| abstract
| - Brahma Kumaris has done pioneering work in solar energy and sustainable energy, including developing the world's largest solar cooker. Prajapita Brahma Kumaris Ishwariya Vishwa Vidyalaya or Brahma Kumaris World Spiritual University is a monastic, renunciantsor semi-monastic Millenarian New Religious Movement (NRM) of Indian origin." It teaches a form of meditation called Raja Yoga, although not classical Raja Yoga as described by Patanjali, involving spirit possession and mediumistic channelling. By the early 1990s, students and teachers from over 60 countries were regularly visiting Mount Abu to take benefit from the University's spiritual education and it was clear that further facilities were required to accommodate all those wishing to attend. In 1995 the WRST started work at a 25-hectare plot of land named Shantivan just outside Abu Road, the town at the base of the Aravali Hills, at the top of which Mount Abu is located, for building a 20,000 seat auditorium, dining facilities and simple accommodation for 15,000 people. Taking advantage of the experience and expertise in renewable energy systems developed over the previous years, the planning process include proposals for a major solar steam cooking facility. Image:Solar-cooker-designs-Abu1-P5a.jpg In order to maximise output, a new design concept was developed jointly by Wolfgang Scheffler and ECO Centre, both of whom had also worked on the first system at the Academy, together with the WRST's Department of Renewable Energy. The system comprises 84 improved parabolic concentrators, shell type receivers and large diameter header pipes which serve the dual purpose of treated water storage as well as steam reservoirs. The improved parabolic concentrators are oval in shape and each has a reflective surface area of 9.2 square metres. The dish is fitted to a rotating support which itself rests on a stand, all built of mild steel and locally made in WRST workshops. Each concentrator reflects sunlight by means of 260 pieces of special white glass, 165 x 200 mm in size and imported from Germany, with an optical reflection rate close to 93%. Each disc has a maximum output of 4 kw solar radiation reaches temperatures up to 800 degrees Celsius at the focal point. The system's concentrators are arranged in pairs, with one in a higher position and one lower, and their reflected sunlight is focused on 42 shell type receivers each of 350 mm diameter and made of boiler-grade steel, situated three metres from the centre of the concentrator. Tracking of each module is controlled by a semi-automatic centralised system comprising a winch, steel wires, a photovoltaic-powered DC motor and an electronic timer; each evening the system is reset to its morning position. Steam gathers in six independent header-pipes, each with a diameter of 35 cm and 24 metres long, from where it is concentrated to a common steam drum and then fed through insulated pipes directly to cooking vessels in the kitchens. The system works on the thermo-siphon principle so that each concentrator's well-insulated header pipe itself acts as a steam reservoir, obviating the need for a separate steam generator, heat exchanger or electrical back-up for circulation pumps, and thereby increasing efficiency and preventing disruption by power cuts. The day-to-day operation and maintenance of the system is easily handled by a team of three local residents. Features incorporated in the system include a water-softening system to prevent salt formation in the header pipes and receivers, a pressure reducer station to maintain consistent steam flow and a high-efficiency diesel-fuelled back-up system for days of low solar radiation or extra demand to ensure round the clock steam availability. The only time that the back-up is put to full use is during the monsoon season when, for a period of about ten weeks, it is not practicable to rely on solar functionality. The system is protected against excessive pressure by safety valves and an automatic shutdown mechanism while temperature and pressure metres and a computerised six-channel data logger monitor the status of the system as a whole. Installation was completed in January 1998 and the system, through all six of its modules, can generate 3,500 kg of steam per day, which is used for cooking, water sterilization and preparing hot drinks. Although originally designed to cater for 20,000 meals per day, during periods of peak solar radiation the system's output has been sufficient to cook a maximum of 38,500 meals per day. Supported and approved by the MNES, the system attracts considerable attention and was described in a BBC World Service TV programme as the largest solar cooker in the world.
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