Thursday, December 29, 2005

Solar Mass Cooking at Tirupathy By Chanak Balram IITM 1969

Solar Mass Cooking at Tirupathy
By Chanak Balram IITM 1969

Hi Rambo and All IIT-Global members,

In the field of solar mass cooking, you will all be happy to learn that the world's largest solar mass cooking system has just been inaugurated by Chief Minister Chandrababu Naidu of Andhra Pradesh and commissioned by Gadhia Solar Energy Systems
Pvt. Ltd. at Tirumala Tirupati Devastanam at Tirupati.

The system is installed on the roof of the Nitya Annadanam building complex, which is where free meals (prasadam) is provided to all the pilgrims who come to the temple

I have attached a few pictures of the installation which is quite magnificent.

The core of the system consists of a parabolic reflector/concentrator dishes, designed by Wolfgang Scheffler of ULOG (Switzerland) & Solare-Bruecke (Germany).

The system at Tirumala consists of 106 parabolic concentrators (53 pairs) called Scheffler dishes of 9.2 each. Solar rays are concentrated by these 53 pairs of parabolic dishes onto 53 receivers placed at the foci of the dishes. Water delivered by gravity, to the steam header above the receivers gets heated due to the high temperatures of 550 to 650 degrees C achieved by the concentrators and gets converted to steam, circulation being achieved by the thermo-syphon principle. The steam is conveyed by insulated pipeline to the kitchen to cook 30,000 meals per day.

The header is only partially filled (upto half) and steam accumulates in the upper half of the steam header which also is a storage till the steam is drawn into the kitchen for cooking. The solar cooking system is integrated with the existing diesel fired boiler system to ensure that cooking in not interrupted at night or during the
monsoons or very cloudy weather.

All 106 solar concentrator dishes rotate continuously to synchronize with the movement of the sun, in order to continuously concentrate the solar rays on the receivers. This tracking is continuous and is controlled by a timer mechanism which is fully automatic and powered by a 37 watt solar PV panel during the day.

Once a day in the morning the dishes have to be manually turned to the morning starting position, after which the automatic tracking mechanism takes over.

The total cost of the system was Rs. 1.1 crores.

About 400 litres of diesel fuel are saved per day which translates to a saving of Rs.17,25,000 per annum. The TTD's investment was only Rs.63,25,000 because of the subsidy granted by the Govt.of India's Ministry for Non-Conventional Energy Sources and the payback period (taking operational and maintenance costs into account)is estimated to be between 3-4 years. Evironmental benefits include Carbon emissions reduction estimated at 1.2 tonnes per day.

Incidentally, the parabolic dishes use acrylic mirrors for reflection/concentration. Higher temperatures upto 1000 degrees Centigrade can be achieved if one uses glass mirrors which have nil iron content according to Scheffler. Some tests have been carried out and temperatures of 750 degrees Centigrade have been obtained which
is good enough for cremation of human bodies. We are now cremating using wood as a fuel and in some cities, using electric furnace crematoriums. Solar crematoriums would certainly be much more environmentally friendly as well as save a lot of power!

Chanak Balaram
B.Tech 1969
16th october 2002