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Steam can be generated by harvesting sun light using concentrated mirrors. This technology is being perfected during the last 10 years and more than 200 numbers of solar steam generators are being used in different parts of India. These units are working perfectly and the customer satisfaction is very high as they are getting huge savings from these units. |
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The Solar heat generators consist of the following parts.
1) Concentrating Reflector
2) Receiver - heat exchanger
3) Header Pipe
4) Steam Storage tank
5) Tracking device |
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The Concentrating Reflector is a flexible parabolic reflector. The frame is made up of mild steel and the reflecting surface is high quality glass with silver coating. In the focus of the solar concentrator reflector is the receiver which is a heat exchanger. |
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Solar rays falling on the dish are getting reflected and concentrated on the receiver placed in its focus. Due to concentration of heat, the temperature rises to 10000 C at the focal point. Thus the water in the receiver comes to boiling and steam is generated.
Receiver is a well insulated block of steel with stainless steel coil inside through which water is circulated. The receiver is mounted below a header pipe. |
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The header pipe is a seamless, well insulated pipe with 12 inch diameter. The header pipe is placed above the receiver and is half filled with water.
The cold water enters into the receiver through the inlet of the coil and gets heated up. The heated water moves up to the header pipe. The cold water from header pipe enters through the inlet and the cycle continues till the steam is generated. |
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The generated steam will moves up to the header pipe. Then the pressure keeps on rising. The steam is then sent to cooking or for laundry through insulated pipeline. |
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On a full sunny day it will take 3 hours to produce steam at a high temperature of more than 4000 C.
Ie, by 10 am the steam generator starts producing steam. |
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According to the rotation of earth the sun will move from east to west. So the Dish has to be rotated according to the movement of sun to keep the focus on the receiver. This is achieved by an automatic tracking mechanism using a small motor.
For seasonal changes, the dish is to be adjusted once in 2 months manually. |
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By installing Solar steam generators the cost of fuel used for generating steam can be brought down. There will be a saving in the tune of 50% - 70 % depending up on the steam usage time. Absence of brightness of sun up to 1 hr will not make any difference in the production of steam. |
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During rainy season and cloudy days the steam cannot be produced as sun will not be there. So the steam generator cannot be used as a stand alone system. |
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| Block Type Solar Steam Generators |
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Block type Solar Steam Generators have a single parabolic concentrator mirror. The sun light is focused to an insulated block of solid steel. |
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Block type Solar Steam Generators are used to produce steam at 2500 C at a low pressure. These systems are ideal for Autoclaves in hospitals. The steam produced in this system can feed to the autoclaves for sterilizing instruments. For a 150 bed hospital a system with 4 parabolic reflectors will be needed. |
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| The main parts of the system are concentrating reflector, Insulated Heat Exchanger and a Tracking device. |
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• In hospitals or sterilization
• In hotels & hospitals for laundry purpose. |
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Advantages :
• Annual saving of 40-50% on energy bills can be obtained. Usually autoclaves work with electricity or diesel. So there will be a reduction of 40-50% either on electricity bill or in
diesel bill.
• Since the steam enters very fast in the autoclave the sterilization time will be very short. So
Staffs can save a lot of time to wait through the sterilization of hospital equipments.
• Steam can also be used for washing clothes.
• 100% depreciation can be availed in the first year itself.
Disadvantages :
• During winter or cloudy days solar steam generators does not produce enough steam for
Sterilization. |
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| Solar Community Concentrator Cooker |
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A Solar Community concentrator cooker is used for indoor cooking for 100-1000 meals a day. Concentrator cookers are of two type : |
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| 1. Solar Community Concentrator Cooker - Direct Heating |
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This model is used for cooking meals for less than 100 people at a time. An opening is made in the kitchen wall at the focal point. A second reflector is used to direct the heat to a vessel with 35-40 cm diameter. The main parts of a direct heating model concentrator cooker are; parabolic reflector mirror, Secondary reflector and a Tracking device. |
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| 2. Solar Community Concentrator Cooker - Indirect Heating |
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This type of Solar Concentrator cooker is used to prepare more than 10,000 meals a day. Instead of heat steam is directly used to cook the meals. The system consists of parabolic concentrating reflector, receiver, header pipe, steam storage tank and tracking system. Steam generated in the header pipe is passed through the cooking vessels to cook the meals. These solar steam generators can be easily incorporate in places where steam is used as a medium for cooking. |
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