The efficiency of material consumption is an important consideration for production processes; this is particularly true for processes that use waste materials. Dry ice extrusion serves as a good example. An examination of the literature on this subject leads to an observation that the commercially available machines for dry ice compression are characterized by a high value of working force. Consequently, the effectiveness of the source consumption, electric energy and carbon dioxide, is very low. The subject of the experimental research presented in the article is the influence of the density of dry ice on the value of Young’s modulus. The first part of the article presents the test methodology and the special test stand that was developed to accommodate the unique characteristics of solid-state carbon dioxide. The test results present the characteristics of compaction and relaxation used as the basis for determining the value of Young’s modulus. Based on the test results obtained for various material density values, the characteristics of Young’s modulus are developed and graphed as a function of the density. The presented results are important for furthering the research on the development of extrusion and compaction processes; for example, using the Drucker–Prager/Cap model for the purpose of optimizing the geometrical characteristics of the work assembly components.
This article presents the outcome of research on modelling the process of the extrusion of crystalline dry ice. The purpose of this process is to densify the material and obtain pellets of several millimeters in diameter. This reduces the sublimation rate in ambient conditions of the material whose temperature in a solid state is 195 K. A lower sublimation rate means a reduction of the loss of product in its final applications, which include refrigeration and reduction of atmospheric emissions of gaseous CO2. A ram-type extruder was considered in this analysis, in which dry ice was extruded through a single-hole die of varying geometry. The article presents the results of numerical analyses of the extrusion process, using a simulation method based on the Smoothed Particle Hydrodynamics (SPH) approach. The results from simulations were verified by the experimental data in terms of the maximum force required to complete the process, in order to assess the applicability of the proposed method in further research on dry ice compression.
This article presents the results of a numerical experimental study on the simulation of the dry ice compaction process. The first part of the article presents a description of the material used, material models and the methodology of experimental research. In the second part, numerical and experimental study results are presented. For the purpose of comparison, a parametric method based on the residual sum of squares was used. The application of the indicated method fills the gap in the available literature as the authors are not aware of any existing data from previous studies on the method of comparing the results of numerical tests in terms of the obtained results and the change of the value of the tested parameter as a function of another variable. The results of this study can be useful in research work aimed at further development of the process of extrusion and compaction of dry ice using Drucker-Prager/Cap and modified Cam-Clay material models for instance for optimization of geometric parameters of parts and components of the main assembly of the machine used in the process of dry ice extrusion.
In the processing of waste materials, attention must be given to the efficient use of energy. The pelletization of dry ice is a good example of such processes. A literature review shows that in the pelletizers available on the market, the force applied in the process is excessive. As a result, the efficiency of the utilization of inputs, including electricity and carbon dioxide, is at a very low level. This article presents the results of experimental research on the effect of the degree of dry ice compression on the value of the Poisson ratio. The first part of this article presents the research methodology and a description of the test stand, developed specifically for this research, bearing in mind the unique properties of carbon dioxide in the solid state. The results presented show the behavior of dry ice during compression in a rectangular chamber for different final densities of the finished product. As a result, it is possible to determine the values of the Poisson ratio as a function of density, using for this purpose four mathematical models. The findings of this research may be useful for research work focused on the further development of this process, such as by using the Drucker–Prager/Cap numerical model to optimize the geometric parameters of the parts and components of the main unit of the machine used in the extrusion process of dry ice.
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