Heat HIGEE

Unfortunately, the available data are sparse at present. From the heat transfer point of view, the suitability of the reactors may be put in deceasing order as SSTR, stator-rotor SDR, HEX reactors, AFR, SDR, ACR/ATR, OBR and HIGEE. If the interphase transfer dictates the reaction rate, the volumetric mass-transfer coefficient plays a dominant role. The micro-mixing and residence time also are of importance in the case of fast reactions and thermally unstable products. The above ordering (but for the SDR) could be used for gas-liquid or liquid-liquid phases. If solid-liquid or solid-liquid-gas are involved, the decreasing order could be OBR, ACR/ATR, AFR, HIGEE, stator-rotor SDR, and SSTR. Studies are underway on the characteristics of the reactors. These would help to ascertain their relative merits quantitatively in the future. 

For HIGEE, residence time 0.1-1 s voidage 90-95% 2 m diameter max., area per volume 2000-5000 m /m. 1000 rpm film thickness 100 pm. Overall heat transfer coeffident 1/ = 10 kW/m K. See also Reactive distillation. Section 6.35. 

It may be said that advances in separation technology during the past 20 years should enable this concern to be overcome - HiGee and the micro-distillation column of Velocys are two examples in support of this. In a positive vein the report suggests that by combining multi-phase metering and pumping capabilities with intensified separations and heat transfer equipment, subsea completions and transfer of products to shore may be feasible. 

Thermodynamic functions for the ideal gas (molar heat capacity C°, entropy S°, Gibbs free energy function (G°- H298)/T, all in cal- mol K" enthalpy H - HIge in kcal/mol) were calculated from the molecular constants between T = 0 and 6000 K at 100 K intervals [3]. Some values are given on the following page. 

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