Expansion of gases

Pressure rupture, due to rapid release of high pressure. Blast is generated by rapid expansion of gas down to atmospherie pressure and rupture of the eontainer generates missiles. 

Choking, or expansion of gas from a high pressure to a lower pressure, is generally required for control of gas flow rates. Choking is achieved by the use of a choke or a control valve. The pressure drop causes a decrease in the gas temperature, thus hydrates can form at the choke or control valve. The best way to calculate the temperature drop is to use a simulation computer program. The program will perform a flash calculation, internally balancing enthalpy. It will calculate the temperature downstream of the choke, which assures that the enthalpy of the mixture of gas and liquid upstream of the choke equals the enthalpy of the new mixture of more gas and less liquid downstream of the choke. 

Figures 12-12A and 12-12B illustrate various paths of the compression or expansion of gas that can take place, depending on the properties of the gas/vapor.

The molecular beam is formed by the supersonic expansion of gas through a pulsed nozzle. It is then collimated by two skimmers, and enters... 

Fig. 2. Successive, slow adiabatic expansions of gas through porous plugs.

The expansion of an ideal gas in the Joule experiment will be used as a simple example. Consider a quantity of an ideal gas confined in a flask at a given temperature and pressure. This flask is connected through a valve to another flask, which is evacuated. The two flasks are surrounded by an adiabatic envelope and, because the walls of the flasks are rigid, the system is isolated. We now allow the gas to expand irreversibly into the evacuated flask. For an ideal gas the temperature remains the same. Thus, the expansion is isothermal as well as adiabatic. We can return the system to its original state by carrying out an isothermal reversible compression. Here we use a work reservoir to compress the gas and a heat reservoir to remove heat from the gas. As we have seen before, a quantity of heat equal to the work done on the gas must be transferred from the gas to the heat reservoir. In so doing, the value of the entropy function of the heat reservoir is increased. Consequently, the value of the entropy function of the gas increased during the adiabatic irreversible expansion of gas. 

Hilligardt K, Werther JW. 1986. Local bubble gas hold-up and expansion of gas/solid fluidized beds. Germ. Chem. Engng 9 215-221. 

For gases, this may be positive or negative, depending on conditions. Note that it is zero for an ideal gas. It applies directly to the Joule expansion, an adiabatic expansion of gas confined in a portion of a container to fill the entire container. 

Determination of the volume Vt of the empty bulb at ambient temperature (i.e. in the air thermostat) by expansion of gas from the dosing volume. 

Some simplified analyses have been performed for the combustion (1-9) and pure vaporization (10,11,12) of sprays. Recently more elaborate numerical codes on the unsteady, two-dimensional, two-phase, chemically reacting flows are also being developed (13), In all these studies the spray is frequently assumed to be sufficiently dilute such that the mutual interferences between the motion and the vaporization processes of the individual droplets are either completely neglected or are manifested only through their collective modifications of the state of the bulk gas. (The term vaporization is used here to imply both combustion and pure vaporization.) Hence the vaporization and kinematic behavior of a single, isolated droplet in an infinite expanse of gas serve as fundamental inputs to the spray analysis. These single-droplet phenomena are discussed in this chapter. 

A B constants a=coefficient of expansion of gas e=thermal coefficient, of capillary const.) ... 

E. F. Kondis (Mobil Research Development Corp., Paulsboro, N. J. 08066) We confirmed some of the trends in nonisothermal results which you report. Our data are in a flow system and hence discount the possibility of heat effects caused by expansion of gas using your Cahn instrument. 

With the front mount place on the barrel, slip the silencer onto the gun as far aa possible. The gun s muz e will be resting against the rear and of the altencar s inner brass tuba. The silencer is now moved forward ona inch. This creatas a two Inch chamber between the muzzle and the rear baffle. This space Is necessary for the Initial expansion of gas as It leaves the muz zte. Place a mark on the barrel that corresponds to the rear edge of the silencer tube. 

The nature of reversible processes is illustrated by the example of a simple expansion of gas in a piston/cylinder arrangement. The apparatus shown in Fig. 2.2 is imagined to exist in an evacuated space. The gas trapped inside the cylinder is chosen as the system all else is the surroundings. Expansion processes result when mass is removed from tlie piston. F or simplicity, assume that the piston slides within the cylinder without friction and that the piston and cylinder neither absorb nor transmit heat. Moreover, because the density of the gas in the cylinder is low and because the mass of gas is small, we ignore the effects of gravity on the contents of the... 

Expansion of gas-filled beads by application of heat or expansion of these beads in a polymer mass by the heat of reaction, e.g. expansion of polystyrene beads in a polyurethane or epoxy resin system. 

The above gas flow pattern is not desirable for a CVD process, and the sudden expansion design shown in Figure 3.15 is the gas flow simulation result of a typical early reactor chamber design. It is clear from the simulation that there is a sudden expansion of gas flow and this causes turbulent flow, which in turn results in uneven deposition. 

Expansion of gas or vapor usually gives rise to an unacceptable noise level. However, this is not a problem with liquid relief. There are two sources of noise ... 

The theoretical agitation effect of aeration alone can be easily calculated. There are two separate forces, the first caused by the free rise of bubbles. The bubbles rise from the sparger at a pressure equal to the hydrostatic pressure of the liquid and as they rise to the surface, the gas bubble pressure remains in constant equilibrium with the hydrostatic pressure above it until it escapes fi om the liquid surface. The temperature of the air in the bubble is equal to the fermentation temperature and remains constant due to heat transfer from the fermentation broth. These conditions describe an isothermal expansion of gas gas pressure and gas volume change at constant temperature. Using the formula from Perry and Chilton,the theoretical horsepower for the isothermal expansion of air can be calculated. 

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