Adiabatic compressibility

Compression Adiabatic compression results in high temperatures determined by the compression and specific heat ratios, as shown in Eq. (26-46) ... 

Compress adiabatically along AB till the temperature reaches T. 

Figure 9-2 provides a convenient way of solving compressible adiabatic flow problems for piping systems. Some iteration is normally required, because the value of K( depends on the Reynolds number, which cannot be determined until G is found. An example of the procedure for solving a typical problem follows. 

Step 1. From a to b and c. When the pressure rises, the gas element moves through the regenerator in the direction of the heat exchanger E2 (from a to b). According to the assumptions, the heat exchange is perfect, and the temperature of the gas element is equal to the temperature of the regenerator. At point b, the gas element leaves E2 and enters the tube with the temperature Th. From b to c, the gas element is compressed adiabatically, while it moves towards the orifice. Its temperature rises together with the pressure. 

In this example we describe the calculation of the minimum work for ideal compressible adiabatic flow using two different optimization techniques, (a) analytical, and (b) numerical. Most real flows lie somewhere between adiabatic and isothermal flow. For adiabatic flow, the case examined here, you cannot establish a priori the relationship between pressure and density of the gas because the temperature is unknown as a function of pressure or density, hence the relation between pressure and... 

It has long been known that acetylene explodes under the influence of compression. Experiments by Rimarski and Metz [99] showed that at a temperature below 500°C acetylene does not explode if the pressure is lower than 3 kg/cm2. An explosion may occur at 510°C under a pressure of 2.05 kg/cm2. At room temperature acetylene may explode provided it is compressed adiabatically with a pressure of 170 kg/cm2. 

Finally, the gas is further compressed adiabatically and reversibly to the initial state A. Therefore q, >A = 0 and... 

Fig. 1. Variation de la compressibility adiabat iquedu pentachlorure de diph nyle en fonction de la temperature, pour trois frequences d excitation indiqu6es (Litovitz et Lyon, 1958)...

One mole of an ideal gas, CP = (7/2)R and Cv = (5/2)R, is compressed adiabatically in a piston/cylinder device from 1 bar and 40°C to 4 bar. The process is irreversible and requires 30 percent more work than a reversible, adiabatic compression from the same initial state to the same final pressure. What is the entropy change of the gas7... 

An elementary nuclear-powered gas-turbine power plant operates as shown in Fig. P16.22. entering at point 1 is compressed adiabatically to point 2, heated at constant pressure between ... 

Saturated steam at 175 kPa is compressed adiabatically in a centrifugal compressor to 650 kPa at the rate of 1.5 kg s 1. The compressor efficiency is 75 percent What is the power requirement of the compressor and what arc the enthalpy and entropy of the steam in its final state ... 

Solution Saturated steam at 100 kPa is compressed adiabatically to 300 kPa with a compressor efficiency of 0.75. From the results of Example 7.8, we have ... 

The effect of increasing tlie compression ratio, defined as tlie ratio of the volumes at the begimiing and end of tlie compression stroke, is to increase the efficiency of tlie engine, i.e., to increase the work produced per imit quantity of fuel. We demonstrate this for an idealized cycle, called the air-standard Otto cycle, shown in Fig. 8.9. It consists of two adiabatic and two constant-volume steps, which comprise a heat-engine cycle for which air is tlie working fluid. In step DA, sufficient heat is absorbed by tlie air at constant volmiie to raise its temperature and pressure to the values resulting from combustion in an actual Otto engine. Then the air is expanded adiabatically and reversibly (step AB), cooled at constant volume (step BC), and finally compressed adiabatically and reversibly to the initial state at D. 

Finally, let the gas be surroimded by a non-conducting layer, as in 2, and compressed adiabatically imtil its temperature has returned to its initial value We shall suppose the volume to have been chosen so that the subsequent adiabatic compression would just bring the volume back to its initial... 

One pound of steam at 130 psia and 600"F is expanded isothermally to 75 psia in a closed system. Thereafter it is cooled at constant volume to 60 psia. Finally, it is compressed adiabatically to back to its original state. For each of the three steps of the process, compute AU and AH. For each of the three steps, where possible, also calculate Q and W. 

One kilogram of steam goes through the following reversible process. In its initial state (state 1) it is at 2700 kPa and 540 C. It is then expanded isothermally to state 2, which is at 700 kPa. Then it is cooled at constant volume to 400 kPa (state 3). Next it is cooled at constant pressure to a volume of 0.4625 mVkg (state 4), Then it, is compressed adiabatically to 2700 kPa, and 425 C (state 5), and finally it is heated at constant pressure back to the original state. 

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