PREAMBLE TO THE DESCRIPTION

The following specification particularly describes the invention and the manner in
which it is to be performed:

TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to a solar
energy driven food preparation system, and more particularly to solar thermal cooking
system for all weather for mass population/community particularly where daily cooking
demand is fixed.

BACKGROUND
[002] The use of solar thermal energy for cooking purpose is not new in India.
The existing mechanism is the replete with various solar cooking system configurations.
15 Many such prior art cooking system are configured to utilize the reflectors having plan,
parabolic or spherical dish form that reflect sunlight to the target point or focal point
located on or directly adjacent to a cooking container.
[003] In the early 80s, the first variant of the existing solar cooking system is
20 popularly called a box type cooker. These types of cooker are limited for fulfilling of
cooking needs for 2 to 3 people. Further, these are capable for doing only boiling kind
of food (< 100°C) and also takes 3 to 4 hours of time for the cooking
[004] The next variant in the solar cooking category is parabolic type
25 concentrator which has an arrangement of placing a pot / vessel at the focal point of the
concentrator. These concentrators are capable for cooking the food which has required
a temperature up to 200–220°C. Baking, that includes but not limited to roti making, is
not possible in this type of system. The tracking of sun has to be done manually.
30 [005] The next variant of solar energy assisted cooking system is steam based
cooking system. In this system, steam is produced at 170 to 2000C and then passes
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through the jacket of specially designed utensils where the enthalpy of steam is
transferred to the utensils and hence the food is cooked. However, frying and baking
type of cooking is not possible. For producing steam both line focus or point focus
concentrators is used. The most popular solar concentrator technology used in solar
steam cooking system is scheffler dish. This dish can be used for direct 5 cooking also
where sunlight is reflected and diverted via secondary reflector to the kitchen. In this
type of cooking frying and baking is also possible. The drawback of such system is
cumbersome process for controlling the temperature.
10 [006] Reference is made to an application EP 1685762 A2, wherein an elevated
cooking system working in a temperature range of 315 to 400 0C is disclosed. The
temperature is elevated by using ‘synthetic thermic fluid’ circulating in heat exchanger
installed in enclosed housing. Fins are attached on ‘heat exchanger’ for maximum and
air is blown over these fins which transfers their heat via convection and radiation to the
15 cooking food which is continuously circulated by conveyor belt. A conventional gas
fired ‘thermic fluid heater’ is used here as a heat source to elevate the temperature. The
system is also able to fulfill frying requirement (260 -270C) as separate facility is
installed there in other housing. However, this cooking system does not use any
renewable or solar energy for heating the ‘thermic fluid’. Secondly there is no storage
20 facility for hot thermic fluid which could be used later for low temperature cooking
requirements. Further to this, system does not appropriate for Indian food cooking
requirement at it needs all three modes of cooking i.e. boiling, frying and baking on
everyday basis.
25 [007] Reference is made to an application US 2012/0145145, wherein a
compact device for cooking food by using solar thermal energy is disclosed. The device
consist of an evacuated tube solar heat collector, heat storage material, cooking utensil
and an element rod as a heat source for extra temperature is fitted in a single tube
assembly. There are number of tubes fitted in one collector. The collector faced N-S
30 with inclination as per latitude to absorb solar energy. The food cooked inside this
4
assembly is kind of boiling type. However, frying and baking of items is not possible in
such system.
[008] Reference is made to an application US 2009/0165781 A1, wherein a
system which can be used for cooking the food in forest area 5 is disclosed. The
availability of solar radiation is very limited under the canopy of trees in forest. In such
places tribal family or tourist can use the said system to fulfill their cooking
requirement. System consist number of support members mounted with reflectors,
placed independently adjacent to an object to be heated. A user may manually adjust the
10 angle of each reflector with respect to support member so as to reflect a focused beam
of light on to the object to be cooked. The maximum achievable temperature of the
system is approximately 330°C and it solely depends upon direct solar insolation (DNI).
However, the said system is useful for fulfilling the cooking need of maximum of 2 to 3
people. Further, the tracking of the sun is manually which is sometime not possible
15 under the canopy of tall trees for which the said system is invented. Besides, frequently
adjustment of reflectors for maintaining focus may also results in un-even cooking.
[009] Reference is made to Chinese patent application CN 200996730 Y,
wherein an energy storage automatically tracking solar cooker is disclosed, which
20 comprises a condenser plate, a supporting rod to fix the condenser plate, a central axis, a
base and a supporter. The supporting rod is connected with the top end of the supporter
by a movable axis. The utility model has a good integrity and a strong practicality, can
automatically follow the motion of the sun lights to obtain the highest heating
efficiency, and can transfer the heat energy to the cooker by the energy storage device to
25 solve the problem that the solar cooker cannot be used in the cloudy day and night,
therefore, the utility model can be used indoor no matter it is cloudy and rainy days or
the night and is an ideal new-type solar cooker. The patent application is for Solar
paraboloid dish only which includes reflector area and receiver (here canister) with
insulation.
30
5
[0010] From the hitherto references, it has been observed that solar energy is an
intermittent source of energy that is utilized in a food preparation system. However, to
make the system reliable, there is a need for utilizing the source of energy efficiently.
Further, there exists a need for a provision of energy storage or other heating source or
combination of both, which makes solar cooking system more reliable 5 and deliver
quality food items.
SUMMARY OF THE INVENTION
10 [0011] The following presents a simplified summary of the invention in order to
provide a basic understanding of some aspects of the invention. This summary is not an
extensive overview of the present invention. It is not intended to identify the key/critical
elements of the invention or to delineate the scope of the invention. Its sole purpose is to
present some concept of the invention in a simplified form as a prelude to a more
15 detailed description of the invention presented later.
[0012] The object of the present invention is to provide a solar thermal cooking
system with a provision of energy storage as well as external source of heat, to ensure
operation of the cooking system during non-solar or low solar period.
20
[0013] Another object of the present invention is to provide a solar thermal
cooking system with a provision for automatic tracking of sun radiation.
[0014] Yet another object of the present invention is to provide a solar thermal
25 cooking system that is capable of baking, frying and boiling of food items.
[0015] Still another object of the present invention a solar energy assisted all
weather food preparation system as well as improved reliability of the system.
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[0016] Accordingly, in first implementation, the present invention provides a
solar thermal cooking system comprising: at least one solar section to supply at least
one thermic fluid to perform cooking; at least one cooking section comprises:
means for receiving at least one utensil; and
at least one thermic fluid heater to provide heating to said thermic 5 fluid during
non- solar or low solar operation;
wherein, said solar section comprises: at least one solar concentrator with at least two
axis tracking mechanism, wherein said solar concentrator adapted to receive heat energy
from solar radiation during solar operation, and supply heated thermic fluid to said
10 cooking section; at least one thermic fluid storage tank and expansion tank, adapted to
pump thermic fluid to said solar concentrator and store excess heating source, wherein
during non-solar operation said thermic fluid storage tank and expansion tank is adapted
to supply said stored excess heating source to said cooking section.
15 [0017] In second implementation, the present invention provides a method for
cooking using a system during solar and/or non-solar operation, said method
comprising:
• receiving, by means of a receiver of at least one solar concentrator, heat
energy from solar radiation during solar operation;
20 • pumping, by means of at least one thermic fluid storage tank and
expansion tank, at least one thermal fluid to said solar concentrator, and
generating, by means of said solar concentrator, heated thermic fluid at a
temperature range of 100 to 270 0C;
• supplying, by said solar concentrator, said heated thermic fluid through a
25 thermic fluid heater to at least one a cooking section for cooking of at
least one food items;
• passing, said thermic fluid passes through the periphery of thermally
insulated jacket of said utensil to perform said cooking;
• storing, by said thermic fluid storage tank and expansion tank, excess
30 heating source, wherein said excess heated thermic fluid is supplied during low
or non-solar operation for cooking of said one food items.
7
[0018] Other aspects, advantages, and salient features of the invention will
become apparent to those skilled in the art from the following detailed description,
which, taken in conjunction with the annexed drawings, discloses exemplary
embodiments 5 of the invention.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0019] The above and other aspects, features, and advantages of certain
10 exemplary embodiments of the present invention will be more apparent from the
following description taken in conjunction with the accompanying drawings in which:
[0020] Figure 1 illustrates a solar thermal cooking system in accordance with an
embodiments of the present invention
15
[0021] Persons skilled in the art will appreciate that elements in the figures are
illustrated for simplicity and clarity and may have not been drawn to scale. For example,
the dimensions of some of the elements in the figure may be exaggerated relative to
other elements to help to improve understanding of various exemplary embodiments of
20 the present disclosure. Throughout the drawings, it should be noted that like reference
numbers are used to depict the same or similar elements, features, and structures.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
25 [0022] The following description with reference to the accompanying drawings
is provided to assist in a comprehensive understanding of exemplary embodiments of
the invention. It includes various specific details to assist in that understanding but these
are to be regarded as merely exemplary.
30 [0023] Accordingly, those of ordinary skill in the art will recognize that various
changes and modifications of the embodiments described herein can be made without
8
departing from the scope of the invention. In addition, descriptions of well-known
functions and constructions are omitted for clarity and conciseness.
[0024] The terms and words used in the following description and claims are not
limited to the bibliographical meanings, but, are merely used by the inventor 5 to enable a
clear and consistent understanding of the invention. Accordingly, it should be apparent
to those skilled in the art that the following description of exemplary embodiments of
the present invention are provided for illustration purpose only and not for the purpose
of limiting the invention as defined by the appended claims and their equivalents.
10
[0025] It is to be understood that the singular forms “a,” “an,” and “the” include
plural referents unless the context clearly dictates otherwise.
[0026] By the term “substantially” it is meant that the recited characteristic,
15 parameter, or value need not be achieved exactly, but that deviations or variations,
including for example, tolerances, measurement error, measurement accuracy
limitations and other factors known to those of skill in the art, may occur in amounts
that do not preclude the effect the characteristic was intended to provide.
20 [0027] Features that are described and/or illustrated with respect to one
embodiment may be used in the same way or in a similar way in one or more other
embodiments and/or in combination with or instead of the features of the other
embodiments.
25 [0028] It should be emphasized that the term “comprises/comprising” when
used in this specification is taken to specify the presence of stated features, integers,
steps or components but does not preclude the presence or addition of one or more other
features, integers, steps, components or groups thereof.
30 [0029] Reference is made to figure 1 that illustrates the solar thermal cooking
system (STCS) in accordance with an embodiments of the present invention. The
9
system consist of 2-axis tracking solar concentrators, Thermic Fluid (TF), TF heater, TF
pump, TF storage and expansion tank and TF jacketed utensils.
[0030] In one embodiment, the various elements shown in figure 1 is as follows:
• Solar concentrators (1) - concentrate solar energy at focal 5 point to heat
up thermic fluid;
• Thermic fluid storage and expansion tank (2) - to store excess energy and
to expand thermic fluid when heat up;
• Solenoid valve (3) – to control fluid flow in concentrator;
10 • Thermic fluid pump (4) – to circulate the thermic fluid in the system;
• Thermic fluid heater (5) – to heat up thermic fluid;
• Baking plate (6) - for making chapattis and other equivalent item;
• Boiling utensil (7) – for boiling type cooking;
• Frying utensil (8) - for frying type cooking;
15 • Three-way motorized valve (9) (10) – to bypass the thermic fluid path as
per the requirement.
[0031] As shown in figure 1, in one embodiment, the solar thermal cooking
system comprises of two sections-solar section and cooking section. The solar section
20 consists of solar concentrators (1), thermic fluid storage and expansion tank (2) and
thermic fluid pump (4). Cooking section comprises of means for receiving varied type
of cooking vessel that may be required for baking, frying and boiling along with
Liquified petroleum gas (LPG) fired thermic fluid heater which will be able to cater the
cooking needs during non-solar period and/or lean solar period.
25
[0032] The schematic in figure 1 shows embodiment of the desired system used
for cooking with the help of Solar Thermal Energy. It includes solar concentrator (1)
including with two axis tracking facility. Sun radiation falls on reflector area and
concentrates on focal point of the concentrators, called receiver. Inside the receiver
30 there is thermic fluid which is desired to be heated up to 270°C. The reflector is
10
designed in such a way that it could deliver the required temperature of thermic fluid at
a certain optimum level of Direct Normal Insolation (DNI). The heated thermic fluid
hence can be utilized for different kind of cooking purpose. The purpose of the two axis
tracking is for tracking the sun on daily basis for east to west movement and also for
seasonal version for north to south movement (of sun) as well. This will 5 result in more
efficient capture and utilization of solar radiation.
[0033] In one embodiment, the geometry of reflector area may be parabolic or
paraboloid type which reflects incident solar radiation from reflectors / mirrors to the
10 focal point of parabolic / paraboloid i.e. at centre of reflector area with some height. At
this point 'receiver' may be fitted in which thermic fluid is routed. At receiver, reflected
solar radiation gets concentrate and increases the temperature of fluid inside the
receiver. This heated thermic fluid may then passes through jacketed vessels once set
temperature is achieved. The hot thermic fluid transfers its heat via conduction
15 phenomena to the food items inside the vessels and hence food cooks. The thermic fluid
passes through the periphery of thermally insulated jacket of said utensil to perform
cooking.
[0034] In one embodiment, the said cooking system is broadly categorized into
20 two parts. First part is work in day operation or sun-shine time operation. Second is
night or non-solar operation. Further to this, day time operation is further divided in two
sub parts. First is low solar time operation and another is peak solar time operation
[0035] In one embodiment, during Day Operation or Sun-shine Time Operation:
25 This mode is a base mode of the newly designed solar thermal energy assisted cooking
system. This mode is further divided into two sub parts:
• First sub part is low insolation (approximately < 400 w/m2) level operation-
In this mode, thermic fluid is pumped (4) from expansion cum storage tank
(2) to solar concentrator (1) partially and rest may be bypassed to the
30 thermic fluid heater (5). The mass flow rate of thermic fluid passing
through the concentrator (1) via solenoid valve (3) may be lower compare
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to passing through thermic fluid heater (5). The path of movement of
thermic fluid in this operation is D-3-H-E-A-G. The path of higher flow rate
can be D-F-E-A-G.
• In the second sub part is meant for the moderate / high rate of insolation
(approximately > 400 W/m2). Once the outlet temperature 5 of thermic fluid
from concentrators reaches more than set temperature (e.g.200 0C) then the
bypass flow to thermic fluid heater (5) will be minimizes and flow through
the concentrator will be maximizes. The path of thermic fluid is D-H-E-AG.
This operation can be achieved by motorized three - way valve (10).
10
[0036] In one embodiment, during Night or Non solar Operation: This mode of
operation can be designed for cooking at night time or during non-solar period
operation. In this mode thermic fluid pump (4) does not take suction from expansion
cum storage tank (2). In this mode, thermic fluid can bypass the tank (2) with the help
15 of three-way motorized valve (9). And the only fluid pumps through the heater (5) may
be the one that has been left in the pipelines. This may reduce the heating load on
thermic fluid heater (5). The direct effect of this mode can be saving of LPG which
would have otherwise exhausted for heating all the thermic fluid (piping and tank) exist
in the system. The thermic fluid flow path for this mode can be A-B-C-D-F-E.
20
[0037] In one embodiment, the solar thermal assisted cooking system receives
wherein said solar radiation on the reflector area and concentrates on a focal point of the
said solar concentrator (1). The solar thermal cooking system operates with at least one
selected from a direct normal radiation, global radiation, diffuse radiation of sun or any
25 combination thereof.
[0038] In one embodiment, the solar concentrator (1) adapted to receive solar
radiation using at least one receiver, transform said solar radiation into said thermic
fluid; and thereby provide heat to the thermic fluid to generate heated thermic fluid.
30 Solar concentrator (1) transmit the heated thermic fluid as a heat energy to said cooking
section during solar operation. The solar concentrator (1) may be configured to
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automatically to track the sun during the operation. Further to this, the thermal fluid
(TF) heater may be installed downside of the solar concentrator (outlet) so as to heat up
the temperature of the thermic fluid in a controlled manner as per requirement.
[0039] In one embodiment, the said solar radiation is transformed 5 into thermal
energy and said thermic fluid is generated. During solar operation said thermic fluid is
heated by said solar concentrators to a temperature range of100 to 270 0C.
[0040] In one embodiment, during low or non-solar operation, excess thermic
10 fluid is supplied from said thermic fluid storage tank (2) to said solar concentrator (1)
by means a solenoid valve (3). Subsequently, the stored excess thermic fluid may be
supplied to the cooking section in a controlled manner based on positive difference
between cooking load and stored thermic fluid. Thus, in present disclosed invention, if
there is no requirement of cooking and ample amount of solar energy (solar radiation /
15 DNI / DNR) is available, then this energy may be stored in Thermal Fluid (TF) storage
tank with bypassing utensils. During sunset or at the lean solar period, the stored excess
thermic fluid may be utilized based on positive difference between temperature of TF
storage tank and the cooking requirement. In one example, if the cooking requirement is
120° C and the excess thermic fluid stored is of 150 °C, hence the net positive
20 temperature difference is + 30 °C which can be utilized for cooking.
[0041] In one embodiment, during non-solar operation said thermic fluid
bypasses said thermic fluid storage tank (2) by means of a three way motorized valve
(9).
25
[0042] In one embodiment, during non-solar operation, the method comprises,
supplying, by means of said thermic fluid heater, residual thermic fluid said cooking
section.
30 [0043] Some of the benefits of the present invention is as follows:
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1. A sun radiation based food preparation system which is capable for
functioning during lean and non-sun period.
2. A sun radiation based food preparation system wherein all kinds of
cooking that may include but not limited to boiling (7), frying (8) and baking (6)
based food preparation 5 can be done.
3. A sun radiation based food preparation system wherein food preparation
can be done in-door.
4. A sun radiation based food preparation system wherein there is a
provision to store excess energy storage or other heating source or any
10 combination thereof, which makes the system more reliable and deliver quality
food item.
5. A sun radiation based food preparation system that includes provisions
for removing of sludge.
15 [0044] Although a solar energy assisted all weather food preparation system and
a method thereof have been described in language specific to structural features and/or
methods, it is to be understood that the embodiments disclosed in the above section are
not necessarily limited to the specific features or methods or devices described. Rather,
the specific features are disclosed as examples of implementations of the solar energy
20 assisted all weather food preparation system and a method thereof.
14

WE CLAIM:
1. A solar thermal cooking system comprising:
at least one solar section to supply at least one thermic fluid to 5 perform cooking;
at least one cooking section comprises:
means for receiving at least one utensil; and
at least one thermic fluid heater to provide heating to said thermic fluid
during non-solar or low solar operation;
wherein, said solar section comprises:
at least one solar concentrator (1) with at least two axis tracking
mechanism, wherein said solar concentrator adapted to receive heat
energy from solar radiation during solar operation, and supply heated
thermic fluid to said cooking section;
at least one thermic fluid storage tank and expansion tank (2), adapted to
pump (4) thermic fluid to said solar concentrator (1)and store excess heating
source, wherein during non-solar operation said thermic fluid storage tank and
expansion tank is adapted to supply said stored excess heating source to said
cooking section.

2. The solar thermal cooking system as claimed in claim 1, wherein said solar
radiation is received on a reflector area and concentrates on a focal point of said
solar concentrator.
3. The solar thermal cooking system as claimed in claim 2, wherein said solar
radiation is transformed into thermal energy and said thermal energy is transferred
to the thermic fluid received from said thermic fluid storage tank (2) and expansion
tank.

4. The solar thermal cooking system as claimed in claim 1, wherein during solar
operation said thermic fluid is heated by one or more reflectors in said solar
concentrators to a temperature range of 100 to 270 0C.
5. The solar thermal cooking system as claimed in claim 4, 5 wherein said solar
concentrators supply heated thermic fluid to said cooking section by means of at
least one thermic fluid heater (5).
6. The solar thermal cooking system as claimed in claim5, wherein in said cooking
10 section said thermic fluid passes through the periphery of thermally insulated jacket
of said utensil to perform cooking.
7. The solar thermal cooking system as claimed in claim 1, wherein during low solar
operation, excess heated thermic fluid is stored in thermic fluid storage tank and is
supplied to the solar concentrator by means of at least one three-way motorized
valve.
8. The solar thermal cooking system as claimed in claim 7, wherein stored said excess
heated thermic fluid is supplied to said cooking section in controlled manner based
on positive difference between cooking load and stored thermic fluid.
9. The solar thermal cooking system as claimed in claim 1, wherein said thermic fluid
storage tank and expansion tank (2) adapted to store excess heat energy or excess
thermic fluid or any combination thereof.

10. A method for cooking using a system as claimed in claim 1 during solar and/or
non-solar operation, said method comprising:
receiving, by means of a receiver of at least one solar concentrator, heat energy
from solar radiation during solar operation;
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pumping, by means of at least one thermic fluid storage tank and expansion tank, at
least one thermal fluid to said solar concentrator, and generating, by means of said
solar concentrator, heated thermic fluid at a temperature range of 100 to 270 0C;
supplying, by said solar concentrator, said heated thermic fluid through a thermic
fluid heater to at least one a cooking section for cooking of at least 5 one food items;
passing, said thermic fluid passes through the periphery of thermally insulated
jacket of said utensil to perform said cooking;
storing, by said thermic fluid storage tank, excess heating source, wherein said
excess heated thermic fluid is supplied during low or non-solar operation for
cooking of said one food items.
11. The method as claimed in claim 10, wherein during non-solar operation (all season),
said method comprises, supplying, by means of said thermic fluid heater, residual
heated thermic fluid to the said cooking section.