Vai al contenuto| Home page|

   Ti trovi in: HOME »Programmi, progetti e risultati »I progetti »PRIN - Programmi di ricerca di Rilevante Interesse Nazionale»Programma di ricerca
INIZIO_TESTO_DA_INDICIZZARE

RESEARCH PROGRAM

italiano - inglese
Research Units
Similar research programs:
Scientific and education field classification
International Patent Classification
  • ELECTRICITY
    • BASIC ELECTRONIC CIRCUITRY
      • AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (of dynamo-electric generators H02P)
  • MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING ENGINES OR PUMPS
    • HEAT EXCHANGE IN GENERAL
      • HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of general
  • PHYSICS
    • MEASURING (counting G06M); TESTING
      • MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME (milk flow sensing devices in milking machines or devices A01J5/01; measuring or recording blood flow A61B5/02, A61B8/06; metering media to the human body A61M5/168; burettes or pipettes B01L3/02; arrangements of liquid volume meters or volume-flow meters in liquid-delivering apparatus, e.g. for retail sale purposes, B67D5/16; pumps, fluid motors, details common to measuring or metering devices and pumps or fluid motors F01 to F04; [N: sampling G01N1/00]; locating, determining distance or velocity using reflection or reradiation of radio waves, analogous arrangements using other waves G01S; systems for ratio control G05D11/00; [N: coin-freed apparatus for metering flow of liquid or gas G07F15/00]) [C9607]
Geographical classification
Keywords
THERMAL CONTROL; FREE CONVECTION; THERMAL OPTIMIZATION; CONFINED SYSTEMS; LOOPS; TURBULENCE PROMOTERS; OPTICAL METHODS; COMPUTATIONAL THERMAL FLUID DYNAMICS; GENETIC ALGORITHMS

Study and Optimization of Buoyancy-controlled Thermal Systems

Università degli Studi di Modena e Reggio Emilia
Abstract
The project is centred on the study of free convection flows of single-phase fluids in totally or partially confined environments. The research program is mainly aimed to provide updated criteria and methodologies useful in the design of a variety of thermal control devices.
Fundamental aspects of the thermal-fluid behaviour of confined buoyant systems are covered by this project, as well as the development of enhanced experimental methods and theoretical tools for system analysis.
Also, a pilot test is attempted on use of automatic optimisation procedures in the context of the thermal design of buoyancy-controlled devices.
Activities will focus on systems in the following typologies: confined fluid systems containing thermal sources, natural circulation loops, buoyant flows through open-ended vertical channels.
As for confined systems, much attention will be devoted to supercritical natural convection regimes, with special concern with the effects of geometrical details on flow stability, and the system behaviour under transient conditions. Thermo-gravitational diffusion in binary mixtures, and the related component separation effects, will finally be investigated.
Interest in natural circulation loops is driven by the present trend towards system-size reduction, in view of possible use of this technology in hi-tech applications. Theoretical and experimental characterization of small- and medium-size loops, in terms of either stability >>>

Principal Investigator
Giovanni Sebastiano BAROZZI Università degli Studi di MODENA e REGGIO EMILIA
Research Objectives
The general objective of this research program is to provide new criteria and reliable predictive tools for the design and optimization of those thermal systems and devices, whose effectiveness totally relies upon buoyancy-induced flow and circulation. Appropriate technical directions, and design methodologies will possibly be derived for a number of technological applications.

The project is centred on the study of free convection flows in totally or partially confined environments. The program collects different previous experiences of the Research Units (R.U.) in the frame of National Research Projects (PRIN). These were devoted to the development of experimental and numerical methods for investigating combined and free convection heat transfer. The competences gained and the facilities acquired by the Research Units are fully exploited in this project, towards new methodological and technological objectives.

Attention is deliberately restricted and focused on the following single-phase buoyant systems: i. Confined cavities containing immersed thermal sources or having thermally active boundary-walls; ii. Open-ended vertical channels with heating surfaces; hermetic natural circulation (or thermosyphon) systems.

With reference to the above systems, the aims of the research program are detailed as follows:

1) to probe into a few fundamental aspects of thermal control by pure free convection, not completely >>>

Timescale
24 months
National and international background
Natural (or free) convection flows are induced by buoyancy forces in fluids under the action of the gravity field. In homogeneous fluids these forces are generated by density gradients, due to temperature differences deriving by heat transfer processes. Natural convection flows are also designated as "thermogravitational flows". In the case of mixtures, buoyancy forces can also be promoted by concentration gradients.
Free convection effects are directly exploited in a variety of technological applications. A non exhaustive list of examples would include thermal control of electronic devices, natural ventilation and exhaust systems, air distribution in halls, thermal storages, thermosyphon loops, and thin-film-deposition technologies.
Free-convection-based systems are very attractive due to their reliability and low cost. They are free from moving parts, and are automatically activated by the thermal system itself. Their range of application is however limited by low heat transfer coefficients, and difficulties in controlling the transport processes. In fact, buoyancy effects are difficult to improve when heat transfer needs to be increased and impossible to suppress when heat loss reduction is of concern. The efficiency of these processes is also very unpredictable, particularly in confined systems, where the thermal-fluid behaviour of buoyant flows is significantly dependent on geometrical details.
The non dimensional groups relevant to free convection >>>