Luís Augusto Barbosa Cortez

Prospects for green cane harvesting and cane residue use in Brazil

Abstract Mechanisation of sugarcane harvesting is growing rapidly in Southern Brazil where nearly 80% of Brazil’s crop is cultivated. Currently a maximum of 20% of the cane is mechanically harvested and the proportion is expected to rise to about 50% by 2005. However, most of the cane is burned prior to harvesting and less than 2% is harvested green. Issues such as topography, crop cultivation and management methods, labour costs, machine performance, environmental legislation and markets for sugarcane residues will influence the increase in mechanical harvesting of burned or green cane. This paper discusses the prospects for green cane harvesting technology, with emphasis on Southern Brazil, and compares harvesting technologies which are being commercialised today. The paper also addresses the recovery of cane residues (dry and green tops and leaves) and comments on their possible use and commercialisation, particularly for electricity generation.

EFFECT OF CONTAINER OPENING AREA ON AIR DISTRIBUTION DURING PRECOOLING Of HORTICULTURAL PRODUCE

An existing research tool was used to investigate air distribution in horticultural produce containers during forced-air precooling. This tool consisted of an instrumented produce simulator that allowed indirect measurement of surrounding air velocity at different positions inside a package. Using this new research tool for different forced-air cooling conditions, the surrounding air velocity was inferred as a function of the simulator’s location in reference to the air entrance. The air pathway during the cooling process was investigated for three total package-opening areas (0.67%, 2%, 6%) at airflow rates ranging from 0.125 to 3.9 L s-1 kg-1. The air approach velocity at each position inside a package rose as the opening area increased. More vented area also enhanced the cooling efficiency. However, increasing the airflow rate resulted in a greater air pressure drop. Opening areas more than 6% of the package surface should be tested to achieve the maximum necessary vented configuration that meets the structure constraints and generates air distribution and cooling efficiency not significantly different from fully open.

Effect of Container Openings and Airflow Rate on Energy Required for Forced-Air Cooling of Horticultural Produce

A research tool previously developed to investigate air distribution in horticultural produce containers during forced-air precooling was used to determine the effect of airflow rate and opening configuration on air pressure drop and rate and uniformity of cooling process. Further analysis performed on previously tested opening configurations determined their influence on energy efficiency. A system efficiency coefficient, consisting of the overall Energy Added Ratio (EAR) was demonstrated as a functional tool during the container design, since it considers peculiarities of the forced-air cooling system and produce physiology. The results obtained for containers with handling openings and 2, 4, 8, and 16% opening area were used to evaluate the additional energy required to remove the heat generated by the forced-air fan and produce respiration. These results were also compared to produce in bulk and to produce packed in containers having 4-0.5%-holes in the corners to analyze the influence of hole positioning. A four large 0.5% opening configuration results in poor energy performance and cooling uniformity when compared to uniformly distributed smaller holes. Furthermore, the airflow rate could be optimized based on the respiration rate of the produce and container opening area.

Bioenergy and African transformation

Among the world’s continents, Africa has the highest incidence of food insecurity and poverty and the highest rates of population growth. Yet Africa also has the most arable land, the lowest crop yields, and by far the most plentiful land resources relative to energy demand. It is thus of interest to examine the potential of expanded modern bioenergy production in Africa. Here we consider bioenergy as an enabler for development, and provide an overview of modern bioenergy technologies with a comment on application in an Africa context. Experience with bioenergy in Africa offers evidence of social benefits and also some important lessons. In Brazil, social development, agricultural development and food security, and bioenergy development have been synergistic rather than antagonistic. Realizing similar success in African countries will require clear vision, good governance, and adaptation of technologies, knowledge, and business models to myriad local circumstances. Strategies for integrated production of food crops, livestock, and bioenergy are potentially attractive and offer an alternative to an agricultural model featuring specialized land use. If done thoughtfully, there is considerable evidence that food security and economic development in Africa can be addressed more effectively with modern bioenergy than without it. Modern bioenergy can be an agent of African transformation, with potential social benefits accruing to multiple sectors and extending well beyond energy supply per se. Potential negative impacts also cut across sectors. Thus, institutionally inclusive multi-sector legislative structures will be more effective at maximizing the social benefits of bioenergy compared to institutionally exclusive, single-sector structures.

Preliminary tests with a sugarcane bagasse fueled fluidized-bed air gasifier

This paper discusses the performance characteristics of a 280 kWth fluidized bed gasifier fueled with bagasse pellets. The gasifier was designed by the State University of Campinas (UNICAMP) and built by TERMOQUIP Energia Alternativa Ltda, based in Campinas, Brazil. Preliminary tests were performed in 1996 to determine the reactor performance as part of the gasification pilot plant test programme. A series of parameters, such as the lower heating value, heat losses, cold and hot gas thermal efficiency and gas yield, were measured as a function of the gasification air factor.

Influência da embalagem no desenvolvimento de injúrias mecânicas em tomates

Five different packages (2 made of plastic, 2 of cardboard, and 1 made of wood) were evaluated with respect to the protection of tomatoes (Santa Clara variety) during their transportation and handling. These tomatoes were compared to control samples, as related to fruits with no physical impact or vibration, considering the percentage of those fruits with mechanical injuries and their severity. The fruits were stored at ambient temperature for 7 days until they reached full-color and then evaluated regarding the incidence of decay, weight loss, and flavor by Brix/acidity ratio and sensory analysis. The results have shown that the tomatoes on the bottom of the boxes had worse bruises and that the separated clapboards and the clues of wooden boxes caused the most severe injuries. The results also permitted the conclusion that there were less bruised tomatoes in the smaller cardboard package compared to the plastic and wooden boxes.

Considerations on the worldwide use of bioethanol as a contribution for sustainability

The use of ethanol from biomass as a gasoline substitute in cars and light trucks is possibly one of the most attractive and feasible alternatives to deal with global warming. As environmental concern grows, many countries are increasing their efforts to consolidate bioethanol processes and supply. The sustainable production of bioethanol requires well planned and reasoned development programs to assure that the many environmental, social and economic concerns related to its use are addressed adequately. The key for making ethanol competitive as an alternative fuel is the ability to produce it from low‐cost biomass. Many countries around the world are working extensively to develop new technologies for ethanol production from biomass, from which the lignocellulosic materials conversion seem to be the most promising one. This paper aims at providing some information about the status of bioethanol production and use around the world.

Estudo comparativo do resfriamento de laranja valência com ar forçado e com água

This work presents a study to compare the orange Valencia (Citrus sinensis O.) cooling with forced-air cooling and hydrocooling. The forced-air cooling system operated with air flow of 1933m3/h, at 1oC, RH= 88,4 ± 2,0% and air velocity around 1m/s. The experiments with immersion hydrocooling systems with capacity of 0,23m3 of water at 1oC, approximately. The half-cooling time and seven-eighths cooling time, they are determinate with the temperature data, made two repetitions. The results showed that the cooling the bed fruits, with air cooling, is not homogeneous, and obtained cooling time average, between 107min and 170min, depending on the position the fruit in the package. In the hydrocooling system, the cooling of the bed fruits happens uniformly in the bed, with average cooling time of 57min.

ESTUDO TEÓRICO DO RESFRIAMENTO COM AR FORÇADO DE FRUTAS DE GEOMETRIAS DIFERENTES

This paper presents a numerical study for obtaining cooling curves of orange Valencia (Citrus sinensis O.) and banana Prata (Mussa Balbisiana Colla), in different positions along the bed and conditioned in package with 40% of effective opening area. The fruits were pre-cooled in a forced-air system (1.933m3/h), at 1°C and 7°C, RH= 88,4 ± 2,0% and air velocity around 1m/s. A two-dimensional mathematical model was applied, assuming prolate spheroid coordinate, to characterize the transient heat transfer process inside the fruits considering convective profile conditions at the surface of the body. The generated equations were numerically solved by finite-volume method. The convective heat transfer coefficients were obtained using the least square method by comparison between experimental and numerical data. The comparative analysis of the theoretical and experimental curves presented a satisfactory agreement, with error between 5% and 7%. It was noted that the convective heat transfer coefficient changes with the fruits position in the bed and cooling time present a variation of approximately 38% among the different points. The spatial distributions of temperature inside the fruits, for three times, demonstrate the existence of a temperature differential between the center and the surface of 30%, approximately. The model predicts that the cooling rate is in the extremes of the banana. The Bi and Fo numbers obtained represent very well the heat transfer process in the fruits under different relationships of volume/area.

Avaliação física do tomate de mesa 'Romana' durante manuseio na pós-colheita

Tomato postharvest losses are very high in Brazil and the goal of this research was to evaluate the effect of handling and the transport of tomato fruits, cultivar Romana on the steps of harvesting, weight and transportation to the packinghouse, pointing some critical points. Tomatoes were harvested at plastic boxes, weighted and shipped to a packinghouse. Fruits taken directly from the plant were determined as reference. The parameters evaluated were weight loss and mechanical injury and tomato physical quality after storage during 21 days. It was observed an increasing on the weight loss, external damage, and postharvest losses, after storage. Handling and transportation were the cause of an increase in 6.6% in external damage and 1.93% of weight loss after storage, when comparing harvested fruits and fruits evaluated on the packing-house. The main reason for postharvest losses was due to mechanical injury caused during transportation mainly due to the compressure force among fruits and against the plastic boxes.