Intensified heat transfer

Contrary to RPBRs, in SDRs, intensified heat transfer presents the most important advantage. Liquid reactant(s) are fed on the surface of a fast rotating disk near its center and flow outward. Temperature control takes place via a cooling medium fed under the reaction surface. The rotating surface of the disc enables to generate a highly sheared liquid film. The film fiow over the surface is intrinsically unstable and an array of spiral ripples is formed. This provides an additional improvement in the mass and heat transfer performance of the device. 

The slow-speed anchor stirrer is generally utilized with close wall clearance (D/d < 1.05) to intensify heat transfer in high viscosity liquids. 

The intensified heat transfer has spawned a myriad of studies, particularly for reactions where precise temperature profile control is crucial. Examples are given in Refs. [19-21]. 

Pan, M., Bulatov, I., Smith, R., and Kim, J.K. (2013) Optimisation for the retrofit of large scale heat exchanger networks with different intensified heat transfer techniques. Applied Thermal... 

SOME WAYS IN WHICH GAS MOTION CAN BE SPEEDED IN ORDER TO INTENSIFY HEAT TRANSFER IN METALLURGICAL FURNACES. 

Next to the so far mentioned intensification of classical heat exchanger concepts, there are also different reactors for intensified heat transfer. Reay et al. have classified the enhancement strategies for heat transfer into passive and active enhancement strategies [6]. While the so far mentioned strategies for intensifying heat exchangers are mainly passive (extended surfaces, inserts etc.), new reactor concepts for intensified heat tfansfer mainly... 

Multi-scale design, by providing an additional degree of freedom, can open up new paths to true sustainability. In the case examined here, analysis of friction losses in tubular reactors provides a solution capable of intensifying heat-transfer performance without additional energy dissipation. The multi-scale design solution consists of subdividing the main reactant flow in order to apply the intensified conditions to each sub-flow in the system. 

Since this analysis aims at intensifying heat transfer in the reactor, these values of the exponent indicate that a two-fold decrease in the heat-transfer time implies at least an eight-fold increase in the required mechanical power. As a result, the desired intensification of an existing reactor cannot be attained vhthout an increase in the required mechanical power, which is not compatible with the obj ectives of sustainable intensification. An additional analysis is therefore required to combine heat-transfer intensification and sustainability criteria, while maintaining reactor flexibility. 

Heat transfer in static mixers is intensified by turbulence causing inserts. For the Kenics mixer, the heat-transfer coefficient b is two to three times greater, whereas for Sulzer mixers it is five times greater, and for polymer appHcations it is 15 times greater than the coefficient for low viscosity flow in an open pipe. The heat-transfer coefficient is expressed in the form of Nusselt number Nu = hD /k as a function of system properties and flow conditions. 

Anxionnaz, Z., Cabassud, M., Gourdon, C., and Tochon, P. (2010) Transposition of an exothermic reaction from a batch reactor to an intensified continuous one. Heat Transfer Eng., 31 (9), 788-797. 

C >70% accumulation of energy Very fast <1 s mixing controlled High quality mixing and mass transfer. High heat transfer area gives temperature control. Intensified and/or structured reactors. 

The external-loop slurry airlift reactor was used in a pilot plant (3000 t/a) for one-step synthesis of dimethyl ether (DME) from syngas. Specially designed internals were used to intensify mass transfer and heat removal. This new technology is highly efficient and easy to scale-up to industrial. 

The investigations refer to the general capability of micro reactors to perform short-time processing with highy intensified mass and heat transfer. A special focus of most investigations on the oxidation of ammonia was the heat management. The use of new concepts for heat supply and removal opens the door to operation in new process regimes with very different product spectra. 

As the diameter is decreased, the heat transfer from a unit volume intensifies because of the increase in the ratio of surface to volume (d-1) heat exchange per unit surface also intensifies. For a constant value of the Nusselt number the heat exchange coefficient is proportional to d l. Under the rough assumption that Tc and E change little from one case to the next, we come to the conclusion that at the limit the Peclet number (numerically equal for gases to the Reynolds number), based on the flame velocity (or adiabatic flame velocity u0) has a specific value... 

These include standard mass transfer operations, such as absorption and stripping, but also include reaction systems. The following section highlights some of the applications for which data are available and suggests other opportunities for exploitation of the intensified mass and heat transfer capabilities. 

As part of a general development to use spinning discs in an intensified absorption heat pump, Aoune and Ramshaw (16) measured both the local and average heat transfer performance on smooth rotating surfaces. The disc surface... 

At the most basic level, the SDR is an extremely effective gas-liquid contacting device. This makes it ideal for performing many intensified heat or mass transfer operations and, as will be discussed later, it may be deployed as an evaporator or an aerator/desorber. However, its principal application in the process industry is likely to be as a very high-performance reactor. Since the reactor is the heart of... 

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