Chemical Engineering Journal 102 (2004) 11–24 Pressure drops of single and two-phase flows through T-type microchannel mixers Jun Yue, Guangwen Chen ∗ , Quan Yuan Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Group 903, 457 Zhongshan Road, Dalian 116023, China Received 14 November 2003; received in revised form 20 January 2004; accepted 5 February 2004 Abstract In this paper, preliminary experimental results are presented on pressure drop characteristics of single and two-phase flows through two T-type rectangular microchannel mixers with hydraulic diameters of 528 and 333 m, respectively. It is shown that both N 2 and water single-phase laminar flows in microchannels, with consideration of experimental uncertainties, are consistent with classic theory, if additional effects, such as entrance effects that will interfere with the interpretation of experimental results, are eliminated by carefully designing the experiments. The obtained pressure drop data of N 2 –water two-phase flow in micromixers are analyzed and compared with existing flow pattern-independent models. It is found that the Lockhart–Martinelli method generally underpredicts the frictional pressure drop. Thereafter, a modified correlation of C value in the Chisholm’s equation based on linear regression of experimental data is proposed to provide a better prediction of the two-phase frictional pressure drop. Also among the homogeneous flow models investigated, the viscosity correlation of McAdams indicates the best performance in correlating the frictional pressure drop data (mean deviations within ±20% for two micromixers both). Finally it is suggested that systematic studies are still required to accurately predict two-phase frictional performance in microchannels. © 2004 Elsevier B.V. All rights reserved. Keywords: Microchannel; Micromixer; Two-phase flow; Laminar flow; Pressure drop 1. Introduction Rapid progresses in microelectromechanical systems (MEMS) and miniaturization technologies are bringing sig- nificant changes to chemical process engineering. By means of these technologies, we can build microstructured devices to intensify mixing, heat and mass transfer, and also reac- tions in chemical processes. Some successful efforts have already been reported in recent years [1–3]. Nevertheless, the fundamentals of transport phenomena and reactions oc- curring in such microchannel devices are still unclear, mak- ing it difficult to predict the performance of these devices precisely and quantitatively. Among these issues waiting to be addressed, single and two-phase flow behaviors in microchannels have the priority for the investigation, since these are crucial for successful designs and applications of microreaction technologies, e.g., gas–liquid microreactors [4,5], single and two-phase flow microchannel heat sinks [6,7], etc. ∗ Corresponding author. Tel.: +86-411-437-9031; fax: +86-411-469-1570. E-mail address: gwchen@dicp.ac.cn (G. Chen). 1.1. Single-phase flow in microchannels For gas and liquid single-phase flows in microchan- nels, contradictory experimental and simulation results exist [8–25]. From the viewpoints of actual applications of microchannel reactors, we are mainly interested in fluid laminar flow behavior in microchannels with diameters of several hundred micrometers (termed “large microchannels” in the following paragraphs), where compressible effects and rarefaction effects are thought to be negligible. Currently available research papers on fluid laminar flow in large microchannels reveal that the conclusions can be mainly classified into three categories (divided by the rela- tionship between fRe and C): (1) fRe > C, i.e., fluid lami- nar flow in microchannels exhibits a higher pressure drop [8–16]; (2) fRe < C, i.e., the pressure drop of fluid laminar flow in microchannels is less than that predicted by classic theory [17,18]; and (3) fRe = C, i.e., fluid laminar flow in microchannels is still consistent with classic theory [19–25]. More details are tabulated in Table 1. Here fRe represents the product of friction factor, f, with Reynolds number, Re, and C is laminar friction constant according to classic the- ory for a specific geometrical microchannel. 1385-8947/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.cej.2004.02.001