Title of Invention


Abstract The invention relates to Solar Powered Closed Cubinet Food Dryer with electric stand-by facility for dehydration of fruits and vegetables and other applications. The design of this dryer is based on the combination of solar thermal and solar photovoltaic technologies in aluminum closed cabinet dryer in a forced circulation mode with exhaust fan, driven by power generated by solar photovoltaic panels. The ambient air enters into the cabinet through bottom louvers of the closed cabinet and gets heated up by solar radiation that enters through glass on the top which is placed in oblique angle to the horizontal plane of the cabinet. Exhaust fan facilitates removal of hot air containing moisture from the material kept in for drying. The numbers of food trays are adjusted proportional to volume of cabinet and area of trays for effective drying. The dryer is high efficient and maintains higher temperature over ambient. The process of dehydration of products in a clean, environment meets hygienic and safe food practives applications.
Full Text

The present invention relates to Solar Powered Closed Cabinet Food Dryer with electric standby facility, a device for drying various kinds of perishable materials like fruits, vegetables various powders and not limited to, and those that require regulated uniform temperature and humidity.
The equipments that have been used in the drying art consist of photovoltaic system, solar thermal energy, metal cabinet, glass windows, fan for forced circulation and trays for keeping the various items to be dried. Agro-Horticultural products, such as cereals, pulses, vegetables, fruits, spices, egg-powder, forest produce like herbs and gums do not have long shelf life without proper post harvest treatment. Some of them like fruits, vegetables etc. are perished in very short time and become unusable and others like tea. pepper, ginger and gums loose their quality over a short period. The main reason for this deterioration in quality is moisture content in the food products. Higher the moisture content higher is the formation of mould leading to fermentation and spoilage.
The other quality control specification is the limits of contamints rising of filth from birds, insects, rodents, mammals, dust and dirt. The countries which import the Indian food products, are insisting on the Food and Drugs Regulations of the respective importing countries. In general, most of our products do not meet their specifications due to absence of appropriate drying, higher moisture content and consequent deterioration. Hence the two major factors in the dehydration of the

food products are clean, hygienic method and reliable drying regulated temperature and moisture control The present practices are:
1) Open sun drying on smatt scale.
2) Large oven drying, run by electrical power or furnace oi! or wood.
The cost of the electricity and fossil fuel is high and makes the cost of production

i. Referring to figure 01 a closed large cabinet especially for dehydration of fruits,
agri-horticuitural products such as fruits, vegetables, spices, herbs and marine foods as well as food processing products, having a top transparent glazing glass (2) through which solar radiation passes into the chamber (1) and the same source

of radiation simultaneously incident on solar photovoltaic panels (6 ) of suitable wattage and voltage to generate the current to drive the solar fans (5) situated on the back wall of chamber to exhaust moisture air "0' to atmosphere in forced circulation mode, and the chamber is mounted on 4 or more caster wheels (9) and orientated to south direction to about 20°C tilt for maximum solar energy collection.

one to reduce the thermal loss and Electric heaters (AC 220 Volts) of special rod type design (7) and wattage to distribute the heat energy evenly and to attain 70°C
or so maximum temperature with control or without control is provided in the bottom plane above insulating cover, an Aluminum thin sheet (11) is located above heaters to spread the heat energy uniformly and to make the wet product in trays, exposed only to radiant heat energy mstead of directly delivering heat energy from rod heaters. The tray compartments are closed with doors, having provision in the bottom of doors for air let /louvers and also locking system.
5. Referring to figure (05) characterized in that on the back wall of the chamber,
electrical switch boards (5) are provided to each fan and A.C. rod heaters
corresponding to each compartment; and the switch boards (5) consisting of fuse,
power indicator lamp, electrical connection to heater, two way switch to fan,
connecting to solar photovoltaic fan and to A,C. to DC. adopter connection and to
A.C. power line connection.
6. Referring to figure (06) characterized a smaller sized chamber (I) made of
aluminum alloy, coated with high temperature polyester or similar paint of black
coaling outside the chamber walls for maximum absorption of solar energy, with
glass window (2) on top with durable synthetic rubber beading to make it
rainproof; 2 tire system, thereby establishing the scalability of dryers and also
provision with the ultraviolet (TJ.V ) reduction filter (9) of about 20% U.V
reduction and total intensity reduction of 40%, for simulation of shade drying of
medicinal, herbal and oilier products,, in conjunction with top glass.

1. Solar Powered Closed Cabinet Food Dryer with electric stand-by facility,
a. Closed Cabinet with a glass at the top
b. Racks for placing trays
c. Trays for placing articles to be dried
d. Photovoltaic panel and at least one exhanst fan, and
e. Electric heater and adopter and switch board.
2. Food dryer as claimed in claim 1, which is movable, modular and easy to
install and operate.
3. Food dryer as claimed in claim 1, wherein side walls of cabinet are
provided with louvers at the bottom (for entry of air into cabinet).
4. Food dryer as claimed in claim, wherein outer walls of cabinet are
coated with black paint (high tempertue polyester black coating).
5. Food dryer as claimed in claim 1, wherein the top glass is placed in
oblique angle to the horizontal plane.
6. Food dryer as claimed in claim 1, wherein number of racks are adjusted
proportional to the volume of the cabinet so that drying is effective.
7. Food dryer as claimed in claim 1 wherein the area of trays is adjusted
proportional to the area of glass and volume of the cabinet so that the
drying of the articles to be dried is effective.
8. Food dryer as claimed in claim 1, wherein the height of the trays' side-
walls is sufficient for accommodating food material to dry effectively and
9. Food dryer as claimed in claims 6, 7 & 8 where trays and racks are
configurated such that sufficient volume of air circulates for effective
drying in a closed cabinet of volume specific and to match with the speed
of the exhaust fan.

10. Food dryer as claimed in claim 1-9 wherein speed of exhaust fan is kept proportional to intensity of solar radiation such that the amount of air removal from the cabinet and the volume of air entering the cabinet through the louvers is sufficient for effective drying.
11. Food dryer as claimed in claim 10, wherein photovoltaic panel rating is
sufficient to the specified wattage of exhaust fan
12. Food dryer as claimed in claim 1, wherein electric heater, AC to DC
converter and switch board forms an integral part of the dryer.
13. Food dryer as claimed in claim 12, wherein A.C to D.C converter is provided to convert AC. into DC for operating the D.C. fan and the electrical heater draws the A.C. power directly to heat the products in the cabinet, when solar radiation is not available.
14. Food dryer as claimed in claim 1, wherein different ratings of fans of varying numbers are used depending on the size of the dryer
15. Food dryer as claimed in claim 1 14 which are of different loading
capacity of wet products.
16. Food dryer as claimed in 1 ~ 15 which are used for drying solids,
powders, pulps, viscous and such other food articles pre or post
processed or in raw form. 17. Solar Powered Closed Cabinet Food Dryer with electric stand-by facility
as herein substantially described with reference to description and
accompanying drawings.



326-mas-1999-claims filed.pdf

326-mas-1999-claims granted.pdf







326-mas-1999-form 1.pdf

326-mas-1999-form 19.pdf

326-mas-1999-form 5.pdf

Patent Number 211911
Indian Patent Application Number 326/MAS/1999
PG Journal Number 02/2008
Publication Date 11-Jan-2008
Grant Date 13-Nov-2007
Date of Filing 22-Mar-1999
Applicant Address PLOT 30, ROAD 5, JUBILEE HILLS, HYDERABAD - 500 033,
# Inventor's Name Inventor's Address
PCT International Classification Number F26B 3/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA