Experimental study on the performance of insulation materials in Mediterranean construction

It is well known that it is necessary to insulate the buildings to decrease the thermal demand and to decrease the use of heating and cooling. Due to the high cost of fossil fuels and to the necessity to reduce CO₂ emissions, and also due to the new building regulations more attention is paid to the insulation of buildings. Different insulation materials are available in the market. Usually, they are compared by their thermal conductivity and with theoretical calculations, but there are no experimental comparisons available, where the behavior of such insulation materials in a building is compared over time. This is why the authors started a comparison of three typical insulation materials, polyurethane, polystyrene, and mineral wool. For this purpose, four house-like cubicles were constructed (with a size of 2.4 m × 2.4 m × 2.4 m) and their thermal performance throughout the time was measured. The cubicles were built under a conventional Mediterranean construction system, differing only in the insulation material used. During 2008 and the first months of 2009 the performance of these cubicles was evaluated, and the results are presented in this paper.     

Impact of load profile and collector technology on the fractional savings of solar domestic water heaters under various climatic conditions

This paper investigates the influence of the domestic hot water load profiles and the collector's technology (Flat Plate FPC, Evacuated Tube ETC and Compound Parabolic CPC) on the performance of forced circulation solar water heaters operating under various climatic conditions. For this end, a typical single family house composed of five occupants located in Morocco was considered. It is found that, the solar fraction can reach annual average values of 80% especially in areas with high solar energy potential. For a fixed consumption profile, the simulations showed that the installations with FPC, ETC and CPC can consume about 1644, 1199 and 1481 kWh/year of auxiliary energy, respectively. Moreover, it is found that, adapting the consumption profile, can save approximately 43 kWh/year for FPC, 13 kWh/year for ETC and about 29 kWh/year for CPC of energy.     

Thermal pasteurization of ready-to-eat foods and vegetables: Critical factors for process design and effects on quality

Increasing consumer desire for high quality ready-to-eat foods makes thermal pasteurization important to both food producers and researchers. To be in compliance with the Food Safety Modernization Act (FSMA), food companies seek regulatory and scientific guidelines to ensure that their products are safe. Clearly understanding the regulations for chilled or frozen foods is of fundamental importance to the design of thermal pasteurization processes for vegetables that meet food safety requirements. This article provides an overview of the current regulations and guidelines for pasteurization in the U.S. and in Europe for control of bacterial pathogens. Poorly understood viral pathogens, in terms of their survival in thermal treatments, are an increasing concern for both food safety regulators and scientists. New data on heat resistance of viruses in different foods are summarized. Food quality attributes are sensitive to thermal degradation. A review of thermal kinetics of inactivation of quality-related enzymes in vegetables and the effects of thermal pasteurization on vegetable quality is presented. The review also discusses shelf-life of thermally pasteurized vegetables.     

First-principle study of magnetic,elastic and thermal properties of full Heusler Co2MnSi

In this work, first principles calculation of structural, electronic magnetic and elastic properties of the half-metallic ferromagnetic Heusler compound Co₂MnSi are presented. We have applied the full-potential linearized augmented plane waves plus local orbitals (FP-L/APW+lo) method based on the density functional theory (DFT). For the exchange and correlation potential generalized-gradient approximation (GGA) is used. The computed equilibrium lattice parameters agree well with the available theoretical and experimental data. Elastic constants and their pressure dependence are also calculated. The calculated total magnetization of 5 μ_B is in excellent agreement with recent experiments. We also presented the thermal effects using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account. Temperature and pressure effects on the structural parameters, heat capacities, entropy, thermal expansion coefficient, and Debye temperatures are determined from the non-equilibrium Gibbs functions.     

THERMOELASTICITY AND HEAT CONDUCTION WITH MEMORY EFFECTS

The thermodynamical foundations of generalized thermoelasticity formulated by Lord and Shulman are reviewed and memory effects on the heat flux are generalized. An existence and uniqueness theorem for the evolution integro-differential equations is obtained using semi-group theory.     

In-situ monitoring of lowermost amounts of hydrogen desorbed from materials

A recently developed thermal desorption spectrometry variant, Molecular Beam–Thermal Desorption Spectrometry (MB–TDS) is used, to monitor in real time and in-situ the dehydriding kinetics from hydrogen storage materials.     

Co-evaporative multi-component fuel design for in-cylinder PLIF measurement and application in gasoline direct injection research

For in-cylinder fuel mixture distribution measurement, a method for designing a multi-component fuel for planar laser-induced fluorescence (PLIF) experiments is developed based on thermal gravity analysis and vapor–liquid equilibrium calculation. The goal is to create fuel that has a volatility similar to real gasoline and good co-evaporation ratios (near 1.0) with tracers. Acetone, toluene, and trimethylbenzene are chosen as tracers for light, medium, and heavy fractions, respectively, and a five-component test fuel is developed. The test fuel is used to study the influence of components and temperature on co-evaporation ratios. Any variation in tracer or fuel component proportions affects all co-evaporation ratios, but a variation within 5% is considered acceptable. Results show that acetone presents the most significant influence on co-evaporation ratios. Temperature is also a key factor. Saturated vapor pressure and activity coefficient of the tracer and components in a fraction group affect co-evaporation optimization substantially, indicating that these values are a primary consideration in tracer selection. Finally, the test fuel is applied to an in-cylinder gasoline direct injection fuel mixture distribution measurement using PLIF. Differences between light, medium, and heavy fraction groups are studied under different strategies. Cycle-to-cycle variation analysis shows that the influence of absorption attenuation of the aromatic is distinct in a typical stratified strategy. In the area near the spark plug, cycle-to-cycle variation decreases as injection is delayed.     

A novel concept for improved thermal management of the planar SOFC

A new design for the solid oxide fuel cell (SOFC) planar stack is proposed to minimise the thermal gradients in the cell. This design involves including a secondary air channel with flow in the counter direction to the cathodic air channel. The effectiveness of the new design is tested by means of a tank in series reactor (TSR) model of the SOFC. It is found that the new design is capable of reducing the steady state temperature difference across the cell to less than 2 K over a range of voltages, while satisfying the requirements on fuel utilisation (FU) and cell average temperature. This is achieved by manipulating the primary air channel inlet flow rate and the secondary air channel inlet temperature. More modelling and experimental studies are required to further investigate the proposed design.     

Thermal analysis of cylinder head carbon deposits from single cylinder diesel engine fueled by palm oil–diesel fuel emulsions

This paper aims to evaluate the cylinder head carbon deposit from diesel engine fuelled by four samples of diesel fuel emulsions containing 0%; 5%; 10% and 15% vol. water and 20% Palm Oil Methyl Ester (POME) were subjected to thermogravimetric analysis (TGA/DSC) in air medium. The deposit build up processes were performed on a single-cylinder direct-injection diesel engine for period of 25 h for each set of test fuel under constant speed 2500 rpm. The TGA system was used and then correlated with elemental analysis as well as infrared spectra for microscopic observations. It has been found that, as the water increases in fuel, less aromatic and less reactive of deposits would be formed. Therefore, such method of analyses can be used as an indicator to verify the stability of carbon deposit inside the combustion chamber that could substantiate the applicability of a particular fuel to be accepted.