Natural zeolites include a group of minerals consisting of hydroaluminosilicates of alkaline and earthalkaline metals: analcam, clinoptilolite, mordenite, shabazite, filipsite and...
Natural zeolites include a group of minerals consisting of hydroaluminosilicates of alkaline and earthalkaline metals: analcam, clinoptilolite, mordenite, shabazite, filipsite and laumontite. This natural mineral is especially valuable by its structure that determines its properties. This zeolite has a free space in its internal structure and channels, so-called. active sites for which harmful or useful components can be attached or adsorbed. This active sites in this mineral can serve as centers for the binding of some of the new compounds. Thus, the mineral gets some new features which significantly expands its application. When this mineral unite with some free radicals then receives a qualitatively new product that has a sophisticated application.
Zeolite is considered to be a mineralogy of the future, which will be increasingly used in ecology and environmental protection. Thanks to the general characteristics of natural zeolites, three main areas of their application are highlighted: industry, agriculture and ecology.
In addition to the above mentioned application areas, high efficiency of zeolite use has already been demonstrated, and in many other agricultural branches: for the wet grain drying, as anti-settling agent of fertilizers, and in their processing in order to obtain the highest possible quality.
In addition to a more detailed analysis of the application of zeolite in the industry, experimental drying of zeolites will be shown in this paper, given the fact that it is very usable in the dry state.
USE OF CFD ANALYSIS TO ACHIEVE ENERGY EFFICIENT DATA CENTER
Several parameters impacting airflow and the achievement of defined work conditions of datacom equipment have been analyzed in an existing data...
Several parameters impacting airflow and the achievement of defined work conditions of datacom equipment have been analyzed in an existing data center. First, the necessary measurements were carried out inorder to establish the features of the center, as well to use them to create the basis of the numerical model of the data center, via the program package PHOENISC. Simulating the numerical model of the data center, the temperature field, pressure field and velocities within the data center were being achieved. The results obtained by the simulations were compared with the
measurements done, showing quite a high concurrence, and thereby confirming the model and becoming available for further data center analyses. The model includes several factors influencing the airflow. Analyzing the obtained results from the model simulations, hints were obtained how to implement changes in the data center, in order to comply with the recommended work conditions for the datacom equipment, and at the same time to achieve reduced energy costs.
A Numerical Study of Perforated Plate Local Heat Transfer Coefficient
The need for compact heat exchangers has led to the development of many types of surfaces that enhance the rate of...
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 and perforated plate 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 local heat transfer characteristics of flow through a perforated plate with 2 mm in diameter, hole length to diameter ratio of 1 and porosity of 25.6%. For the determination of the local heat transfer, numerical simulations were performed. Reynolds numbers based on the perforated plate pitch were in the range from 80 to 300. The results of average Nusselt number prediction were compared with the related experimental correlations. The experimental results agreed on qualitatively with the results obtained using a CFD.
Observation of Human Thermal Comfort in a Naturally-Ventilated Educational Building
Thermal comfort is a complex phenomenon, which is influenced by several parameters: environmental (physical), personal and psychological. Two of the most...
Thermal comfort is a complex phenomenon, which is influenced by several parameters: environmental (physical), personal and psychological. Two of the most common indicators to quantitatively expressing thermal comfort and thermal sensation are Predicted Mean Vote (PMV) and Predicted Percent Dissatisfied (PPD) after Fanger (1970). In this paper, it has been represented statistical analysis of thermal comfort indicators based on EN ISO 7730. The presented results of statistical analysis were based on survey data of school children aged between 8 and 9 years old.
EXPERIMENTAL INVESTIGATION OF THERMAL AND FLUID FLOW PROCESSES IN A PERFORATED PLATE HEAT EXCHANGER
The goal of this paper is to investigate thermal and fluid flow processes in a air/water perforated plate heat exchanger. The...
The goal of this paper is to investigate thermal and fluid flow processes in a air/water perforated plate heat exchanger. The experimental investigation was carried out over a single perforated plate which was installed in an experimental chamber and heated by hot water. A fan with variable flow was connected to the experimental chamber, and the flow rates were varied from 100 up to 360 m3/h. The thermocouples were attached to the surface of the perforated plate along upwind and downwind side, as well as at the inlet and outlet of the chamber. During each experiment, the readings of thermocouples were recorded alongside with air and water volume flow and temperatures of water at the inlet and outlet of the chamber. On the basis of the experimental results equations for heat transfer and pressure drop were established. On the end, a comparison was done with other authors.
Investigation of temperature distribution for turbulent Rayleigh–Benard convection in a rectangular tank
Measurements of temperature distribution were performed in a rectangular tank with aspect ratios 4x2x1, using different working fluids. The experimental setup...
Measurements of temperature distribution were performed in a rectangular tank with aspect ratios 4x2x1, using different working fluids. The experimental setup was adjusted taken to be as close to real fuel tanks exposed to solar radiation, as in airplane wings. The measurements were taken at fifteen different positions on the faces of the tank. Probes used are PT100 elements. As to obtain as uniform temperature as possible, double bottom was used, with water as medium for obtaining of the constant surface tmperature. The results are compared with the those obtained by IR camera.
Matrix heat exchangers and their application
Matrix heat exchangers, also known as perforated plate heat exchangers, invented in 1940-is are finding increasing use in cryiogenics. They are...
Matrix heat exchangers, also known as perforated plate heat exchangers, invented in 1940-is are finding increasing use in cryiogenics. They are representing an effective heat transfer devices, because of their high surface-to-volume ratio. The mechanism of heat transfer process in a matrix heat exchanger is very complex. There are two heat conduction paths: one along the perforated plates, and the other across the spacer plates, as well as three convection surfaces: front face of a plate, back face of a plate, and the inner wall surface area of every perforation. There have been many derived correlations of Nusselt number, heat transfer coefficient and friction factor in terms of Reynolds number, and matrix heat exchanger geometry (plate thickness, spacer thickness, porosity, perforation arrangements etc.). This paper summarizes a literature review performed in order to study current work in matrix heat exchangers.
Convecton instability in an inclined viscous fluid layer
We present in this paper the numerical simulation of the full Navier-Stokes equation in vorticity-stream function form for the case of...
We present in this paper the numerical simulation of the full Navier-Stokes equation in vorticity-stream function form for the case of an inclined fluid layer with temperature modulation on the lower plate. The fluid flows on the plate which is inclined with some angle alfa with respect to the horizontal plane. The upper side of the viscous fluid layer is free surface.
Since we do not have constant temperature on the lower
plate, Rayleigh-Benard convection sets in immediately, for any value of Rayleigh number. We investigate the
stability of this convection for water as a working fluid. The results of direct numerical simulation are presented as fields of temperature, vorticty, stream function and velocity.
Numerical simulation of Coanda effect in mechanical and ventilated office
It is well known fact that, the flow of air movement indoor spaces in residential rooms is a very complex structure....
It is well known fact that, the flow of air movement indoor spaces in residential rooms is a very complex structure. In practice, usually there is in use ventilation systems with a number of air changes during the day. Also it was noted that the main air flow has a fully developed turbulent flow in ventilation ducts, grilles at the entrance and exit and downstream along the edges of obstacles. In the indoor space the main stream flow of air will have poorly developed properties of turbulent flow. Turbulence is directly caused by the presence of the wall causing border flow of Coanda effect.
Far from grille, velocity profile of supplying air and turbulent kinetic energy decreases, leading to a laminated mainstream in some cases. In practical applications, most of the air flow is three-dimensional and unstable.
These features make the simulation of supplying air flow in the room represent a great challenge for existing numerical codes and models. In this work, the main task is examination of the distribution of the effects of mechanical ventilation mainstream supplying air jets through the mask grid diffuser passes under a certain temperature and the room is heated, and the different positioning of masks grid diffuser inlet and outlet causes the main fluid flow affects the development of a turbulent flow in the area.
EXPERIMENTAL INVESTIGATION OF THERMAL AND FLOW PROCESSES IN SHELL AND TUBE HEAT EHCHANGERS
Experimental investigations were done to identify influence of thermal and flow quantities and shell side geometry to STHE’s heat exchange intensity....
Experimental investigations were done to identify influence of thermal and flow quantities and shell side geometry to STHE’s heat exchange intensity. In this paper special attention was made to number of segmental baffles (with baffle cut of 22%) influence on apparatus efficiency investigation.