Electro-spraying and catalytic combustion characteristics of ethanol in meso-scale combustors with steel and platinum meshes

© 2018 Elsevier Ltd An experimental study on electro-spraying and catalytic combustion of ethanol at meso-scale is carried out. The electro-spraying process of ethanol is visualized and four typical spraying modes are identified. Based on droplet size measurements by a Phase Doppler Anemometer, the spraying at the cone-jet or multi-jet mode is suitable for meso-scale combustion. Two meso-combustors without and with the platinum catalyst, denoted as combustor A and combustor B, respectively, are designed to conduct the comparative experiments. The flame temperature at the cone-jet mode is higher than those at other modes when equivalence ratio φ = 1.0, and for the combustor with catalyst, fuel-lean conditions are favorable for stable combustion. It is also found that the carbon monoxide mole fraction in the exhaust decreases by at least 25% due to the catalytic effect. At the cone-jet electro-spraying mode, the combustion efficiencies of ethanol reach the highest value for both combustor A and combustor B due to smaller droplet size and more uniform droplet size distribution. Under the same conditions, combustion efficiency of ethanol can be improved by 4.5% for combustor B, which proves that the platinum catalyst can accelerate the decomposition of ethanol

Thermal performance of a meso-scale combustor with electrospray technique using liquid ethanol as fuel

A new meso-scale combustor designed to couple with energy conversion modules is fabricated. The volume of the combustor is of the order of a few cubic centimeters. Liquid ethanol is electrosprayed at a flow rate of 3.50 ml/h. The stable flame is observed to be in a disc shape near the mesh of the combustor when the equivalence ratios varying from 0.9 to 1.7 without external heating and catalyst. The temperatures of flame, combustor outer wall and exhausted gas are measured. Flame temperatures are within the range of 1134–1287 K. Exhausted gas components are detected by a gas chromatograph and the combustion efficiencies of ethanol are calculated, which are from 51.2% to 92.4%. Heat loss from the combustor wall is evaluated and it accounts for 29.2–43.6% of the input energy. The outer wall temperature distributions along the flow direction are obtained and a heat recirculation zone is found at about 10 mm away in the upstream of the mesh, which is beneficial to stable combustion. The mesh in the present combustor is used not only as a collector for gathering charged droplets but also a flame holder. The thermal efficiencies of the combustor are found to vary from 22.0% to 48.8%

Nanoindentation on micromechanical properties and microstructure of geopolymer with nano-SiO<inf>2</inf> and nano-TiO<inf>2</inf>

Fly ash-based geopolymers incorporated with 2% nano-SiO2 (NS)/nano-TiO2 (NT) particles were subjected to microstructural and statistical nanoindentation analysis. With the addition of both types of nanoparticles, the compressive strength of geopolymer and the micromechanical properties of N-A-S-H gel were increased. NS exhibited higher reinforcement effect than NT on macro-strength. However, NT more significantly enhanced gel micromechanical properties. NT and especially the NS were found to have a positive effect on the early reaction rate of geopolymer. After 28 days, the gel proportion obtained by Backscattered electron (BSE) images analysis was close values of 49.16%, 55.69% and 54.02% for reference sample and NS, NT reinforced geopolymer, which were more than two times of that from the statistical nanoindentation. The effects of NS and NT on microstructure, gel proportion and gel micromechanical properties were discussed to reveal the macro-strength reinforcement mechanism. The results obtained from different techniques were also compared and discussed

Natural SQL: Making SQL Easier to Infer from Natural Language Specifications

Addressing the mismatch between natural language descriptions and the corresponding SQL queries is a key challenge for text-to-SQL translation. To bridge this gap, we propose an SQL intermediate representation (IR) called Natural SQL (NatSQL). Specifically, NatSQL preserves the core functionalities of SQL, while it simplifies the queries as follows: (1) dispensing with operators and keywords such as GROUP BY, HAVING, FROM, JOIN ON, which are usually hard to find counterparts for in the text descriptions; (2) removing the need for nested subqueries and set operators; and (3) making schema linking easier by reducing the required number of schema items. On Spider, a challenging text-to-SQL benchmark that contains complex and nested SQL queries, we demonstrate that NatSQL outperforms other IRs, and significantly improves the performance of several previous SOTA models. Furthermore, for existing models that do not support executable SQL generation, NatSQL easily enables them to generate executable SQL queries, and achieves the new state-of-the-art execution accuracy

Antioxidant N-acetylcysteine attenuates the reduction of brg1 protein expression in the myocardium of type 1 diabetic rats

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