Volumetric energy consumption

The design optimization of an electrolytic cell aims at a high throughput with a low energy consumption at the lowest feasible cost. The throughput of an electrochemical reactor is measured in terms of the space time yield, Yt, defined as the volumetric quantity of the metal produced per unit time per unit volume of the process reactor. This quantity is expressed as ... 

Apart from the above-mentioned commercial impasse, which delays the development of the hydrogen economy, there are two important technical issues that also need to be solved hydrogen s volumetric density and energy consumption during hydrogen production. 

The fan energy consumption E (in W) may be calculated by means of the following relationship between the volumetric airflow rate V (m /s) and the total pressure drop that must be overcome, AP (Pa) ... 

The selection of a reactor, from those described above as an alternative to the STR, depends on the heat reaction, the nature of the phases involved and the rate of production. The safety, reliability, energy consumption and cost have to be considered. The volumetric heat- and mass-transfer coefficients can be viewed as measures of process intensification. The attainable coefficients in the reactors dictate the yield, selectivity and size reduction. 

Specchia et al. (1974) reported ratios of G/L- and L/S-areas between 0.6 and 2, depending on a parameter for the energy consumption (dimensionless pressure drop). For the volumetric mass transfer coefficients h found values between 0.01 and 1 s A safe average would be around 0.1 s For more accurate estimates, the reader is referred to the aforementioned literature. 

The volumetric mass transfer coefficient is used by this comparison because it is reverse proportional to fee packing volume, and feus it can be used as a measure for fee capital investments. The pressure drop per mass transfer unit can be used as a comparable measure for fee operating cost, or more precisely, for fee operating cost for energy consumption of fee movement of fee gas flow trough fee packing. 

The dilemma can be summarized as follows. Plug-flow mass and thermal energy balances in a packed catalytic tubular reactor are written in terms of gas-phase concentrations and temperature of the bulk fluid phase. However, the volumetrically averaged rate of reactant consumption within catalytic pellets is calculated via concentrations and temperature on the external surface of the pellets. When external transport resistances are negligible, design of these reactors is simplified by equating bulk gas-phase conditions to those on the external catalytic surface. In this chapter, we address the dilemma when bulk gas-phase conditions are different from those on the external surface of the pellet. The logical sequence of calculations is as follows ... 

The energy performance of a dryer and a drying process is characterized by various indices such as volumetric evaporation rate, surface heat losses, steam consumption, unit heat consumption, and energy (thermal) efficiency. Of all these indices, the energy efficiency / is most frequently quoted in technical specifications. It commonly relates the energy used for moisture evaporation at the solids feed temperature ( , ) to the total energy supplied to the dryer ( ,) ... 

Calcium carbonate (CaCOj) Fumaric acid yield and volumetric productivity are always high Low solubility of calcium fumarate in water (2.1% at 30°C), more consumption of energy and mineral acids in the downstream processing... 

In the United States, for instance. Volumetric Excise Tax Credits for the blending of fuel ethanol and biodiesel are being provided to biofuel producers under the American Jobs Creation Act since 2004. In the European Union, the Energy Taxation Directive permits exemptions or reductions from energy taxation for biofuels (Directive 2003/96/EC). Currently, nearly all EU member states (with the exception of Finland and the Netherlands) provide partial or total tax exemptions or deduction, most aimed at hnal consumption (European Commission, 2011). Because the tax exemption has an upper bound equal to the acmal level of the fossil fuel tax, the instrument has proven to be highly effective in those EU member states with fossil fuel tax levels high enough to compensate for the additional production costs of biofuels (Wiesenthal et al., 2009). 

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