Solar energy available and energy generated in photovoltaic systems in different inclinations and orientations of roofs of buildings

This work aimed to determine the solar energy available in different inclinations and orientations of roofs of buildings in the four seasons, using data of Global Solar Irradiation in the horizontal plane, temperatures, and wind speed. The inclined hourly solar irradiation and the energy generated by photovoltaic systems of different capacities installed in Cascavel-PR were simulated, with different orientations and inclinations and types of roofs (ceramic, fiber cement and metal). SWERA (Solar and Wind Energy Resource Assessment) daily global solar irradiation and wind velocity data were used to simulate daily inclined global solar irradiation in PVSyst software. Thus, also with the help of the software, the energy generated by photovoltaic systems of different capacities installed in Cascavel - PR, with different orientations and inclinations of roofs was determined. Consequently, the levels of losses in different seasons of the year were calculated and an analysis of the economic viability of the undertakings was made. Thus, the losses, profits and income of the systems were compared. Solar panels installed in northern oriented ceramic roofs provide better energy production performance throughout the year compared to metallic roofs and fibrocement. However, for the other orientations (South, East and West), the losses for ceramic roofs were twice as high as the metallic and fibrocement roofs in relation to their respective northern orientated slopes. Regarding orientation, roofs oriented to the North receive more Irradiation annually and therefore produce more energy. Then there is East, West and South as the most unfavorable condition.

Electrospun Ceramic Nanofibers for Photocatalysis

Ceramic fiber photocatalysts fabricated by electrospinning hold great potential in alleviating global environmental and energy issues. However, many challenges remain in improving their photocatalytic efficiencies, such as the limited carrier lifetime and solar energy utilization. To overcome these predicaments, various smart strategies have been invented and realized in ceramic fiber photocatalysts. This review firstly attempts to summarize the fundamental principles and bottlenecks of photocatalytic processes. Subsequently, the approaches of doping, surface plasmon resonance, and up-conversion fluorescent to enlarge the light absorption range realized by precursor composition design, electrospinning parameter control, and proper post heat-treatment process are systematically introduced. Furthermore, methods and achievements of prolonging the lifetime of photogenerated carriers in electrospun ceramic fiber photocatalysts by means of introducing heterostructure and defective composition are reviewed in this article. This review ends with a summary and some perspectives on the future directions of ceramic fiber photocatalysts.

Catalytic Tar Conversion in Two Different Hot Syngas Cleaning Systems

Tar in the product gas of biomass gasifiers reduces the efficiency of gasification processes and causes fouling of system components and pipework. Therefore, an efficient tar conversion in the product gas is a key step of effective and reliable syngas production. One of the most promising approaches is the catalytic decomposition of the tar species combined with hot syngas cleaning. The catalyst must be able to convert tar components in the synthesis gas at temperatures of around 700 °C downstream of the gasifier without preheating. A Ni-based doped catalyst with high activity in tar conversion was developed and characterized in detail. An appropriate composition of transition metals was applied to minimize catalyst coking. Precious metals (Pt, Pd, Rh, or a combination of two of them) were added to the catalyst in small quantities. Depending on the hot gas cleaning system used, both transition metals and precious metals were co-impregnated on pellets or on a ceramic filter material. In the case of a pelletized-type catalyst, the hot gas cleaning system revealed a conversion above 80% for 70 and 110 h. The catalyst composed of Ni, Fe, and Cr oxides, promoted with Pt and impregnated on a ceramic fiber filter composed of Al2O3(44%)/SiO2(56%), was the most active catalyst for a compact cleaning system. This catalyst was catalytically active with a naphthalene conversion of around 93% over 95 h without catalyst deactivation.

Mechanical modeling of a stitched sandwich thermal protection structure with ceramic-fiber-reinforced SiO2 aerogel as core layer

Ceramic-fiber-reinforced SiO2 aerogel (CFRSA) composite was used as core layer to prepare a stitched sandwich thermal protection structure (SSTPS). Mechanical properties of the SSTPS were experimentally investigated and compared with that of CFRSA, including flatwise tension, flatwise compression, edgewise compression and shear. Research results showed that the SSTPS can greatly improve the mechanical properties of CFRSA. To further understand the non-linear, tension-compression asymmetric and transversely isotropic properties of the SSTPS, inner configurations were investigated by X-ray computed tomography and scanning electron microscopy. Mechanical models were established to predict the overall properties of the SSTPS through performance of each component, including theoretical model and finite element analysis (FEA) model. Mixed series-parallel spring models were constructed to theoretically predict the effective elasticity modulus of the SSTPS. Representative volume element (RVE) was selected for FEA modeling of the SSTPS, which can not only predict the equivalent elastic modulus of SSTPS, but also predict the nonlinear flatwise compression behavior. In order to verify whether the mechanical properties of large area SSTPS under complex stress can be represented by the properties of uniform materials through RVE analysis, four-point bending test and FEA modeling were carried out on a large scale SSTPS specimen. Results showed that when analyzing the macro bending behavior of large area SSTPS, the method of equivalent SSTPS to uniform material were of relatively high accuracy and efficiency.

Performance Comparison of Aerospace High-Temperature Resistant Ceramic Fiber Felt

Be aimed at the development and application of aerospace high-temperature resistant ceramic fiber felt, in this paper, as the common ceramic fiber felt in the field of high temperature resistance, quartz fiber felt, high silica fiber felt and mullite fiber felt were compared. The microstructure, thermal insulation, temperature resistance and mechanical properties were analyzed respectively, the performance advantages and disadvantages of three kinds of ceramic fiber felt were given, and its internal causes were studied. The results show that, the temperature resistance of mullite fiber felt is better than that of quartz fiber felt and high silica fiber felt, mainly due to its polycrystalline mullite structure, the thermal insulation performance of mullite fiber felt and high silica fiber felt is better than quartz fiber felt at high temperature, mainly due to the thermal reflection of polycrystalline mullite and the small pore structure of high silica fiber felt, the compressibility of quartz fiber felt is better than high silica fiber felt and mullite fiber felt.

Development of a System for Additive Manufacturing of Ceramic Matrix Composite Structures Using Laser Technology

Ceramic matrix composites (CMCs) are refractory ceramic materials with damage-tolerant behavior. Coming from the space industry, this class of materials is increasingly being used in other applications, such as automotive construction for high-performance brake discs, furnace technology, heat coatings for pipe systems and landing flaps on reusable rocket sections. In order to produce CMC faster and more cost-efficiently for the increasing demand, a new additive manufacturing process is being tested, which in the future should also be able to realize material joints and higher component wall thicknesses than conventional processes. The main features of the process are as follows. A ceramic fiber bundle is de-sized and infiltrated with ceramic suspension. The bundle infiltrated with matrix material is dried and then applied to a body form. During application, the matrix material is melted by laser radiation without damaging the fiber material. For the initial validation of the material system, samples are pressed and analyzed for their absorption properties using integrating sphere measurement. With the results, a suitable processing laser is selected, and initial melting tests of the matrix system are carried out. After the first validation of the process, a test system is set up, and the first test specimens are produced to determine the material parameters.

Mechanical Behavior of Reinforced Silty Sand: Focus on Application of Nano-Silica or Kaolin Coated Ceramic Fibers as a Reinforcement Material

Many studies have been done on the stabilization of weak soil using conventional chemical stabilizers such as lime, cement as well as modern materials such as nanoparticles; however, very few studies have examined the effect of coated fibers on the strength of stabilized soil. This paper presents the results of a series of direct shear tests on soil specimens treated with ceramic fiber, nanosilica, and kaolin. The effects of ceramic fibers, fiber length, nanosilica, and kaolin on the mechanical characteristics and shear strength of silty sand was investigated. The results show that the addition of fiber to silty sand resulted in a significant increase in the strength of the soil specimens. The dilative behavior of the soil specimen decreased with the addition of ceramic fibers. The cohesion of the fiber-reinforced specimens increased when the fiber surface was coated with nanosilica or kaolin particles. The friction angle of the coated fiber-reinforced specimens decreased with the addition of nanosilica particles; however, the friction angle of the coated fiber-reinforced specimens was practically independent of the kaolin content.