Insight - Mechanics

Evaluating the efficiency of renewable energy technologies through thermodynamic analyzes

Yasin Furkan Gorgulu — 2023-11-08

Renewable energy systems hold the key to a sustainable energy future, and at their core lies the pivotal influence of thermodynamics. This article comprehensively explores the fundamental thermodynamic principles that underpin renewable energy technologies, providing a robust foundation for understanding and optimizing their performance. In the context of renewable energy, temperature differentials drive energy flows, pressure and volume changes play crucial roles, and the conservation of energy is paramount. The Second Law of Thermodynamics, represented by entropy, guides the direction of natural processes within these systems. Exergy, a related concept, assesses the quality of energy within a system, facilitating efficiency evaluations. Renewable energy systems often operate on thermodynamic cycles, forming the basis for technologies like solar power plants and geothermal facilities. Heat transfer mechanisms, including conduction, convection, and radiation, are integral to these systems and influence their design and operation. This article summarizes these thermodynamic fundamentals in the context of renewable energy, offering insights into the principles that drive efficiency and sustainability. Understanding these principles is crucial for harnessing renewable energy’s full potential and aligning with global efforts to transition toward cleaner and more sustainable energy sources.

Low-cost heterogeneous composite photocatalyst consisting of TiO2, kaolinite and MMT with improved mechanical strength and photocatalytic activity for industrial wastewater treatment

Pitipanage Pasindu Bhanuka Gunarathne — 2023-11-10

The industrially feasible TiO₂-clay-based photocatalysts are essential to overcome practical barriers that are inherent to currently available TiO₂-based photocatalysts. The current study demonstrates the fabrication of heterogeneous photocatalyst using TiO₂, kaolinite, and montmorillonite (TKMCP), which has shown improved catalytic activity and mechanical strength, resulting in an industrially feasible photocatalyst. The TKMCP is prepared in a cost-effective manner using 60% TiO₂ and 40% clay with different kaolinite to MMT ratios (1:3 TKMCP1, 1:1 TKMCP2, and 3:1 TKMCP3) by employing mechanical compression and dehydroxylation. The clay ratio predominantly determines the TKMCP mechanical strength and photocatalytic efficiency, where the lowest MMT percentage results in a uniform matrix, in which TiO₂ particles are embedded on clay-sheets. The TKMCP surface became uniform when the MMT percentage is low, whereas a high MMT fraction results in a disordered catalytic surface due to large clay fragments and agglomerates. All three composites accounted for more than 85% of the degradation rate, exhibiting pseudo first order kinetics, resulting in high-rate constants, with the highest observed for TKMCP3, which is 1.55 h^–1. The TKMCP3 accounts for the highest mechanical strength, which is 5.83 MPa, while the lowest is observed with TKMCP1, indicating that the TKMCP strength decreases significantly with high MMT fraction. TKMCP has several advantages, including easy fabrication, low cost, free of hazardous chemicals, high production capacity with minimal machinery/supervision, non-self-degradability, easy disposal, easy installation in pilot-scale reactors, compatibility with both batch and flow reactors, environmental, and user-friendliness. TKMCP can also be obtained in variable sizes and shapes that ensure dynamic wastewater treatment applications.

ZA models of neutron and proton in scale electric field originated by the Planck particle

Bernie Yaping Zong — 2023-08-29

A new ZA matter model has been established to explain why mass has the instinct property of electricity. It is shown that the pure energy particle to originate matter is an electric pulse called ZA0 and it was proved being the Planck particle. Matter formation was derived by theoretical analysis based on a suggested binary growth law of quantum mechanics. It is found that there is a smallest matter particle called as ZA1 with a same format of ZA0 but different size to form any other matter particles. Structures of electron, neutron and proton have been suggested and prediction of their mass meets experiments wonderfully. It was found that matter mass consists of two parts: one (a scale electric field) is electric pure mass coming from motion energy of the photon in minimum size and the other (the overlapped gravity field) coming from potential energy of the bent space. Sizes of basic matter particles were discussed based on the particle nature of isolated electric field. The size predictions can explain the weird experimental phenomenon that size of an electron is significantly larger than that of a neutron. It was found that electric charges in micro scale like γ-ray are represented at the zero potential nodes by opposite two momentum directions. It is shown by photoelectric effect experiments that electric force in micro by ZA model in form of light can be exchanged into the macro electric force to drive electrons in macro current. The proton ZA model can be applied to explain why many protons can be collaborated in a nucleus as the reactive binding force between protons and neutrons can overcome the electric repelling force between positive charges.

A model for polyatomic gases with hyperbolicity and H-theorem satis- fied up to whatever order

Sebastiano Pennisi — 2023-12-04

A relativistic model for polyatomic gases with an arbitrary but fixed number of moments is well- known in the literature. The model’s balance equations have symmetric hyperbolic form in their left-hand sides because the tensors that derivated with respect to x^α are gradients of a 4-potential. Here, the symmetric form and a 4-potential are obtained for their right-hand side also, i.e., the production terms. Moreover, this will allow us to prove the H-theorem up to whatever order, while in other articles present in the literature, this result was achieved only up to the second order concerning equilibrium. These obtained results can be derived by either following the Eckart approach or the Landau-Lifshitz one.

Numerical study of mass and heat transport within a ceramic porous tank

Ramzi Rzig — 2023-09-07

In porous media, the thermal transfer phenomenon is widely applied in diverse energy-intensive industrial processes. This research paper aims to elucidate the simultaneous transfer of mass and heat within a ceramic porous tank. To simulate these transport phenomena, a numerical method is developed: Control Volume Finite Element Method (CVFEM), in conjunction with the utilization of a free mesh generator called Gmsh. The study showcases numerous simulation results that depict the transport phenomenon, such as the three-dimensional evolution of three parameters (temperature, saturation and pressure) during the heating of the ceramic tank. By employing this numerical model, a more comprehensive comprehension of these transport phenomena can be achieved.

Development of pressure infiltration preparation of metal matrix composites

Haofeng Zhao — 2023-08-16

This paper summarizes the process of metal matrix composites from pressure infiltration preparation to pressure ultrasonic assisted infiltration to pressure solvent assisted infiltration. The advantages of preparing metal matrix composites by pressure infiltration alone are low cost and convenient for mass production. However, the equipment and process requirements are too high, and the quality of composite materials can not be guaranteed. Because of the high pressure of ultrasound, ultrasonic infiltration has become an auxiliary physical method for the preparation of metal matrix composites by pressure infiltration. But this method tends to damage the fibers. Therefore, the fibers need to be coated. The coating on the fiber surface is divided into metal coating and non-metal coating. Some people mixed SiC particles or whiskers in continuous carbon fibers to prepare aluminum alloy composite materials, forming a hybrid assisted infiltration method. Later, people began to pay attention to the flux-assisted role of pressure infiltration. Therefore, solvent-assisted infiltration of fiber-reinforced metal matrix composites has become an important research field.

Impulse as a true measure of inertia

Valeriy Abramovich Etkin — 2023-09-12

Based on the system-energodynamic method of analyzing natural and technological processes, the necessity of abandoning the paradigm of homogeneity and isotropy of space filled with matter is substantiated, and a retrospective analysis of the state of mechanics is given. The principles of the determinism of the state and the opposite direction of processes in inhomogeneous (internally non-equilibrium) systems are formulated and proved. The inevitability of the emergence of an oscillatory form of energy in them and the need to consider the latter in the law of its conservation are revealed. In this way, the necessity and possibility of generalizing all three “beginnings” of Newton’s mechanics and considering irreversibility in its equations with the introduction of the “force” efficiency of mechanical processes are shown. The non-equivalence of the momentum to Descartes’ momentum is revealed, and the invariance of the mass in acceleration is proved. It is shown that the true measure of the inertial properties of a substance is the impulse, not the mass, and a generalization of the concept of inertia to non-mechanical forms of motion is proposed. The principle of interconvertibility of the oscillatory, translational, and rotational components of the impulse of internal motion in isolated systems is proved, and thus the possibility of creating a new class of propellers in outer space on this basis is substantiated.