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Energy Balance without Reaction

The general balance equation for an open continuous system at steady state in the absence of generation/consumption term is [Pg.121]

Energy output = Uout + E/t, out F Ep out F Toutl ut Energy transferred = Q - Ws Energy transferred = Energy out - Energy in [Pg.121]

Rearranging the above equations leads to the first Law of Thermodynamics for an open system at steady state. [Pg.122]

A shell and tube heat exchanger is used to cool hot water with cold water. Hot water enters through the tube side of a heat exchanger with a mass flow rate 0.03 kg/s and 80°C to be cooled to 30°C. Cold water in the shell side flows with a mass flow rate of 0.06 kg/s at a temperature of 20°C. Determine the outlet temperatures of the cold water. [Pg.122]

Heat transfer rate can be calculated using energy balance equation  [Pg.122]


One point bf speciarimporfance Concerns the"formation of water in a chemical reaction. When water participates in a chemical reaction in solution as a reactant or product of the reaction, you must include the heat of formation of the water as well as the heat of solution in the energy balance. Thus, if 1 mole of HCl reacts with 1 mole of sodium hydroxide to form water and the reaction is carried out in only 2 moles of water to start with, it is apparent that you will have 3 moles of water at the end of the process. Not only do you have to take into account the heat of reaction when the water is formed, but there is also a heat of solution contribution. If gaseous HCl reacts with crystalline sodium hydroxide and the product is 1 mole of gaseous water vapor, you could employ the energy balance without worrying about the heat of solution eff ect. [Pg.470]

Those based on strictly empirical descriptions Mathematical models based on physical and chemical laws (e.g., mass and energy balances, thermodynamics, chemical reaction kinefics) are frequently employed in optimization apphcations. These models are conceptually attractive because a gener model for any system size can be developed before the system is constructed. On the other hand, an empirical model can be devised that simply correlates input-output data without any physiochemical analysis of the process. For... [Pg.742]

A similar finite-differenced equivalent for the energy balance equation (including axial dispersion effects) may be derived. The simulation example DISRET involves the axial dispersion of both mass and energy and is based on the work of Ramirez (1976). A related model without reaction is used in the simulation example FILTWASH. [Pg.247]

Inputs + Sources = Outputs + Sinks + Accumulations where each of these terms may be a quantity or a rate. Inputs and Outputs are accomplished by crossing the boundary of the reference volume. In case of mass transfer this occurs by bulk flow and diffusion. Sources and Sinks are accretions and depletions of a species without crossing the boundaries. In a mass and energy balance, sinks are the rate of reaction, rdVr, or a rate of enthalpy change, AHrpdC. Accumulation is the time derivative of the content of the species within the reference volume, for example, (<9C/3t)dVr or... [Pg.16]

Under some circumstances the system may be maintained at a fixed temperature. In this case only the reaction chemistry is considered, without explicit concern for an energy balance. Alternatively, the reactor temperature may be determined from an energy balance. In general, there may be a heat-transfer rate between the reacting gases and the reactor walls, Q. There may also be surface reaction at the walls. [Pg.661]

Equation 11.3-7 is simple in appearance, but its solution is still generally difficult to obtain. If, for example, the composition or temperature of the system contents varies with position in the system, it is difficult to express the total internal energy t/sys in terms of measurable quantities, and a similar problem occurs if phase changes or chemical reactions take place in the course of the process. To illustrate the solution of energy balance problems without becoming too involved in the thermodynamic complexities, we will impose the additional restrictions that follow. [Pg.555]

Energy Balances for Closed Systems (without Chemical Reaction)... [Pg.410]

If a mixture enters and leaves a system without a reaction taking place, we would find that the same species entered and left so that the enthalpy change in Eq. (4724a) would not be any different-with the-modification-described above than what we have used before, because the terms that account for the heat of formation in the energy balance would cancel. For example, for the case of two species in a flow system, the output enthalpy would be... [Pg.438]

Let us now consider an open system with chemical reaction to illustrate how the previously discussed concepts are incorporated. Without loss of generality, let us consider a steady-state flow process with a reactor having a single inlet and outlet stream. The open-system energy balance then becomes... [Pg.385]

The material balances for the feed-heating section are simple because reaction does not take place without the catalyst. Without reaction, the molar flow of ail species are constant and equal to their feed values and the energy balance for the feed-heating section is... [Pg.179]

In conclusion, one solves two coupled first-order ODEs for the molar density profile of reactant A under isothermal conditions, without considering the thermal energy balance. Then, a volumetric average of the rate of conversion of reactant A to products due to multiple chemical reactions is obtained by focusing on the reactant concentration gradient at the external surface of the catalyst ... [Pg.752]

Without the Frost diagram, the Latimer diagram data can be used through application of Hess law. The sum of the free energies of the component half-reactions affords the free energy of the sum of these half-reactions. The balanced half-reaction... [Pg.639]

The "statistical formulation (67.Ill) cannot be applied to unimolecular reactions for which the classical activation energy and the reaction heat are equal (E = Q) without introducing some additio-nal assumptions which are necessary for the definition of the transition state. One usually considers the "activated complex (AB) as a rotating "diatomic molecule in which the centrifugal force is balanced by an attractive dipole-induced dipole or dispersion force /HO/. This "diatomic model implies that the angular momentum... [Pg.237]


See other pages where Energy Balance without Reaction is mentioned: [Pg.121]    [Pg.121]    [Pg.348]    [Pg.1152]    [Pg.365]    [Pg.54]    [Pg.418]    [Pg.384]    [Pg.21]    [Pg.86]    [Pg.254]    [Pg.212]    [Pg.437]    [Pg.438]    [Pg.10]    [Pg.12]    [Pg.61]    [Pg.117]    [Pg.160]    [Pg.561]    [Pg.352]    [Pg.418]    [Pg.97]    [Pg.752]    [Pg.7]    [Pg.194]    [Pg.117]   


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