Interaction of equatorial waves through resonance with the diurnal cycle of tropical heating

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cogasification of solid fuels

High efficiency gas turbine based systems, utility deregulation and more stringent environmental regulations strongly favor the use of natural gas over coal and other solid fuels in new electricity generators. Solid fuels could continue to compete, however, if a low cost gasifier fed by low cost feedstocks can be coupled with a gas turbine system. We examine on-site gasification of coal with other domestic fuels in an indirectly heated gasifier as a strategy to lower the costs of solid fuel systems. The systematics of gaseous pyrolysis yields assembled with the help of thermal measurement data and molecular models suggests blending carbonaceous fuels such as coal, coke or char with oxygenated fuels such as biomass, RDF, MSW, or dried sewage sludge. Such solid fuel blending can, with the help of inexpensive catalysts, achieve an optimum balance of volatiles, heating values and residual char thus reducing the technical demands upon the gasifier. Such simplifications should lower capital and operating costs of the gasifier to the mutual benefit of both solid fuel communities.

Costs estimates and rentability of the guava culture {psidium guajava l. patuma cv.) in monte alto county, Sao Paulo state

This work intended to calculate the rentability of the guava culture Paluma cv. in Monte Alto region-SP, estimating the costs of the implantation, maintenance, production and the gross income of this culture in the first three years of cultivation. The production system utilized refers to the cultural treatments usually used in this culture in the region. The costs estimates were based on the total operational costs methodology used by the Agricultural Economics Institute (I.E.A.). The results obtained showed that the implantation and maintenance costs of the culture, in the two first years was Rs7.402,31/alqueire. Considering the possibility that in guava orchard, on irrigated conditions, reach in the fourthy year a productivity of 80t/alqueire and that the current price is Rs0,20/kg, it is possible to estimate the gross income around of Rs16.000,00/alqueire, resulting in a net income of Rs9.497,06/alqueire.

Analysis of aluminum plates under heating in electrical and natural gas furnaces

This paper analyzes the thermal storage characteristics of aluminum plates in furnaces during their heating for lamination under two sources of heat: an electrical resistance bank and a combustion process carried out with natural gas. The set of equations to model the furnace under operation with electrical energy, for air as the fluid, is presented. This supports the theoretical analysis for the system under operation with natural gas combustion products. A numerical procedure, using the software ANSYS, is applied to determine the convection heat transfer coefficients for heating by the air flow. Temperatures measured in a plate inside a real furnace are used as parameters to determine these coefficients. Then convection and radiation heat transfer coefficients are determined for the natural gas combustion products. Results are compared, indicating a possible gain of 5.5 h in relation to a 19.5 h period of conventional electrical heating per plate.

An improved three-dimensional model for growth of oxide films induced by laser heating

In this paper we consider a three-dimensional heat diffusion model to explain the growth of oxide films which takes place when a laser beam is shined on and heats a metallic layer deposited on a glass substrate in a normal atmospheric environment. In particular, we apply this model to the experimental results obtained for the dependence of the oxide layer thickness on the laser density power for growth of TiO2 films grown on Ti-covered glass slides. We show that there is a very good agreement between the experimental results and the theoretical predictions from our proposed three-dimensional model, improving the results obtained with the one-dimensional heat diffusion model previously reported. Our theoretical results also show the occurrence of surface cooling between consecutive laser pulses, and that the oxide track surface profile closely follows the spatial laser profile indicating that heat diffusive effects can be neglected in the growth of oxide films by laser heating. © 2001 Elsevier Science B.V.

One-dimensional analytical model for oxide thin film growth on Ti metal layers during laser heating in air

This paper presents the theoretical and experimental results for oxide thin film growth on titanium films previously deposited over glass substrate. Ti films of thickness 0.1 μm were heated by Nd:YAG laser pulses in air. The oxide tracks were created by moving the samples with a constant speed of 2 mm/s, under the laser action. The micro-topographic analysis of the tracks was performed by a microprofiler. The results taken along a straight line perpendicular to the track axis revealed a Gaussian profile that closely matches the laser's spatial mode profile, indicating the effectiveness of the surface temperature gradient on the film's growth process. The sample's micro-Raman spectra showed two strong bands at 447 and 612 cm -1 associated with the TiO 2 structure. This is a strong indication that thermo-oxidation reactions took place at the Ti film surface that reached an estimated temperature of 1160 K just due to the action of the first pulse. The results obtained from the numerical integration of the analytical equation which describes the oxidation rate (Wagner equation) are in agreement with the experimental data for film thickness in the high laser intensity region. This shows the partial accuracy of the one-dimensional model adopted for describing the film growth rate. © 2001 Elsevier Science B.V.

The sugar cane vegetal residues unloaded in the sugar mill: Operational costs and physical characteristics

Brazil produced in 2002/03 season 317.87×106tons of sugar cane stalks and 36.88×106tons of vegetal residues (green leaves, dry leaves and tops) in a planted area of 4.61×106 hectares (ha). These residues have a useful heat of 3,613.14Mcal.t-1. Currently most of this biomass is burned as a pre-harvest practice. The doubt persists in the system type that it must be adopted to pick up, load, transport and unload this biomass at the sugar mill boilers. This study analyzed 22 variables related to operational costs and physical characteristics of these residues in a field situation using a JOHN DEERE® 6850 forage harvester with two different treatments: T1 and T2 (two types of rakes) with 6 repetitions each one. The geographic location of the studied area that belongs to COSTA PINTO MILL (COSAN® Group) is: Latitude 22°40'30S and Longitude 47°36'38W. The adopted methodology was proposed by Ripoli et al. (2002). The obtained results at a 5% level of significance showed that both treatments did not differed significantly between them. Some of the results were, where EBP stands for Oil Equivalent Barrel: Windrowing (T1=US$0.17.EBP-1 and US$9.59.ha-1, T2=US$0.08.EBP-1 and US$4.27.ha-1); Pick up (T1=US$1.31.EBP-1 and US$44.29.ha-1, T2 =US$1.37.EBP-1 and US$48.36.ha-1); Transportation (T1=US$1.27.EBP-1 and US$14,30.ha -1, T2=US$1.33.EBP-1 and US$14,80.ha -1), Unloading at the sugar mill (T1=US$0.30.EBP-1 and US$3.39.ha-1, T2=US$0.32.EBP-1 and US$3.51.ha-1); Total (T1=US$3.05.EBP-1 and US$71.57.ha-1, T2=US$3.10.EBP-1 and US$70.94.ha-1). Confronting the obtained data with the ones in the bibliography, this system revealed itself more expensive than the baling system or the integral harvest system using combines.

Densification of Mn-doped tin oxide films by conventional heating and microwave heating treatment

Mn(II) doped SnO2 thin films used for shielding fluoride glasses against corrosion were investigated by x-ray absorption spectroscopy (EXAFS and XANE)S at the Sn and Mn K-edges. The effect of firing treatment on the densification of the films was studied. It has been evidenced a partial change of Mn valence from 2.3 to 2.6 upon heating which is attributed to a change of ratios of two Mn sites: grafted divalent Mn ions at the surface of SnO 2 nanocrystallites and trivalent Mn ions embedded into a substitutional solid solution with Sn. © Physica Scripta 2005.

Heating time required for an MgO-graphite refractory during a hot modulus of rupture test

In the work described in the present paper, an analytical solution of the general heat conduction equation was employed to assay the temperature profile inside a solid slab which is initially at room temperature and is suddenly plunged into a fluid maintained at a high temperature. The results were then extrapolated to a simulation of a hot modulus of rupture test of typical MgO-graphite refractory samples containing different amounts of graphite in order to evaluate how fast the temperature equilibrates inside the test specimens. Calculations indicated that, depending on the graphite content, the time to full temperature homogenization was in the range of 80 to 200 s. These findings are relevant to the high temperature testing of such refractories in oxidizing conditions in view of the graphite oxidation risks in the proper evaluation of the hot mechanical properties.

Heating rate and temperature effects on the BaTiO3 formation by thermal decomposition of (Ba,Ti) organic precursors during the Pechini process

Different thermal treatments for the synthesis of BaTiO3 powder obtained through the Pechini method were studied. The synthesis of BaTiO3 starts at 150 °C by the thermal dehydration of organic precursors. The usual inevitable formation of barium carbonate during the thermal decomposition of the precursor could be retarded at lower calcination temperatures and optimized heating rates. The organic precursors were treated at temperatures between 200 and 400 °C. Then, the samples were calcined at 700 and 800 °C for 4 and 2 h, respectively. The resulting ceramic powders were characterized by gravimetric and differential thermal analyses, X-ray powder diffraction and infrared spectroscopy. It was found that depending on the heating rate and final temperature of the thermal treatment, high amounts of BaCO3 and TiO2 could be present due to the high concentration of organics in the final calcination step. © 2007 Elsevier B.V. All rights reserved.

Effect of pre-heating resin composite and light-curing units on monomer conversion

The purpose of this study was to evaluate the effect of pre-heating resin composite photo-cured with light-curing units (LCU) by FT-IR. Twenty specimens were made in a metallic mold (4 mm diameter × 2 mm thick) from composite resin-Tetric Ceram® (Ivoclar/Vivadent) at room temperature (25°C) and pre-heated to 37, 54, and 60°C. The specimens were cured with halogen curing light (QTH) and light emitted by diodes (LED) during 40 s. Then, the specimens were pulverized, pressed with KBr and analyzed with FT-IR. The data were submitted to statistical analysis of variance and Kruskal-Wallis test. Study data showed no statistically significant difference to the degree of conversion for the different light curing units (QTH and LED) (p > 0.05). With the increase of temperature there was significant increase in the degree of conversion (p < 0.05). In this study were not found evidence that the light curing unit and temperature influenced the degree of conversion. © 2010 Pleiades Publishing, Ltd.

Methodology for DSC calibration in high heating rates

Despite the large use of differential scanning calorimetry (DSC) technique in advanced polymer materials characterization, the new methodology called DSC in high heating rates was developed. The heating rate during conventional DSC experiments varying from 10 to 20°C.min-1, sample mass from 10 to 15mg and standard aluminum sample pan weighting, approximately, 27mg. In order to contribute to a better comprehension of DSC behavior in different heating rates, this work correlates as high heating rate influences to the thermal events in DSC experiments. Samples of metallic standard (In, Pb, Sn and Zn) with masses varying from 0.570mg to 20.9mg were analyzed in multiples sample heating rate from 4 to 324°C. min-1. In order to make properly all those experiments, a precise and careful temperature and enthalpy calibrations were performed and deeply discussed. Thus, this work shows a DSC methodology able to generate good and reliable results on experiments under any researcher choice heating rates to characterize the advanced materials used, for example, for aerospace industry. Also it helps the DSC users to find in their available instruments, already installed, a better and more accurate DSC test results, improving in just one shot the analysis sensitivity and resolution. Polypropylene melting and enthalpy thermal events are also studied using both the conventional DSC method and high heating rate method.

Brazilian solar water heating systems evaluation

The Brazilian National Electricity Conservation Program - PROCEL - runs regular surveys in the electric-energy-consumption market. These studies are used as valuable data to better plan the actions of this program. These data also evaluate the program's performance by identifying the level of penetration of the most efficient electric equipment within the residential sector. PROCEL's main lines of action is to promote and make available the most efficient technologies. Based on the results from the latest survey, it is estimated that 24% of the electric-energy consumption of the residential sector is used by electric shower devices, which instantaneously heat the water that flows through them, normally using an electric resistance of 5 kW. These are an important factor in a country where electric-heating devices are present in about 73% of Brazilian households. Keeping that in mind, the purpose of this work is to present the main results of the Brazilian Solar-Water-Heating-Systems Evaluation, finished in 2010, where 535 installations were visited and more than 50 researchers from different universities participated in the project. Moreover, seven Brazilian cities were selected to be studied. The information was collected from field research and statistically treated. The collected information focused on the adequacy of the project to the household, installation, operation and life cycle of the systems, as well as the users' satisfaction level. Technical questionnaires were developed to summarize all the required information, such as a Web site designed to organize and manage the data collected and a Matlab application that performed the dimensioning and F-chart systems evaluation. Quality indicators were created through a full system monitoring, with thermographic analysis and evaluation of shading influence at the system's efficiency, using the Ecotect software.

Tocopherol content and fatty acid profile in soybean oil supplemented with salvia extract (Salvia officinalis L.) during heating

This paper aimed to assess the tocopherol content and evaluate the fatty acid profile in soybean oil supplemented with salvia extract during heating, so as to verify the isolated and synergistic effect of natural and synthetic antioxidants. In order to obtain the extract, the lyophilized and crushed salvia was subjected to extraction by ethyl alcohol for 30 min, with a 1:20 salvia:ethyl alcohol ratio, under continuous agitation. Afterwards, the mixture was filtered and the supernatant was subjected to the rotary evaporator at 40 °C. Later the control treatments, ES (3000 mg kg-1 salvia extract), TBHQ (50 mg kg-1), and mixture (ES+50 mg kg-1 TBHQ) were prepared and subjected to 180 °C for 20 h. Samples were taken in time intervals 0, 10, and 20 h and analysed in terms of tocopherol content and fatty acid profile. Regarding the tocopherol and fatty acid profile analysis, it was found that the extract proved efficient in oil protection, when added isolated to soybean oil subjected to thermo oxidation. According to the results, salvia extract is a viable alternative that might be applied in industrialized processing of oils as natural antioxidant.