Utwór w całości ani we fragmentach nie może być powielany ani rozpowszechniany za pomocą urządzeń... more Utwór w całości ani we fragmentach nie może być powielany ani rozpowszechniany za pomocą urządzeń elektronicznych, mechanicznych, kopiujących, nagrywających i innych, w tym również nie może być umieszczany ani rozpowszechniany w postaci cyfrowej zarówno w Internecie, jak i w sieciach lokalnych bez pisemnej zgody posiadacza praw autorskich. 4.
Abstract The small physical size of electronic equipment, space limitation for installing air-coo... more Abstract The small physical size of electronic equipment, space limitation for installing air-cooling systems and high heat flux produced from a single chip have attracted a great deal of interest in more efficient heat dissipation equipment such as high-performance liquid cooling systems and mini-rectangular fin heat sinks. In this study, the influence of nanofluids on the performance of heat sink for CPU cooling is investigated experimentally and numerically. The former is carried out for water and nanofluid CuO-water at two solid concentrations of 0.86 and 2.25 vol.%. While in the latter, numerical simulations are validated for the laminar flow model with the application of the commercial package ANSYS Fluent 13. For the investigated range of mass flow rate and heat load (115 and 130 W), up to 7.7% of thermal conductance improvement is observed in case of nanofluids in comparison to water. The results of this study pave the way for more credible designs of cooling systems of electronic devices to promote a high-performance and longer life cycle.
Four samples of com. soda ash were studied for bulk d., grain size distribution and flowability a... more Four samples of com. soda ash were studied for bulk d., grain size distribution and flowability at varying air humidity and moisture content. The flowability index decreased with the increasing moisture content in the soda ash grains. Przedstawiono wyniki badań wpływu wilgoci na sypkość surowca w produkcji detergentów. Po-miarów dokonano, wykorzystując urządzenie opracowane w Katedrze Inżynierii Chemicznej i Projektowania Procesowego Politechniki Ślą-skiej w Gliwicach. W wyniku przeprowadzonych badań stwierdzono silny wpływ wilgoci na obni-żenie sypkości materiału, co może być przyczyną zawieszania się sody w zbiornikach dozujących. Sypkość jest parametrem trudno definiowalnym z inżynierskiego punktu widzenia. Najczęściej przez analogię do płynów, a zwłaszcza cieczy, sypkość jest rozumiana jako zdolność materiałów ziarnistych do płynięcia. Sypkość jest właściwością materiałów ziarnistych, która zależy zarówno od natury samego materiału, jak i od warunków oto-czenia, produkcji i spos...
Abstract In this study, a commercial heat sink was employed for cooling a PC processor. Two liqui... more Abstract In this study, a commercial heat sink was employed for cooling a PC processor. Two liquids were used (i) water and (ii) copper oxide (II) nanofluids with 0.0086 and 0.0225 volume fractions. In the experiments, the heat sink was fixed to the CPU. The maximal power dissipated by the investigated processor was 115 W. The mass flow rate of the liquids was in the range of 0.009 to 0.05 kg/s and the inlet temperature was in the range of 300 to 305 K. The experimental results were used to validate the numerical model of the analyzed system. The commercial package ANSYS Fluent 13 was employed to generate a CFD heat transfer simulation. A laminar flow regime was proposed in a fin array area of the heat sink. An appropriate grid quality model was developed and validated. The obtained results showed that water was sufficient enough for CPU cooling.
This article presents a bi-variant dynamic model of continuous mixed-suspension, mixed-product-re... more This article presents a bi-variant dynamic model of continuous mixed-suspension, mixed-product-removal (MSMPR) precipitation with agglomeration (aggregation and disruption) using the dual particle coordinate (agglomerate size and primary crystal number) population balance approach. Several finite difference methods were first examined for numerical solution of simplified model equations. The implicit forward time central space (FTCS j+ 1) was selected as the best for prediction of dynamic particle size distribution (PSD) and then applied to the agglomerative case. For specific values of aggregation and disruption coefficients, K I and Ko, bimodal distributions are observed and the system can also exhibit unstable dynamics. It is also predicted, however, that a supersaturation dependence of aggregation efficiency together with crystal disruption can stabilize the system transient response.
In order to help answer the question can particle disruption occur during agglomerative precipita... more In order to help answer the question can particle disruption occur during agglomerative precipitation of calcium carbonate and give rise to PSD (particle size distribution) bimodality? we report explicit experimental evidence of an attrition process for crystal agglomerates. To avoid the complications of crystal growth, nucleation and aggregation we use inert solutions at zero supersaturation for which, from the results of Wojcik and Jones (1997), aggregation should be at a minimum whilst attrition is at a maximum. Hydrodynamic conditions are comparable to those used in previous experimental precipitation studies. Particle aggregation and disruption rates are inferred from an analysis of the attrition data using an aggregation-disruption population model. These are then compared with those reported from precipitation studies (Wojcik and Jones, 1997) and crystal attrition experiments (Synowiec et al., 1993).
Chemical Engineering and Processing: Process Intensification, 2013
Fluidized-bed crystallizers are widely utilized across numerous branches of industry. However, th... more Fluidized-bed crystallizers are widely utilized across numerous branches of industry. However, they have proven difficult to scale up. The present work reports the scale-up of an Oslo fluidized-bed crystallizer with a classification leg using computational fluid dynamic (CFD) methods. The apparatus was modeled in six volumes: 0.039, 0.33, 2.64, 29, 97, and 230 m 3. Calculations cover polydispersive suspension of NaCl crystals with the initial concentration equal to 10 vol.%. Ten size classes of the crystal diameter were assumed, varying from 0.4 to 3 mm. Simulations were run using the commercial package Fluent. To model two-phase flow, an Eulerian multiphase model was used with the standard k-ε method. The chosen scale-up factor was the outlet liquor velocity. Results are compared with industrial data.
Chemical Engineering and Processing: Process Intensification, 2009
This article presents modeling of fluidized-bed crystallizers with use of the multiphase CFD meth... more This article presents modeling of fluidized-bed crystallizers with use of the multiphase CFD method for the first time. There are substantial differences in predictions of the model and one-phase simulations.
Natural gas, biogas, and refinery gas all include H2S, which has adverse effects not only on the ... more Natural gas, biogas, and refinery gas all include H2S, which has adverse effects not only on the environment and human health but also on the equipment and catalysts that are employed in the relevant processes. H2S is removed from the aforementioned gases using a variety of techniques in order to fulfill the necessary sales criteria and for reasons of safety. The adsorption method stands out among various other approaches due to its straightforward operation, high level of efficiency, and low overall cost. This technique makes use of a variety of adsorbents, such as metal-organic frameworks (MOFs), activated carbon, and zeolites. The use of zeolite-based adsorbents is by far the most common of these various types. This is due to the specific properties of zeolite-based adsorbents, which include a high adsorption capacity, the ability to be regenerated, a high temperature stability, a diversity of types, the possibility of modification, high efficiency, and low cost. In addition, res...
Seventh International Conference on CFD in the Minerals and Process Industries CSIRO, Melbourne, ... more Seventh International Conference on CFD in the Minerals and Process Industries CSIRO, Melbourne, Australia 9-11 December 2009 ... CFD SIMULATION OF A CONICAL-CYLINDRICAL CRYSTALLIZATION UNIT USING MULTI-PHASE EULERIAN MODEL
The precise control of crystallization is a key issue in providing a high quality crystalline pro... more The precise control of crystallization is a key issue in providing a high quality crystalline product. It has to be achieved by, among other means, a proper choice of the solution processing temperature, which is determined on the basis of the metastable zone width and type of solubility curve. In this article experimental data for potassium chloride solution density, as a function of temperature and its correlation in the range from under-to supersaturation, are reported for solution concentrations between 24.62 % w/w and 31.84 % w/w. As could be expected in the case of undersaturated solutions and low supersaturation, the temperature dependence of density for solutions of different saturation may be described by a linear equation within the investigated range of concentrations. It was also proved that for the undersaturation range there exists a pole point, which allows calculation of the saturation temperature, based on the density measured at any temperature.
Utwór w całości ani we fragmentach nie może być powielany ani rozpowszechniany za pomocą urządzeń... more Utwór w całości ani we fragmentach nie może być powielany ani rozpowszechniany za pomocą urządzeń elektronicznych, mechanicznych, kopiujących, nagrywających i innych, w tym również nie może być umieszczany ani rozpowszechniany w postaci cyfrowej zarówno w Internecie, jak i w sieciach lokalnych bez pisemnej zgody posiadacza praw autorskich. 4.
Abstract The small physical size of electronic equipment, space limitation for installing air-coo... more Abstract The small physical size of electronic equipment, space limitation for installing air-cooling systems and high heat flux produced from a single chip have attracted a great deal of interest in more efficient heat dissipation equipment such as high-performance liquid cooling systems and mini-rectangular fin heat sinks. In this study, the influence of nanofluids on the performance of heat sink for CPU cooling is investigated experimentally and numerically. The former is carried out for water and nanofluid CuO-water at two solid concentrations of 0.86 and 2.25 vol.%. While in the latter, numerical simulations are validated for the laminar flow model with the application of the commercial package ANSYS Fluent 13. For the investigated range of mass flow rate and heat load (115 and 130 W), up to 7.7% of thermal conductance improvement is observed in case of nanofluids in comparison to water. The results of this study pave the way for more credible designs of cooling systems of electronic devices to promote a high-performance and longer life cycle.
Four samples of com. soda ash were studied for bulk d., grain size distribution and flowability a... more Four samples of com. soda ash were studied for bulk d., grain size distribution and flowability at varying air humidity and moisture content. The flowability index decreased with the increasing moisture content in the soda ash grains. Przedstawiono wyniki badań wpływu wilgoci na sypkość surowca w produkcji detergentów. Po-miarów dokonano, wykorzystując urządzenie opracowane w Katedrze Inżynierii Chemicznej i Projektowania Procesowego Politechniki Ślą-skiej w Gliwicach. W wyniku przeprowadzonych badań stwierdzono silny wpływ wilgoci na obni-żenie sypkości materiału, co może być przyczyną zawieszania się sody w zbiornikach dozujących. Sypkość jest parametrem trudno definiowalnym z inżynierskiego punktu widzenia. Najczęściej przez analogię do płynów, a zwłaszcza cieczy, sypkość jest rozumiana jako zdolność materiałów ziarnistych do płynięcia. Sypkość jest właściwością materiałów ziarnistych, która zależy zarówno od natury samego materiału, jak i od warunków oto-czenia, produkcji i spos...
Abstract In this study, a commercial heat sink was employed for cooling a PC processor. Two liqui... more Abstract In this study, a commercial heat sink was employed for cooling a PC processor. Two liquids were used (i) water and (ii) copper oxide (II) nanofluids with 0.0086 and 0.0225 volume fractions. In the experiments, the heat sink was fixed to the CPU. The maximal power dissipated by the investigated processor was 115 W. The mass flow rate of the liquids was in the range of 0.009 to 0.05 kg/s and the inlet temperature was in the range of 300 to 305 K. The experimental results were used to validate the numerical model of the analyzed system. The commercial package ANSYS Fluent 13 was employed to generate a CFD heat transfer simulation. A laminar flow regime was proposed in a fin array area of the heat sink. An appropriate grid quality model was developed and validated. The obtained results showed that water was sufficient enough for CPU cooling.
This article presents a bi-variant dynamic model of continuous mixed-suspension, mixed-product-re... more This article presents a bi-variant dynamic model of continuous mixed-suspension, mixed-product-removal (MSMPR) precipitation with agglomeration (aggregation and disruption) using the dual particle coordinate (agglomerate size and primary crystal number) population balance approach. Several finite difference methods were first examined for numerical solution of simplified model equations. The implicit forward time central space (FTCS j+ 1) was selected as the best for prediction of dynamic particle size distribution (PSD) and then applied to the agglomerative case. For specific values of aggregation and disruption coefficients, K I and Ko, bimodal distributions are observed and the system can also exhibit unstable dynamics. It is also predicted, however, that a supersaturation dependence of aggregation efficiency together with crystal disruption can stabilize the system transient response.
In order to help answer the question can particle disruption occur during agglomerative precipita... more In order to help answer the question can particle disruption occur during agglomerative precipitation of calcium carbonate and give rise to PSD (particle size distribution) bimodality? we report explicit experimental evidence of an attrition process for crystal agglomerates. To avoid the complications of crystal growth, nucleation and aggregation we use inert solutions at zero supersaturation for which, from the results of Wojcik and Jones (1997), aggregation should be at a minimum whilst attrition is at a maximum. Hydrodynamic conditions are comparable to those used in previous experimental precipitation studies. Particle aggregation and disruption rates are inferred from an analysis of the attrition data using an aggregation-disruption population model. These are then compared with those reported from precipitation studies (Wojcik and Jones, 1997) and crystal attrition experiments (Synowiec et al., 1993).
Chemical Engineering and Processing: Process Intensification, 2013
Fluidized-bed crystallizers are widely utilized across numerous branches of industry. However, th... more Fluidized-bed crystallizers are widely utilized across numerous branches of industry. However, they have proven difficult to scale up. The present work reports the scale-up of an Oslo fluidized-bed crystallizer with a classification leg using computational fluid dynamic (CFD) methods. The apparatus was modeled in six volumes: 0.039, 0.33, 2.64, 29, 97, and 230 m 3. Calculations cover polydispersive suspension of NaCl crystals with the initial concentration equal to 10 vol.%. Ten size classes of the crystal diameter were assumed, varying from 0.4 to 3 mm. Simulations were run using the commercial package Fluent. To model two-phase flow, an Eulerian multiphase model was used with the standard k-ε method. The chosen scale-up factor was the outlet liquor velocity. Results are compared with industrial data.
Chemical Engineering and Processing: Process Intensification, 2009
This article presents modeling of fluidized-bed crystallizers with use of the multiphase CFD meth... more This article presents modeling of fluidized-bed crystallizers with use of the multiphase CFD method for the first time. There are substantial differences in predictions of the model and one-phase simulations.
Natural gas, biogas, and refinery gas all include H2S, which has adverse effects not only on the ... more Natural gas, biogas, and refinery gas all include H2S, which has adverse effects not only on the environment and human health but also on the equipment and catalysts that are employed in the relevant processes. H2S is removed from the aforementioned gases using a variety of techniques in order to fulfill the necessary sales criteria and for reasons of safety. The adsorption method stands out among various other approaches due to its straightforward operation, high level of efficiency, and low overall cost. This technique makes use of a variety of adsorbents, such as metal-organic frameworks (MOFs), activated carbon, and zeolites. The use of zeolite-based adsorbents is by far the most common of these various types. This is due to the specific properties of zeolite-based adsorbents, which include a high adsorption capacity, the ability to be regenerated, a high temperature stability, a diversity of types, the possibility of modification, high efficiency, and low cost. In addition, res...
Seventh International Conference on CFD in the Minerals and Process Industries CSIRO, Melbourne, ... more Seventh International Conference on CFD in the Minerals and Process Industries CSIRO, Melbourne, Australia 9-11 December 2009 ... CFD SIMULATION OF A CONICAL-CYLINDRICAL CRYSTALLIZATION UNIT USING MULTI-PHASE EULERIAN MODEL
The precise control of crystallization is a key issue in providing a high quality crystalline pro... more The precise control of crystallization is a key issue in providing a high quality crystalline product. It has to be achieved by, among other means, a proper choice of the solution processing temperature, which is determined on the basis of the metastable zone width and type of solubility curve. In this article experimental data for potassium chloride solution density, as a function of temperature and its correlation in the range from under-to supersaturation, are reported for solution concentrations between 24.62 % w/w and 31.84 % w/w. As could be expected in the case of undersaturated solutions and low supersaturation, the temperature dependence of density for solutions of different saturation may be described by a linear equation within the investigated range of concentrations. It was also proved that for the undersaturation range there exists a pole point, which allows calculation of the saturation temperature, based on the density measured at any temperature.
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Papers by Janusz Wójcik