O2 Efficiency Economy

This term refers to the quotient of the OTR and the power used per volume 

As an approximation suitable for small units that can be considered ideal (that is, without internal temperature gradients and with a constant transport coefficient) and in equilibrium situation, AT can be calculated from (Ebert, 1971) 

The total heat balance, available on the basis of the directly accessible quantity of the volumetric heat of reaction hy [kJT ], is made up of several terms, ( [kJ-r h ] 

The various terms take into account the various sinks q 0) or sources q 0) of the heat balance. These include, specifically, the reaction itself, transport, agitation, radiation, and heat loss through evaporation and gas stream. In most cases the last four terms can be neglected (Bronn, 1971 Cooney, Wang, and Mateles, 1968 Mou and Cooney, 1976). The term for the reaction, the heat produced, is represented in Equ. 2.4c. The kinetics are, as always, introduced in the balance equation. All heats of reaction can be calculated from a series of T/t measurements using Equ. 3.70 when the specific heat capacity of the reactor system is known 

This Uhlich approximation uses the value of the specific heat capacity Cp [kJ kg °C ] multiplied by the mass of the fermentation medium per unit volume, M/V/ [kg/1]. Typical values for fermentation processes are given in Table 3.4 (Conney et al., 1968). 

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