A И-Shaped Curve of Hot Tearing Susceptibility in Magsimal®-59-Based Alloys

The hot tearing susceptibility of Al-6Mg-xSi (x = 0-6.0 wt.%) alloys was studied using constrained rod casting. Addition of Si content resulted in double ternary eutectic reactions and then changed the freezing range and eutectic liquid fraction greatly, which made the hot tearing susceptibility show a И-curve with the increasing of Si content. The И-curve was obviously different from the λ-curve that supported by most researchers.

Manufacturing of Hybrid Al-Cu-Heatsinks by Combining Powder Pressing with Thixoforming

Hybrid material structures allow different material properties to be combined in one single component and thus to meet high functional requirements. When manufacturing such hybrid components, particular attention must be paid to the transition zones between metallic composite partners. These transition zones need to show largely homogeneous and materially bonded structures in order to ensure ideal transmission of the material properties and to prevent component failure due to material defects. In this respect, this paper focuses on a newly developed process in which a powder metallurgical route is combined with semi-solid forming technology. Here, porous copper green bodies are inserted into a forming die and subsequently forged together with a semi-solid aluminium alloy. In this way, it was tried to combine both metal materials into a material locking or at least into a form locking manner in order to achieve ideal material properties in the final hybrid component. The aim of this paper is to find suitable process parameters to infiltrate the porous copper inlay with the semi-solid aluminium alloy during thixoforming. Therefore, different process parameters such as varying liquid fraction of the aluminium alloy and different densities of the green bodies were examined during the production of simply shaped hybrid Al-Cu-components. Afterwards the infiltration depth and produced microstructure of the components was analysed. In the future, this process allows for producing aluminium-copper hybrid heat sinks with improved heat transfer properties compared to conventional produced heat sinks.

Impact of Simulated Human Gastrointestinal Digestion on the Bioactive Fraction of Upcycled Pineapple By-Products

Pineapple by-products (peels and stems) from fruit processing industries were evaluated to understand its potential application as a functional food. Therefore, the bioactive compounds of pineapple by-products were characterized for prebiotic and antioxidant activities. A total characterization of soluble carbohydrates profile (simples and complex carbohydrates), as well as polyphenols was performed, after removal of enzymatic fraction from pineapple crude juice, allowing the decrease of proteolytic activity and improving the other biological activities. Results showed that pineapple liquid fraction, from stem and peels, can be applied as a prebiotic enhancer, promoting the growth of five probiotic microorganisms (two strains of Lactobacillus sp. and three strains of Bifidobacterium sp.), as a single carbohydrate source. Moreover, through HPLC (High Performance Liquid Chromatography) analysis, 10 polyphenols were identified in pineapple liquid fractions, with some expected differences between both evaluated by-products. Gastrointestinal tract was simulated, in a continuous mode to understand the impact of pH changes and gastrointestinal enzymes into pineapple liquid fractions. Results showed a digestion of high molecular weight polysaccharides into small molecular weight tri-, di-, and monosaccharides. There was an increase of samples antioxidant activity through the gastrointestinal stage, followed by the release of specific polyphenols, such as chlorogenic, coumaric, and ferulic acids. The prebiotic activity did not improve throughout the simulation, in fact, the prebiotic potential decreased throughout the different stages.

Ultrasound Assisted Pretreatments Applied to Cupuaçu Husk (Theobroma grandiflorum) from Brazilian Legal Amazon for Biorefinery Concept

Cupuaçu husk (CH) is the waste of a common fruit from a native species of the Brazilian Legal Amazon. The current study investigated the influence of ultrasound (US) combined with aqueous, acid, alkaline, and ionic liquid (IL) pretreatments on the chemical and physical aspects of CH and the yield of chemical platforms production, 5-hydroxymethylfurfural (HMF) and furfural (FF), using IL. Scanning electron microscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy were used to feature the raw and pretreated biomass. The highest levels of glucose (9.90 g L-1) were observed in the liquid fraction resulting from the acid + US pretreatment followed by acid hydrolysis. The IL + US pretreatment recorded the best performance in removing lignin. Based on XRD analyses, ultrasound increased crystallinity of all pretreated samples as a result of the removal of cellulose’s amorphous fraction. However, it promoted accessibility to adopted reagents by increasing biomass exposure due to cavitation. The best yields of HMF and FF were recorded from hydrolysis of the solid fraction resulting from the acid + US (12.94%) and alkaline + US (48.84%) pretreatment, respectively. These results indicate satisfactory performance of ultrasound assisted pretreatments to the simplified and economic conversion of biomass into value-added products.

Enhanced Heat Transfer for NePCM-Melting-Based Thermal Energy of Finned Heat Pipe

Using phase change materials (PCMs) in energy storage systems provides various advantages such as energy storage at a nearly constant temperature and higher energy density. In this study, we aimed to conduct a numerical simulation for augmenting a PCM’s melting performance within multiple tubes, including branched fins. The suspension contained Al2O3/n-octadecane paraffin, and four cases were considered based on a number of heated fins. A numerical algorithm based on the finite element method (FEM) was applied to solve the dimensionless governing system. The average liquid fraction was computed over the considered flow area. The key parameters are the time parameter (100 ≤t≤600 s) and the nanoparticles’ volume fraction (0%≤φ≤8%). The major outcomes revealed that the flow structures, the irreversibility of the system, and the melting process can be controlled by increasing/decreasing number of the heated fins. Additionally, case four, in which eight heated fins were considered, produced the largest average liquid fraction values.

Replacing Mineral Fertilisers for Bio-Based Fertilisers in Potato Growing on Sandy Soil: A Case Study

The refinement level of bio-based fertilisers (BBFs) can influence environmental and agronomic performance. This study analyses the environmental and agronomic effect of different BBFs on potato growing in sandy soil. A less refined product (liquid fraction of digestate (LFD)), two refined products (ammonium sulphate (AS) and potassium concentrate (KC)), and mineral fertilizer (MF) are compared by conducting: (i) a nitrogen (N) incubation experiment where the N release rate of the BBFs is determined, (ii) a greenhouse gas emission experiment where N2O, CO2, and CH4 emissions after BBF application are measured, (iii) a pot experiment where the nutrient fertiliser replacement value (NFRV) of the BBF is calculated, and (iv) a full-scale field trial where the potato quality and quantity and the remaining N residues in the soil after harvest are assessed. The N release rate and the NFRV of AS (142 ± 19% and 1.13, respectively) was higher compared with the LFD (113 ± 24% and 1.04) and MF (105 ± 16% and 1.00). Lowest N2O emissions were observed after the application of the less refined product (0.02 ± 0.01 per 100 g N applied) and highest for MF urea (0.11 ± 0.02 per 100 g N applied). In the full-scale field trial, no significant difference in potato yield was observed in the plots that received manure in combination with BBF or MF. This study showed that all three BBFs can safely be used in potato growing on sandy soils. However, the adoption of BBFs can be stimulated by (i) solving the practical issues that occurred during the application of LFD, (ii) making sure BBFs are on the list of RENURE materials so they can legally replace mineral fertiliser, and (iii) reducing the surplus of slurry manure to stimulate the use and fair pricing of BBF products.

Production and characterization of bio-oil from algae using pyrolysis

Pyrolysis of the algae (chlorophyceac) was carried out using fixed bed reactor at 4500C. The mass balance of the pyrolysed algae were liquid fraction (oil) (10%), gaseous product (11%), solid product (char) (79%) and extent of conversion (21%. The proximate analysis of powdered sample was carried out in accordance with the official method of analytical chemistry (AOAC). The moisture content, ash content, volatile matter and fixed carbon determined were 3 + 0.33, 70.3 + 0.5, 6.3 + 0.3 and 20.2 + 0.07 respectively. The result obtained indicate that algae (chlorophyceae) could be used as feedstock for generation of pyrolysed oil which could probably be upgraded to fuel for both domestic and industrial purposes.

Oil Recovery from Dry Grind Ethanol Plant Coproducts Using Ethanol

Corn ethanol bio-refineries are seeking economic processing strategies for recovering oil from their coproducts. The addition of ethanol can be an efficient method to recover the oil from the coproducts as the industry has available ethanol. This study considered the effects of ethanol on oil recovery from distillers’ dried grains with solubles (DDGS) and oil partitioning from whole stillage (WS) on a laboratory scale. Ethanol was added with original and heavier fraction DDGS in different temperatures (room temperature ~20 °C, 30 °C, 40 °C, and 50 °C) and solids loadings (20%, 30%, and 40%), and their effects on oil recovery were evaluated. The whole stillage was incubated with ethanol at room temperature (~20 °C) and 50 °C separately to analyze WS’s oil distribution in the liquid and solid phases. The amount of recovered oil from the original and heavier fractions of DDGS varies from 25–45% and 45–70%, respectively, with an increment of temperature. Increasing solids loadings up to 30% had no effect on oil recovery from either DDGS sample. Ethanol treatment in WS resulted in 8–10% higher wet yield of liquid fraction and 17–20% of oil increase in liquid fraction than the control treatment. It is also notable that temperature positively impacted oil partitioning from WS. The results showed that ethanol could improve oil recovery from DDGS and oil partition in WS by varying different process conditions. This outcome is beneficial to ethanol plants to increase corn oil yield using their existing setup and in-situ product.

Investigation of Optimal Aspect Ratio and Optimal Number of Fins for Thermal Performance of Finned-Concentric-Tube Thermal Energy Storage

This research focuses on the enhancement of the heat transfer in the concentric tube type of thermal energy storage (TES). The collective influence of the aspect ratio and number of fins is investigated. First, an optimal aspect ratio of the concentric tube TES is found. Additionally, then, the optimal number of fins is found. This combined optimal configuration of TES is then compared with concentric tube TES without. Liquid fraction of the combined optimal configuration was increased by 100% for case of charging as compared to TES without fins.