![]() ![]() Now we are in a position to define quality. Therefore requires a larger volume and the piston rises to accomodate it. Much smaller than those of liquids.) When a unit mass of liquid vaporizes, it (Remember, specific volume is the reciprocal of density and densities of vapors are Two phase mixture is simply a mixture of saturated liquid and saturated vapor.Ĭhanges from state C to E is because v g is much larger than v f. Phase is always saturated liquid and the vapor phase is always saturated vapor. States C and E is always equal to the saturated vapor specific volume v g. Liquid phase is equal to v f all the way between C and E.īy the same argument, the specific volume of the vapor between Liquid in state C was defined as v f, it follows that the specific volume of the Since the specific volume of the saturated Of a single phase fixes the rest, it must follow that the specific volume of the liquid Now focus for a moment only on the liquid phase as the system movesįrom C to E: Since neither T or P is changing, and since specifying two properties Recall also that the experiment was done atĬonstant pressure and that temperature did not change as the system evolved from state C Remember that the liquid in C was called saturated liquid and the Theįigure below shows several steps of our piston-cylinder experiment, specifically those Lies, we will define a new parameter called the quality.īefore defining quality though, we need to discuss one more concept. To help us determine where inside the two phase region our state In other words, many different states can exist at the same temperature and Specific volume v - it could be any number between v f and v g. However, specifying P in the two phase region does not fix Pressure and temperature have a one-to-one relation in the two phase region. Now we know the temperature is T b because Now suppose we specify the pressure at P and restrict ourselves to We should have known this anywayīecause we saw on page two that it takes specification of two intensive properties to fix We would also have to specify specific volume v. Know only that the state lies somewhere on the blue part of the isobar. Just specifying P is not enough to fix T. The pressure P as the pressure along the isobar shown and consider only the superheated To see why, consider the Tv diagram to the right. It turns out that we need one additional property for use in the two-phase Since most problems in introductory thermodynamics courses involve vapors and liquids. At this point we will focus on the two-phase vapor-liquid region, ![]()
0 Comments
Leave a Reply. |