Processes polytropic

The work in a compressor under ideal conditions as previously shown occurs at constant entropy. The actual process is a polytropic process as shown in Fig. 10-65 and given by the equation of state Pv = constant. 

Similarly, the cycle work required in a polytropic process is given by the following expression ... 

For a polytropic process the change of state does not take place at constant entropy, hut for an adiabatic process, it does. Heat may he added to or rejected from a gas in a polytropic process. For a polytropic process, the correlating exponent for the PiVi" component is the exponent n, which becomes an important part of the compressor design, n values are determined from performance testing. 

Polytropic system. Figures 12-37D and 12-37E, gets nearer to the conditions of a practical system, with polytropic process having n = 1.2. The gray area Wi compresses air from 1 to 2 while the air rejects heat to atmosphere through compressor cylinder walls. equals area 1-2-y-z in 4e. In the aftercooler-receiver, the air rejects heat Q i equal to gray area 2-3-w-y. 

The polytropic process is mathematically easier to handle than the adiabatic approach for the following (1) determination of the discharge temperature (see later discussion under Temperature Rise During Compression ) and (2) advantage of the polytropic efficiency ... 

Mass flow rate, kg/s Mean effective pressure, kPa Polytropic process exponent Pressure, kPa... 

We give first a general treatment of paths on a PT diagram for an ideal gas with constant heat capacities undergoing reversible polytropic processes. Equation (3.35c), p. 78, may be rewritten as... 

Polytropic process. Compression and expansion are important processes in chemical industry. The changes in enthalpy and... 

The direction facctor D (=TqAS/AH) is given as To/Tln for thermal processes, To/Teq for chemical reactions, and To[(cp/cm)Tlnl for polytropic processes. Based on it,... 

Polytropic process, 68-69 Potential energy, 14-17, 22-24, 31-33, 212-213 Power-plant cycles, 247-271 Rankine, 250-253 regenerative, 255-256 thermodynamic analysis of, 556-561 Poynting factor, 329 Pressure, 9-11 critical, 55-56, 571-572 partial, 300... 

Since polytropic means "timriirg marry w s polytropic process suggests a model of some versatility. Witir 6 a constairt, it is defiired as a process for which... 

Figure 3.6 Paths of polytropic processes characterized by specific values of 6...

Relationships may be developed between the temperature, pressure, and volume for a polytropic process between state 1 and state 2. The ideal gas law states that ... 

Real compression processes operate between adiabatic and isothermal compression. Actual compression processes are polytropic processes. This is because the gas being compressed is not at constant entropy as in the adiabatic process, or at constant temperature as in the isothermal processes. Generally, compressors have performance characteristics that are analogous to those of pumps. Their performance curves relate flow capacity to head. The head developed by a fluid between states 1 and 2 can be derived from the general thermodynamic equation. 

A process that obeys Eq. 4.3-20 is referred to as a polytropic process. For an ideal gas it is easy to show that... 

Here is supposed that gas in the bubble follows polytropic process with exponent X This equation was solved in linear approximation by operational method with the aim to analyze small amplitude, natural oscillations of the constant mass bubble in relaxing liquid. It was taken R = Rq + AR, AR/Ro 1, AR exp(ht) with h being the complex natural frequency. Logarithmic decrement. A, and dimensionless frequency, [t, of the oscillations are defined according to formulas... 

The volume of methane afti For this polytropic process ... 

For a polytropic process, we use n = 1.45. From the physical properties of hydrogen and water, we calculate the amoimt of water held by the saturated gas after each cooler, and from that, the amount condensed and the total duty of each cooler ... 

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