This page has only limited features, please log in for full access.
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.
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.
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.
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.
This paper concerns the issue of the proper selection of the operating parameters of the fluidised desiccant cooler. Despite the fact that fluidised desiccant cooling technology is being reported in the literature as an efficient way to provide cooling for the purposes of air-conditioning, the improper control of its operation can lead to a significantly worse performance than expected. The objective of the presented theoretical study is to provide guidelines on the proper selection of such operating parameters of a fluidized desiccant cooler, such as superficial air velocity, desiccant particle diameter, bed switching time, and desiccant filling height. The influence of the chosen operating parameters on the performance of fluidised desiccant cooling technology is investigated based on their impact on electric and thermal coefficients of performance (COP) and specific cooling power (SCP). Moreover, the influence of the outlet air temperature, humidity, and desiccant water uptake on the adsorption/desorption characteristics was investigated, contributing to better understanding of sorption processes.
Zbigniew Rogala; Piotr Kolasiński; Przemysław Błasiak. The Influence of Operating Parameters on Adsorption/Desorption Characteristics and Performance of the Fluidised Desiccant Cooler. Energies 2018, 11, 1597 .
AMA StyleZbigniew Rogala, Piotr Kolasiński, Przemysław Błasiak. The Influence of Operating Parameters on Adsorption/Desorption Characteristics and Performance of the Fluidised Desiccant Cooler. Energies. 2018; 11 (6):1597.
Chicago/Turabian StyleZbigniew Rogala; Piotr Kolasiński; Przemysław Błasiak. 2018. "The Influence of Operating Parameters on Adsorption/Desorption Characteristics and Performance of the Fluidised Desiccant Cooler." Energies 11, no. 6: 1597.
Micro-power domestic organic Rankine cycle (ORC) systems are nowadays of great interest. These systems are considered for combined heat and power (CHP) generation in domestic and distributed applications. The main issues of ORC systems design is selection of the expander and the working fluid. Thanks to their positive features, multi-vane expanders are especially promising for application in micro-power ORC systems. These expanders are very simple in design, small in dimensions, inexpensive and feature low gas flow capacity and expansion ratio. The application of multi-vane expanders in ORC systems is innovative and currently limited to prototype applications. However, a literature review indicates the growing interest in these machines and the potential for practical implementation. For this reason, it is necessary to conduct detailed studies on the multi-vane expanders operation in ORC systems. In this paper the results of experimental and numerical investigations on the influence of the applied working fluid and the arrangement of the steering edges on multi-vane expander performance in micro ORC system are reported. The experiments were performed using the specially designed lab test-stand, i.e. the domestic ORC system. Numerical simulations were proceeded in ANSYS CFX software (ANSYS, Inc., Canonsburg, PA, USA) and were focused on determining the expander performance under various flow conditions of different working fluids. Detailed numerical analysis of the arrangement of the machine steering edges showed existence of optimal mutual position of the inlet and outlet port for which the multi-vane expander achieves maximum internal work and internal efficiency.
Józef Rak; Przemysław Błasiak; Piotr Kolasiński. Influence of the Applied Working Fluid and the Arrangement of the Steering Edges on Multi-Vane Expander Performance in Micro ORC System. Energies 2018, 11, 892 .
AMA StyleJózef Rak, Przemysław Błasiak, Piotr Kolasiński. Influence of the Applied Working Fluid and the Arrangement of the Steering Edges on Multi-Vane Expander Performance in Micro ORC System. Energies. 2018; 11 (4):892.
Chicago/Turabian StyleJózef Rak; Przemysław Błasiak; Piotr Kolasiński. 2018. "Influence of the Applied Working Fluid and the Arrangement of the Steering Edges on Multi-Vane Expander Performance in Micro ORC System." Energies 11, no. 4: 892.
Multi-vane expanders are positive displacement volumetric machines which are nowadays considered for application in micro-power domestic ORC systems as promising alternative to micro turbines and other volumetric expanders. The multi-vane expander features very simple design, low gas flow capacity, low expansion ratios, an advantageous ratio of the power output to the external dimensions and are insensitive to the negative influence of the gas-liquid mixture expansion. Moreover, the multi-vane expander can be easily hermetically sealed, which is one of the key issues in the ORC system design. A literature review indicates that issues concerning the application of multi-vane expanders in such systems, especially related to operating of multi-vane expander with different low-boiling working fluids, are innovative, not fully scientifically described and have the potential for practical implementation. In this paper the results of numerical investigations on multi-vane expander operating conditions are presented. The analyses were performed on three-dimensional numerical model of the expander in ANSYS CFX software. The numerical model of the expander was validated using the data obtained from the experiment carried out on a lab test-stand. Then a series of computational analysis were performed using expanders' numerical model in order to determine its operating conditions under various flow conditions of different working fluids.
Józef Rak; Przemysław Błasiak; Piotr Kolasiński. Numerical modelling of multi-vane expander operating conditions in ORC system. E3S Web of Conferences 2017, 22, 142 .
AMA StyleJózef Rak, Przemysław Błasiak, Piotr Kolasiński. Numerical modelling of multi-vane expander operating conditions in ORC system. E3S Web of Conferences. 2017; 22 ():142.
Chicago/Turabian StyleJózef Rak; Przemysław Błasiak; Piotr Kolasiński. 2017. "Numerical modelling of multi-vane expander operating conditions in ORC system." E3S Web of Conferences 22, no. : 142.
Piotr Kolasiński; Przemysław Błasiak; Józef Rak. Experimental investigation on multi-vane expander operating conditions in domestic CHP ORC system. Energy Procedia 2017, 129, 323 -330.
AMA StylePiotr Kolasiński, Przemysław Błasiak, Józef Rak. Experimental investigation on multi-vane expander operating conditions in domestic CHP ORC system. Energy Procedia. 2017; 129 ():323-330.
Chicago/Turabian StylePiotr Kolasiński; Przemysław Błasiak; Józef Rak. 2017. "Experimental investigation on multi-vane expander operating conditions in domestic CHP ORC system." Energy Procedia 129, no. : 323-330.
Gas pressure reduction stations are commonly applied to decrease the pressure of natural gas in the transmission pipelines. In such stations, natural gas is expanded in throttling valves without producing any energy. Through the use of expander in natural gas pressure reduction stations, it is possible to recover the pressure energy of the natural gas during expansion, and drive the electrical generator. Possible solutions include turbines and volumetric expanders. However, turbines are complicated and expensive, while volumetric expanders are simple and cheap. This paper presents an analytical modeling of rolling piston expander work conditions when adopted to natural gas expansion. The main objective of this research was therefore a comprehensive analysis of influence of varied sizes of the expander components and natural gas thermal properties at the inlet and at the outlet of the expander, on the expander output power. The analysis presented in this paper indicates that the rolling piston expander is a good alternative to the turbines proposed for energy recovery in natural gas pressure reduction stations.
Piotr Kolasiński; Michał Pomorski; Przemysław Błasiak; Józef Rak. Use of Rolling Piston Expanders for Energy Regeneration in Natural Gas Pressure Reduction Stations—Selected Thermodynamic Issues. Applied Sciences 2017, 7, 535 .
AMA StylePiotr Kolasiński, Michał Pomorski, Przemysław Błasiak, Józef Rak. Use of Rolling Piston Expanders for Energy Regeneration in Natural Gas Pressure Reduction Stations—Selected Thermodynamic Issues. Applied Sciences. 2017; 7 (6):535.
Chicago/Turabian StylePiotr Kolasiński; Michał Pomorski; Przemysław Błasiak; Józef Rak. 2017. "Use of Rolling Piston Expanders for Energy Regeneration in Natural Gas Pressure Reduction Stations—Selected Thermodynamic Issues." Applied Sciences 7, no. 6: 535.
The paper deals with the research of temperature fields in the proximity of heated pipes arranged above each other in a natural air convection. The holographic interferometry method was used for the visualization of temperature fields. The experiments were made with pipes, diameter of 20 mm, length 200 mm, spacing two-dimensional (2D) at surface temperatures of 40 °C, 50 °C, and 60 °C, with the vertical arrangement of the pipes as well as with the horizontal shift of their centers by 1/4D and 1/2D (on a surface temperature of 50 °C). Temperature profiles were determined from the experimentally obtained images of temperature fields, and local parameters of heat transfer were calculated. Under the same marginal and geometric conditions, computational fluid dynamics (CFD) simulations of temperature fields were performed as well, while the results (temperature fields, local and mean parameters of heat transfer) were also calculated for various distances between the pipe centers (1D, 2D, and 3D). From the obtained experimental results and CFD simulation results, it is possible to observe the impact of the arrangement and spacing of pipes on heat transfer parameters. The achieved results imply the change in the spacing of the pipes has a greater impact on heat transfer parameters in the bundle of heated pipes located above each other than a moderate horizontal shift of their centers.
Jozef Cernecky; Zuzana Brodnianska; Przemyslaw Blasiak; Jan Koniar. The Research of Temperature Fields in the Proximity of a Bundle of Heated Pipes Arranged Above Each Other. Journal of Heat Transfer 2017, 139, 082001 .
AMA StyleJozef Cernecky, Zuzana Brodnianska, Przemyslaw Blasiak, Jan Koniar. The Research of Temperature Fields in the Proximity of a Bundle of Heated Pipes Arranged Above Each Other. Journal of Heat Transfer. 2017; 139 (8):082001.
Chicago/Turabian StyleJozef Cernecky; Zuzana Brodnianska; Przemyslaw Blasiak; Jan Koniar. 2017. "The Research of Temperature Fields in the Proximity of a Bundle of Heated Pipes Arranged Above Each Other." Journal of Heat Transfer 139, no. 8: 082001.
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.
Micro (0.5–10 kW) organic Rankine cycle (ORC) power systems are nowadays considered for domestic power generation. Selection of a suitable expander is one of the most important problems connected with the domestic ORC system design. Volumetric machines or micro-turbines can be adopted as an expander in domestic ORC systems. Scroll and screw expanders are a common choice and were successfully applied in different small- and micro-power applications. However, micro-turbines as well as scroll and screw expanders are mechanically complicated and expensive. An alternative are rotary-vane machines, which are simple and cheap compared to micro-turbines. This paper documents a study providing the experimental and numerical analyses on the rotary vane expander operating conditions in a micro-ORC system. A test-stand was designed and set up and a series of experiments was performed using the test-stand. Results of these experiments were further used as an input to numerical simulations of an expander operation. In order to simulate the expander operating conditions, a three-dimensional numerical model has been prepared. The analysis presented in this paper indicates that a properly designed multi-vane expander is a cheap and mechanically simple alternative to other expansion devices proposed for domestic ORC systems.
Piotr Kolasiński; Przemysław Błasiak; Józef Rak. Experimental and Numerical Analyses on the Rotary Vane Expander Operating Conditions in a Micro Organic Rankine Cycle System. Energies 2016, 9, 606 .
AMA StylePiotr Kolasiński, Przemysław Błasiak, Józef Rak. Experimental and Numerical Analyses on the Rotary Vane Expander Operating Conditions in a Micro Organic Rankine Cycle System. Energies. 2016; 9 (8):606.
Chicago/Turabian StylePiotr Kolasiński; Przemysław Błasiak; Józef Rak. 2016. "Experimental and Numerical Analyses on the Rotary Vane Expander Operating Conditions in a Micro Organic Rankine Cycle System." Energies 9, no. 8: 606.
Przemysław Błasiak; Sławomir Pietrowicz. Towards a better understanding of 2D thermal-flow processes in a scraped surface heat exchanger. International Journal of Heat and Mass Transfer 2016, 98, 240 -256.
AMA StylePrzemysław Błasiak, Sławomir Pietrowicz. Towards a better understanding of 2D thermal-flow processes in a scraped surface heat exchanger. International Journal of Heat and Mass Transfer. 2016; 98 ():240-256.
Chicago/Turabian StylePrzemysław Błasiak; Sławomir Pietrowicz. 2016. "Towards a better understanding of 2D thermal-flow processes in a scraped surface heat exchanger." International Journal of Heat and Mass Transfer 98, no. : 240-256.
In this paper steady state two-dimensional mixed convection heat transfer problem in a lid-driven cavity heated via an uniformly distributed heat flux on the bottom wall is investigated numerically. The lid moves with constant velocity and is kept at low constant temperature, between two ideally thermally insulated vertical walls. A wide range of Prandtl Pr and Richardson Ri number is examined to study their effects on heat transfer rate and fluid flow. Governing parameters are 0.001 ≤ Ri ≤ 1.0 and 0.71 ≤ Pr ≤ 56.00. Grashof number Gr is fixed at 104. The results are presented in the form of isotherms and streamlines plots. Also, local and mean Nusselt number are depicted on charts. Numerical values of the surface averaged Nusselt number are also presented. Results show that increase of Prandtl number strongly influences enhancement of heat transfer rate and that decreasing of Richardson number increases surface averaged Nusselt number. Mechanisms responsible for intensification of heat transfer are identified and physical explanation of this phenomenon are also given.
Przemysław Błasiak; Piotr Kolasinski. Modelling of the mixed convection in a lid-driven cavity with a constant heat flux boundary condition. Heat and Mass Transfer 2015, 52, 595 -609.
AMA StylePrzemysław Błasiak, Piotr Kolasinski. Modelling of the mixed convection in a lid-driven cavity with a constant heat flux boundary condition. Heat and Mass Transfer. 2015; 52 (3):595-609.
Chicago/Turabian StylePrzemysław Błasiak; Piotr Kolasinski. 2015. "Modelling of the mixed convection in a lid-driven cavity with a constant heat flux boundary condition." Heat and Mass Transfer 52, no. 3: 595-609.