Heat transfer enhancement with condensation by surface rotation

Vasiliev, L. L.; Khrolenok, V. V.

doi:10.1016/0890-4332(93)90006-h

Cited by 3 publications

(1 citation statement)

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“…Alternatively, h c can be increased using active methods of enhancement, of which the application of centrifugal fields is most widely applied. For the case of film condensation on a rotating disc in a quiescent vapor environment (termed “free disc”), it is shown both theoretically as well as experimentally that application of a centrifugal force decreases the condensate film thickness and thus increases h c .…”

Section: Introductionmentioning

confidence: 99%

Convective condensation in a stator–rotor–stator spinning disc reactor

et al. 2016

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Centrifugal intensification of condensation heat transfer in the rotor-stator cavities of a stator-rotor-stator spinning disc reactor (srs-SDR) is studied, as a function of rotational velocity x, volumetric throughflow rate / v , and average temperature driving force DT. For the current range of x, heat transfer from the vapor bubbles to the condensate liquid is limiting, due to a relatively low gas-liquid interfacial area a GL . For x > 84 rad s 21, a strong increase of a GL , results in increasing the reactor-average condensation heat transfer coefficient h c from 1600 to 5600 W m 22 K 21, for condensation of pure dichloromethane vapor. Condensation heat transfer in the srs-SDR is enhanced by rotation, independent of the vapor velocity. The intensified condensation comes at the cost of relatively high energy dissipation rates, indicating condensation in the srs-SDR is more suited as a means to supply heat (e.g. in an intensified reactor-heat exchanger), rather than for bulk cooling purposes. V C 2016 American Institute of Chemical Engineers AIChE J, 00: 000-000, 2016 Keywords: intensification, condensation, heat transfer, rotor-stator spinning disc reactor, multi-phase flow IntroductionConvective condensation processes are an integral part of the chemical process industry, e.g., as unit operation in distillation processes, in refrigeration cycles and in the supply of heat to chemical reactors with integrated heat exchange. Applying a condensing fluid as a source of heat allows reactor operation at a fairly constant temperature, depending on the pressure drop, and condensation heat transfer coefficients are generally high compared to single phase coefficients.1 Therefore, intensification of reactor-heat exchangers for endothermic processes leads to increasing condensation rates, and requires a higher degree of control. The rate of condensation is generally limited by the removal of evaporation enthalpy through the formed liquid film.2 Consequently, research efforts to increase the convective condensation heat transfer coefficient h c focus on decreasing the condensate film thickness and/or increasing the turbulence intensity in the liquid film. This can be realized by both passive (without the input of an external force, apart from pressure drop) and active (with the input of an external force) means.Passive convective condensers can easily be integrated within chemical reactors, and include horizontal or vertical tubes, [3][4][5][6][7] plate heat exchangers (PHE) [8][9][10] and minichannels. [11][12][13] Surface enhancement techniques such as the corrugated surface of a PHE 8 and micro-fins in tubes and PHEs 9,14 increase h c by a factor 2-3 compared to their smooth equivalents, which is explained by increased convection within the liquid film. With an increasing h c , the pressure drop DP over the condenser length increases as well. For all passive convective condensers (i.e., plain as well as enhanced surfaces), h c is mainly determined by the local vapor shear stress. This is caused by the large difference i...

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Section: Introductionmentioning

confidence: 99%