This page has only limited features, please log in for full access.
Project Goal: The overall aim of this study is a better understanding of dynamic capillary phenomena. A coordinated experiment in microgravity and mathematical model development will result in new flow patterns maps for dynamic capillary flow. Ultimately especially in the application of PHPs, the outcome of the proposed experiment will result in better heat management in space applications like electronic cooling, uniform heat distribution in radiative panels, etc. Every application involving the capillary confinement will contribute from the results of the proposed experiment, e.g. liquid propellant and waste-water management, blood vessels in biomedical studies.
Current Stage: We are currently, after the measurements using the drop tower in Bremen.
Project Goal: Investigation of the centrifugal force effect on the evaporation/condensation processes inside the capillary tube.
Current Stage: The project is already finished.
The scientific and technical issues related to energy harvesting and conversion are inseparably bound to the issues of environmental protection. Energy conversion systems and devices that are applied for converting the chemical energy contained in different fuels into heat, electricity, and cold in industry and housing are sources of different gases and solid particle emissions. Thus, the development of different technologies for energy conversion and environmental protection that can be jointly applied to cover growing energy needs has become a crucial challenge for scientists and engineers around the world. Progress in the precise description, modeling, and optimization of physical and chemical phenomena related to these energy conversion systems is a key research and development field for the economy. Legal and social issues that are affecting key aspects and problems related to the energy conversion and power sector are also significant and worth investigating. The aim of Energy Processes, Systems and Equipment Special Issue is to publish selected high-quality papers from the XV Scientific Conference POL-EMIS 2020: Current Trends in Air and Climate Protection—Control Monitoring, Forecasting, and Reduction of Emissions (29–31 March 2021, Wrocław) and other papers related to the field of energy conversion.
Izabela Sówka; Sławomir Pietrowicz; Piotr Kolasiński. Energy Processes, Systems and Equipment. Energies 2021, 14, 1701 .
AMA StyleIzabela Sówka, Sławomir Pietrowicz, Piotr Kolasiński. Energy Processes, Systems and Equipment. Energies. 2021; 14 (6):1701.
Chicago/Turabian StyleIzabela Sówka; Sławomir Pietrowicz; Piotr Kolasiński. 2021. "Energy Processes, Systems and Equipment." Energies 14, no. 6: 1701.
The article deals with the experimental and numerical thermal-flow behaviours of a low-temperature Phase Change Material (PCM) used in Thermal Energy Storage (TES) industrial applications. The investigated PCM is a composition that consists of a mixture of paraffin wax capsuled in a melamine-formaldehyde membrane and water, for which a phase change process occurs within the temperature range of 4 ∘C to 6 ∘C and the maximum heat storage capacity is equal to 72 kJ/kg. To test the TES capabilities of the PCM for operating conditions close to real ones, a series of experimental tests were performed on cylindrical modules with fixed heights of 250 mm and different outer diameters of 15, 22, and 28 mm, respectively. The module was tested in a specially designed wind tunnel where the Reynolds numbers of between 15,250 to 52,750 were achieved. In addition, a mathematical model of the analysed processes, based on the enthalpy porosity method, was proposed and validated. The temperature changes during the phase transitions that were obtained from the numerical analyses in comparison with the experimental results have not exceeded 20% of the relative error for the phase change region and no more than 10% for the rest. Additionally, the PCM was examined while using a Scanning Electron Microscope (SEM), which indicated no changes in the internal structure during phase transitions and a homogeneous structure, regardless of the tested temperature ranges.
Agnieszka Ochman; Wei-Qin Chen; Przemysław Błasiak; Michał Pomorski; Sławomir Pietrowicz. The Use of Capsuled Paraffin Wax in Low-Temperature Thermal Energy Storage Applications: An Experimental and Numerical Investigation. Energies 2021, 14, 538 .
AMA StyleAgnieszka Ochman, Wei-Qin Chen, Przemysław Błasiak, Michał Pomorski, Sławomir Pietrowicz. The Use of Capsuled Paraffin Wax in Low-Temperature Thermal Energy Storage Applications: An Experimental and Numerical Investigation. Energies. 2021; 14 (3):538.
Chicago/Turabian StyleAgnieszka Ochman; Wei-Qin Chen; Przemysław Błasiak; Michał Pomorski; Sławomir Pietrowicz. 2021. "The Use of Capsuled Paraffin Wax in Low-Temperature Thermal Energy Storage Applications: An Experimental and Numerical Investigation." Energies 14, no. 3: 538.
A special type of oscillating heat pipe in a rotary system of coordinates, called a Flower Shape Oscillating Heat Pipe (FSOHP) was experimentally investigated. The unique rotary experimental set-up consists of 8 horizontal bends located on the bottom (evaporator) and the top (condenser), respectively, which were connected by a 1.1m long vertical quasi-adiabatic section of capillaries with an internal diameter of 2.7mm and filled with de-ionized water. In the performed research various rotational speeds, from 0 to 300rpm and heat loads of between 1.5 and 2.0kW (from 73.8 to 98.4kW/m2) were studied with a different volumetric Filling Ratio (FR) of 50,70 and 80%. The experimental results have shown that a higher temperature amplitude in the rotary system is associated with obtaining the appropriate level of pressure required to cause the slug-plug internal displacement flow, in the direction of from the evaporator to the condenser. This phenomenon directly affects the increase in the flow rate of the Working Fluid (WF). By obtaining Start-Up (SU) conditions, the type of flow pattern changes from oscillatory to directional, always fixed in a clockwise direction. It was found that the heat transport capabilities of the FSOHP improve as the centrifugal acceleration increases up to 5g. In these conditions, the tested device reached a minimum thermal resistance of 0.012°C/W with a heat load of 2kW and FR=70%.
Cezary Czajkowski; Andrzej I. Nowak; Sławomir Pietrowicz. Flower Shape Oscillating Heat Pipe – A novel type of oscillating heat pipe in a rotary system of coordinates – An experimental investigation. Applied Thermal Engineering 2020, 179, 115702 .
AMA StyleCezary Czajkowski, Andrzej I. Nowak, Sławomir Pietrowicz. Flower Shape Oscillating Heat Pipe – A novel type of oscillating heat pipe in a rotary system of coordinates – An experimental investigation. Applied Thermal Engineering. 2020; 179 ():115702.
Chicago/Turabian StyleCezary Czajkowski; Andrzej I. Nowak; Sławomir Pietrowicz. 2020. "Flower Shape Oscillating Heat Pipe – A novel type of oscillating heat pipe in a rotary system of coordinates – An experimental investigation." Applied Thermal Engineering 179, no. : 115702.
The paper analyzes the influence of specific parameters such as scroll vane shape, discharge pressure and the rotational speed of a scroll compressor, on the thermal balance inside of a working chamber with tangential leakages. A two-dimensional numerical model of unsteady flow including leakages between working chambers and a special numerical grid deformation procedure is proposed. The developed set of governing equations of mass conservation, momentum, and energy is solved using the Finite Volume Method. In order to determine the upper limit of the heat transfer between vanes and the working medium - air and carbon dioxide, three cases such as: both vanes are assumed to be adiabatic, on one vane a constant temperature is applied and both vanes held at a constant temperature, are investigated. The average values of the Nusselt number inside a working chamber were elaborated and compared with other relations available in the literature, called the lumped model. It was found that tangential leakages have a high effect on thermal processes. A new relation to the Nusselt number including leakages is proposed. After the introduction of the correction factor, the deviation from the lumped model is reduced to less than 15% compared to the numerical model.
Józef Rak; Sławomir Pietrowicz. Internal flow field and heat transfer investigation inside the working chamber of a scroll compressor. Energy 2020, 202, 117700 .
AMA StyleJózef Rak, Sławomir Pietrowicz. Internal flow field and heat transfer investigation inside the working chamber of a scroll compressor. Energy. 2020; 202 ():117700.
Chicago/Turabian StyleJózef Rak; Sławomir Pietrowicz. 2020. "Internal flow field and heat transfer investigation inside the working chamber of a scroll compressor." Energy 202, no. : 117700.
The paper presents the experimental investigation of a large scale Pulsating Heat Pipe (PHP) operating under high heating power load of up to 2 kW (56 kW/m2). Different Filling Ratios (FR) equal to 25, 50 and 75%, the lengths of the adiabatic Section 500, 750 and 1000 mm, respectively, and types of working fluid such as: acetone, ethanol and water were incorporated. The unique test stand consists of a meandrically arranged capillary tube with 14 bends, and a 2.5 mm internal diameter. The geometry of the PHP’s tube was determined using the Bond criterion and matched to maintain capillary diameter with a wide range of used working fluid properties. For FR values of 50% and 75%, two different flow regimes were observed. It was noticed that at FR=25% even a minimum heat load often causes dry-out phenomena. For the large PHP’s scale, the maximum thermal performances were observed for FR equal to 75%. Further, water was characterized by the lowest value of thermal resistance. For acetone, at the same operational parameters, faster initiation of the pulse process and a lower value of thermal resistance was observed. The experiment indicated that for a specific liquid, the tested length of the adiabatic section does not have a significant influence on the performances. However, the impact of the adiabatic section length differed for different working fluids was recorded.
Cezary Czajkowski; Andrzej I. Nowak; Przemysław Błasiak; Agnieszka Ochman; Sławomir Pietrowicz. Experimental study on a large scale pulsating heat pipe operating at high heat loads, different adiabatic lengths and various filling ratios of acetone, ethanol, and water. Applied Thermal Engineering 2019, 165, 114534 .
AMA StyleCezary Czajkowski, Andrzej I. Nowak, Przemysław Błasiak, Agnieszka Ochman, Sławomir Pietrowicz. Experimental study on a large scale pulsating heat pipe operating at high heat loads, different adiabatic lengths and various filling ratios of acetone, ethanol, and water. Applied Thermal Engineering. 2019; 165 ():114534.
Chicago/Turabian StyleCezary Czajkowski; Andrzej I. Nowak; Przemysław Błasiak; Agnieszka Ochman; Sławomir Pietrowicz. 2019. "Experimental study on a large scale pulsating heat pipe operating at high heat loads, different adiabatic lengths and various filling ratios of acetone, ethanol, and water." Applied Thermal Engineering 165, no. : 114534.
Purpose This paper aims to describe and investigate the mathematical models and numerical modeling of how a cell membrane is affected by a transient ice freezing front combined with the influence of thermal fluctuations and anisotropy. Design/methodology/approach The study consists of mathematical modeling, validation with an analytical solution, and shows the influence of thermal noises on phase front dynamics and how it influences the freezing process of a single red blood cell. The numerical calculation has been modeled in the framework of the phase field method with a Cahn–Hilliard formulation of a free energy functional. Findings The results show an influence scale on directional phase front propagation dynamics and how significant are stochastic thermal noises in micro-scale freezing. Originality/value The numerical calculation has modeled in the framework of the phase field method with a Cahn–Hilliard formulation of a free energy functional.
Przemysław Smakulski; Sławomir Pietrowicz; Jun Ishimoto. The numerical modeling of cell freezing in binary solution under subcooling conditions. International Journal of Numerical Methods for Heat & Fluid Flow 2019, 30, 3005 -3025.
AMA StylePrzemysław Smakulski, Sławomir Pietrowicz, Jun Ishimoto. The numerical modeling of cell freezing in binary solution under subcooling conditions. International Journal of Numerical Methods for Heat & Fluid Flow. 2019; 30 (6):3005-3025.
Chicago/Turabian StylePrzemysław Smakulski; Sławomir Pietrowicz; Jun Ishimoto. 2019. "The numerical modeling of cell freezing in binary solution under subcooling conditions." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 6: 3005-3025.
The work deals with an experimental and numerical analysis on disturbed thermal boundary layer obtained in a heat exchanger by two rotating blades (scrapers). A three-dimensional numerical model of unsteady forced convection in an analyzed device is proposed and taken into consideration. The model allows for the transient nature of the processes occurring in a very efficient in terms of heat transfer the Scraped Surface Heat Exchanger (SSHE) and the impacts on the body forces such as gravity, centrifugal and Coriolis forces on processes. In order to validate the model, a specially constructed experimental test stand was designed and manufactured. The series of experiments for the Reynolds number equal to 1100 and the Nusselt number in the range of 10–25 were performed and compared with numerical results achieving satisfactory agreement, with the error smaller than 5% for temperature and 9% for the heat flux values. The set of governing equations of conservation of mass, momentum, and energy was solved within the framework of the Finite Volume Method (FVM). The movement of the scrapers was incorporated into the model with the use of the Sliding Mesh Method (SMM). The distributions of temperature and velocity were elaborated and scrutinized. It was found that in the analyzed flow regime, the gap width between the stator wall and the scraping blade tip highly affects the Nusselt number. Moreover, the numerical results were compared with other mathematical models available in the literature and the discrepancy between the conventionally used model based on penetration theory was found.
Przemysław Błasiak; Sławomir Pietrowicz. A numerical study on heat transfer enhancement via mechanical aids. International Journal of Heat and Mass Transfer 2019, 140, 203 -215.
AMA StylePrzemysław Błasiak, Sławomir Pietrowicz. A numerical study on heat transfer enhancement via mechanical aids. International Journal of Heat and Mass Transfer. 2019; 140 ():203-215.
Chicago/Turabian StylePrzemysław Błasiak; Sławomir Pietrowicz. 2019. "A numerical study on heat transfer enhancement via mechanical aids." International Journal of Heat and Mass Transfer 140, no. : 203-215.
All the cryogenic systems of large scientific facilities using He II technologies apply the Joule-Thomson expansion for final production of superfluid helium. Their cryogenic plants supply subcooled liquid helium at 4.5 K which is precooled to 2.2 K before throttling to a sub-atmospheric pressure in Joule-Thomson valves. The precooling of the 4.5 K helium can be done in one central heat exchanger or in a number of small heat exchangers located just at the throttling valves. Since there are cons and pros for the both architectures, it is important to take into account all thermodynamics and financial aspects in choosing the best layout in the preliminary design of any new large He II system. The paper presents a comparative thermodynamic analysis of the both cooling schemes in respect to the size of cryogenic distribution systems and heat loads subjected to their components. The analysis is based on calculations of the second-law efficiencies which are preceded by a numerical modelling of temperature and pressure distributions along the process lines.
J Fydrych; Slawomir Pietrowicz. A comparative thermodynamic analysis of helium distribution systems with central and distributed precooling heat exchangers. IOP Conference Series: Materials Science and Engineering 2019, 502, 012173 .
AMA StyleJ Fydrych, Slawomir Pietrowicz. A comparative thermodynamic analysis of helium distribution systems with central and distributed precooling heat exchangers. IOP Conference Series: Materials Science and Engineering. 2019; 502 (1):012173.
Chicago/Turabian StyleJ Fydrych; Slawomir Pietrowicz. 2019. "A comparative thermodynamic analysis of helium distribution systems with central and distributed precooling heat exchangers." IOP Conference Series: Materials Science and Engineering 502, no. 1: 012173.
The work deals with an experimental and theoretical analysis of a special heat exchanger filled with the PCM (Phase Change Material) mixture of paraffin wax capsuled in the melamine-formaldehyde membrane and water, dedicated to low-temperature storage applications. In the first part of the article, the PCM topic was introduced. The next part consists information about the designed and manufactured special heat exchanger with the PCM. During the experiment as a PCM is utilized mixture of paraffin wax in microcapsules within the water. The experimental results of temperature distributions and stored energy in the heat exchanger were compared with the theoretical model proposed in the literature. In the discussion section, the authors describe a new idea of the PCM storage tank application, which could be applied e.g. in nuclear facilities.
Agnieszka Ochman; Sławomir Pietrowicz. The thermal behaviour of a special heat exchanger filled with the phase change material dedicated for low – temperature storage applications. EPJ Web of Conferences 2019, 201, 01003 .
AMA StyleAgnieszka Ochman, Sławomir Pietrowicz. The thermal behaviour of a special heat exchanger filled with the phase change material dedicated for low – temperature storage applications. EPJ Web of Conferences. 2019; 201 ():01003.
Chicago/Turabian StyleAgnieszka Ochman; Sławomir Pietrowicz. 2019. "The thermal behaviour of a special heat exchanger filled with the phase change material dedicated for low – temperature storage applications." EPJ Web of Conferences 201, no. : 01003.
The presented research aims to establish a theoretical framework for the analysis of the transient behaviour of vapour bubbles resulting from superfluid helium boiling under the conditions of microgravity. As long as the volume of a bubble is small in comparison with the volume of a container, the dynamics of the surrounding liquid and interfacial momentum transfer seem to be the dominant factors determining the pace of bubble growth. This notion leads to a relatively clear mathematical description of the system. A pair of 1st order ODEs was formulated on the basis of the mass and momentum conservation principles applied to the liquid phase as well as the assumption of the perfect spherical symmetry of a bubble. In order to obtain the empirical data necessary for the validation of the model, an experimental campaign has been conducted at the ZARM Drop Tower. A dedicated cryostat equipped with optical windows has been utilised in order to achieve superfluidity. The boiling was procured using a 1.88 mm long segment of manganin wire, measuring 50 μm in diameter. The vapour-liquid interface was tracked using a high-speed camera equipped with two separate heads positioned along two perpendicular axes. A reasonable agreement between the model predictions and the empirical data has been observed, indicating the suitability of the framework for the analysis of superfluid helium boiling.
Krzysztof Grunt; Marek Lewkowicz; Sławomir Pietrowicz; Suguru Takada; Nobuhiro Kimura; Masahide Murakami. Dynamics of vapour bubbles induced during the boiling of superfluid helium under microgravity conditions. International Journal of Heat and Mass Transfer 2019, 134, 1073 -1083.
AMA StyleKrzysztof Grunt, Marek Lewkowicz, Sławomir Pietrowicz, Suguru Takada, Nobuhiro Kimura, Masahide Murakami. Dynamics of vapour bubbles induced during the boiling of superfluid helium under microgravity conditions. International Journal of Heat and Mass Transfer. 2019; 134 ():1073-1083.
Chicago/Turabian StyleKrzysztof Grunt; Marek Lewkowicz; Sławomir Pietrowicz; Suguru Takada; Nobuhiro Kimura; Masahide Murakami. 2019. "Dynamics of vapour bubbles induced during the boiling of superfluid helium under microgravity conditions." International Journal of Heat and Mass Transfer 134, no. : 1073-1083.
The influence of thermal fluctuations and anisotropy on the solidification process of a pure component is analyzed. It helps to understand the unstable freezing process where complicated structures such as dendrites could be formed due to a supercooling event reached during the cooling of the biological material. The study consists of mathematical modeling, validation with an analytical solution, and shows the influence of thermal noises on phase front dynamics. The analysis has been modeled in the framework of the Phase Field Method with Cahn-Hilliard formulation of a free energy functional [1]. The phase front is described by the Eulerian approach of fluid fields and formulated as a Phase Field scalar variable (order parameter) with a predefined, diffused boundary thickness. The results describe an influence scale onto directional phase front propagation dynamics, and how significant are stochastic thermal noises in micro-scale freezing.
Przemysław Smakulski; Jun Ishimoto; Sławomir Pietrowicz. Numerical research of solidification dynamics with anisotropy and thermal fluctuations. MATEC Web of Conferences 2018, 240, 05028 .
AMA StylePrzemysław Smakulski, Jun Ishimoto, Sławomir Pietrowicz. Numerical research of solidification dynamics with anisotropy and thermal fluctuations. MATEC Web of Conferences. 2018; 240 ():05028.
Chicago/Turabian StylePrzemysław Smakulski; Jun Ishimoto; Sławomir Pietrowicz. 2018. "Numerical research of solidification dynamics with anisotropy and thermal fluctuations." MATEC Web of Conferences 240, no. : 05028.
A novel idea of heat transfer enhancement using a U-shaped pulsating tube in a rotating system of coordinates is presented and studied in the paper. The analyzed case consists of a U-shaped tube that rotates around the axis of revolution which is perpendicular to the tube axis. Similar to the classical Pulsating Heat Pipe (PHP), it is composed of an evaporation section, located at the ends of the U-tube, and a condenser section located in a tube bend. In the curved section of the tube a liquid slug is surrounded by two vapor plugs. Assuming laminar flow and ideal gas law for the vapor, the governing equations for the pulsating flow in a rotating system of coordinates are derived and non-dimensionalized, finally solved numerically using an explicit scheme. The goal of the analysis was to investigate the influence of the angular velocity and non-dimensional parameters on the thermal performance of the described device. It was found that the centrifugal force generated by rotational motion positively affects the thermal conductivity by increasing the pulsation frequency and decreasing the amplitude of the liquid slug displacement. The proposed buoyancy enhancement method may lead to new solutions during the cooling processes for the moving machinery elements.
Cezary Czajkowski; Przemysław Błasiak; Józef Rak; Sławomir Pietrowicz. The development and thermal analysis of a U-shaped pulsating tube operating in a rotating system of coordinates. International Journal of Thermal Sciences 2018, 132, 645 -662.
AMA StyleCezary Czajkowski, Przemysław Błasiak, Józef Rak, Sławomir Pietrowicz. The development and thermal analysis of a U-shaped pulsating tube operating in a rotating system of coordinates. International Journal of Thermal Sciences. 2018; 132 ():645-662.
Chicago/Turabian StyleCezary Czajkowski; Przemysław Błasiak; Józef Rak; Sławomir Pietrowicz. 2018. "The development and thermal analysis of a U-shaped pulsating tube operating in a rotating system of coordinates." International Journal of Thermal Sciences 132, no. : 645-662.
The experimental and numerical analysis of the standard fume hood features in order to determine the nature of the flow phenomena within the working chamber are presented and studied in the paper. The experiments were carried out for three characteristic heights of the vertical sliding sash, i.e., the lowest (closed), working and the highest (fully opened) heights. The air flow parameters such as: mass flow rate, local distribution of velocity at the exhaust plenum and inlet and pressure drop were measured and analyzed. Assuming isothermal, incompressible and turbulence flow of the air treated as ideal gas, the numerical model based on the continuity and momentum equations was proposed and solved using the Finite Volume Method (FVM). The numerical model was validated against the obtained experimental results. The goal of the numerical simulations was to investigate the flow structure and condition inside the fume hood for different heights of a vertical sliding sash. The obtained numerical results indicated the intensified air recirculation zones within the fume hood chamber and showed the complicated nature of the flow. The conclusions and fume hood design guidelines aimed at reducing the size of the recirculation zones and thus reducing the noise and power needed to drive the exhaust fan were determined. On the basis of the performed calculations four modifications of the fume hood design were proposed and numerically analyzed. Finally, the reduction of the recirculation zones therefore a decrease of pressure drop by 30.5 % was achieved.
Sławomir Pietrowicz; Piotr Kolasiński; Michał Pomorski. Experimental and numerical flow analysis and design optimization of a fume hood using the CFD method. Chemical Engineering Research and Design 2018, 132, 627 -643.
AMA StyleSławomir Pietrowicz, Piotr Kolasiński, Michał Pomorski. Experimental and numerical flow analysis and design optimization of a fume hood using the CFD method. Chemical Engineering Research and Design. 2018; 132 ():627-643.
Chicago/Turabian StyleSławomir Pietrowicz; Piotr Kolasiński; Michał Pomorski. 2018. "Experimental and numerical flow analysis and design optimization of a fume hood using the CFD method." Chemical Engineering Research and Design 132, no. : 627-643.
Suguru Takada; Nobuhiro Kimura; Slawomir Pietrowicz; Krzysztof Grunt; Masahide Murakami; Takahiro Okamura. Visualization of He II boiling process under the microgravity condition for 4.7 s by using a drop tower experiment. Cryogenics 2018, 89, 157 -162.
AMA StyleSuguru Takada, Nobuhiro Kimura, Slawomir Pietrowicz, Krzysztof Grunt, Masahide Murakami, Takahiro Okamura. Visualization of He II boiling process under the microgravity condition for 4.7 s by using a drop tower experiment. Cryogenics. 2018; 89 ():157-162.
Chicago/Turabian StyleSuguru Takada; Nobuhiro Kimura; Slawomir Pietrowicz; Krzysztof Grunt; Masahide Murakami; Takahiro Okamura. 2018. "Visualization of He II boiling process under the microgravity condition for 4.7 s by using a drop tower experiment." Cryogenics 89, no. : 157-162.
The cryogenic systems of large scientific facilities using superfluid helium technologies include a cold helium circuit composed of a subcooled liquid helium supply line and a low-pressure return line. Due to long distances between the cryogenic plant and cryogenic users the line lengths can reach hundreds or even thousands of meters. Usually the low-pressure return line is a large size pipe, which inner diameter can exceed 300 mm. In some cases the accelerators and also the cold helium circuit lines are sloped. In some transient modes there is a risk of a counter flow in the low-pressure return line. This counter flow phenomenon can be driven mainly by free convection and it can disturb the cool down dynamics or affect the performance characteristic of some cryogenic devices, which are sensitive to cool down rates. This paper presents a numerical analysis of free convection in cold helium vapor flows in a long straight and sloped line. The methodology of numerical modeling of the thermo-hydraulic phenomena is described in detail. The results of the numerical simulations performed for various pipe lengths, slopes and mass flow rates are compiled and discussed.
J Fydrych; Slawomir Pietrowicz. Numerical analysis of free convection in cold helium vapor flows in a long sloped pipe. IOP Conference Series: Materials Science and Engineering 2017, 278, 012058 .
AMA StyleJ Fydrych, Slawomir Pietrowicz. Numerical analysis of free convection in cold helium vapor flows in a long sloped pipe. IOP Conference Series: Materials Science and Engineering. 2017; 278 (1):012058.
Chicago/Turabian StyleJ Fydrych; Slawomir Pietrowicz. 2017. "Numerical analysis of free convection in cold helium vapor flows in a long sloped pipe." IOP Conference Series: Materials Science and Engineering 278, no. 1: 012058.
An experiment regarding boiling of superfluid helium (He II) has been carried out under conditions of microgravity, in order to investigate the dynamics of the phase transition. A small cryostat equipped with visualization setup has been utilized for this purpose. Presence of two orthogonal optical axes allowed for registering of 3-dimensional images of a vapor bubble induced by a micro heater. Microgravity environment has been produced for about 4.7 s using the 122 m high drop tower facility at ZARM (Center of Applied Space Technology and Microgravity), University of Bremen, Germany. The experimental campaign consisting of 32 drops has been successfully conducted, while avoiding any damage to the equipment.
S Takada; N Kimura; Slawomir Pietrowicz; K Grunt. The first results of He II boiling visualization experiment conducted under 4.7 seconds microgravity conditions. Journal of Physics: Conference Series 2017, 897, 012013 .
AMA StyleS Takada, N Kimura, Slawomir Pietrowicz, K Grunt. The first results of He II boiling visualization experiment conducted under 4.7 seconds microgravity conditions. Journal of Physics: Conference Series. 2017; 897 (1):012013.
Chicago/Turabian StyleS Takada; N Kimura; Slawomir Pietrowicz; K Grunt. 2017. "The first results of He II boiling visualization experiment conducted under 4.7 seconds microgravity conditions." Journal of Physics: Conference Series 897, no. 1: 012013.
Przemysław Błasiak; Sławomir Pietrowicz. An experimental study on the heat transfer performance in a batch scraped surface heat exchanger under a turbulent flow regime. International Journal of Heat and Mass Transfer 2017, 107, 379 -390.
AMA StylePrzemysław Błasiak, Sławomir Pietrowicz. An experimental study on the heat transfer performance in a batch scraped surface heat exchanger under a turbulent flow regime. International Journal of Heat and Mass Transfer. 2017; 107 ():379-390.
Chicago/Turabian StylePrzemysław Błasiak; Sławomir Pietrowicz. 2017. "An experimental study on the heat transfer performance in a batch scraped surface heat exchanger under a turbulent flow regime." International Journal of Heat and Mass Transfer 107, no. : 379-390.
In last decades the technology of superfluid helium has become very advantageous for large-scale scientific facilities dedicated to high-energy physics. Superconducting cavities or magnets are usually immersed in helium baths at a temperature of 1.8 to 2.0 K. This temperature is produced by a JT cycle where the return line works at a subatmospheric pressure of 16 to 31 mbar. The subatmospheric line lengths can reach even several thousand meters. The helium flows in the subatmospheric lines are driven by cold compressors or vacuum pumps. Due to a limited pressure drop requirement the line diameters can exceed even 300 mm. Since the thermal conductivity of the line material is very small and the flow rate at some operation conditions can be much lower than at the normal operating conditions, a thermal stratification in the helium flow can appear together with a significant temperature gradient along the pipe circumference. These phenomena can affect the thermo-hydraulic behaviour of the line as well as the operation of the entire cryogenic system. The paper presents the numerical simulations of cold helium vapour flows in a long straight line. The stratification phenomenon is discussed and the potential temperature gradient in the pipe wall is evaluated.
J Fydrych; Slawomir Pietrowicz. Numerical analysis of temperature stratification in a subatmospheric cold helium line. IOP Conference Series: Materials Science and Engineering 2017, 171, 012023 .
AMA StyleJ Fydrych, Slawomir Pietrowicz. Numerical analysis of temperature stratification in a subatmospheric cold helium line. IOP Conference Series: Materials Science and Engineering. 2017; 171 (1):012023.
Chicago/Turabian StyleJ Fydrych; Slawomir Pietrowicz. 2017. "Numerical analysis of temperature stratification in a subatmospheric cold helium line." IOP Conference Series: Materials Science and Engineering 171, no. 1: 012023.