Process conditions adiabatic

The process of adiabatic saturation in Section 24.4 assumed that the spray water temperature had no effect on the final air condition. If, however, a large mass of water is used in comparison with the mass of air, the final condition will approach the water temperature. If this water is chilled below the dew point of the entering air, moisture will condense out of the air, and it will leave the washer with a lower moisture content (see Figure 24.7). 

To evaluate the integral in Equation B.l requires the pressure to be known at each point along the compression path. In principle, compression could be carried out either at constant temperature or adiabatically. Most compression processes are carried out close to adiabatic conditions. Adiabatic compression of an ideal gas along a thermodynamically reversible (isentropic) path can be expressed as ... 

If there is no heat transfer or energy dissipated in the gas when going from state 1 to state 2, the process is adiabatic and reversible, i.e., isentropic. For an ideal gas under these conditions,... 

Investigation of the global rates of reaction can be carried out in instrumented bench-scale equipment, such as the RC1 (Mettler-Toledo) plus on-line chemical analysis. Commercially available equipment allows well-controlled process conditions, and can be used in a variety of modes (e.g., isothermal, adiabatic, temperature programmed). The test volumes, which may be up to 2 liters depending on the energy involved, enable reasonable simulation of process conditions, and are more representative than very small samples, particularly for mixed phase systems. The scale of such equipment permits the collection of accurate data. 

KINPTR s real-time activity kinetics determine the adiabatic reactor inlet temperature required to make a target octane. The accuracy of KINPTR s reactor inlet temperature predictions is shown in Fig. 30 for a wide range of process conditions. The average deviation is + 3.8 K with no significant bias. This degree of accuracy is very reasonable considering the sensitivity of catalyst activity to start-up conditions and initial catalyst state (e.g., chloride added). 

The central term in Equation 2.5 enhances the fact that the adiabatic temperature rise is a function of reactant concentration and molar enthalpy. Therefore, it is dependant on the process conditions, especially on feed and charge concentrations. The right-hand term in Equation 2.5, showing the specific heat of reaction, is especially useful in the interpretation of calorimetric results, which are often expressed in terms of the specific heat of the reaction. Thus, the interpretation of calorimetric results must always be performed in connection with the process conditions, especially concentrations. This must be accounted for when results of calorimetric experiments are used for assessing different process conditions. 

The expansion has been assumed to be adiabatic, and thus the entropy generated equals the entropy increase of the gas, AS, as the entropy change of the environment, AS0, can be set to zero because the process is adiabatic. The amount of lost work can now be calculated from the entropy values Sj and S2 of 1 mol of methane at the initial and final conditions, respectively. However, this requires knowledge not only of the final pressure P2, which is known, but also of the final temperature T2, which is unknown. Here, the first law helps us out. Applying Equation 2.39 and substituting zero for Win and Qout, we find AH = 0 or H2 = Hv From the IUPAC data series number 16, dealing with methane [1], we find that the molar enthalpy and entropy at initial conditions are, respectively,... 

It is unlikely that the reaction can be carried out under such conditions that the process is adiabatic (i.e., no heat is lost to the surroundings). However, when there is adequate premixing of fuel and air so that a short non-luminous flame is obtained the combustion is expected to be very nearly adiabatic and the flame temperature is high. 

Determining the final proiduct temperature,, based upon the above is exemplified by the following example What is the adiabatic temperature of the product gases from the detonation of PETN The gases are allowed to expand freely at one atmosphere (a constant-pressure process), but adiabatic conditions are maintained. 

Define the terras closed process system, open process system, isothermal process, and adiabatic process. Write the first law of thermodynamics (the energy balance equation) for a closed process system and state the conditions under which each of the five terms in the balance can be neglected. Given a description of a closed process system, simplify the energy balance and solve it for whichever term is not specified in the process description. 

A single gas stream enters a process at conditions T, P, and leaves at pressure P2. The process is adiabatic. Prove that the outlet temperahire T2 for the actual (irreversible) adiabatic process is greater than that for a reversible adiabatic process. Assume the gas is ideal with constant heat capacities. 

A small adiabatic air compressor is used to ptunp air into a 20-ni insulated tank. The tank initially contains air at 298.15 K (25°C)and 101.33 kPa, exactly tlie conditions at wliich air enters tlie compressor. The pumping process continues until tlie pressure in tile tank reaches 1000 kPa. If tlie process is adiabatic and if compression is isentropic, wliat is tile shaft work of tlie compressor Assume air to be an ideal gas for wliich Cp = (7/2)P and Cy = (5/2)P. 

The product acetic acid and a majority of the light ends (methyl iodide, methyl acetate, water) are separated from the reactor catalyst solution and forwarded with dissolved gases to the distillation section by an adiabatic single-stage flash. This crude separation also functions to remove the exothermal heat of reaction. The catalyst solution is recycled to the reactor. Under the process conditions of the flash, the rhodium catalyst is susceptible to deactivation at the low CO partial pressure of the flash vessel [46]. 

The HS diagram of Fig. 4-2 compares the path of an actual expansion in a turbine with that of an isentropic expansion for the same intake conditions and the same discharge pressure. The isentropic path is the dashed vertical line from point 1 at intake pressure Pi to point 2 at P2. The irreversible path (solid line) starts at point 1 and terminates at point 2 on the isobar for P2. The process is adiabatic, and irreversibilities cause the path to be directed toward increasing entropy. The greater the irreversiblity, the farther point 2 hes to the right on the P2 isobar, and the lower the value of q. 

Following the results of the adiabatic reactor concept it is expected that high selective membranes will further improve the economics. However, it should be recognised that the process conditions in an isothermal concept are more severe than in an adiabatic concept. In particular, decoking conditions can be a problem in using high selective membranes. Detailed calculations on the isothermal membrane reactor concept are being performed and will be reported in future. 

Consider an ideal gas of 2N molecules, each containing one chiralic center. Initially, we prepare the system in such a way that all the molecules are in one of the enantiomeric forms, say the d enantiomer. We then introduce a catalyst which induces a racemization process in adiabatic conditions. At equilibrium, we obtain N molecules of the d enantiomer and N molecules of the l enantiomer. The entropy change in this spontaneous process is well known ... 

WET-BULB TEMPERATURE. The wet-bulb temperature is the steady-state, non-equilibrium temperature reached by a small mass of liquid immersed under adiabatic conditions in a continuous stream of gas. The mass of the liquid is so small in comparison with the gas phase that there is only a negligible change in the properties of the gas, and the effect of the process is confined to the liquid. The method of measuring the wet-bulb temperature is shown in Fig. 23.4. A thermometer, or an equivalent temperature-measuring device such as a thermocouple, is covered by a wick, which is saturated with pure liquid and immersed in a stream of gas having a definite temperature T and humidity ff. Assume that initially the temperature of the liquid is about that of the gas. Since the gas is not saturated, liquid evaporates, and because the process is adiabatic, the latent heat is supplied at first by cooling the liquid. As the temperature of the liquid decreases below that of the gas, sensible heat is transferred to the liquid. Ultimately a steady... 

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