RICERCA ITALIANA     

Technological Applications of Microfluidics

Università degli Studi di Parma

Abstract

The goal of the proposed research project is the analysis of transport phenomena in single and two-phase flows in microducts having a hydraulic diameter less than 4 mm, with the aim to obtain correlations able to give the designers the tools required for the correct choice of dimensions and configurations of microdevices. The investigation shall be carried out both theoretically and experimentally, with the intent of exploring how the transport phenomena are modified by scaling effects, which are typical of the reduced dimensions, and by the effects which induce a new modelization of the balance equations for continuum flow, and/or of the boundary conditions (micro-effects).
The investigation shall aim at thoroughly investigating the role played by the single scaling effects and micro effects, on the pressure drop and the convective heat transfer coefficient. The project shall deal with the analysis of single-phase flows (liquid and gaseous) and two-phase flows (flow boiling and condensation). The working fluids shall be chosen bearing in mind possible technological applications of microfluidics in the thermal control of electronic components (refrigerants such as HCF, FC72, R404a, CO2, air, N2) and in the development of "lab-on-a-chip" (H2O). Table 1 shows the program assigned to the different research Units. One can observe that single phase flows will be analysed both theoretically and experimentally. The study of two-phase flows shall be carried out with >>>

Principal Investigator

Marco SPIGA Università degli Studi di PARMA

Research Objectives

Microfluidics, involving fluid-dynamics and heat transfer in microchannels, is a paramount topic for scientists and technicians. This is proved by the many papers published in this area, by the birth of several new International Journals (since Microscale Thermophysical Engineering in 1998, to Microfluids & Nanofluids in 2004), by several International Conferences (since Int. Conference on Heat Transfer and Transport Phenomena in Microscale, Banff 2000, to the next third edition of Int. Conference on Microchannels and Minichannels which will be held in Toronto, in June 2005).
In this last decade, the papers appeared in literature highlights how the classical correlations used in macro-scale to evaluate the pressure drops and the convective heat transfer coefficients can predict values well different from those obtained experimentally. The reason for these discrepancies can be explained, because the miniaturization is responsible for scale-effects which imply the correction of classical models or the proposal of new models to represent the fluid-mechanics and heat transfer in isothermal and non-isothermal flows. The continuum flow theory, based on the Navier-Stokes and energy equations with no-slip boundary conditions for velocity and temperature, must be revised.
At the moment it is not yet clear how and when the micro scale-effcts and the micro-effects play a significant role on the transport phenomena.
For this reason, the basic objective of this >>>

Timescale

24 months

National and international background

Fluid dynamical and thermal analysis of microchannels is a subject of remarkable scientific and technological interest, as testified by several works being published on the most renowned journals in this field or presented at conferences dedicated to the subject in the last years (from the held in Banff in the year 2000 to the oncoming third edition of ASME's Int. Conference on Microchannels and Minichannels which shall be held in Toronto in June 2005) and by the foundation of periodicals dedicated to the subject (from Microscale Thermophysical Engineering to Micro- and Nanofluidics)
Most of the research in this field is of the applicative kind and is oriented to the fabrication of microcomponents with well-defined functions. The enormous progress that surface microfabrication and micromachining techniques enjoyed in recent years allowed a proliferation of technical applications of microcomponents using or circulating fluids (Micro Flow Devices, MFDs). MFDs allow a vast range of tasks: from microcomponents devised for elementary operations such as transport or dosing of a fluid up to complex MFDs that are miniaturised chemical labs (lab-on-a-chip) where mixing and synthesis of fluid and fluid mixtures – sometimes quite complex in nature – take place. One of the main difficulties in engineering these components lies in the control of flow rates, of the volumes of the fluids to handle and of the temperature. In order to successfully design such components it is thus >>>