This paper presents a numerical and experimental analysis of the heat transfer process that takes place while melting a solid material, in a rectangular enclosure. Natural convection is present in the melt layer, and the solid phase is assumed to be isothermal. Very detailed and precise experimental results are given that are used to validate a particularly rapid numerical code. Some insights into the kinetics of the melting process lead to a deeper understanding of the coupling between convection and phase change and allow us to propose a simple algebraic correlation that predicts the time evolution of the melting front to within 5 percent.

Introduçãouitos países estão enfrentando dificuldades para suprir a demanda crescente de energia de suas populações e, ao mesmo tempo, fornecer recursos energéticos para suprir seu crescimento econômico. Cabe, cada vez mais, ao poder público conhecer o comportamento dos consumidores para criar mecanismos que promovam o uso racional de energia nos diferentes setores e, assim, otimizar o uso de energia pela sociedade (Jannuzzi, 2005).Mecanismos legais de incentivo à conservação de energia têm sido empregados por vários países para reduzir o consumo de energia e as emissões de gases de efeito estufa. Os Estados Unidos, por exemplo, formularam suas primeiras normas de eficiência energética na década de 1970, quando ocorreu a crise de suprimento de petróleo (Dixon et al., 2010). A União Europeia também começou a formular seus instrumentos legais na mesma época, fixando metas de redução da demanda de energia e de emissão de poluentes, a serem atingidas pelos estados-membros (Fouquet, 2013).O Brasil começou a formular suas legislações de incentivo à eficiência energética na década de 1980. Segundo Geller et al. (2004, políticas nacionais para aumentar a geração de energia por fontes renováveis e a oferta interna de petróleo têm se mostrado bem-sucedidas. Enquanto políticas nacionais para promover o uso de medidas de eficiência energética, por sua vez, foram moderadamente bem-sucedidas.Há muito espaço para ampliar a gestão governamental na área de conservação de energia no Brasil, principalmente quanto à criação de instrumentos legais de incentivo à geração descentralizada de energia por fontes renováveis e de incentivo à eficiência energética. Objetivou-se com este trabalho discutir as atuais políticas brasileiras de eficiência energética, bem como desafios e oportunidades associados.

This paper develops an energy analysis for an existing near Zero Energy (nZEB) and Zero Carbon Emissions building called LUCIA, located at the university campus in Valladolid (Spain). It is designed to supply electricity, cooling and heating needs through solar energy (Photovoltaic Systems, PV), biomass and an Earth-Air Heat Exchanger (EAHE), besides a Combined Heat Power (CHP). It is currently among the top three buildings with the highest LEED certification in the World. The building model is simulated with DesignBuilder version 5. The results of the energy analysis illustrate the heating, cooling and lighting consumptions expected, besides other demands and energy uses. From this data, we carried out an energy balance of the nZEB, which will help to plan preventive actions when compared to the actual energy consumptions, improving the management and control of both the building and its systems. The primary energy indicator obtained is 67 kWh/m 2 a year, and 121 kWh/m 2 a year for renewable energy generation, with respect to 55 kWh/m 2 and 45 kWh/m 2 set as reference in Europe. The Renewable Energy Ratio (RER) is 0.66. These indicators become a useful tool for the energy analysis of the nZEB according to the requirements in the European regulations and for its comparison with further nZEB.

Nowadays, radiant ceiling systems can be considered among the technologies capable of meeting sustainable heating and cooling requirements. In order to adequately address design and simulation issues concerning these systems, correct evaluation of the heat transfer process is needed. The aim of this research is to present further evidence on the cooling capacity and heat transfer coefficients for a cooled radiant ceiling, assuring adequate thermal comfort levels in those possible different operation conditions. An experimental setup into a climate test room was developed and used to derive convenient results. The obtained values revealed that heat transfer evaluations on the basis of operative temperature as the unique reference temperature and corresponding total coefficient are not appropriate in real situations, but considering radiant and convective phenomena separately is strongly recommended.

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