View the article online for updates and enhancements. Abstract. Cryogenic engine capable of delivering 200 kN thrust is being developed for the first time in the country by ISRO for powering the upper stage of GSLV Mk-III, the next generation launch vehicle of ISRO capable of launching four tonne class satellites to Geosynchronous Transfer Orbit(GTO). Development of this engine started a decade ago when various sub-systems development and testing were taken up. Starting with injector element development, the design, realization and testing of the major sub-systems viz the gas generator, turbopumps, start-up system and thrust chamber have been successfully done in a phased manner before conducting a series of developmental tests in the integrated engine mode. Apart from the major sub-systems, many critical components like the igniter, control components etc were independently developed and qualified. During the development program many challenges were faced in almost all areas of propulsion engineering. Systems engineering of the engine was another key challenge in the realization. This paper gives an outlook on various technological challenges faced in the key areas related to the engine development, insight to the solutions and measures taken to overcome the challenges.
Solar refrigeration may have applications in both developed and developing countries. Applications in developing countries such as airconditioning, vaccine storage or large scale food preservation have been the subject of scientific research. Ammonia-water based system has good COP but generally vapor absorption refrigeration system requires high generator temperature and high circulating ratio aided by a powerful pump. Our objective was to trivialize the role of circulating ratio and simultaneously achieve higher COP. A prototype model was designed, fabricated in laboratory using scrap material and tested; performance of the unit has been analyzed. A parabolic solar trough was used as a source of heat. Various components were modeled in computer and analyzed using ANSYS. The performances and effectiveness of the unit was studied by determining refrigeration effect (RE) and coefficient of performance (COP).
Abstract-Hot Mix Asphalt (HMA) is an old technology, which involves in production, laying and compaction at a higher temperature, which emits more pollution and increases the energy requirement. The Warm Mix Asphalt (WMA), which is produced, laid and compacted in temperature, which is much lower than conventional mix. The WMA is produced by adding chemical additives to the bitumen during mixing to obtain same performance at lower temperature. The strength, durability and workability of asphalt paving mixtures have changed significantly due to the use of additives. Warm Mix Asphalt (WMA) is an example of such additives, which lowers the temperature of the asphalt mix between 20 0 C to 40°C as compared to conventional HMA. A research study was conducted to evaluate the Dense Bituminous concrete Mix with additives such as Sasobit, Evotherm, Rediset and Zycotherm. These additives were added as per the company specified optimum dosage to the Dense Bituminous concrete Mix(DBM)and the specimens with varying binder content of 4.50%, 5.50% and 6.50% were prepared. These specimens were tested for their volumetric properties by using Marshall Stability test such as Marshall Stability, Flow value, Air voids percentage, Voids filled with bitumen, Marshallquotient, the test results were obtained and correspondingly the results are analysed through graphs. According to the comparative analysis of DBM with different additives, the warm mix asphalt with Sasobit (WMA-S) of dosage 3% at Optimum Bitumen Content of 5.45% was found to be economical and satisfied all the aspects and represents the better performance. Keyword -WMA1, HMA2, DBM3, Zycotherm4, Evotherm5, Rediset6, Sasobit7.
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