WO2022245197A1

WO2022245197A1 - Solar energy collector

Info

Publication number: WO2022245197A1
Application number: PCT/MX2022/050041
Authority: WO
Inventors: Jacobo ZYMAN REINISCH
Original assignee: Joske´S De Mexico S.A. De C.V.
Priority date: 2021-05-21
Filing date: 2022-05-23
Publication date: 2022-11-24
Also published as: MX2021006045A

Abstract

The present invention relates to a parabolic solar energy collector, comprising: a paraboloid-shaped reflecting surface; a collector tube located at the level of an imaginary line formed by the foci of differential parabolas that make up the reflecting surface; a mobile upper support structure mounted on a fixed lower support structure; a first motor for providing tilting movement to the mobile upper support structure and a second motor for providing rotational movement to the mobile upper support structure; where the first motor is located in an upper portion of the mobile upper support structure; the second motor is located in a lower portion of the mobile upper support structure; and a control unit is located in the mobile upper support structure.

Description

SOLAR ENERGY COLLECTOR Field of the invention

The present invention is related to the capture of solar energy, and particularly, to a solar collector that forms a parabola in one of its dimensions, in such a way that it concentrates the reflected radiation on its focal line, and a follower to orient the collector towards a perpendicular incidence of sunlight for maximum use.

Background In the state of the art, sensors with tracking mechanisms are known in which the movement is carried out manually or automatically.

An example of a solar collector with a tracking mechanism on one axis is disclosed in US patent 6,058,930, where the solar collector and tracker has at least one north-south oriented torque tube supporting an array of rectangular solar panels. blueprints.

Likewise, the patent document MX2011/007070 reveals an electronic device for the automation and control of solar monitoring, for example solar collectors in thermal and electrical applications, which is composed of a control circuit, power circuit, sensors of: radiation, position and limit, power supply and a housing for protection against environmental conditions. The control circuit microcontroller contains an algorithm, which allows positioning by means of photoelectric sensors and astronomical equations, in one and two axes.

In the present invention, astronomical equations are not used because the control algorithm, based exclusively on the measurement of 4 photo-elements, is adaptive, in the sense that it changes its control laws dynamically to adapt to any atmospheric disturbance that occurs. prevent locating the position of the Sun, such as clouds, occasional shadows and the night itself.

Document MX2011 /007070 requires the use of accelerometers and quantified radiation measurements, which which makes the device more complex, however, the present invention has a mechanism of a tilting axis and the other rotary, plus the location of the tilting axis of rotation in the center of mass and the focal line, is totally different from the one disclosed in said document.

The "sun sensors" of the present invention are totally different from those of document MX2011/007070.

Apparatus adapted to follow the sun as it passes overhead is disclosed in US4,179,612. Such an apparatus can take any form, such as a parabolic reflector-type solar collector that receives the impact of the sun's rays. The apparatus can be rotated about a vertical axis as by means of a motor, and also about a horizontal axis by the motor to achieve such tracking, and for this purpose the motor is carried by a U-shaped frame which in turn rotates around the axis by the motor.

The system presented in patent US4,179,612, at least if it were built based solely on the principles set forth therein, if it were to work at all, would require permanent manual adjustments and even so, it would not operate at full efficiency all day or throughout the day. of the year, much less in different terrestrial latitudes.

There are several reasons why this would happen. The photo elements used in this patent are so-called passive (photo-resistors), unlike the ones we use (photo-transistors), the latter are not only much more sensitive but also, due to the fact that we evaluate their condition by means of 10-bit analog-to-digital converters, which allows us to detect light levels within a much higher range, making a compensating circuit unnecessary for us, as required by the apparatus of the mentioned patent (components marked as 112 , 103 and 110 in figure 4 of said patent) and that in any case must have a very poor result.

Again, the reason for the poor result would be because it uses the same type of photo element for the compensating circuit.

More important than the above, is the basic conception that fundamentally stems from the fact that electro-mechanical elements (relays) are intended to be directly activated by the previously said passive sensors. Although it is true that the current that would circulate through the coils of the relays would depend on the difference between the incident light intensities and this, in turn, on the voltage provided by the transistor (110), the non-linearities of both the photoresistors like the transistor, would make the range of light intensities for which it might work very narrow.

Another major difference has to do with how to retrieve the sunrise position.

The solution proposed in the referred patent is using a switch at the end of the daytime travel, which turns on a fixed time timer (10 hours), after which the device returns to the quadrant where sunrise should be.

In that same patent, the imprecision of this alternative is mentioned, but in terrestrial latitudes where there are important differences in the duration of the nights throughout the year, this imprecision would produce important decreases in efficiency.

The sensor of the present invention actually solves the situation of returning to the sunrise position by means of an adaptive algorithm that intelligently analyzes the specific situation, both geographically and environmentally. This cannot be done solely with relays, passive sensors and a transistor, as the aforementioned patent claims to do. In the present invention, this algorithm resides in a micro-controller that obtains the information of the environment conditions through active sensors, processes that information to finally drive the motors with the purpose of maintaining the direction of the Sun. All the actions of apparatus of the invention are fed back, not as in the case of patent US4,179,612.

Although patent US4,179,612 mentions the use of the compensatory sensor to be able to track the Sun even in low light conditions, such as in the presence of mist or clouds, but as long as the shadow can be detected. If the absence of shadows lasts longer than the time necessary to exceed 90 ^° of rotation, the system could not react for the rest of the day and could only be located in the dawn condition, if the last position was within the first quadrant, because that day it would not arrive to activate the limit switch.

As with the previous problem, our system can recover from any of these situations as soon as the shadow reappears, thanks to the same mechanism mentioned.

In patent US4,179,612, only the intention of the movements is shown schematically, but does not describe the mechanics of its operation.

The known collectors lack one or more of the characteristics that the present invention has, and which are:

Reliable, fully automated operation under any position of the Sun, high efficiency, reasonable cost, flexibility of use, reliability, does not require external energy sources (besides solar), modest maintenance requirements, low weight, high volume ratio useful with respect to the total volume and non-polluting operation of the environment.

The present invention manages to overcome the disadvantages of other similar devices of the state of the art by using: a) A movement system with two degrees of freedom, one for rolling or azimuthal and the other for rotation. b) For the rolling movement, a construction based on the concept of making the center of mass coincide with the focus of the central parabola and with the axis of rotation of its azimuthal movement. This achieves the minimization of the torque required for this movement and therefore the use of a very small motor. c) The axis of the rotary movement is located in the geometric center of a fully symmetrical construction and is supported on a packed mechanism, so it can also be activated by a very small motor. d) Both motors operate on separate gear arrangements with which high mechanical torques and low rotational speeds are achieved, in turn allowing low precision error tolerances. of positioning, errors that in turn are compensated by the dimensions of the components, effectively nullifying the errors due to both the positioning and the imperfection tolerances of the components themselves. d) Both movements correspond to a closed loop system whose feedback comes from the position of the Sun. e) All the operation logic is included in a program stored in a micro-controller that in turn receives the information from the different sensors and orders the actuation of the motors. f) The location of the Sun is indicated to the micro-controller by means of light sensors arranged on the sides of opaque walls and by means of detecting the difference in the amounts of light incident on the illuminated and shaded sensors. g) The electrical power comes from a battery that is in turn recharged by photoelectric cells mounted parallel to the display surface, so they are also dynamically located perpendicular to the sun's rays and therefore maximizing its performance.

The present invention is a device that is automatically oriented towards the position of the Sun and therefore allows any surface that is installed to remain perpendicular to the sun's rays. The fundamental benefit is that it increases the efficiency of solar energy capture compared to static systems, significantly exceeds the efficient capture time of other dynamic systems and, together with the architecture of its design, allows obtaining the following advantages compared to known systems:

• Greater efficiency, implying greater collection and/or smaller size.

• Easier insulation to reduce heat losses.

• Less weight.

• Lower cost.

• Fully automatic operation. • Its only source of energy is solar, it does not require additional external sources such as electrical, pneumatic, fuel, etc.

• Its operation does not pollute the environment in any way.

• Great flexibility for different applications.

• Ease of manufacture, transportation, installation and maintenance.

This invention can be used for both thermal and photoelectric, plane or paraboloid and reflective or concentrating lens systems.

The present invention provides a parabolic solar energy collector, comprising: a reflecting surface with a paraboloid shape; a collector tube located at the level of an imaginary line formed by foci of differential parabolas that constitute the reflecting surface; a movable upper support structure mounted on a fixed lower support structure; a first motor to provide rocking movement to the mobile upper support structure and a second motor to provide rotary movement to the mobile upper support structure; the first motor is located in an upper part of the mobile upper support structure; the second motor is located in a lower part of the mobile upper support structure; a control unit located in the mobile upper support structure; a first solar sensor to feed back to the control unit for tilting movement; a second solar sensor to feed back to the control unit for rotary movement; a plurality of photoelectric cells connected to a rechargeable electric battery to supply power to the control unit, the first motor and the second motor.

Brief description of the figures

To give a better understanding of the invention, a description thereof is provided below, together with the accompanying drawings and in which: Figure 1 is a front perspective view of the solar energy collector according to the present invention;

Fig. 2 is a view of the structure of the movement mechanism of the solar energy collector according to the present invention;

Fig. 3 is an electrical diagram of the control of the solar energy collector according to the present invention; Y

Fig. 4 is a flowchart of controlling the collector to rotate according to the movement of the sun.

Detailed description of the invention

With reference to figures 1 and 2, a solar energy collector is illustrated that has a reflective surface (10) in the shape of a translational paraboloid, locating the collector tube (20) at the level of an imaginary line formed by the foci of the parabolas. differentials that constitute the reflective surface (10).

The collector tube (20) is in turn the axis of rotation of the geared motor (40) that performs the tilting movement and in the geometric center of the collector tube (20) is located the position of the center of mass of the structure that supports to the reflective surface (10), which gives it the mechanical balance that allows the use of a small geared motor and avoids the need for counterweights that would increase the size, weight and cost.

Direct current motors coupled to reducers with large speed ratios are also used, achieving large mechanical torques with low power motors, low final speeds of rotation that allow greater precision in positioning and no energy is required to maintain a static position. The latter has an impact on high energy efficiency, since only little energy is needed to change position and no energy to maintain it.

The collector tube (20) is supported at its ends by the mobile upper support structure (14) formed by two triangle-shaped lateral structures (15 and 16) that rotatably support the collector tube (20) and the reflecting surface (10), and the lower parts of the side structures (15 and 16) are joined through two crosspieces that form a cross (17 and 18). In one of the lateral structures (16), the motor-reducer (40) for the tilting movement is located, which transfers its movement to the reflecting surface (10) by means of gears (41).

The support structures can be made of metal profiles and joined by plastic connectors or the like, in such a way that a light structure is provided to achieve the movement of the solar energy collector, in addition to facilitating manufacturing, packaging, transportation, assembly at the place of installation and eventual repair.

The entire set of the mobile support structure (14) and the components it supports are, in turn, supported on a rotating disk (not illustrated), whose mobile plate is located in the lower and central part of the mobile structure (14). . The motor-reducer (50) for the rotary movement is located in this same region.

The movement of the second degree of freedom, instead of also being tilting, is rotating, which allows a great simplification in the transmission system of this movement.

The fixed plate (not illustrated) of the rotating disk is attached to a fixed lower support structure (22), which, as its name indicates, is fixed to the ground.

The transmission of the rotary movement of the mobile upper support structure (14) with respect to the fixed structure (22) is transferred by means of gears (51).

The motor-reducer (50) for the rotary movement is located in the mobile upper support structure (14) instead of in the fixed lower structure (22), where there is a gear (51) that receives the movement. This arrangement allows the power cables of this motor to have no movement. The elimination of the movement of the cables has an impact on a reduction in the probability of failure due to their breakage.

The collector of the present invention also includes a control unit (not shown) electrically powered by a rechargeable battery (not shown) which in turn is recharged by photoelectric cells (not shown) when there is sufficient solar energy incident on the cells. With this arrangement, you do not need any other external energy source (electricity, fuel, steam, etc.), apart from solar.

This same control unit manages the electrical supply from the photoelectric cells, both to properly charge the battery and to protect it from overload.

There are also solar sensors made up of a pair of photoelectric sensors separated by an opaque wall. When they are not oriented towards the light source (the Sun), the opaque wall casts a shadow on one of the two sensors, while when they are oriented towards the light source, both sensors are illuminated by approximately the same light intensity. . The sensors present an electrical signal as a function of the light intensity that falls on them.

This configuration of the sun sensors only requires 2 photoelectric sensors per sun sensor and the indication of the light source position corresponds to one of three discrete conditions (in the opposite sense of analog): the light source is a) To the left, b) To the right or c) In the center.

The control unit periodically reviews the differences in the electrical signals produced by each pair of sensors; If the two sensors have similar electrical signals, it means that the corresponding sun sensor is oriented and no action is required. If the sensors present a difference in their electrical signals, depending on which of the two is more illuminated, the control acts on the motor associated with that solar sensor so that it rotates in one direction or the other to seek to achieve orientation.

In figure 3, the photo-elements (101), (102), (103) and (104) are configured in such a way that the voltages they deliver are inversely proportional to the intensity of the incident light.

These voltages are frequently read by the microcontroller (109) by means of two inputs equipped with analog-digital converters (110), (111), (112) and (113).

The photo-elements (101) and (102) are physically located on a platform directed towards the sky and separated by an opaque wall.

(105), which constitutes the tilting solar sensor (107).

The photo-elements (103) and (104) are physically located on a platform facing the sky and separated by an opaque wall.

(106), which constitutes the rotary sun sensor (108). The walls (105) and (106) form an angle of 90°.

If the solar sensors are not directed towards the Sun, the walls (105) and/or (106) will cast a shadow on one or two of the photo-elements, making the incident light intensity less than that of its photo-element. complementary. The only way for all solar sensors to generate similar voltages when there is enough light to generate defined shadows is for the sun's rays (124) to strike perpendicular to all their surfaces.

Both solar sensors work in a similar way, except that the sensor (107) operates on the motor (115) and the sensor (108) operates on the motor (116).

If sensors 101 and 102 (or 103 and 104) receive a similar light intensity, no action is taken.

The motors (115) and (116) are for direct current and therefore rotate in the direction corresponding to the polarity of the applied voltage.

If the sensor (101) receives a light intensity greater than (102), the microcontroller (109) tells the bipolar motor controller (114) to apply a positive voltage to the motor (115), making it rotate in the clockwise direction.

If the sensor (101) receives a lower light intensity than (102), the microcontroller (109) tells the bipolar motor controller (114) to apply a negative voltage to the motor (115), making it rotate in the opposite direction. counterclockwise.

If the sensor (103) receives a light intensity greater than (104), the micro-controller (109) tells the bipolar motor controller (114) to apply a positive voltage to the motor (116), making it rotate clockwise.

If the sensor (103) receives a lower light intensity than (104), the microcontroller (109) tells the bipolar motor controller (114) to apply a negative voltage to the motor (116), making it rotate in the opposite direction. counterclockwise.

Because the motors rotate in such a way that their corresponding solar sensor reduces the size of the shadow, there comes a time when the shadow disappears and then the movement stops because the position of the Sun has been located. As the day progresses, the shadows begin to form again, causing the reaction described above.

Electrical power comes from a rechargeable battery (1 19) that supplies a voltage regulator (120) that powers the entire circuit.

The battery (1 19) is in turn recharged by the solar cells

(117).

The battery charge (119) is controlled by the microcontroller (109) measuring its voltage level through the analog-digital converter (123), in such a way that, if the battery is fully charged, the cells are disconnected. solar panels by deactivating the rewasher (118) through the output (122) of the micro-controller. In this way the battery is protected from overload.

The battery charge (1 19) is controlled by the microcontroller (109) measuring its voltage level through the analog-digital converter (123), in such a way that, if the battery is fully charged, it disconnects the cells. through the relay (118), protecting it from overload.

The diode (121) prevents the battery from discharging on the solar cells (117) when there is not enough light energy.

The solar cells (117) are located physically parallel to the surface that remains perpendicular to the sun's rays, maximizing their efficiency.

Figure 4 illustrates a flow diagram of the collector operation, where the control unit initiates a self-test to verify the mechanical, electrical-electronic and power supply operation and if it finds any error, it sets the azimuth angle parameter to zero degrees, the rotational angle to zero and a report is issued.

If the proper functioning of the sensor is verified, the azimuth angle parameter is positioned at 90 degrees and the rotational angle at zero degrees.

Subsequently, the lighting level of the front photo element and the rear photo element are compared.

If the illumination level of the front photo element is the same as the illumination level of the rear photo element, it is verified that the illumination level of the East photo element is the same as the illumination level of the West photo element. If in this comparison the illumination level of the East photo element is higher, the control unit generates a rotation of the sensor in the west direction. Otherwise, the control unit generates a rotation of the sensor in the East direction.

If the illumination level of the front photo element is greater than the illumination level of the rear photo element, the sensor rotates on the tilting axis counterclockwise. Otherwise, the control unit generates a rotation of the tilting axis of the collector in favor of the hands of the clock.

In either of the two movements, it is verified if the end of the path has been reached as a safety measure to guarantee the integrity of the apparatus. In the event that any end of the path is reached, the system positions the capture surface perpendicular to the vertical, allowing the surfaces of the solar sensors to be at an angle equal to or less than 90 degrees and therefore perceive the reappearance of shadows. as soon as they occur and then execute the tracking routines to locate the position of the Sun.

Whenever the apparatus is oriented towards the Sun, it is verified that the temperature of the collector tube does not exceed a pre-established limit, for safety reasons, since in the event of a malfunction of the apparatus itself or of the equipment connected to it , bliss If the temperature is not verified, it could exceed safe values. If the temperature exceeded is detected, the collection surface is positioned in a vertical position, preventing the subsequent collection of solar energy and a malfunction warning is generated. It is also verified that not too much time has elapsed in the same position, which would mean, given a good operation, that the Sun has hidden, either because the sunset occurs, the presence of clouds or some obstacle stands in the way. Under these conditions, the system positions the capture surface perpendicular to the vertical, allowing the surfaces of the solar sensors to be at an angle equal to or less than 90 degrees and therefore perceive the reappearance of shadows as soon as they occur and then execute the follow-up routines to locate the position of the Sun. Whenever such a situation occurs (for example, every night), it is used to perform an automatic review of the entire system.

The present invention has been described and illustrated in its preferred form, however, an average person skilled in the art will be able to see variations that fall within the scope of the following claims.

Claims

1 A parabolic solar energy collector, comprising:

A reflective surface with a paraboloid shape;

A collector tube located at the level of an imaginary line formed by differential parabolic foci that constitute the reflecting surface; a movable upper support structure mounted on a fixed lower support structure; a first motor to provide rocking movement to the mobile upper support structure and a second motor to provide rotary movement to the mobile upper support structure; the first motor is located in an upper part of the mobile upper support structure; the second motor is located in a lower part of the mobile upper support structure; a control unit located in the mobile upper support structure; a first solar sensor to feed back to the control unit for tilting movement; a second solar sensor to feed back to the control unit for rotary movement; a plurality of photoelectric cells connected to a rechargeable electric battery to supply power to the control unit, the first motor and the second motor.

2. The solar energy collector of claim 1, wherein the first motor and the second motor are direct current motors.

3. The solar energy collector of claim 2, wherein the rotary movement and the tilting movement are transmitted to the mobile upper support structure through gears.

4. The solar energy collector of claim 1, wherein the mobile upper support structure and the fixed lower support structure are made of metal profile and joined with plastic connectors.