MODIFICATION OF POWDER MATERIAL BY COMPACTION PROCESSING

There are different criteria for assessing the appropriateness of an agglomeration technology in the deployment processing of dry, fine and dirty dust burdening in the communal and working environment. Besides the benefit of the environment components, the agglomeration technology offers the possibility of re-processing the material as the primary raw material within a wide range of industries. Preliminary tests have shown that the compressed material remains in the memory from the previous compression. For returning the already processed material into a primary production, it is essential that it is reformed without the need for additional materials, a requirement that can be problematic. This article deals with the modification of a powder material (powder dust from the manufacture of friction components) and the investigation of its properties before and after the compaction processing

DESIGN OF PARTICULATE MATERIAL COMPACTOR ROLLS DIAMETER

At present, in a period of an industrial expansion great emphasis is placed on the environment. That means aiming for a reduced energy consumption, and also lessening dustiness from very fine powder material. This category also includes particulate material agglomeration processes. Because this process is very energy-intensive, it is necessary to correctly design these devices. The aim of this paper is to focus on a theoretical design of a production compactor with the rolls diameter for an experimental particulate material, based on Johanson’s theory and experimentally measured material properties. The material used for experimental measurements was an NPK-based industrial fertilizer consisting of several components. The results of this paper is the dependence of the ratio of the maximum compression pressure to the initial compression pressure from the rolls diameter of the proposed compactor

HVAC Systems Heat Recovery with Multi-Layered Oscillating Heat Pipes

The aim of this work is to investigate a heat performance of a Multi-Layered Oscillating Heat Pipes Heat Exchanger (ML-OHPHE) for the application of heat recovery in heating, ventilation and air conditioning systems (HVAC systems). The heat exchanger is investigated experimentally under different conditions of heat loads and filling ratios. The experimental data results are compared to the data obtained from Honeywell’s UniSim® Design Suite software. In the end the NTU analysis of the ML-OHPHE is done and a value of overall heat transfer coefficient is calculated. The results of the experiments indicate that the ML-OHPHE could serve as a completely passive heat transfer device in the application of heat recovery in HVAC systems

Pen & Paper & Xerox: Early History of Tabletop RPGs in Czechoslovakia

The study presents preliminary research focused on the history of tabletop role-playing games (RPGs) in the former Czechoslovakia, especially Dungeons & Dragons (1974) and its local clone Dračí doupě (transl. Dragon’s Lair, 1990). Based on theoretical literature, period sources and semi-structured interviews with first-generation players, it gives an overview of the first contacts with RPG in the specific post-communist cultural and economic context, focusing on the distribution and reception of Dragon’s Lair, mainly in the Slovak part of the former common state. As a partial outcome of an ongoing research into the local gaming experience, the focus is not on the game itself or its commercial success, but rather on its players, their characteristics and initial experiences with tabletop RPGs in the early 1990s

Shell and Tube Heat Exchanger – the Heat Transfer Area Design Process

Nowadays, the operating nuclear reactors are able to utilise only 1 % of mined out uranium. An effective exploitation of uranium, even 60 %, is possible to achieve in so-called fast reactors. These reactors commercial operation is expected after the year 2035. Several design configurations of these reactors exist. Fast reactors rank among the so-called Generation IV reactors. Helium-cooled reactor, as a gas-cooled fast reactor, is one of them. Exchangers used to a heat transfer from a reactor active zone (i.e. heat exchangers) are an important part of fast reactors. This paper deals with the design calculation of U-tube heat exchanger (precisely 1-2 shell and tube heat exchanger with U-tubes): water – helium

Separation of VOC Gaseous Mixtures Using an Adsorption–Desorption Device

The aim of this work was to separate ethanol in an experimental adsorption–desorption device. We focused on concentrating ethanol by adsorption onto granulated activated carbon in its gaseous phase, which was produced by stripping a matrix with different ethanol concentrations (2, 5, 10, and 15% v/v). For adsorption, three kinds of granulated activated carbon (GAC) were used, marked as GAC1, GAC2, and GAC3. The separation product had a higher ethanol concentration than the initial ethanol concentration before the adsorption–desorption process. The enrichment factor was, in the case of the initial ethanol concentration, 2% v/v at the level of 10. With our new adsorption–desorption device, it is possible to achieve a product with an ethanol concentration of 59.0% v/v with stripping, adsorption, desorption, and condensation. To verify the separation efficiency, a real matrix (fermentation broth) was used. The ethanol concentration in the real matrix was, at the beginning of the separation process, 0.65% v/v; after using our separation device, it was 11.35% v/v. Using a real matrix, the enrichment factor was at the level of 18. The main advantage is the use of our new adsorption–desorption device for the continuous separation of ethanol from fermentation broth. A mathematical model was created, based on which it is possible to calculate the ethanol concentration in the product of the separation process with high accuracy

The Influence of Wet Granulation Parameters on the Compaction Behavior and Tablet Strength of a Hydralazine Powder Mixture

The aim of this paper was to describe the influence of high-shear wet granulation process parameters on tablet tensile strength and compaction behavior of a powder mixture and granules containing hydralazine. The hydralazine powder mixture and eight types of granules were compacted into tablets and evaluated using the Heckel, Kawakita and Adams analyses. The granules were created using two types of granulation liquid (distilled water and aqueous solution of polyvinylpyrrolidone), at different impeller speeds (500 and 700 rpm) and with different wet massing times (without wet massing and for 2 min). Granulation resulted in improved compressibility, reduced dustiness and narrower particle-size distribution. A significant influence of wet massing time on parameters from the Kawakita and Adams analysis was found. Wet massing time had an equally significant effect on tablet tensile strength, regardless of the granulation liquid used. Granules formed with the same wet massing time showed the same trends in tabletability graphs. Tablets created using a single-tablet press (batch compaction) and an eccentric tablet press showed opposite values of tensile strength. Tablets from granules with a higher bulk density showed lower strength during batch compaction and, conversely, higher strength during eccentric tableting