The existing designs of domestic and foreign matrices lack pre-compaction, plasticization and heating of dough, which leads to significant hydraulic resistance in the area where dough flow enters the forming holes of the dies and increases energy consumption, while in typical matrices the cross section of deep and empty wells is much larger than the total area of forming holes. The dough flow almost becomes uncontrollable, and this leads to water hammer effect and destruction of dies. This problem can be solved by installing special inserts in in the matrix wells (depth of wells is 50-120 mm). The paper shows a new direction in design of matrices for production of pasta, in particular, it is proposed to install spiral inserts in the wells of matrix, manufactured in the form of Venturi tubes. Rheological basis of dough flow in the cylindrical channels of the insert are considered, mathematical models for determination of the dough volume flow rate and dough flow rate are constructed. It is theoretically established that the volume flow rate of the dough Q0 and its flow rate depend on the length of the cylindrical channel and the viscosity of dough. The results of experimental researches are presented. It is empirically established that the inserts located in the wells of the matrix pre-compact dough, plasticize and heat it, the productivity of the press machine MIT-2 due to increasing the speed of extrusion is increased averagely by 25-26 % with significant improvement in quality of the formed semi-finished products and reduction of energy consumption.
The scientific basis for the design of noise suppressors for internal combustion engines with exhaust gas heat recovery, providing the release of gas flows with improved gas-dynamic and acoustic characteristics, is presented. The thermodynamic analysis of the processes of energy utilization of exhaust gases has been studied. Thermodynamic analysis showed that the utilization of exhaust gas heat leads to an increase in the coefficient of performance (COP) of the Otto cycle. An exergy analysis of heat exchange processes in the muffler was also carried out, and ways to increase its thermodynamic efficiency were determined. It has been established that a noise silencer with a heat exchanger-coil installed inside, from the position of the second law of thermodynamics, expressed by means of exergy analysis, is a more advanced thermodynamic system compared to a conventional silencer. A mathematical description of the recycling processes under conditions of external thermal exposure is given, while the nature of the influence of thermal exposure on changes in pressure, temperature and density is established. Based on the method of L.A. Vulis analytical equations for changes in pressure, temperature and density are obtained. Exhaust gas energy recovery processes contribute to a decrease in gas temperature, an increase in density, a decrease in flow velocity and a pressure drop, i.e. there is an effect (law of L.A. Vulis) of thermal stagnation of the gas flow, which causes a decrease in the noise level with less back pressure and an increase in engine efficiency.
A new design of the pressing unit is proposed, which uses a processing center for controlling the flow of pasta dough in the pre-matrix chamber of the optimal configuration. The internal configuration of the pre-matrix chamber is made in the form of a Venturi pipe, while the pipe is connected to the rod chamber by a confuser, and the diffuser is connected to the forming holes of the matrix, i.e. the mechanism for using the pre-matrix space for pre-compaction, plasticization and heating of the dough is implemented Laboratory experiments on the MIT-2 press machine for the production of pasta using a Venturi pipe gave positive results, and the expected economic effect due to increasing the productivity of the press, reducing specific energy consumption while improving the quality of products is about 20%.
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