This study conducts a comparative performance analysis of three different low-temperature solar collector systems: flat plate solar collectors (FPCs), heat pipe evacuated tube solar collectors (HPETCs), and heat pipe flat plate solar collectors (HPFPCs). Key performance parameters, such as heat transfer coefficients, useful heat, and thermal efficiency, are analyzed under varying mass flow rate, fluid temperature, and antifreeze concentration. The objective is to evaluate the thermal performance of these systems using different heat transfer fluids, specifically water, and mixtures of 30% and 50% ethylene glycol and propylene glycol. The performance data indicate that the heat transfer coefficient in the HPFPC diminishes by 28% and 41% when antifreeze is employed at concentrations of 30% and 50%, respectively. Furthermore, the integration of heat pipes with water in a flat plate solar collector results in efficiency enhancements, with respect to FPCs, of up to 13% at a fluid temperature of 30 °C, and up to 21% at 80 °C. At the elevated fluid temperature of 80 °C, an efficiency increase of 13% is observed with a 30% ethylene glycol concentration. The incorporation of heat pipes leads to an efficiency improvement of up to 6.5% in comparison to traditional flat plate solar collectors. This study highlights the significant impact of fluid properties, affecting the convective heat transfer coefficient, on the overall efficiency of solar collectors, emphasizing the importance of optimizing fluid composition and operating conditions for enhanced thermal performance.

A concept for the design of energy absorber system is presented, which consist basically of tube type structural elements coupled. The system considers the absorbed energy for levels of kinetic energy corresponding to similar fall arrest systems used to prevent injuries during fall incidents. The energy dissipation in the proposed passive system is developed by means of mechanical contact, friction phenomena and plastic strain. The analysis of conditions in the system is supported by the finite element software Abaqus, which permits the simplification of the body fall process. The application of structural elements in the system is based in its mechanical characteristic for energy dissipation by deformation. Plastic deformation in structural tubes is an irreversible process, which is a desirable condition for fall arrest systems. Finally, the numerical results to show the dissipation of kinetic energy in the proposed system are presented.

In this work, the tensile behaviour of an isolated maguey manso cuticle is studied from an engineering perspective. The maguey manso is a plant in the Agavaceae family that grows in the semi-dry and cold Central Valley of Mexico, among the States of Mexico, Hidalgo, Puebla and Tlaxcala. The leaves of a maguey, known as pencas, are formed basically by sap, fibers along their full length, and the cuticle. It was found that the maguey cuticle behaves as a viscoelastic material. Once the tensile stress is reached, the cuticle breaks catastrophically in a brittle way. Scanning electron microscopy reveals that the complex and homogeneous microstructural arrangement of stomata in the cuticle contributes to anisotropic and brittle crack propagation behaviour, due to preferential stomatal alignment.