Perfect Gas Equation

Charles and Gay-Lussac, working independently, found that gas pressure varied with the absolute temperature. If the volume was maintained constant, the pressure would vary in proportion to the absolute temperature [1]. Using a proportionality constant R, the relationships can be combined to form the equation of state for a perfect gas, otherwise known as the perfect gas law.


P = absolute pressure v = specific volume

R = constant of proportionality

T = absolute temperature

If the specific volume v is multiplied by mass m, the volume becomes a total volume V. Therefore, multiplying both sides of Equation 2,1 by m, yields

In process engineering, moles are used extensively in performing the calculations. A mole is defined as that mass of a substance that is numeri cally equal to its molecular weight. Avogadro's Law states that identical volumes of gas at the same temperature and pressure contain equal numbers of molecules for each gas. It can be reasoned that these identical volumes will have a weight proportional to the molecular weight of the gas. If the mass is expressed as rn = n x raw

where n = number of moles mw = molecular weight then,

If the value mw R is the same for all gases, the universal gas constant IJgc is defined and R becomes the specific gas constant.

Another useful relationship can be written using Equation 2.2.

PiVi mR


If in Equation 2.2 both sides are divided by time, the term V becomes Q, volumetric flow per unit time, and the mass flow per unit time becomes w,

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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