Scientific work

Scientific achievement by the year 2008 of professor J. Mikielewicz encompass: 185 published works, including 47 individual papers and 138 in collaboration with others.

The topics of his primary interest can be summarised as follows:

  • analysis of new thermodynamic cycles of power plants,
  • heat transfer in heat exchangers using new devices called liquid fins,
  • flow boiling problems and non-isothermal vapour-liquid flows,
  • evaporation in thin liquid films,
  • split of thin liquid films into rivulets, problems of wetting,
  • two-phase vapour-liquid flow stability problems in channels,
  • critical flows of two-phase vapour-liquid mixtures,
  • natural convection in thermosyphons and its application to the "thermal diode",
  • fuel rods flooding during emergency cooling in nuclear reactors,
  • direct contact condensation on a subcooled liquid layer,
  • distribution and heat transfer in single and two-phase impinging jets,
  • analysis of non-conventional devices and systems for energy conversion, and the analysis of solar collectors and their application in domestic conditions in particular.

The work on the problem of a new device intensifying heat transfer, a so called liquid fin, have been awarded by the Technical Sciences Department PAS in 1974. The problems of boiling, two-phase flows, stability of thin liquid films are of fundamental importance in steam generators, nuclear reactors, chemical engineering reactors, refrigeration evaporators as well as in many other technical applications. Developed by him semi-empirical method for calculation of heat transfer coefficients during flow boiling has ben widely acknowledged. It had been published in Int. Journal of Heat and Mass Transfer and widely cited. Another work, regarding the method for determination of the characteristics of pumps operating with the two-phase medium under conditions of the reactor breakdown, where he was the principal contributor (of theoretical concept), developed in USA, also attracted a wide interest of specialists. It was discussed several times and cited. The concept was correct, which has been proved by the experimental investigations. The method was introduced into the calculation codes of reactor breakdown by the Electric Power Institute w USA.

Prof. J. Mikielewicz is also a principal author of a new mathematical model of breakdown of liquid film into rivulets. The correctness of that model has been proved by the experimental investigations conducted within his group and also other authors. The model has been widely cited in the literature. Developed model of wetting, where he is a contributor is characteristic for its novel approach to the phenomenon.

Apart from the works of fundamental character professor J. Mikielewicz was involved in a series of technical applications, amongst the others connected with realisation of experimental two-component power plant of 2MW power contracted by the ZAMECH in Elbląg, which unfortunately could not reach realisation, ammonia turbine using the waste heat (Institute of Artificial Fertilisers in Puławy), reduction of erosion effects in coated blades by steam drying - ZAMECH Elbląg, systems of tank heating in the contemporary tank-ships (Paris Commune Shipyard in Gdynia), expert works for the Marine Technology Centre in Gdańsk.

Subsequently to receiving the title of professor, prof. J. Mikielewicz undertakes with his group new complex and challenging problems such as heat transfer in supercritical pressures, flow boiling crisis, two-phase annular flows with account of mass of separating droplets from the surface of liquid film, heat transfer in the presence of the medium vibration, natural circulation in closed space with application to so called thermal diodes. The results have been mostly published in international journals. During his stay at the Brown University, Providence, USA and after return to Poland he is involved with the problem of two-phase critical flows in channels. As a result of these works developed has been theory of singular points in multi-dimensional space. Other works regarding the fundamentals of two-phase flows are: development of the method of analysis of such flows based on the criteria of thermodynamics of reversible and irreversible processes, analysis of closures of two-phase flow models, flows in branching conduits. Such topics have a fundamental importance in the development of a branch of science known as two-phase flows. In 1986 he was distincted with the Award of the Secretary of PAN for managing and contribution to the work titled Models of phenomena taking place in two-phase flows. He was also involved in the problems of coupled heat transfer (convection and conduction) when solving the problems linked to emergency flooding of fuel rods in the nuclear reactor, direct contact condensation on a subcooled liquid layer and the split and heat transfer of single and two-phase jets impinging on a solid surface. The model of flooding not only enables determination of the liquid front velocity, but also determination of the structure of two-phase flow during flooding. Steam condensation on a liquid layer was solved with an approximate analytical method. In the model included has been a specific turbulence in the vicinity of the phase separation vapour-liquid surface. This has been a novel approach to the problem, which stroke interest amongst many domestic and foreign authors. In his recent works he considers the split and heat transfer in a liquid layer formed by the impingement of a liquid jet or a jet of air with droplets on a solid body. He analyses the shape of the jet on an inclined surface as well as the conditions of the flow transition from supercritical into subcritical state (a hydraulic jump) utilising developed earlier by himself theory of singular points.

A summary of works by prof. J. Mikielewicz on the motion and heat transfer of thin liquid layers flowing on a surface of solids is a co-authored monograph Motion and heat transfer of thin liquid layers published by the Publishing House Fluid-Flow Machinery, vol. 23.

Another area of prof. J. Mikielewicz interest is energy conversion in non-conventional devices and systems, and domestic utilisation of solar energy in particular. In the frame of that problem he developed a series of applications of flat solar collectors in agriculture. In the course of specific applications he had to develop simple, but effective algorithms of thermal calculations of solar collectors under stationary and non-stationary conditions. He is a co-author of a new concept of a collector with absorption of radiative energy in a volume of a semi-transparent bed. His interest in radiative heat transfer borne fruits in several other fundamental works. Amongst the topic connected to energy conversion in non-conventional devices, apart from original fundamental works, prof. J. Mikielewicz is a co-author of a monograph Non-conventional devices and systems for energy conversion published by the Publishing House Fluid-Flow Machinery, vol. 24.

A summary prof. J. Mikielewicz knowledge on the phenomena of mass, momentum and energy transport is a monograph titled Modelling of thermal-hydraulic phenomena, published by the Publishing House Fluid-Flow Machinery, vol. 17, 1995.

Apart from works of fundamental character prof. J. Mikielewicz, after receiving the title of professor, developed together with his group a series of implementations. Amongst others, the following concepts must be mentioned: solar collectors used in agriculture for product drying, soil heating in foil tunnels, water heating in fish-breeding ponds, collectors for sand drying using solar energy for the Tomaszów Mine for Mineral Resources Biała Góra. He received two awards of the Co-ordinator of PR-8 problems together with his group for the contribution to the grand works. To the works on utilisation of solar energy belongs also the development of a solar heating of Mikołajów Tower - a resort of Warsaw Automobilclub. Other application works encompass refinement of a heating-cooling system of an autoclave for Polfa-Starogard, evaluation and modification of heat exchangers and air conditioning units of Klimor - Gdańsk, utilisation of waste heat from the greenhouse furnaces for production of electricity using a freon cycle, development of a production technology and investigations of intensity of heat transfer of rolled tubes for refrigeration and heating purposes. Recently, he developed a theory of steam separators with swirlers for two-phase flows, contracted by ABB Atom from Sweden.

He took part in a series of national and international conferences presenting papers or taking an active part in discussion, amongst the others in former Soviet Union, Great Britain, USA, Romania, Germany, Yugoslavia, Italy. He was invited to present his works in most prominent centres in the world, amongst the others in the former Soviet Union, USA, Great Britain, Germany, France, Canada, Sweden. He reviewed papers to the prominent international journal Multiphase Flow Mag., Int. Journal of Heat and Mass Transfer and many domestic journals, monographs of prominent Polish scientists from the area of thermodynamics and heat transfer, for the Central Qualification Commission for Degrees and Titles and the Polish State for Scientific Research grants. He is the Editor-in-Chief of „Archives of Thermodynamics and the Publishing House of the Institute of Fluid Flow Machinery. At present he is a member of the Central Qualification Commission for Degrees and Titles. In 2000 he was elected to the Editorial Board of a prestigious British journal Nature. In 2001 he received a subsidy for scientists of a Polish Science Foundation.