This paper aims to identify performance improvements in cooker-top gas burners for changes in its original geometry, with aspect ratios (ARs) ranging from 0.25 to 0.56 and from 0.28 to 0.64. It operates on liquefied petroleum gas (LPG) and five thermal power (TP) levels. Considering the large number of cooker-top burners currently being used, even slight improvements in thermal performance resulting from a better design and recommended operating condition will lead to a significant reduction of energy consumption and costs. Appropriate instrumentation was used to carry out the measurements and methodology applied was based on regulations from INMETRO (CONPET program for energy conversion efficiency in cook top and kilns), ABNT (Brazilian Technical Standards Normative) and ANP—National Agency of Petroleum, Natural Gas (NG) and Biofuels. The results allow subsidizing recommendations to minimum energy performance standards (MEPS) for residential use, providing also higher energy conversion efficiency and/or lower fuel consumption. Main conclusions are: (i) Smaller aspect ratios result in the same heating capacity and higher efficiency; (ii) higher aspect ratios (original burners) are fuel consuming and inefficient; (iii) operating conditions set on intermediate are lower fuel consumption without significant differences in temperature increases; (iv) Reynolds number lower than 500 provides higher efficiencies.

A qualidade internacional do aço brasileiro é a razão do uso de carvão vegetal no processo siderúrgico, com Mato Grosso do Sul - o maior produtor nacional em 2011 (~356 mil toneladas). O objetivo deste artigo é avaliar a qualidade energética deste biocombustível sólido oriundo de madeiras de espécies nativas (supressão vegetal, sem desmatamento) e disponibilidade geográfica, para atender a demanda regional das indústrias siderúrgicas, cerâmicas, energéticas e afins. A metodologia considerou base de dados do IBGE (2007-2016), determinação de qualidade (PCS, análises imediata e elementar) e comparação com parâmetros do carvão vegetal de outras espécies nativas, plantadas e de biomassas residuais. Resultados indicam: a) MS é um dos quatro maiores produtores anuais, e o segundo maior produtor nacional (2007-2016); b) microrregiões mais produtivas são “Aquidauana” (~21%) e “Três Lagoas” (~23%); c) distribuição geográfica da produção atual é equilibrada nas mesorregiões Centro-Norte (~34%), Leste (~30%) e Pantanais (~25%); d) produção regional é de qualidade média, com TCZ~0,9%, TUM,BU~5%, TMV~33%, TCF~66%; PCS~20,7 MJ.kg-1 (↓TCF), TH~5,0%, TO~3,9% e TC~86,3%, com C/H~17,3; e) potencial para melhorar qualidade (↑TCF, ↓TMV e ↑PCS) e produtividade (ηGravimétrico, %).

The objective is to investigate radial burners through experimental tests, looking for its thermal performance behavior. Gas burners in domestic cookers operate on LPG, typically with two different geometries and five thermal power conditions. Usually, those thermal equipment lacks information on its whole operating conditions range for higher energy conversion efficiency and lower fuel consumption; it is not pointed out by the manufacturer or by energy efficiency labeling, what could result in a recommendation for widely effective performance. Appropriate instrumentation was used to carry out the measurements and methodology used as a guideline regulations from INMETRO/CONPET, ABNT - Brazilian Technical Standards Normative, and ANP - National Agency of Petroleum, Natural Gas and Biofuels. Experimental measurements and uncertainties are for the following parameters: fuel mass consumption (kg.s-1), test time elapsed (s), temperature (°C), water mass (kg) and flame temperature by K-type thermocouples (quantitative) and a thermal camera (qualitative). Main conclusions are: a) Operating domestic cookers with handle position selector on middle position (TP3) provides almost the same temperature rise as maximum fuel consumption (TP5), i.e., ΔT in the water container; b) Heat is better transferred (Qgas → Qwater) with the handle position selector fully opened (TP5@B1) and just before fully opening (TP4@B2); c) A non-linear behavior occurs for ηThermal, when moving forward the handle position selector; maximum efficiency occurs at fully open (TP5@B2) and middle opening (TP3@B1); d) Higher values for TPexperimental occurs for B2, in comparison to B1, in whole operational condition ranges; differences are mainly due to geometric parameters (ARB2/ARB1~0.82). In general, B2 has a better geometric design; e) Uncertainty analysis indicate values lower than ±3%, proving to be a suitable methodology for the experimental results in this work; f) Flame temperatures are entirely consistent with both, ηThermal and heat energy delivered, reaching higher temperature values at TP4 for both burners; 751.5°C (B1) and 830.7°C (B2).