Eksperimentalno i numeričko istraživanje termo-strujnih procesa u paketu perforiranih ploča

One of the most important characteristics of heat exchangers, besides thermal efficiency, is their compactness or surface area to volume ratio. The need to achieve high efficiency in a compact unit with high operating pressure has led to the development of heat exchangers with perforated plates or, as they are called in the literature, the Matrix Heat Exchangers (MHE). In this PhD thesis experimental and numerical research was undertaken to measure the thermal and flow characteristics of an assembly of perforated plates, in an effort to obtain indications for engineering calculations. The study was undertaken in the Laboratory for Thermal Engineering at the Faculty of Mechanical Engineering, Niš. In the experimental part of the study, packages of one, two and three 2 mm thick plates were used, with a porosity of 25.6% and a square arrangement of holes that were 2 mm in diameter. Water was used as the heating fluid, while the heated fluid was air. The package of plates was placed in the experimental chamber which had a fan as an inlet, with the ability to control the flow. The fluid flow rate, pressure drops and the temperatures of the fluids at the inlet and outlet of the chamber, as well as the temperature of air between the plates, were measured at the pre-defined locations in the perforated plate heat exchanger. Also, the pressure drop was measured for the perforated plate package with and without the water collector. In the numerical part of this research, the PHOENICS 2014 software package was used. In the first part of the numerical study the heat transfer from plates with the porosity from 10 to 50% was investigated. In the second part of the numerical study, a package of three plates was established and the effect of distance between the plates was also examined. Experimental results and the results of other authors were used to validate the numerical experiment. iv On the basis of experimental and numerical results, criterial equations for heat transfer and formulas for pressure drop equations were established

Specific approach for continuous air quality monitoring

Rapid industry development as well as increase of traffic volume across the world have resulted in air quality becoming one of the most important factors of everyday life. Air quality monitoring is the necessary factor for proper decision making regarding air pollution. An integral part of such investigations is the measurement of wind characteristics, as the wind is the most influential factor in turbulent pollution diffusion into the atmosphere. The most of the air pollution originates from combustion processes, so it is important to make quantitative, as well as qualitative analysis, as the sources of pollution can be very distant. In this paper, specific methodology for continuous wind, temperature and air quality data acquisition is presented. Comparison of the measured results is given, as well as the detailed presentation of the characteristics of the acquisition software used

Experimental and Analytical Research of the Heat Transfer Process in the Package of Perforated Plates

The need for compact heat exchangers has led to the development of many types of surfaces that enhance the rate of heat transfer, among them the perforated plate heat exchangers, also known as matrix heat exchangers. The perforated plate heat exchangers consist of a series of perforated plates that are separated by a series of spacers. The present study investigates the heat transfer characteristics of the package of perforated plates. Perforated plates were 2 mm thick, with holes with 2 mm in diameter and porosity of 25.6%. The package of one, two, and three perforated plates was set in the channel of the experimental chamber at which entrance was a thrust fan with the ability to control the flow rate. The fluid flow rates, the temperatures of the fluids at the inlet and outlet of the chamber and the temperature of the air between the plates, were measured at the pre-defined locations in the package and the experimental chamber. Based on the measurements, heat transfer coefficients for the individual plates, as well as for the packages of perforated plates were determined. In further research, an iterative analytical procedure for investigation of the heat transfer process and the overall heat transfer coefficient for the package of perforated plates were developed. Based on these analytical and experimental results, conclusions were drawn about the heat transfer in a package of perforated plates.17th Symposium of the Society-of-Thermal-Engineers-of-Serbia (SIMTERM), Oct 20-23, 2015, Sokobanja, Serbi

Eksperimentalno i numeričko istraživanje termo-strujnih procesa u paketu perforiranih ploča

One of the most important characteristics of heat exchangers, besides thermal efficiency, is their compactness or surface area to volume ratio. The need to achieve high efficiency in a compact unit with high operating pressure has led to the development of heat exchangers with perforated plates or, as they are called in the literature, the Matrix Heat Exchangers (MHE). In this PhD thesis experimental and numerical research was undertaken to measure the thermal and flow characteristics of an assembly of perforated plates, in an effort to obtain indications for engineering calculations. The study was undertaken in the Laboratory for Thermal Engineering at the Faculty of Mechanical Engineering, Niš. In the experimental part of the study, packages of one, two and three 2 mm thick plates were used, with a porosity of 25.6% and a square arrangement of holes that were 2 mm in diameter. Water was used as the heating fluid, while the heated fluid was air. The package of plates was placed in the experimental chamber which had a fan as an inlet, with the ability to control the flow. The fluid flow rate, pressure drops and the temperatures of the fluids at the inlet and outlet of the chamber, as well as the temperature of air between the plates, were measured at the pre-defined locations in the perforated plate heat exchanger. Also, the pressure drop was measured for the perforated plate package with and without the water collector. In the numerical part of this research, the PHOENICS 2014 software package was used. In the first part of the numerical study the heat transfer from plates with the porosity from 10 to 50% was investigated. In the second part of the numerical study, a package of three plates was established and the effect of distance between the plates was also examined. Experimental results and the results of other authors were used to validate the numerical experiment. iv On the basis of experimental and numerical results, criterial equations for heat transfer and formulas for pressure drop equations were established

Experimental and numerical investigation of thermal and fluid-flow processes in a matrix heat exchanger

The need for compact heat exchangers has led to the development of many types of surfaces that enhance the rate of heat transfer, among them the matrix heat exchangers. These heat exchangers consist of a series of perforated plates mutually separated and sealed by spacers. The goal of this research was to investigate the heat transfer process of matrix heat exchangers on the air side, at the close to ambient conditions. The research was conducted in two directions – experimental research and CFD research. The experimental investigation was carried out over a perforated plate package with the porosity of 25.6%. The air/water matrix heat exchanger was heated by hot water and was installed in an experimental chamber at which entrance was a fan with the variable flow rate and heated by hot water. The thermocouples were attached to the surface of the perforated plate at the upwind and downwind sides, as well as at the inlet and the outlet of the chamber. During each experiment, the thermocouple readings and the air and water-flow and temperatures were recorded. In the numerical part of the research, the matrix heat exchangers with different plate porosity from 10 to 50% were investigated. The results of the numerical simulations were validated against the experimental results. On the basis of the experimental and numerical results, equations for heat transfer as the function of Reynolds number and geometrical parameters was established. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 42008

Measurement and improvement of indoor air quality in an information technology classroom

With the rapid development of information technology equipment and its use in the teaching and learning activities, the working environment (especially indoor air quality) in which students and pupils spend a great deal of time in educational institutions has been changing. Therefore, special attention must be paid to indoor air quality and comfort. It is of great importance to maintain indoor air quality in an object, such as information technology classrooms, where a large number of students spend long periods of time. Poor indoor environment can negatively affect scholarly performances and cause discomfort and poor work performance. The problem of indoor air quality in educational institutions can be more serious than in other types of objects, because of the higher concentration of students and information technology equipment. This paper analyzes the changes in air quality in an information technology classrooms, when occupied with students, for the period from March to April. The changes of indoor air temperature, relative humidity, and carbon dioxide concentration are monitored in the classroom, as well as outdoor temperature and relative humidity. Several cases are studied: the classroom with closed windows and doors (closed classroom), the classroom with natural ventilation, the classroom cooled with a split system (cooled classroom). Responses of students are followed for each case. The analysis is performed based on the measurement results and numerical simulations using the computational fluid dynamics package, and measures are proposed to improve the indoor air quality in the considered classroom

Air quality estimation by computational intelligence methodologies

The subject of this study is to compare different computational intelligence methodologies based on artificial neural networks used for forecasting an air quality parameter - the emission of CO2, in the city of Niš. Firstly, inputs of the CO2 emission estimator are analyzed and their measurement is explained. It is known that the traffic is the single largest emitter of CO2 in Europe. Therefore, a proper treatment of this component of pollution is very important for precise estimation of emission levels. With this in mind, measurements of traffic frequency and CO2 concentration were carried out at critical intersections in the city, as well as the monitoring of a vehicle direction at the crossroad. Finally, based on experimental data, different soft computing estimators were developed, such as feed forward neural network, recurrent neural network, and hybrid neuro-fuzzy estimator of CO2 emission levels. Test data for some characteristic cases presented at the end of the paper shows good agreement of developed estimator outputs with experimental data. Presented results are a true indicator of the implemented method usability. [Projekat Ministarstva nauke Republike Srbije, br. III42008-2/2011: Evaluation of Energy Performances and br. TR35016/2011: Indoor Environment Quality of Educational Buildings in Serbia with Impact to Health and Research of MHD Flows around the Bodies, in the Tip Clearances and Channels and Application in the MHD Pumps Development

Perforated plate convective heat transfer analysis

The need for high performance heat exchangers has led to the development of many types of surfaces that enhance the rate of heat transfer. One of the heat exchanger types are the matrix heat exchangers. Matrix heat exchangers consist of a series of perforated plates, separated by a series of spacers. The present study experimentally investigates the overall heat transfer characteristics of flow through a perforated plate with 2 mm in diameter, the hole length to diameter ratio of 1 and 25.6% porosity. Numerical simulations were performed to determine the overall heat transfer in the function of geometric parameters. Reynolds numbers based on the perforated plate pitch were set in the range from 50 to 500. The results of the average Nusselt number prediction were compared with the related experimental correlations. The experimental data agreed on qualitatively with the results obtained using a CFD. Using these data, a Nusselt criterial equation was obtained

Experimental and analytical research of the heat transfer process in the package of perforated plates

The need for compact heat exchangers has led to the development of many types of surfaces that enhance the rate of heat transfer, among them the perforated plate heat exchangers, also known as matrix heat exchangers. The perforated plate heat exchangers consist of a series of perforated plates that are separated by a series of spacers. The present study investigates the heat transfer characteristics of the package of perforated plates. Perforated plates were 2 mm thick, with holes with 2 mm in diameter and porosity of 25.6%. The package of one, two, and three perforated plates was set in the channel of the experimental chamber at which entrance was a thrust fan with the ability to control the flow rate. The fluid flow rates, the temperatures of the fluids at the inlet and outlet of the chamber and the temperature of the air between the plates, were measured at the predefined locations in the package and the experimental chamber. Based on the measurements, heat transfer coefficients for the individual plates, as well as for the packages of perforated plates were determined. In further research, an iterative analytical procedure for investigation of the heat transfer process and the overall heat transfer coefficient for the package of perforated plates were developed. Based on these analytical and experimental results, conclusions were drawn about the heat transfer in a package of perforated plates. [Projekat Ministarstva nauke Republike Srbije, br. III 42008

Exposing mammoths: From loess research discovery to public palaeontological park

This paper is dedicated to the palaeontological and geoheritage potential and conservation values of recently discovered mammoth fossils in the Drmno open-cast mine area. These palaeontological resources provide an excellent basis for the establishment of the first ever palaeontological park in Serbia. In addition, the paper also proposes possible interpretation methods and to determine the current state and tourism potential of the Drmno mammoth fossils, by using the M-GAM model for geosite assessment and comparing this site with two similar world famous sites, the Mammoth Site of Hot Springs and the La Brea Tar Pits in the USA. Results of the assessment indicate that the fossils from the Drmno open mine have similar scientific and educational values as the fossils from two other analysed sites, whereas scenic and tourist values are much lower in comparison with those sites. This means that the Drmno site possesses great potential and resources which should be used and managed in a better way. Hopefully, the newly constructed palaeontological park with all of its supporting infrastructure and newly employed people will eliminate the currently existing gap between the Drmno fossil site and other similar world famous fossil sites