation heater battery can be rewritten as follows P = constant * T which is the equation of a line passing through the origin of the axes. Let us now compare the transformation at constant volume of an ideal gas at constant volume heater battery with the transformation of a system of water vapor and liquid. Assume that a certain amount of ideal gas has a pressure of 1 atmosphere 101235Pa ie at a temperature of 100 C. In isochoric conditions, a lowering of its temperature causes a reduction in linear pressure, a rise in temperature causes a linear increase of the pressure. The following graph shows what happens to the pressure when the temperature varies heater battery in the same temperature range already seen for the water (the graph stops on 370 C as for the water but could continue "indefinitely").
The superposition of the two patterns on the same graph shows unambiguously the different behavior of the two fluids: the pressure increase is much more marked in the case of the vapor pressure of the water compared to the case of the ideal gas. Above 100 C the vapor pressure of water increases faster than the gas pressure reaching to 150 C a value of 4,7atm against 1,13atm gas. Below 100 C the vapor pressure of the water drops more rapidly than the pressure of the gas reaching already at 50 C a value of 0,1atm against 0,87atm gas. Obviously such important variations of the vapor pressure are associated with equally important transfers thermal heater battery energy in the form of heat, but this will be the topic of the next post.
Index
Thermodynamic cycles (10) thermodynamic heater battery cycles gases (6) thermodynamic cycles of steam (7) Cold Fusion (3) E-Cat (3) Cold Fusion (3) Electricity Generation (3) The Brayton cycle (2) The cycle Carnot heater battery (1) Stirling cycle (2) The cycle isobaric-isochoric gases (1) The cycle isobaric-isochoric Steam (1) The Rankine Cycle (2) The motor Cayley heater battery exothermic (9) The motor Manson ( 9) The adiabatic (2) isobaric transformation (2) The transformation at constant volume (2) The transformation isoenthalpic heater battery (2) The isothermal transformation (2) Motor Hummingbird (15) Engines double effect (9) Engines heater battery monoeffetto (22) Regenerator heat (6) thermal sources (2) Clinical (7) theory (22) Theory of Gases (10) Theory heater battery of vapor (15) Heat Transfer (4) Transformations gases (7)
Source Thermal Price [EUR / kWh] Ethanol 0.20 0.20 LPG tank Unleaded Fuel 0.20-0.25 0.20 Electricity 0.18 0.10 Methane Pellets 0,050 heat pump COP = 4 0,050- 0.062 E-Cat (COP = 6) 0.038 0.033 to 0.042 Wood Ni-H 2 (?) 0,001 (?)