The article addresses the need to improve the performance of hot water systems in buildings by proposing a novel technique based upon the use of PCM. A heat exchanger using a PCM was developed and tested. By resorting to numerical models, different assembling processes were tested in order to combine low fin-pipe thermal resistances with high output manufacturing processes. Experimental tests have shown that the system can provide instant hot water for an adequate period of time hence preventing the use of circulating loops with high installation costs and reducing the waste of energy and water.

Domestic refrigeration and freezing appliances can be used for electrical load shifting from peak to off-peak demand periods, thus allowing greater penetration of renewable energy sources (RES) and significantly contributing to the reduction of CO2 emissions. The full realization of this potential can be achieved with the synergistic combination of smart grid (SG) technologies and the application of phase-change materials (PCMs). Being permanently online, these ubiquitous appliances are available for the most advanced strategies of demand-side load management (DSLM), including real-time demand response (DR) and direct load control (DLC). PCMs are a very cost-effective means of significantly augmenting their cold storage capacity and, hence, their load-shifting capabilities. Yet, currently, refrigerators and freezers equipped with PCMs for DSLM are still absent in the market and research works focusing on the synergy of these technologies are still scarce. Intended for a multidisciplinary audience, this broad-scoped review surveys the literature to evaluate the technological feasibility, economic viability and global impact of this combination. The state-of-the-art of SG-enabling technologies is investigated—e.g., smart meters, Internet-of-Things (IoT)—as well as current and future standards and norms. The literature on the use of PCMs for latent heat/cold storage (LHCS) is also reviewed.

We describe some practical and empirically validated multivariate sensor calibration methods, which have allowed us to successfully obtain usable data from low-cost, low-precision sensors and signal conditioning electronics; we demonstrate the efficacy of these methods with real examples of nonlinear correction of thermocouple measurements from errors originated by the simultaneous influence of the cold junction and the temperature of the signal conditioning and digitizing electronic circuit components.

Densification of the biomass residues as an efficient method to produce a renewable and CO2 neutral energy resource has been in consideration in recent years. However, according to a recent boost in the European wood pellet demand, the importance of R&D studies for substitution and enhancement of current raw materials for pelleting purposes has been increased. A large amount of annual garden waste and agricultural residues in Portugal causes that so-called Mixed Biomass Pelleting (MBP) method becomes a promising approach of the future that by closing the cycles in the agro-economic environments of Portugal, enhances the socio-economic conditions in the rural areas. This itself will have one more important consequence of wildfire prevention in the Portuguese forests. This work as a subset of a broader study that aims to develop an evaluation tool for circular economies will cover the information required for a techno-economic analysis of mixed biomass pelleting by a review on potential assessment methods, a rough-cut assessment of agro-residues potential for Portugal and gathering the required information about pellets origin, characteristics and legislative frames.

The study addresses the potential of using concentrated solar power plants (CSPs) as a sustainable alternative of clean energy generation in the Mediterranean region and, in particular, in its North Africa shore. This location presents attractive conditions for the installation of CSPs, in particular high solar irradiation, good manpower concentration, and proximity and availability of water resources for condenser cooling. Energetic, exergetic, and economic analyses were conducted taking into consideration a particular type of CSPs - the parabolic trough concentrated solar power plant, which incorporates the most proven technology and it is already used in Southern Europe (Spain). In addition, the study considered the impact of project financing and incentives on the cost of energy. The combination of higher values for performance and potentially lower levelized cost of electricity (LCE) for the North Africa Mediterranean Rim than the South of Spain region can yield a very favorable return for the invested capital. Tripoli compared to Almeria presented superior performance and potentially lower LCE values ($0.18/kWh versus $0.22/kWh). This is significant, even when it is taken into consideration the fact that the plant in Tripoli, despite a relatively modest capacity factor of 34%, has a large gross power output of 173,886MWhe. In addition, the implementation at the Tripoli location of a plant similar to the Anadsol plant has a slight advantage (2-3%) in terms of overall efficiency.

Drying of sewage sludge is typically modeled as simultaneous heat and mass transfer phenomena. The capability of conventional models to take into account crust formation, cracks, and shrinking is limited. Artificial neural networks (ANNs) are suitable tools for dynamic representation of drying processes; however, obtaining a suitable database is a resource consuming task. Based on the Taguchi method, nine experiments were defined to set up a training database and to develop an ANN model. A high Pearson correlation coefficient was verified when comparing the drying kinetic curve generated by the ANN model with the one obtained during the validation experiments.

One-dimensional Haldane gap materials, such as the rare earth barium chain nickelates, have received great interest due to their vibrant one-dimensional spin antiferromagnetic character and unique structure. Herein we report how these 1D structural features can also be highly beneficial for thermoelectric applications by analysis of the system CaxBaGd2-xNiO5 0 ≤ x ≤ 0.25. Attractive Seebeck coefficients of 140-280 μV K-1 at 350-1300 K are retained even at high acceptor-substitution levels, provided by the interplay of low dimensionality and electronic correlations. Furthermore, the highly anisotropic crystal structure of Haldane gap materials allows very low thermal conductivities, reaching only 1.5 W m-1 K-1 at temperatures above 1000 K, one of the lowest values currently documented for prospective oxide thermoelectrics. Although calcium substitution in BaGd2NiO5 increases the electrical conductivity up to 5-6 S cm-1 at 1150 K < T < 1300 K, this level remains insufficient for thermoelectric applications. Hence, the combination of highly promising Seebeck coefficients and low thermal conductivities offered by this 1D material type underscores a potential new structure type for thermoelectric materials, where the main challenge will be to engineer the electronic band structure and, probably, microstructural features to further enhance the mobility of the charge carriers.

The reported outcomes of the Elektra thumb carpo-metacarpal joint implant have been very variable. This study evaluates the influence of daily cyclic loads and the type of the screw-fit cup insertion technique in the trapezium, with and without prior threading, on the structural bone behaviour. The study was performed experimentally to predict initial implant stability and cortical bone strains. Computational models were developed to assess the structural cancellous bone behaviour. The use of Elektra implant considerably changed the bone strain behaviour compared with the intact joint. This may be associated with risks of cancellous bone fatigue failure due to overload, particularly in the trapezium. The joint load magnitude has a more important structural role than that of the screw-fit cup insertion technique. Limiting the magnitude of thumb loads after arthroplasty may contribute positively to the longevity of this procedure. Level of evidence: V

The curing process of Toluene 2,4-Dilsocyanate (TDI) pre-polymer with granulate cork is significantly affected by the cork moisture content since the reaction of isocyanate is highly sensitive to water. Two types of moisture are considered: the moisture contained inside the granulate cork, residual moisture, and the moisture intentionally sprayed over the granules of cork, added moisture. This study analyses the curing kinetics of TDI and granulate cork mixtures containing added moisture using Differential Scanning Calorimetry (DSC), and the reaction rate increase associated with the added moisture content (AMC). The underlying objective of this work is to reduce the time needed to obtain agglomerate cork stoppers through AMC increase. (C) 2015 Elsevier Ltd. All rights reserved.

The study aims to study the potential of concentrating solar power (CSP) plants with parabolic trough technology of becoming a viable alternative energy producing system in Libya. Energetic and economic analyses are carried out for a particular type of CSP plants and the investigation is concentrated on a 50MW(e) parabolic-trough plant. Taking into consideration the Libyan territory, the Tripoli region is selected as the specific location of the CSP plant based on its high solar irradiation, consumer proximity and density, and condenser cooling water availability. In the Tripoli region prevails a large-scale Mediterranean climate, where the average annual levels of irradiation are very favorable to practical applications. In addition, the maximum and minimum annual solar days at noon hour for the CSP plant location, as indicated by the present study, are very appealing. Moreover, the annual analysis on an hourly basis also indicates very good potential. The paper presents a brief review of the current cost of energy and the potential for reducing the cost of energy from parabolic trough solar power plant technology. The main technological finding of the present study for the CSP selected is its higher perfoimance and lower levelized cost of electricity (LCE) as compared to a similar plant in Southern Europe.

This paper proposes a high performance nonlinear fuzzy multi-input-multi-output controller for a drying control process. The highly nonlinear characteristics of drying processes make classical control theory unable to provide the same performance results as it does in more well behaved systems. Advanced control strategies may be used to design temperature, relative humidity and air velocity nonlinear tracking controllers to overcome its highly non-linear dynamics over the whole drying operating conditions. Open-loop experiments were carried out to collect experienced-based knowledge of the process. PID and Fuzzy logic (FLC) real-time-based controllers were designed to perform food drying tests and compared without controllers' retuning. Absolute errors reached by FLC-based controller were 3.71 and 3.93 times lower than PID for temperature and relative humidity, respectively.

A viabilidade econômica de um sistema de secagem é de extrema relevância, pois o custo final do produto colocado no mercado depende diretamente de todos os gastos necessários para o seu processamento. Assim, a secagem é uma das etapas de grande importância do ponto de vista da conservação e do custo final do produto. No que diz respeito à secagem de peixes, existem poucos trabalhos que tratam dos custos, apesar do elevado consumo de energia e da importância que a secagem representa após a captura. Assim, este trabalho tem por objetivo apresentar os custos da secagem do bacalhau, mostrando o consumo energético da instalação experimental convectiva para diferentes condições operacionais, bem como realizar a otimização destas condições para reduzir o consumo energético.

Industrial drying of salted fish is an extremely common practice in the Portuguese industry of codfish processing. The present study aims to obtain sorption isotherms of codfish, which will be useful in designing drying processes and prediction of storage conditions for this product. The equilibrium moisture contents (wet basis) were determined for salted codfish at 15, 18, 20, and 23(o)C at relative humidities ranging from 40 to 70%. Experiments were also carried out for fresh codfish at the temperature of 20(o)C for the same values of relative humidity. The sorption capacity of codfish decreased with an increase in temperature at constant relative humidity. Thirteen models were used to correlate the experimental data analysis of salted codfish: modified BET, Cauri, Chung-Pfost, modified Chung-Pfost, GAB, modified GAB, Halsey, modified Henderson, Kuhn, Oswin, modified Oswin, Smith, and modified Smith. Based on the mean relative percentage deviation, standard error of estimate, randomness of residual, and coefficient of determination, experimental data were well described by all the models. The equilibrium moisture content of salted codfish was best predicted using the modified GAB model, with a coefficient of determination of 0.99.

A contribuição deste artigo é a proposta de uma estratégia de controle não linear, composto por quatro controladores difusos: Controladores difusos proporcionais e derivativos para um desumificador, um umidificador, um conjunto de resistências elétricas e um ventilador utilizados na instalação laboratorial de secagem convectiva. Os resultados foram comparados com os obtidos anteriormente através de um controlador linear PID otimizado. O objetivo desta pesquisa é encontrar as condições ótimas para a secagem de bacalhau salgado verde. Os ensaios experimentais de secagem foram realizados para as seguintes condições operacionais: temperaturas do ar de 15, 18, 20 e 23°C; umidades relativas de 40, 45, 50, 55, 60, 65 e 70% e velocidades do ar iguais a 1,5 e 2,5m/s. As limitações da instalação experimental restringem os valores de umidade relativa a um mínimo de 40%. Os valores da velocidade do ar estão dentro do intervalo utilizado para a secagem de peixe. Foram parametrizados um grupo de conjuntos difusos, de forma a assegurar um alto desempenho do controlador, sem necessidade do desenvolvimento do modelo matemático do processo de secagem. A análise dos resultados mostrou um melhor desempenho para o controlador difuso quando comparado ao controle PID.

One main reason for the popularity of microalgae as an acceptable fuel source is their potential to maximize productivity (e.g., gallons of oil or fuel produced per acre per year) by converting the energy of solar photons during the process of carbon dioxide fixation into biomass energy, benefiting the environment. Marketing the coproducts generated (i.e., postextraction algal residue) could make transportation fuel from microalgae a viable product. The biofuel obtained from microalgae is qualitatively and quantitatively analyzed, with a focus on the energetic and environmental feasibility of this fuel for use in the transportation sector. Obstacles to and limitations of the process, in terms of energy and environmental performance, are identified. An important aspect of this issue is the need to improve product processing and recovery, which include mechanical and energy-intensive processes such as centrifugation, filtration, flocculation, and cell disruption. Results obtained so far indicate that the various strains of microalgae obtained from lagoons in Portugal and Spain offer a huge prospect for biodiesel production. However, results of life-cycle analysis with the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation model (updated with Portuguese data) lead to the conclusion that, at this stage, biodiesel from microalgae is not a valid option for the large-scale replacement of conventional fuels. Specifically, the extraction step for biodiesel production is detrimental in terms of energy and solvent use and must be refined.

The correct definition of drying procedures of a vast range of products is crucial in what concerns energy minimization and minimal time of kiln residence without compromising the final product's quality. Several external parameters namely, air temperature, relative humidity and velocity, influence the time required to reduce the moisture content of the product. For whole salted codfish, drying prevents the utilization of temperatures above 20-22C, because they lead to an inevitable deterioration of the product. Taking into account these limitations, whole codfish convective drying kinetics were determined for a temperature of 20C, initial moisture contents comprised between 57 and 65% (wet basis), air velocities of 1.5 and 3 m/s and drying air relative humidities of 40 and 70%. A semi-empirical drying model was developed and validated. The results show that lower relative humidities led to faster drying and that air velocity influences drying rates particularly at high relative humidities.

The objective of the reduction of greenhouse gas emissions by 2050 and the European Union's (EU's) fossil energy dependence are two factors that require political and industrial decision makers to set priorities for energy and environmental strategies. Despite the achieved efficiency in modern vehicles, increasing patterns of private car usage, together with a high dependence on oil, place transportation as the most resilient sector in this period of environmental and energy consciousness. The aim of this research was to disaggregate the existing European transportation energy data and use them to build a model of the current situation. With the model, several scenarios evaluated the well-to-wheel energy and carbon dioxide (CO 2 ) impacts that resulted from improvements in energy efficiency, uptake of biofuels, and electric mobility, as well as a modal shift into collective modes. Analysis of the European study of the Joint Research Centre Biofuel Programme and each member state's national strategy [National Renewable Energy Action Plans (NREAPs)], published in 2010, allowed characterization of the transportation energy situation by 2020 (consumption, efficiency, and new energy). The analysis of mobility surveys from major member states permitted characterization of urban areas within the passenger mobility sector, and the results were integrated into the developed model. The expected improvements in energy efficiency through the Biofuel Programme and the planned increase in biofuel blends and electrified vehicles through the NREAPs combined with an increase in passenger mobility by 2020 resulted in the following 2020 predictions: a 16% reduction in tank-to-wheel and a 12% reduction in well-to-wheel CO 2 emissions in the EU's passenger mobility sector compared with 2007 levels.

SummaryThis work aims to compare the accuracy of several drying modelling techniques namely semi‐empirical, diffusive and artificial neural network (ANN) models as applied to salted codfish (Gadus Morhua). To this end, sets of experimental data were collected to adjust parameters for the models. Modelling of codfish drying was performed by resorting to Page and Thompson semi‐empirical models and to a Fick diffusion law. The ANN employed a neural network multilayer ‘feed‐forward’, consisting of one input layer, with four neurons, one hidden layer, formed by five neurons and one output layer with a convergence criterion for training purposes. The simulations showed good results for the ANN (correlation coefficient between 0.987 and 0.999) and semi‐empirical models (correlation coefficient ranging from 0.992 to 0.997 for Page’s model, and from 0.993 to 0.996 for Thompson’s model), while improvements were required to obtain better predictions by the diffusion model (correlation coefficients ranged from 0.864 to 0.959).