Numerical study of efficiencies for box type solar cooker with internal reflectors

En este trabajo se muestran los resultados del estudio de las eficiencias termodinámicas de 1.a y 2.a ley aplicadas a 4 arreglos diferentes de estufas solares de tipo caja con reflectores internos. La estufa solar tiene 2 vidrios en su cubierta para disminuir la pérdida de calor por radiación y convección, y crear así el efecto invernadero. El interior de la estufa tiene espejos colocados a diferentes ángulos para dirigir la radiación solar hacia un recipiente con agua que se encuentra también dentro de la estufa. Los resultados obtenidos están basados en las temperaturas de calentamiento del agua, las cuales fueron obtenidas por medio de una simulación numérica que permite comparar los 4 arreglos de estufas solares bajo condiciones idénticas. El tratamiento de los resultados revela que la cantidad de energía que impacta en las estufas solares no es aprovechada de manera adecuada para los fines de calentamiento de agua. La mayor parte de la energía aprovechable se almacena en los vidrios de la tapa, lo que evidencia la necesidad de trabajar en el desarrollo de mejores materiales para mejorar tal situación.In this work, results of efficiencies for first and second law of thermodynamics applied to four box-type solar cookers with internal reflectors are shown. The solar cooker has two glasses on its cover to diminish the losses of heat for radiation and convection, besides creating the effect hothouse inside the cooker. The interior of the cooker has flat mirrors placed at different angles to reflect the solar radiation toward a recipient with water inside the cooker. The obtained results are based on heating water temperatures which were obtained by means of numeric simulation, allowing comparison under identical conditions of four solar cookers. The treatment of the results revealed that the quantity of energy that impacts on the solar cookers is not used in right way for the heating water ends. Most of the profitable energy is stored in the glasses of the cover, what evidences the necessity to work in the development of better materials to diminish such situation.Peer Reviewe

Estudo de solos do município de Pinhal, RS.

bitstream/item/47503/1/circular-112.pdf; bitstream/item/46965/1/Pinhal-aptidaoagricola.pdf; bitstream/item/46967/1/Pinhal-capacidade-de-uso.pdf; bitstream/item/46968/1/Pinhal-Relevo93.pdf; bitstream/item/46969/1/Pinhal-Solos.pd

Estudo de solos do município de Seberi, RS.

bitstream/item/47566/1/circular-114.pdf; bitstream/item/47545/1/Seberi-aptidaoagricola.pdf; bitstream/item/47546/1/Seberi-capacidade.pdf; bitstream/item/47547/1/Seberi-Relevo93.pdf; bitstream/item/47550/1/Seberi-solos.pd

HEATING OF BEE HONEY, OLIVE OIL, MILK AND WATER IN A SOLAR COOKER BOX TYPE WITH INTERNAL REFLECTORS

ABSTRACT Numerical simulation results are shown to determine the heating in liquids when a solar cooker box type with internal reflector is used to this end. The data evaluated correspond to temperature values from bee honey, olive oil, milk and water when they are heated in the solar cooker. The maximum simulation temperatures reached are 91.8, 91.6, 86.2 and 85.3 ºC that correspond to bee honey, olive oil, milk and water respectively. A comparative between simulation and experimental results also are shown. The values presented evidence the influence of the specific heat in each fluid considered. In the numerical simulation were used solar radiation and environment temperature values for February 26, 2006 in Mexico City. The experimental data were acquired using an Eppley piranometer and a Field Point device and were used as initial numerical conditions in the simulation. The processing information acquired was made using the LabView 7.0 software

Experimental determination of convection heat transfer coefficient for eggplant, zucchini and potato using a solar cooker box-type

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.In this work, experimental results to determine the convection heat transfer coefficient in the cooking process of eggplant, zucchini and potato using a solar cooker box-type are presented. Experimental data of temperatures for the fluid (water), surface and central point of the vegetables were used. To determine the convection coefficient, the vegetables were modeled as cylinders and a sphere according to their forms. The temperatures evolution was defined using thermocouples located at water, surface and central point in the vegetables. In the experimental process a NI Compact Field Point was used as acquisition data system which allows measure temperatures in simultaneous form. Also, a solar simulator as source of energy for the solar cooker function was used. Using heat transfer convection equations in transitory state and the temperatures measured, the Biot number and the convection coefficient were determined. To define how the cooking process occurs, diffusivity, density and heat specific were considered. Agree to results, the highest values to convection coefficient are obtained for eggplant while the minor values correspond to potato. The experimental tests for the cooking process were done in similar conditions which allow comparing results and generating a discussion for the same ones.dc201

Estudo de solos do município de Vicente Dutra, RS.

bitstream/item/46984/1/circular-113.pdf; bitstream/item/47513/1/Vicente-Dutra-aptidao-agricola.pdf; bitstream/item/47514/1/Vicente-Dutra-capacidade.pdf; bitstream/item/47518/1/Vicente-Dutra-relevo.pdf; bitstream/item/47519/1/Vicente-Dutra-solos.pd

Estudo de Solos do Município de Erval Seco, RS.

bitstream/item/46946/1/circular-111.pdf; bitstream/item/46947/1/ErvalSeco-aptidaoagricola93.pdf; bitstream/item/46948/1/ErvalSeco-capacidadeuso93.pdf; bitstream/item/46950/1/ErvalSeco-relevo93.pdf; bitstream/item/46951/1/ErvalSeco-solos93.pd

Estudos de Solos do Município de Frederico Westphalen, RS.

bitstream/item/45561/1/CIRCULAR-TECNICA-116.pdf; bitstream/item/45562/1/FredericoWestphalen-aptidaoagricola.pdf; bitstream/item/45563/1/FredericoWestphalen-capacidadedeuso.pdf; bitstream/item/45564/1/FredericoWestphalen-relevo2.pdf; bitstream/item/45565/1/FredericoWestphalen-solos.pd

Estudos de solos do município de Iraí, RS.

bitstream/item/39171/1/circular-104.pdf; bitstream/item/39172/1/Irai-aptidaoagricola.pdf; bitstream/item/39173/1/Irai-capacidadeuso.pdf; bitstream/item/39174/1/Irai-Relevo.pdf; bitstream/item/39175/1/Irai-Solos.pd

Estudos de solos do município de Caiçara, RS.

bitstream/item/38012/1/boletim-118.pdf; bitstream/item/38013/1/Caicara-aptidaoagricola93.pdf; bitstream/item/38014/1/Caicara-capacidadeuso93.pdf; bitstream/item/38015/1/Caicara-Relevo.pdf; bitstream/item/38017/1/Caicara-solos93.pd