Exploration of a new affordable thermal protection system utilizing 2.5D silica/polysiloxane composite

Ablative materials are used as thermal protection systems (TPS) for reentry vehicles and solid rocket motor (SRM) nozzle applications. Phenolic and cyanate ester are the state-of-the-art (SOTA) resin systems used in many of the ablative composites today, including MX-2600 (silica/phenolic) from Cytec Solvay Group. While these ablatives have worked well, more demanding requirements drive the need for affordable lightweight advanced composites capable of handling high heat fluxes with minimal mass loss. These advanced ablative composites result in lighter reentry heat shields and solid rocket motors, increasing payload capabilities of spacecraft and rockets. Molding compound made of aerospace grade 99% SiO2 fabric and polysiloxane resin showed considerable improvement over MX-2600 in ablation properties in recent studies. In order to meet increased mechanical strength demands, NASA recently developed an ablative composite using a 3D quartz woven/cyanate ester composite material designed for the Orion spacecraft. While 3D woven composites provide excellent out-of-plane mechanical and ablation properties, they are very expensive, which limits their application. This research explores needle-punched silica fabric, sometimes referred to as 2.5D, which provides similar out-of-plane mechanical benefits to 3D woven composites in a more flexible VARTM manufacturing process at a much lower cost. The needle-punched silica fabric was infiltrated with polysiloxane resin and mechanical tests were performed. The needle-punched composites showed an increase of 181% in flexural strength, 27% in interlaminar shear strength, 2% in tensile strength, and 13% in compressive strength. In aerothermal ablation tests, the 2.5D out-performed the 2D laminate in char yield, mass loss, and recession rate; and in char yield and mass loss (%), the 2.5D out-performed the industry standard MX-2600 molding compound. The increased out-of-plane strength and char yield make it a promising and affordable ablative candidate for ablation performance with enhanced mechanical properties.

Validation of MATLAB algorithm to implement a two-step parallel pyrolysis model for the prediction of maximum %char yield

Numerical modeling of biomass pyrolysis is becoming a cost and time-saving alternative for experimental investigations, also to predict the yield of the by-products of the entire process. In the present study, a two-step parallel kinetic model was used to predict char yield under isothermal condition. MATLAB ODE45 function codes were employed to solve a set of differential equations that predicts the %char at varying residence times and temperatures. The code shows how the various kinetic parameters and mass of pyrolysis products were determined. Nevertheless, the algorithm used for the prediction was validated with experimental data and results from past works. At 673.15 K, the numerical simulation using ODE45 function gives a char yield of 27.84%. From 573.15 K to 673.15 K, char yield ranges from 31.7 to 33.72% to 27.84% while experimental yield decreases from 44 to 22%. Hence, the error between algorithm prediction and experimental data from literature is − 0.26 and 0.22. Again, comparing the result of the present work with the analytical method from the literature showed a good agreement.

Hydrothermal Treatment of Herb Residue for Solid Fuel Production

Hydrothermal processing is appraised as one of advanced technologies for wet solid waste handling. In this study, herb residue was subjected to hydrothermal treatment. Calorific value, yield, and also proximate analysis of obtained hydro-char were investigated. A cylindrical reactor with an internal volume of 2.5 Litres made of stainless steel and a low-tech component was used in the experiment. The reactor was equipped with a stirrer to ensure heat transfer took place through the entire parts of the solid-water mixture. Solid products were dried by a microwave oven before analysis. The results show that the final temperature, holding time, and solid-water ratio have various effects on the hydro-char yield, calorific value, and proximate analysis of the hydrothermal products. The hydro-char yield decreased with the increase in final temperature and holding time. Meanwhile, the highest hydro-char yield was obtained at the solid-water ratio of ¼. The hydro-char calorific value increased with the increase in final temperature, holding time, and solid-water ratio. The rise in final temperature, holding time, and solid-water ratio resulted in a lower moisture content and volatile matter but higher fixed carbon. Meanwhile, the ash content increased with the solid-to-water ratio.

In-Situ Catalytic Pyrolysis of Spirulina platensis residue (SPR): Effect of Temperature and Amount of C12-4 Catalyst on Product Yield

Currently, dependence on fossil energy, especially petroleum, is still high at 96% of the total consumption. One solution to overcome fossil energy consumption is processing alternative energy sources derived from microalgae biomass. This study aims to study the pyrolysis of microalgae with the addition of the C12-4 (Cr2O3+Fe2O3+C+CuO+promoter) catalyst. The biomass used in this study was Spirulina platensis residue (SPR). This study used a fixed bed reactor with an outer diameter of 44 mm, an inner diameter of 40 mm, and a total reactor height of 600 mm. The C12-4 was mixed fifty grams of SPR with a particle size of 100 mesh with a ratio variation of 5, 10, and 15 wt.%. The feed mixture was placed in the reactor (in-situ), and the reactor was tightly closed. The nickel-wire heater wrapped around the reactor wall was employed. The pyrolysis heating rate was 24.33 °C/min on average, and the temperatures were varied as 300, 400, 500, 550, and 600 °C. The research found that the optimum temperature conditions without and with the catalyst to produce bio-oil were different. The pyrolysis without any catalyst (500 ⁰C), with a catalyst of 5 wt.% (500 ⁰C), 10 wt.% (400 ⁰C), and 15 wt.% (550 ⁰C) produced the bio-oil yield of 15.00, 17.92, 16.78 and 16.54, respectively. The use of 5, 10, and 15 wt.% catalysts increased the water phase yield. The char yield was influenced by the amount of catalyst only at 300 ⁰C; i.e., the more catalysts, the less char yield. The pyrolysis without any catalysts produced the highest gas product. A catalyst significantly increased the pyrolysis conversion from 48.69 (without catalyst) to 62.46% (15. wt.% catalyst) at a temperature of 300 ⁰C. The optimum conditions for producing the best bio-oil were at 600 °C and 10 wt.% of catalysts, which resulted in an O/C ratio of 0.14.Keywords: C12-4 catalyst, in-situ catalytic pyrolysis, Spirulina platensis residue, yield bio-oilA B S T R A KKetergantungan terhadap energi fosil khususnya minyak bumi, saat ini masih tinggi yaitu mencapai 96% dari total konsumsi. Salah satu solusi untuk mengatasi ketergantungan energi fosil adalah dengan mengolah sumber energi yang berasal dari biomassa mikroalga. Penelitian ini bertujuan untuk pirolisis mikroalga dengan penambahan katalis C12-4 (Cr2O3 + Fe2O3 + C + CuO + promotor). Sampel yang digunakan adalah residu Spirulina platensis (SPR). Penelitian ini menggunakan reaktor unggun tetap dengan diameter luar 44 mm, diameter dalam 40 mm, dan tinggi reaktor 600 mm. Spirulina platensis dengan ukuran partikel 100 mesh sebanyak 50 gram dicampur dengan katalis C12-4 dengan variasi 5, 10, dan 15 wt.%. Campuran umpan (in-situ) dimasukkan ke dalam reaktor dan ditutup rapat. Pemanas menggunakan arus listrik melalui kawat nikel yang dililitkan pada dinding reaktor. Laju pemanasan pirolisis rata-rata 24,33 °C/menit, variasi suhu 300, 400, 500, 550, dan 600 °C. Kondisi optimum tanpa dan dengan katalis untuk menghasilkan bio-oil memiliki nilai yang berbeda yaitu pirolisis tanpa katalis (500 ⁰C), dengan katalis 5 wt.% (500 ⁰C), 10 wt.% (400 ⁰C) dan 15 wt.% (550 ⁰C) menghasilkan bio-oil 15,00; 17,92; 16,78; dan 16,54. Penggunaan katalis 5, 10, dan 15 wt.% berat dapat meningkatkan fasa air hasil. Yield char dipengaruhi oleh jumlah katalis hanya pada 300 ⁰C, semakin banyak katalis maka yield char semakin menurun. Pirolisis tanpa katalis menghasilkan produk gas tertinggi. Penggunaan katalis sangat signifikan dalam meningkatkan konversi pirolisis dari 48,69 (tanpa katalis) menjadi 62,46% (katalis 15 wt.%) pada suhu 300 ⁰C. Kondisi optimum untuk menghasilkan minyak nabati terbaik adalah pada 600 °C dengan katalis 10% berat, menghasilkan rasio O/C sebesar 0,14.Kata kunci: C12-4 catalyst, in-situ catalytic pyrolysis, Spirulina platensis residue, yield bio-oil

Rheological and Antimicrobial Properties of Silica and silver Nanoparticles-reinforced K-carrageenan/hydroxyethyl Cellulose Composites for Food Packaging Applications

Sustainable food packaging films were developed using a combination of k-Carrageenan (C), hydroxyl ethyl cellulose (H), silicon dioxide (SiO2), and silver (Ag) nanoparticles. The CH-SiO2/Ag nanocomposites showed promising results, mainly due to their transparency, flexibility, low cost, and environmental friendliness. The structure and uniform morphology of the CH-SiO2/Ag nanocomposites were determined by FT-IR, XRD, and SEM analysis. Barrier properties (water vapor permeability-WVP), thermal properties (T5% loss, char yield), and mechanical properties determined for the CH and CH-SiO2/Ag nanocomposites, which improved by 3.3–1.9 ×10− 9gm/m2 Pas (WVP), 59.1-115.7 oC (T5%), 13.4–29.3 % (char yield), 23.8–41.5 MPa(tensile strength), and 22.3–28.9 (EB), respectively. The contact angles of the CH-SiO2/Ag nanocomposites were in the range of 60.1–76.4. The UV transmittance of the CH composites decreased with the addition of SiO2 and Ag nanoparticles. However, the transparency of the composites was not affected, and it inhibited UVA and UVB rays by the addition of Ag nanoparticles. The viscosity of the CH composites increased with the SiO2 content and decreased with the shear rate. All the composites exhibited shear-thinning behavior. The storage modulus of the prepared composites is higher than the loss modulus in the entire frequency region. Overall, SiO2 and Ag nanoparticles improved the hydrophilic nature of the CH-SiO2/Ag films and showed significant activity against six common food pathogens, Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Bacillus subtilis, Salmonella typhi, and Cronobacter sakazakii. The synergistic combination of CH-SiO2/Ag nanocomposite has potential for packaging and other biomedical applications.

Optimization of Slow Pyrolysis of Bamboo for Biochar Production using Taguchi’s L9 Orthogonal Array

This paper investigates the effects of three parameters (reaction temperature, feedstock particle size and nitrogen flow rate) towards the solid (char) yield from the pyrolysis of bamboo. Three-factor, three-level Taguchi’s L9 Orthogonal Array was used as the experimental design. The char yield at reaction temperatures of 300-500°C, feedstock particle size of 100-1000 μm, and nitrogen flow rate of 100-300 ml min−1 were investigated. The maximum solid yield was predicted based on signal-to-noise (S/N) ratio and was found to be at 300°C reaction temperature, 1000 μm feedstock particle size and 100 ml min−1 of nitrogen flow rate. Confirmation runs were conducted to validate the prediction at corresponding predicted conditions.