Model of the pressing and drying system of organic material

The following paper presents a model of a system operating and drying food waste. This paper was written in response to the challenge of reducing food waste, minimizing environmental pollution, decay processes, and exploring the possibility of using said waste. The design of such a system has proven to be innovative, despite still being under construction. Whilst the pressing and drying process itself is not new, the list of process parameters has not previously been used, thus proving innovative in the developed model. High pressure pressing does not only change the geometric form or the physical properties of the material. Such a process also changes the physicochemical properties. The authors' previous experience in pressing organic materials is referenced in this work. Basic parameters such as temperature, pressure and process duration have been developed in earlier studies. In the proposed model, the friction against the walls in the compression chamber have been eliminated. This changes the parameters inside the compression chamber and will certainly improve the lifetime of the system. Previous solutions, such as screw presses, or for higher power - piston ones, were not durable and very energy-consuming. The new solution is much more durable and allows for use of higher pressures. Depending on the materials selected for the process, it will be possible to obtain new products that have not been produced before, due to the limitations of the pressing process. The developed model of pressing and drying organic materials will also allow the further production of ecological fuels from waste materials, like from the waste of the wood industry. It will also allow the use of straw in the production of new building materials. After making the model, there will be a wide scope for further research.

Research improvement of the strength characteristics of rocks under volumetric compression

The article describes some aspects of the research and applied works, which the authors carried out to expand the scope of application in the study of rock strength indicators in the laboratory of KuzSTU (Prokopyevsk branch) on a complex equipment. It consists of an extreme deformation chamber and a volumetric compression chamber. It describes the disadvantages of the volumetric compression chamber. The disadvantages have been eliminated by using a special device for fixing the sample when descending into the volumetric compression chamber. The article also gives the description of the operation of a volumetric compression chamber with the possibility of testing rock samples for a breakage under the volumetric compression. The first test results are presented.

A Design of the Compression Chamber and Optimization of the Sealing of a Novel Rotary Internal Combustion Engine Using CFD

The current paper investigates two particular features of a novel rotary split engine. This internal combustion engine incorporates a number of positive advantages in comparison to conventional reciprocating piston engines. As a split engine, it is characterized by a significant difference between the expansion and compression ratios, the former being higher. The processes are decoupled and take place simultaneously, in different chambers and on the different sides of the rotating pistons. Initially, a brief description of the engine’s structure and operating principle is provided. Next, the configuration of the compression chamber and the sealing system are examined. The numerical study is conducted using CFD simulation models, with the relevant assumptions and boundary conditions. Two parameters of the compression chamber were studied, the intake port design (initial and optimized) and the sealing system size (short and long). The best option was found to be the combination of the optimized intake port design with the short seal, in order to keep the compression chamber as close as possible to the engine shaft. A more detailed study of the sealing system included different labyrinth geometries. It was found that the stepped labyrinth achieves the highest sealing efficiency.

Creation of a Device for Testing of the Rock Samples for Gap in Volumetric Compression Chamber

A device for the volume compression chamber of the samples is described and some possibilities for testing the samples are presented: compressive strength, angle of internal friction, and adhesion values of coal and host rocks. In addition, descriptions of patents for devices allowing to test rocks for breaking during volume compression are given.

On Numerical Investigation of Water Injection to Screw Compressors

Oil injection is widely used in screw compressors for lubrication, sealing and cooling purposes. More recently other, mainly lower viscosity fluids are used for the purpose, for example water. Water introduces new phenomena into the screw compressor process, one among them is evaporation. 3D numerical modelling is employed and presented in this paper for the detailed analysis of flow and thermodynamics process during injection of water in screw compressors. The advantage of such simulations is that realistic geometry of the rotors and the ports can be captured. In addition, the physical effects of fluid thermal interactions and leakage are directly taken into account by these models. Recent studies have shown that for oil free and oil injected air compressors a good agreement is achieved with measurements, in prediction of performance parameters. In these simulations the Eulerian-Eulerian multiphase modelling has been applied. To implement the same model for water injected compressors presents an additional challenge as the liquid water injected into the compression chamber changes phase and evaporates depending on the local saturation and thermodynamic conditions. Water also forms liquid film on the rotors and housing and thereby influences thermal changes. In this paper a numerical model for water injected screw compressor that accounts for evaporation effects has been presented. Empirical form of the Lee (9) evaporation-condensation model for phase change has been applied in the compression chamber using the phase specific mass and energy sources. Calculation of the amount of water required to just saturate the compressed air at delivery pressure is used to set the mass flow rate of water at two operating speeds. The effect of the suction air temperature and relative humidity is studied. Evaporation inside compression chamber has two important physical effects, one is that the latent heat of evaporating water lowers the gas temperature and the other is the change of state from water to vapour. Including vapour as a third phase adds complexity to already challenging deforming grids required for screw domains. Hence a mass and energy source formulation is proposed in the presented study to account for the vapour phase change and evaporation effects, thus limiting the number of phases to be modelled. Local drop in gas temperature, distribution of water and regions of evaporation were identified by the simulations. Thermal hot spots on the rotor were located. Reduction in the leakage of gas and its exit temperature was well predicted by the model. Such simplified evaporation model can be further used in the design of water injected screw compressors and extended to predict thermal deformation of the rotors and the housing.

Numerical Modeling and Simulation of Injection Cooling and Wet Gas Compression

This paper presents application of Computational Fluid Dynamics (CFD) in modeling wet gas compression in a multiphase compressor, where liquid is injected inside the compression chamber to enhance cooling and achieve near isothermal compression. CFD is used for detailed flow field and heat transfer analysis. It includes 3D transient simulations of multiphase compressible turbulent flow. During each cycle, compression and suction chambers keep moving and deforming. Computational domains include a gate that separates compression chamber from the suction chamber. Gate moves up and down to always remain in contact with the rotor. A custom program is used to prescribe motion for the moving and deforming domain. Eulerian-Lagrangian method is used to model continuous and discrete (atomized droplets) phases and their interaction. Droplet dynamics under the influence of turbulence, acceleration, diffusion and body forces are studied. Models to capture droplet breakup and coalescence are included. Results from CFD simulations are used to optimize compressor performance. Temperature and pressure variations during the compression cycle are presented. Most of the pressure and temperature rise occurs towards the end of the compression cycle. Atomization details including droplets trajectory, droplet size distribution and droplet velocity variations are presented. Temperature distribution inside the compression chamber is used to optimize location, size, and flow rate of liquid injections.