Novel patent pending solar stove

Dr. Vishwa Narayan

by

Problem: energy is expensive

Huge numbers of rural and semi-urban people worldwide, especially in developing economies, lack affordable and reliable energy sources

They use kerosene or firewood

They do not have access to LPG or propane gas cylinders or electric stoves

How-ever, many of them live in sunlight abundant areas

But existing solar thermal energy collectors have drawbacks, precluding widespread use

Solution:

Afford-ably and efficiently tap solar energy with new patentedinvention

Competition

Competition; existing portable solar thermal energy harvesters

Almost all existing portable systems such as parabolic solar stoves are based on reflective optics, which are prone to scratching and breaking They also need to track the sun, introducing moving parts, increasing cost, and reducing long term reliability

Also, the heat utilizer (item to be cooked) needs to be placed at the focus of the parabola – a precarious arrangement, especially when the parabola is moving

Non imaging optics based solution such as box cookers are bulky and do not attain higher temperatures

Proposed solution

Solar heat collector uses solar selective absorber material to capture energy from the sun in the form of heat: 150 degrees Celsius

The captured heat is directed to the center of the device through thermo-siphons or heat-pipes; constructs that are extremely efficient heat transfer devices. This is an innovation

The heat at the center may now be utilized; to cook, for example. Or thermally process materials

2 sq m solar thermal collector captures 5 kWh per day = 18 MJ at conservative, 50 % efficiency (sunlight in to heat out)

Payback:

5 kWh of energy per day at Rs 5 per kWh (domestic electricity rates) = Rs 25 per day, or Rs 7500 per year, assuming 300 sunny days. Assume half this energy is utilized per day for cooking. Rs 3750 in energy savings per year

Expected selling price per solar stove = Rs. 5000

Unit pays for itself in less than one and a half years

Solar stove – first proof-of-concept - unoptimized

0.35 m

0.5 m

10 cm

Thermo-siphon aided heat transfer to point of use

0.1 sq m collection area per fin, nine fins in all = 0.9 sq m total collection area

0.12 mm thick copper sheet metal fin coated with solar selective absorber black chrome coating

Solar stove – first proof-of-concept - unoptimized

10 year average insolation for November = 4.36 kWh/m2/day

November, Bangalore, Indialatitude 13 degrees N, longitude 77 degrees E

http://www.apricus.com/html/insolation_levels_asiap.htm

11.58 am, 80.3 °C11.58 am, 80.1°C11.57 am, 79.9 °C

Thermo-couple

11.57 am, 79.1 °C

Air temperature = 28 °C

http://www.gaisma.com/en/location/bangalore.html

November

Solar stove – second proof-of-concept – improved efficiency; still unoptimized

90.4 degrees C

Improvement due to more efficient solar selective absorber material (blue surface)

Larger collection area (0.15 sq m per fin, 9 fins, 1.35 sq m, more efficient solar absorber

Accomplishments:

● Product idea conceived

● Design approach vetted by experts: UT Dallas – Dr. Matthew Goeckner, IIT-M – Dr. K. Srinivas Reddy

● Patent filed in Chennai

● Proofs-of-concept – two iterations - demonstrated

1st unit achieved 80.3 degrees C, second unit achieved 90.4 degrees C

Next steps:

● Develop finite element analysis model of heat collector

● Build market ready prototypes based on FEA model

Accomplishments, next steps

Team advisors

Dr. Duncan MacFarlane – Professor, UT Dallas – Optics

Mr. Vinay Paralikar – MD, Golden Star Pvt Ltd. - Heat pipes and thermo-siphons

Mr. Harshad – Director, Technical – Magod Lasers – thermosiphon to foil attachment

Dr. K Srinivas Reddy – Professor, Thermodynamics Lab

Head, IIT – Madras

- Heat transfer, COMSOL Multi-physics modeling

Dr. Raj Thiagarajan – MD, ATOA Scientific Technologies

– COMSOL Multi-physics modeling

Mr. Richard Bravman – Ex-CEO Symbol Technologies

- Veteran industrialist

Market

Rural and semi-urban populations in sun belt countries

Funds

Seeking Rs. 30 Lakhs (FEA stove model, stove fabrication, materials, salaries)

Goal

Ten production grade solar stoves delivered, ready for mass manufacture

Time lines

Product ready within twelve months from funding

Market validation

From:KarthikNatarajan<karthik@inthreeaccess.com>To:VishwaNarayan<drvishwanarayan@yahoo.com> Sent:Saturday,January31,2015,10:25AMSubject: Re: New solar cooker

Hi Vishwa, Huge opportunity for solar cooking system. When can we meet? We at Inthree are thrilled with your initiative. As discussed, if you could come up with solar cooking system, which can be operated from the existing kitchens of rural/semi-urban households, this will be the “Next Big Thing” for sure. We will help you in field trials, user feedback etc . Look forward to seeing the finished product. Best Regards, Karthik natarajan

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Hello Mr. Karthik, I came to know about your organization through Naru Narayanan of Chennai Angels. I have developed a new solar stove. Proof-of-concept devices have been demonstrated. Please find attached a presentation explaining my work. Do you see potential of this product for rural markets? Thank you , Vishwa . mobile 97410 10556

About Inthree Access: “We are an impact venture that helps the Indian hinterland access the most relevant products and services, by leveraging our rural distribution network and expertise in project management in rural areas and the social sector."

Vishwa Narayan earned his B.E. Honours from REC Trichy, spent 2 years at L&T, moved to the US, earned his Masters and Ph.D. In EE specializing in Optical Devices, Materials and Systems from UT Dallas, and worked in the Telecoms industry with Ericsson Micro-electronics for 5 years in technical customer facing roles handling high speed long haul fiber optic system components.

Vishwa then turned to working at start-ups; as senior manager at Avanex Corp - a Photonics start-up, as Director Engineering at Intelleflex – an RFID start-up, and as Co-founder and VP of Engineering at Pulsar Energy Inc., - a renewable energy start-up.

Vishwa then turned to inventing this new solar stove. He works out of Bangalore.

Vishwa Narayan, +91 97410 10556, drvishwanarayan@yahoo.com