Heat transfer metrology issues in two‐phase bubble column reactors

Abstract

The metrology and the impact of various parameters and operating conditions on the bulk-to-tube heat transfer coefficients in two-phase bubble columns are investigated on a small-scale mock-up. It is shown that (1) quasi-adiabatic conditions can be reached in the column; (2) the bulk-to-tube heat transfer coefficients for each U-tube downward and upward sections may or may not differ significantly, depending on the way uncertainty of the measurements is estimated; (3) using the different measurements and uncertainty estimates for given conditions, a mean heat transfer coefficient over all tubes is estimated within ±5%. The consequences for bulk-to-tube heat transfer coefficient prediction in a larger column are discussed.La métrologie et les répercussions de divers paramètres et différentes conditions d'utilisation sur les coefficients de transfert de chaleur de la calandre aux tubes dans des colonnesà bulles en deux phases sontétudiées sur une maquetteà petiteéchelle. Il est démontré que (1) l'on peut parvenirà des conditions quasi adiabatiques dans la colonne; (2) les coefficients de transfert de chaleur de la calandre aux tubes pour les parties descendante et ascendante de chaque tube en << U >> peuvent différer considérablement ou non, selon la façon dont l'incertitude des mesures est estimée; (3) par l'utilisation des différentes mesures et estimations de l'incertitude pour des conditions données, un coefficient de transfert de chaleur moyen pour tous les tubes est estiméà ±5%. Les conséquences pour la prédiction des coefficients de transfert de chaleur de la calandre aux tubes dans une colonne plus grande sont discutées.

CFD simulations of hydrodynamic/thermal coupling phenomena in a bubble column with internals

“…The experimental value of the shell‐side heat transfer coefficient in the column side in similar experimental conditions is around 1122.7 W m −2 K −1 41. The simulated global heat transfer coefficient compares well with this data.…”

“…The simulated setup is based on an experimental bubble column where temperature and heat transfer data have been measured 41. The column has a diameter of 15.1 cm and is equipped with a bundle of two U‐shaped cooling tubes, each of them being 2.67 cm in diameter.…”

Impact of Internals on the Heat-Transfer Coefficient in a Bubble Column

“…Most academic research on bubble columns has been performed in hollow (empty) ones and the reported studies that involve multiple internals are relatively few . Among these few studies in bubble columns with multiple internals are those of Fair et al, Weinspach and co-workers − in the mid-1980‘s and early 1990‘s, Saxena and co-workers − in the late 1980‘s and early 1990‘s, Al-Dahhan and co-workers since the mid-2000‘s, and more recently Beliard et al Also, several reviews published by Pandit and Joshi, Saxena and Chen, Saxena, Nigam and Schumpe, Li and Prakash, Kantarci et al, Hulet et al, and more recent Jhawar and Prakash include the details of experimental investigations in empty columns along with some findings in columns with internals. Table summarizes recent reported heat-transfer studies in bubble and slurry bubble columns with multiple internals.…”