This paper describes the design of an ultrahigh solar concentration device (C> 10 4 ) and shows the technical feasibility of using solar energy in processes requiring high temperatures with relatively simple devices. The concentration is effected in two stages, using in the first stage a paraboloidal reflective disc of 1.40 m. of diameter, whose focal region is located at CPC-3D without truncating. The ideal concentration achieved was 93 567 suns. A thermal-optical analysis was performed to estimate the actual concentration considering radiant energy losses in both concentration stages and the concentration was estimated to be 30 000 suns. Among the potential applications of this device is the production of hydrogen [1], power generation [2], production of alloys and special materials, destruction of hazardous industrial waste and the use of high energy lasers.
This study compares the energy efficiency of two processes covering the thermal energy demand of a swimming pool: a combined heat and power (CHP) unit on the one hand, and a heat pump with internal combustion engine on the other hand. The thermal energy demand of the swimming pool was 1438 kWh per day (78% heating the pool and 22% providing hot water for showers), owing to temperate climate in the city of Toluca in central Mexico; a mean annual temperature of 13.5 °C (10.5 °C in January and 15.7 °C in June) offers a large potential of renewable thermal energy stored in the atmosphere. Its utilization in heat pumps driven by thermal combustion engines can provide energy below 60 °C; this temperature level provides hot water for showers while a lower temperature level of about 40°C heats up the pool water and swimming hall. Depending on outdoor temperature, which defines the load for the units, the efficiency in terms of total primary energy consumption is better for the CHP solution (100% and 80% load) and is better for the heat pump in the case of a 57% load. The energy losses for the CHP unit on-site are equivalent to half the losses caused by extraction and distribution of natural gas under current circumstances in Mexico. The results provide a decision tool.
A new two-dimensional concentrator for solar energy collection has been developed. The concentrator has the following advantages, when compared with the classic Compound Parabolic Concentrators invented by Roland Winston, W. T. Welford, A. Rabl, Baranov, and other researchers: 1) It allows the use of parabolic mirrors, which have a reflecting area much smaller for a given concentration ratio and acceptance angle. 2) Between the mirror and the absorber, there is a large gap so that conduction losses are reduced. Convection losses can be reduced, too, if the absorber is enclosed within a glass tube. 3) It can be easily manufactured. Instead of seeking the shape of the mirrors for a given shape of the absorber, we have made the inverse statement of the problem, and we have obtained the optimal shapes of the absorbers with a prescribed acceptance angle, for parabolic mirrors, assuming that the intercept factor is unity, the mirrors are perfect, and the absorber surfaces are convex. The concentrator should be east-west oriented, and could be seasonal or monthly tilt adjusted. This concentrator could have many practical applications, such as fluid heating, steam generation, etc.
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. . University of Texas Press is collaborating with JSTOR to digitize, preserve and extend access to Latin American Music Review / Revista de Música Latinoamericana. Reviews ALEJO CARPENTIER, Ese mutsico que llevo dentro. Selecci6n de Zoila Gomez. La Habana, Cuba: Editorial Letras Cubanas, 1980. Three volumes: 1, 479 pp.; 2, 589 pp.; 3, 354 pp. (Each volume includes an "Indice Onomastico" and an "Indice General.") Readers of this review will doubtless recall Carpentier's excellent book La mutsica en Cuba (1946), still indispensable for musicologists and historians. But the vast scope and depth of his interest in the music of the Western world throughout several centuries is only now revealed in the three volumes of the present publication. The articles gathered hereinare grouped in five parts: "Los hombres que hacen la musica," "Musicologia," "Musica en la escena," "Reflexiones en torno a la musica," and "Ensayos." Of the foregoing, the first eighty-five pages of volume 1 are devoted exclusively to compositores latinoamericanos, beginning with Alejandro Garcia Caturla and Amadeo Roldan, with both of whom Carpentier had a close affinity. Regarding Roldan, it is interesting to note that he emphasizes the importance of "la musica vernacula," citing "la funci6n del ritmo" as basic (1:30-43). Other Latino composers included in the first volume are Sojo, and-foremost of all-Heitor Villa-Lobos, who throughout the three volumes gets the lion's share of attention. He is "el fabuloso!" Volume 2, giving (I would say) perhaps too much weight to the term
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