DE202015000182U1 - Concentrating solar cooker with parabolic trough and heat transfer circuit - Google Patents

Abstract

Solar cooker, characterized in that it consists of a parabolic trough collector (1), a cooking unit (2) and a mobile base frame (3).

Description

Thematic background

In many developing countries, biomass, ie. H. Wood, charcoal, crop residues or dried animal manure cooked. The wood is collected or beaten around the villages or towns. In many cities there is no wood left in the vicinity of the cities and then it has to be transported from the surrounding villages for sale in the cities. As cooking with firewood consumes more than regrowth, this leads to progressive deforestation and thus to catastrophic ecological consequences. This shortage of firewood has also led to a dramatic increase in the price of firewood in many developing countries, with the result that less money is available for the purchase of food.

Since many of these countries are in the so-called "sunbelt" of the world has been trying for a long time the energy consumption z. B. by improved stoves but also by the use of solar cookers. Powerful, inexpensive and easy-to-use solar cookers can be a real alternative to traditional fireplaces long-term in sunny countries.

In addition to the market in developing and emerging countries, there is also a certain market for the use of solar cookers in the leisure sector z. B. for grilling. For this purpose, however, it is necessary to operate the solar cooker at a temperature of about 200 ° C-230 ° C in order to be able to grill. This is usually possible only with a concentrating cooking system as shown in the utility model. Similar systems have already been developed by the applicant (utility model G 91 16 691.8 ) built in the past and put into operation in many countries.

State of the art

• • Direkte Systeme
• • Systeme mit Wärmeträgerkreislauf

So far, various solar cookers have been used. The solar cookers can be roughly divided into two classes:

• • Direct systems
• • Systems with heat transfer circuit

• • Flachkollektoren
• • Konzentratoren

In addition, one can make a further distinction in the collectors used:

• • flat plate collectors
• • concentrators

Within each class, there are many different designs or models. The advantage of systems with heat circulation is that they offer the possibility to install a storage and the heat source (collector) and the heat sink (hob) can be installed separately.

The transition between flat-plate collectors with concentrating collectors is also fluid, as most flat-plate collectors are equipped with mirrors and thus additionally concentrate the sunlight. Previous parabolic cookers concentrate the solar radiation on the cooking vessel (direct use), a wire-bound heat transport to the food finds, as shown in the utility model, does not take place.

Description of the solar cooker

The object of the invention is to provide an easily manageable, energy-efficient and inexpensive solar cooker, which can be used as a family cook in sunny developing and emerging countries, but also in the leisure sector can be used for cooking or grilling. For this reason, the solar cooker is designed so that it is easy to install or easy to transport. This will u. A. achieved by a collapsible parabolic troughs and a collapsible pedestal.

The solar cooker ( ) consists of a parabolic trough collector ( 1 ), a cooking unit ( 2 ) from one or more pots or pans and a mobile and foldable chassis ( 3 ). The heat transport from the parabolic trough to the cooking unit takes place in line with heat transfer oil or with water / steam.

Cooking unit with oil or water as heat transfer medium (Fig. 2, Fig. 3 and Fig. 4)

The cooking unit consists of one or more pots ( 4 ) or pans ( 5 ). The pots or pans are designed as double-walled pots or pans with an annulus heat exchanger ( 6 ) ( ). The heat supply can be adjusted with valves (as required). 7 ) to be controlled. In addition, the area around the pots or pans is thermally insulated ( 26 ) in order to reduce the losses during cooking and to keep food warm even after cooking.

Due to the separation of heat sink (pots, pans) and heat source (parabolic trough), the accessibility of the pots is given throughout the cooking process. The pots or pans are insulated with heat-insulated lids ( 8th ) in order to reduce the heat loss during the cooking process and also to keep the food after cooking for a long time warm. As a heat transfer medium can depending on the purpose of oil ( 9 ) or water ( 10 ) be used. When using oil, a high-boiling natural oil or in our latitude silicone oil is used. By heating the oil in the absorber of the parabolic trough by the sun, the oil expands and rises through the associated lower density up to the pots or pans and gives its energy to the food or roast. As a result, the oil cools down about, this increases its specific gravity again and the cooled oil flows back through natural convection back into the parabolic trough and heats up again. The advantage of using oil as a heat transfer medium is that the heat absorption takes place without pressure increase and thus the hotplates can be operated without pressure even at high temperatures.

Heat sink cooking unit with water as the heat transfer medium

Will water ( 10 ) are used as heat transfer medium, the cooking unit consists of one or two pressure cookers ( 11 ). The pressure cookers are each equipped with a safety valve ( 12 ), so that no excessive pressure in the pots can arise. The heat in the pots is made directly by evaporation of water from the parabolic trough. The food is passed through a sieve ( 13 ) from the pot door ( 14 ) and pot outlet ( 15 ) separated from the collector ( ). In addition to a single-walled pressure cooker ( 11 ), double-walled pots ( 4 ). In these systems, the annulus ( 6 ) with a security device ( 12 ) connected. The heat transport into the pot can be achieved via two pipes ( 14 and 15 ) or through an evaporator tube ( 23 ). The heat transfer takes place via vapor bubbles ( 24 ) from the pipe to the pot.

Structure of the parabolic trough collector (Fig. 5 and Fig. 6)

The parabolic trough collector ( 1 ) consists of two hinged parabolic curved side mirrors ( 16 . 27 ) and an absorber tube. The side mirrors ( 16 . 27 ) concentrate the direct solar radiation on the absorber tube consisting of one or two double-walled vacuum glass tubes ( 17 ) or a simple glass tube ( 18 ) without vacuum. The heat transfer in the interior of the double-walled vacuum tube is effected by a tight-fitting heat-conducting sheet ( 19 ) to the heat transfer medium oil or water. In the single-walled vacuum tube or the non-evacuated glass tube, the heat transfer takes place by the direct radiation on a selectively coated absorber sheet ( 20 ) with transport tube ( 14 ). When not using the stove or when transporting the stove, the two side mirrors ( 16 . 27 ) by means of hinges ( 21 ) on the central support element ( 22 ) and thus protect the absorber tube from damage

LIST OF REFERENCE NUMBERS

1

parabolic trough collector

2

cooking unit

3

Foldable chassis

4

pot

5

pan

6

annulus

7

Valve

8th

cover

9

oil

10

water

11

Pressure cooker

12

Pressure relief valve

13

scree

14

pot input

15

pot output

16

parade

17

Double-walled vacuum tube

18

Single-walled glass tube

19

heat conducting

20

Selective coated heat conduction sheet

21

hinge

22

Central support element

23

evaporator tube

24

vapor bubbles

25

Chassis with two wheels

26

thermal insulation

27

mirror sheet

figure description

: Concentrating solar cooker with parabolic trough

: Cooking unit with pot or pan with annulus

: Solar cooker with pressure cooker

: Construction of the solar cooker with evaporator tube

: Construction of the parabolic trough with double-walled vacuum glass tube

: Structure of the parabolic trough with single-walled glass tube

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 9116691 U [0003]

Claims (14)

Solar cooker, characterized in that it consists of a parabolic trough collector ( 1 ), a cooking unit ( 2 ) and a mobile base frame ( 3 ) consists. Solar cooker, characterized in that the cooking unit ( 2 ) separated from the parabolic trough collector ( 1 ) is arranged and so that the cooking unit is always accessible during cooking. Solar cooker, characterized in that the cooking unit consists of double-walled pots ( 4 ) or pans ( 5 ) exists in its annulus ( 6 ) by hot oil ( 9 ) or water / steam ( 10 ; 24 ) the heat is transferred to the food. Solar cooker, characterized in that the parabolic trough collector ( 1 ) arranged below the cooking unit that the heat transfer into the cooking unit ( 2 ) takes place due to the density difference of the heat transfer medium via natural convection Solar cooker, characterized in that when using oil ( 9 ) as the heat transfer medium of the annulus ( 6 ) is atmospherically connected to the environment and thus no pressure buildup takes place in the annulus. Solar cooker, characterized in that when operating the solar cooker with water as the heat transfer medium ( 10 ) the heat transport from the collector through an evaporator tube ( 23 ) by steam blowing ( 24 ). Solar cooker, characterized in that when operating the solar cooker with water as a heat transfer medium, the pots ( 4 ; 11 ) or pans ( 5 ) with a safety valve ( 12 ), so that no unacceptable pressure build-up takes place. Solar cooker, characterized in that heat input into the cooking unit at several pots or pans through valves ( 7 ) can be regulated. Solar cooker, characterized in that via the parabolic trough collector ( 1 ) Pressure cookers ( 11 ) over water ( 10 ) or water vapor ( 24 ) can be operated with natural convection. Solar cooker, characterized in that the pots ( 4 ) or pans ( 5 ) with an insulated lid ( 8th ) to reduce the heat losses of the cooking unit. Solar cooker, characterized in that the absorber system consists of a Wärmeleitblech ( 19 or 20 ) with tube ( 14 ) and a separate cold inlet pipe ( 15 ) consists. Solar cooker, characterized in that the parabolic mirrors ( 16 ) by hinges ( 21 ) are collapsible upwards and thus protect the absorber tube during transport or non-use of the digester. Solar cooker, characterized in that the cooker with a chassis ( 3 ) is equipped with two wheels in the range of the cooking unit and the cooker is therefore easy to drive and the sun can be tracked. Solar cooker, characterized in that the pots or pans are thermally insulated, so that the heat losses during cooking are greatly reduced and the food can be kept warm even after the cooking process.

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