Vladimir Glazar | Technical University in Rijeka (original) (raw)

Papers by Vladimir Glazar

Sustainability

This article presents the performance analysis of a 700 MW future planned advanced ultra-supercri... more This article presents the performance analysis of a 700 MW future planned advanced ultra-supercritical (A-USC) coal-fired power plant fitted with post-combustion carbon capture and storage (CCS) technology. The reference A-USC unit without CCS achieves a net efficiency of 47.6% with CO2 emissions of 700 kgCO2/MWh. Relatively to subcritical units, the net efficiency of the A-USC is 8%-pts higher while CO2 emissions are 16.5% lower. For a CO2 removal rate of 90%, the net efficiency of the CCS integrated A-USC unit is 36.8%. The resulting net efficiency loss is 10.8%-pts and the electricity output penalty is 362.3 kWhel/tCO2 for present state CCS technology. The study continues with the assessment of interface quantities between the capture unit and the steam cycle affecting the performance of the A-USC. Improved CO2 absorbents could alleviate the net efficiency loss by 2–3%-pts, and enhanced CO2 compression strategies and advanced heat integration could further reduce the efficiency l...

Engineering Review, Jul 23, 2010

Sažetak: U radu je naprezanje u korijenu zuba zupčanika izračunato pomoću numeričke metode 2D MKE... more Sažetak: U radu je naprezanje u korijenu zuba zupčanika izračunato pomoću numeričke metode 2D MKE (dvodimenzijska metoda konačnih elemenata) i u skladu s dvjema analitičkim metodama koje su obuhvatile proračun naprezanja prema metodi B, opisanoj u normi ISO 6336-3 i njezin modificirani oblik, metodu MAX. Da bi se vrjednovao faktor debljine vijenca kojim se prema metodi B norme ISO uzima u obzir utjecaj debljine vijenca na nazivno naprezanje u korijenu zuba, naprezanje u korijenu zuba cilindričnog zupčanika s vanjskim ozubljenjem ravnim zubima određeno je krećući od punog zupčanika prema zupčaniku s tankim vijencem, uzimajući pri tome u obzir zupčanik s različitim brojem zubi. Ključne riječi:-naprezanje-korijen zuba-tanki vijenac-ISO Summary: In this work the gear tooth root stress was calculated by means of numerical method 2D FEM (twodimensional Finite Element Method) and according to two analytical methods, that included the stress calculation method B of standard ISO 6336-3 and its modified form-method MAX. In order to evaluate the rim thickness factor introduced by the method B of standard ISO that takes into account the influence of rim thickness on nominal tooth root stress, the stress at a spur tooth root of cylindrical external gearing was determined going from solid towards thin rimmed gear, and considering the gear with various number of teeth.

E3S Web of Conferences, 2019

This paper presents numerical analysis of fluid flow and heat transfer in the heat exchanger with... more This paper presents numerical analysis of fluid flow and heat transfer in the heat exchanger with microchannel coil (MCHX). In accordance with previously published experimental results, 3D mathematical model has been defined and appropriate numerical simulation of heat transfer has been performed. Geometry and working parameters of cross-flow air-water heat exchanger with microchannel coil, installed in an open circuit wind tunnel and used in experimental investigations, have been applied in numerical analysis in order to validate the mathematical model. 3D model with air and water fluid flow and heat transfer domains has been used, as it gives more precise results compared to models that assume constant temperatures or constant heat fluxes on the pipe walls. Developed model comprised full length of air and water flows in the heat exchanger. Due to limitations of computational capacity, domain has been divided in multiple computational blocks in the water flow direction and then solved successively using CFD solver Fluent. Good agreement between experimentally measured and numerically calculated results has been obtained. The influence of various working parameters on heat transfer in air-water heat exchanger has been studied numerically, followed with discussion and final conclusions.

International Journal of Refrigeration, 2015

Experimental and numerical analysis of heat transfer and fluid flow in the compact heat exchanger... more Experimental and numerical analysis of heat transfer and fluid flow in the compact heat exchanger has been done in this paper. In an open circuit wind tunnel, developed on purpose for this investigation, the measurement of working media temperatures and mass flow rates for heat exchanger with microchannel coil has been accomplished. In accordance with the heat exchangers used for experiments, numerical 3D simulation of adequate geometry shapes has been done. With utilization of air/water side numerical simulation, more detailed results have been achieved in relation to the simulation that assumes constant temperature or constant heat flux on the pipe wall. Good agreement between experimentally measured and numerically calculated results has been accomplished. The influence of different microchannel shapes on heat transfer effectiveness and pressure drop has been studied numerically. Comparison of results has been made accompanied by the discussion and final conclusions.

Journal of Energy Storage, 2020

In this paper a number of numerical simulations were performed to determine the geometry and the ... more In this paper a number of numerical simulations were performed to determine the geometry and the process parameters influence on the large volumetric heat storage tank radial plate diffuser pressure drop. The tank is used in district heating systems. To reduce the possibility of a pressure drop in the diffuser below the water saturation pressure, three basic diffuser types were tested sharpe edge joint (SEJ), conical element (COE) and curved element (CUE). The analysis shows the differences and similarities between the diffuser types and their influence on the static and total diffuser pressure drop. The geometric similarity of the hermetic compressor radial valve with heat storage tank radial plate diffuser was used to validate the numerical model. The numerical calculation results were compared with the experimental measurements of the air pressure drop on the radial valves front plate taken from the literature. Good correlation between the calculation results and experimental measurements has been achieved. Along with mentioned, the diffuser model similarity effect is also presented and analyzed. The obtained results showed that, the static pressure drop remains the same for different diffuser sizes, when the geometric similarity of the diffuser is preserved.

Journal of Energy Storage, 2020

Energy, 2020

This paper presents various numerical analyses of two-dimensional temperature and velocity fields... more This paper presents various numerical analyses of two-dimensional temperature and velocity fields in vertical cylindrical large volumetric heat storage tanks used in municipal heating applications. Numerical simulations were performed in order to investigate the shape impact of the heat storage tank (height-to-diameter ratio), the diffuser distance from the top of the tank, temperature difference between the warm and cold water and the volume flow variation on temperature stratification in the tank. The accuracy and precision of the numerical model was verified by comparing the numerical calculation results with the measurement results from the literature. An empirical model for the calculation of the tank wall (mantle) insulation thickness with maximum constant temperature inside the tank was also developed. The effect of reducing the insulation thickness and changing the seasons on quality of the temperature stratification and thermal losses through the tank insulation were analyzed. The financial analysis justified the possible reduction of the insulation thickness, and more flexible investment in the plant is presented.

International Journal of Heat and Mass Transfer, 2020

Multivariate optimization of the air-water heat exchanger with microchannel coil has been present... more Multivariate optimization of the air-water heat exchanger with microchannel coil has been presented in this paper. The effects of four geometry parameters, i.e. fin pitch, microchannel flat tube transversal row pitch, number of small channels and partition wall thickness, on heat transfer rate per volume and mass, pressure drops on air and water side, heat transfer efficiency and rate of compactness have been examined using the Response Surface Methodology. Data set, composed of 27 different geometry models, has been prescribed using Box-Behnken design method. Experimentally validated, 3D mathematical model and numerical procedure have been used for numerical simulations. Fluid flow and heat transfer simulations have been performed using CFD solver FLUENT. Numerical results have been employed to calculate the objective function responses. Obtained contour plots of the objective functions have been shown for various setups. According to objective function results, nonlinear regression models (polynomial functions) have been derived and the Genetic Algorithm has been used to obtain optimal setup. The comparison of results has been given, followed by discussion and conclusions.

Spatial ability has been confirmed to be of particular importance for successful engineering grap... more Spatial ability has been confirmed to be of particular importance for successful engineering graphics education and to be a component of human intelligence that can be improved through instruction and training. Consequently, the creation and communication by means of graphics demand careful development of spatial skills provided by the balanced curricula based on the research results in multi disciplinary area. The approach to engineering graphics education had been transformed to meet spatial skills improvement even before significant and fast changes arose from the development of computer technology enabling the engineer powerful tools and techniques. The correlation and interference between new technologies widely introduced in engineering graphics education and spatial ability/skills, have initiated new studies to establish the basis of holistic engineering graphics education. This paper presents the overview of some efforts and possible answers resulting from intensive research into spatial ability and skills and their implementation in the conception of graphics education in engineering environment.

Experimental and numerical analysis of heat transfer and fluid flow in the compact heat exchanger... more Experimental and numerical analysis of heat transfer and fluid flow in the compact heat exchanger has been done in this paper. In an open circuit wind tunnel, developed on purpose for this investigation, the measurement of working media temperatures and mass flow rates for heat exchanger with microchannel coil has been accomplished. In accordance
with the heat exchangers used for experiments, numerical 3D simulation of adequate geometry shapes has been done. With utilization of air/water side numerical simulation, more detailed results have been achieved in relation to the simulation that
assumes constant temperature or constant heat flux on the pipe wall. Good agreement between experimentally measured and numerically calculated results has been accomplished.
The influence of different microchannel shapes on heat transfer effectiveness and pressure drop has been studied numerically. Comparison of results has been made accompanied by the discussion and final conclusions.

This article presents a review of glyph-based techniques for engineering visualization as well as... more This article presents a review of glyph-based techniques for engineering visualization as well as practical application for the multivariate visualization process. Two glyph techniques, Chernoff faces and star glyphs, uncommonly used in engineering practice, are described, applied to the selected data set, run through the chosen optimization methods and user evaluated. As an example of how these techniques
function, a set of data for the optimization of a heat exchanger with a microchannel coil is adopted for visualization. The results acquired by the chosen visualization techniques are related to the results of optimization carried out by the response surface method and compared with the results of user evaluation.
Based on the data set from engineering research and practice, the advantages and disadvantages of these techniques for engineering visualization are identified and discussed.

The development of three-dimensional Computer Aided Design (3D CAD) technology has additionally s... more The development of three-dimensional Computer Aided Design (3D CAD) technology has additionally spurred research into spatial ability to find the ways for its enhancement through teaching and instruction and to understand the mechanism
of its assessment. The techniques involved in multimedia engineering environment of today as well as their inclusion into engineering curricula and courses have to be strongly supported by wider knowledge of spatial ability. This paper is a review of research results applied to engineering graphics education by respecting spatial ability as a recognized predictor of success in engineering. The development of engineering
graphics teaching based on research suggestions about spatial ability represents an increasingly complex approach that puts additional stress on engineering graphics educators. Thus classical tests for the assessment of spatial ability are
described, the applied strategies for their solving are presented, the selected obtained results are compared, and a distinction is drawn between the strategies employed for more complex spatial tasks that engineering is dealing with.

In the paper three-dimensional case of heat transfer and air flow has been presented for enclosed... more In the paper three-dimensional case of heat transfer and air flow has been presented for enclosed space heating and cooling with unit mounted on the wall. Numerical modelling has been used to analyze effect of space height on temperature and air velocity distribution under standard conditions. Physical processes in two rooms with different heights are modelled using specialized computational fluid dynamics (CFD) software FLUENT. Calculations are carried out in an empty room without any human or mechanical activity and compared with previous experimental measurements. Numerical analysis has shown distinct relationship between room dimensions (height in this case) and state of comfort in the room. Although average values of temperature and air velocity in the room are satisfactory there are local distortions from the standard optimal comfort values. Considerable differences in temperature distribution are observed especially in heating conditions where temperature drop in lower layers of higher room occur due to buoyancy effects. To cancel buoyancy effects it is necessary to increase air inlet velocity from the unit which could lead to local air velocity distortions resulting with disturbed optimal comfort values.

Heat Transfer Engineering, 2012

In this paper an analysis of heat transfer and fluid flow of compact heat exchanger has been done... more In this paper an analysis of heat transfer and fluid flow of compact heat exchanger has been done. 3D numerical simulation results of a heat exchanger with microchannel coil were compared with experimental results carried out in this research. Microchannel coil composed of flat tubes with rectangular microchannels of different geometries has been installed in an open circuit wind tunnel. Air and distilled water were used as working fluids in heat exchanger with single phase heat transfer. Same geometry and parameter setup have been analyzed with commercial fluid flow and a heat transfer solver Fluent. Air/water model has been used. Good agreement between experimentally measured and calculated results has been accomplished. The influence of different microchannel geometry on heat transfer effectiveness and pressure drop have been studied numerically. Comparison of results has been made accompanied by the commentaries and final conclusions.

The efficiency of heat generators (boilers) of different types that are common in today's heating... more The efficiency of heat generators (boilers) of different types that are common in today's heating systems is described in this paper. The dependency of the efficiency on partial load is shown and an analysis of the total efficiency of the heating system is derived. The referent system consists offour boilers guided by the stage sequencing control. Two different construction types of boilers, standard (old) and low temperature boilers have been taken into consideration. The boiler thermal load, number of heating days (hours) and total thermal load are the most important constraints. A numerical example is presentedfor a case of 2 400 kW maximum heating load. Comparison of results has been made followed with the commentary and final conclusions.

In this stU((v IluJllerical alld experimental ana(vsis ol compact heat exchanger has been done. A... more In this stU((v IluJllerical alld experimental ana(vsis ol compact heat exchanger has been done. A microchallllel coil composed olflat tubes with rectallgular l1Iicrochalll1 els has 1Ieell illstalled ill all opell circuit willd tUllnel. Air and \I'ater \I'ere used as workillg fluids. Same geometry and parallleter setup has been ana(rzed using comJllercial.fluid floll' alld a heat transler solver Fluellt. Air/\vater side model has been used because it gives 1Il0re ((CCurare resulrs than simpler II/odel that illcludes 0111), air side .flOlV. COlllparison het\veell Ilumerical model alld experimelltal results has been accoJllplished \Fitll respect ol air alld \\'({ter telllperature. 11 has heell ShOll'1l rhar numerical model results coincide well wirh rhe experilllental c/ata, lVith del'iariolls with ill all acceptable range. Therej()J'e, used air/llater side lIl odel call be lIsed Jhr Jill·ther investigarioll ol more efjicient cOlllpact heat exchanger geolllelrr. Key words: compact heat exchanger, microchannel coil, flat tube. numerical, experimen tal, a ir/watcr model 1.

Sustainability

Engineering Review, Jul 23, 2010

E3S Web of Conferences, 2019

International Journal of Refrigeration, 2015

Journal of Energy Storage, 2020

Energy, 2020

International Journal of Heat and Mass Transfer, 2020

Experimental and numerical analysis of heat transfer and fluid flow in the compact heat exchanger... more Experimental and numerical analysis of heat transfer and fluid flow in the compact heat exchanger has been done in this paper. In an open circuit wind tunnel, developed on purpose for this investigation, the measurement of working media temperatures and mass flow rates for heat exchanger with microchannel coil has been accomplished. In accordance
with the heat exchangers used for experiments, numerical 3D simulation of adequate geometry shapes has been done. With utilization of air/water side numerical simulation, more detailed results have been achieved in relation to the simulation that
assumes constant temperature or constant heat flux on the pipe wall. Good agreement between experimentally measured and numerically calculated results has been accomplished.
The influence of different microchannel shapes on heat transfer effectiveness and pressure drop has been studied numerically. Comparison of results has been made accompanied by the discussion and final conclusions.

Heat Transfer Engineering, 2012