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1
Content available Analysis of a possible application of a small power plant in the Organic Rankine Cycle, which apply waste heat from a combustion engine
Żabski J., Gumkowski S.
Eco-Energetics : technologies, environment, law and economy
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2018
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T. 1
127--135
EN
Some considerations on the waste heat treatment, heat and power combined generation and principles of the Organic Rankine Cycle and its application are produced. A thermodynamic screening of eight working fluids for Organic Rankine Cycle (ORC) was carried out. All investigated agents were single component fluids. The considered ORC systems operated at the upper temperature in the range Tmax=146-185°C and the lower one Tmin=27-37°C. The highest pressure in the cycles equalled pmax=3500 kPa and pmin=85 kPa. The cycles were run at subcritical pressures and the saturated vapour line was of the overhanging type in all cases. Heat regeneration was not considered in this paper. The heat source for the ORC system was heated air exhausted from the cooling system of an opposed-piston engine. The temperature of this heat at the inlet to ORC was equal to Th,in=230°C. Air was also the heat sink for the ORC with the inlet temperature Tcold,in=20°C. The power output of the ORC, neglecting electric generator efficiency, was kept in the range N=10-11 kW. Calculated thermal efficiencies h held values between 0.121 and 0.164.
2
Content available Biomass drying: Experimental and numerical investigations
Żabski J., Lampart P., Gumkowski S.
Archives of Thermodynamics
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2018
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Vol. 39, no 1
39--73
EN
Results of experimental and numerical investigations of wood chips drying are described in the paper. Experiments are carried out on two test facilities: a small laboratory rig and a larger pre-prototype dryer. Both facilities are thorough-circulation convective air dryers. The first one is a batch dryer, whereas the second one is a continuous dryer with wood chips flowing down by gravity from a charging hopper to a gutter with the aid of screw-conveyor. The latter is considered a half scale model (preprototype) for professional drying installations. A low feeding rate of wood chips into the pre-prototype dryer makes the process quasi-stationary and the difference between it and a batch drying is negligible. So, most experiments at this facility were carried out as batch dryers with non-agitated packed beds. The investigations exhibit the same linear correlation between the mass of evaporated water from the packed bed and the drying air velocity for both facilities. Numerical analysis of the drying process is conducted using the Ansys Fluent software enriched in drying capabilities by means of self-written procedures – user defined functions. Simulations confirmed a phenomenon of a drying front observed in the small laboratory rig. A thin layer of wood chips comprises the whole heat exchange and moisture evaporation phenomenon. The drying front travels downstream in the course of the process separating the already dried layer and still wet layer.
3
Content available remote Theoretical analysis of heat transfer between a liquid layer formed by an impinging gas liquid jet and a solid surface
Gumkowski S.
Chemical and Process Engineering
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2007
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Vol. 28, z. 2
347-355
EN
Heat transfer phenomenon between a horizontal solid surface and a liquid layer created on a surface by an axisymmetrical liquid gas impinging jet has been analysed. The analytical treatment of the phenomenon is devoted to the area whose diameter is lower than the diameter of the hydraulic jump.
PL
Przedstawiono opis matematyczny zjawiska wymiany ciepła między poziomą stałą powierzchnią a przepływającą po niej warstwą cieczy powstałej z napływającej na powierzchnię osiowo-symetrycznej strugi gazowo-cieczowej. Analiza dotyczy obszaru o średnicy mniejszej od średnicy powstania uskoku hydraulicznego.
4
Content available remote Phenomenon of hydraulic jump formed on liquid layer by single-phase impinging liquid jet
Gumkowski S.
Transactions of the Institute of Fluid-Flow Machinery
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2005
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nr 117
81-90
EN
In the paper theoretical analysis of the phenomenon of impingement of a circular liquid jet upon a plate has been carried out. In the considered case, spreading of the liquid on a plate is caused by the inertia and gravity forces. For supercritical liquid flow, in certain conditions a hydraulic jump is formed. The circular hydraulic jump exhibits behaviour quite different from that commonly observed in planar jets. In the paper a new theoretical model of the phenomena of hydraulic jump has been formulated. Theoretical treatment have been compared with own and other available experimental data.
5
Badania eksperymentalne stabilności cienkich warstw cieczy powstających na płaskiej powierzchni z uderzającej strugi aerozolu
Gumkowski S.
Inżynieria Chemiczna i Procesowa
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2005
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T. 26, z. 1
173-181
PL
Przedstawiono wyniki badań stabilności warstwy cieczy powstającej na powierzchni ciała stałego z uderzającej strugi aerozolu. Dla pewnych parametrów przepływu następuje pękanie warstwy cieczy i płynie ona w postaci strug. Zjawisko pękania powoduje gwałtowne zmniejszenie intensywności wymiany ciepła między cieczą a płytą, po której ciecz przepływa.
EN
The paper is concerned with the stability of liquid layer formed by an axisymmetrical aerosol jet impinging on a flat plate. The experiments carried out yield that under certain flow parameters, liquid layer formed by an aerosol impinging jet on a target flat plate, experiences a breaking down phenomenon and flows in the shape of rivulets. This phenomenon causes a sudden decrease of heat-transfer rates between the liquid and the target plate.
6
Content available remote Distribution of heat generated by a local heat source
Gumkowski S., Gościk J.
Archives of Thermodynamics
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2005
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Vol. 26, no. 4
69-86
EN
In the paper, results of analytical investigations concerning distribution of heat generated by local heat source placed in a solid plate, have been presented. The analysis yields the conclusion that in the considered case, the distribution of heat depends mainly on the heat transfer coefficient between the surface and liquid layer flowing at that surface. As a result the qualitative formula was obtained, which can be helpful for accurate determination of heat transfer coefficient without commonly applied assumption about negligible conductive heat losses in the plate.
7
Content available remote Experimental investigations of hydraulic jump created by a two-phase impinging jet an a solid surface
Gumkowski S.
Transactions of the Institute of Fluid-Flow Machinery
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2003
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nr 112
119-124
EN
In the paper the results of experimental investigations concerning the hydraulic jump formed by an aerosol impinging jet have been presented. Results of carried out experiments yield that aerosol impinging jet enables to form significantly higher diameter of the hydraulic jump, as compared with single phase, liquid impinging jet. This is caused by shear stresses, between liquid layer, formed by liquid deposited from aerosol, and gas, which is the second component of aerosol.
8
Investigations of hydraulic jump configured by a two-phase air-water jet impinging on a flat plate
Gumkowski S.
Inżynieria Chemiczna i Procesowa
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2003
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T. 24, z. 2
183-191
EN
The paper is concerned with the hydraulic jump formed by an axisymmetrical aerosol jet, impinging upon a flat plate. The experiments carried out yield that liquid layer formed by an aerosol impinging jet experiences a hydraulic jump at more far downstream location, comparing with the same layer configured by a single-phase impinging jet. This means that an aerosol jet forms a far larger area, providing high heat -transfer rates.
PL
Przedstawiono wyniki badań eksperymentalnych uskoku hydraulicznego tworzącego się na warstwie cieczy powstającej z osiowosymetrycznej strugi aerozolu uderzającej o powierzchnię ciała stałego. Badania wykazały, że w warunkach eksperymentalnych uskok hydrauliczny tworzy się znacznie dalej od miejsca uderzenia strugi niż na warstwie powstającej z jednofazowej strugi cieczy. Oznacza to, że struga aerozolu tworzy znacznie większy obszar intensywnie chłodzony (lub grzany) przez powstałą warstwę cieczy.
9
Stan obecny i możliwości wykorzystania energii ze źródeł niekonwencjonalnych w warunkach krajowych. Część I
Gumkowski S., Mikielewicz J., Stąsiek J.
Technika Chłodnicza i Klimatyzacyjna
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1998
|
nr 6
232-235
10
Stan obecny i możliwości wykorzystania energii ze źródeł niekonwencjonalnych w warunkach krajowych. Część 2
Gumkowski S., Mikielewicz J., Stąsiek J.
Technika Chłodnicza i Klimatyzacyjna
|
1998
|
nr 9
372-375
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