Enthalpy balances cell equations

The direct application of the enthalpy balance method to growth reactions such as Equation (13) requires knowledge of the enthalpy of combustion for the cell mass. It is a major difficulty to obtain a clean sample of animal cell biomass... 

The adjustable parameters appearing in Equation (12.6) must be carefully optimized against experimental data. These are either geometric (cell dimensions, molecular position and orientation) or energetic (sublimation enthalpies, lattice frequencies) in nature. Calculation of geometric features depends primarily on a proper balance of the attractive and repulsive parts of the potentials, not on their absolute magnitudes. Calculation of lattice energy (to be compared with sublimation enthalpies) depends primarily on the well depths of individual atom-atom interactions. Finally, lattice vibrations depend critically on the second derivative of the potential and are usually the most difficult to calculate correctly. 

Here, F, Zf and h are, respectively, the molar flow rate, mole fraction of component of i and total enthalpy, all in cell k their subscripts, ret and perm, refer to retentate and permeate streams. Equations (10.4) and (10.5) are mass balances and mass-transfer equations for each of the components present in the membrane feed. The cross-flow model [Equations (10.3)-(10.7)] was implemented in ACM v8.4 and validated against the experimental data in Pan (1986) and the predicted values of Davis (2002). The Joule-Thompson effect was validated by simulating adiabatic throttling of permeate gas through a valve in Aspen Hysys. Both these validations are described in detail in Appendix lOA. 

The solver, second element of a CFD package, transforms the equations of transport phenomena into a system of algebraic equations via discretization and solves them by an iterative approach. These steps can be carried out either by the FEM or by the FVM that are explained in the following sections. The following balance equation in an arbitrarily chosen element or cell can be written for a general flow variable (p, for example, a velocity component or enthalpy [12] ... 

The following conditions should be noted for Equation (13) (a) molecular formulae are used to aid the subsequent material and energy balances (b) any target protein (e.g. IFN-y) is combined with the biomass which is expressed by a C-molar formula as customarily utilised for microbial biomass (see the Chapter by Duboc et al. in this Volume and also Reference [20]) and (c) the stoichiometric coefficient of the cell mass is set at unity and so the enthalpy change of the growth reaction now is based on unit number of C-molar biomass [105], It has been shown from experimentation (see Figure 27) that there is a one-to-one monotonic relationship between the metabolic flux (see Equation (7)) and the stoichiometry of the growth equation (Equation (13)). This can be expressed by ... 

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