CLOSED LOOP FEEDBACK SENSORS IN A LINEAR FRESNEL
REFLECTOR SOLAR ENERGY COLLECTOR SYSTEM
FIELD OF THE INVENTION
Embodiments of the present invention in general relate to a linear fresnel
reflector solar energy collector system, and in particular relates to closed
loop feedback sensors that facilitates the maximization of efficient during
operation of the linear fresnel reflector solar energy collector system.
BACKGROUND
Solar power generation has been considered a viable source to help
provide for energy needs in a time of increasing consciousness of the
environmental aspects of power production. Solar energy production
relies mainly on the ability to collect and convert energy freely available
from the sun and can be produced with very little impact on the
environment. Solar power can be produced without creating radioactive
waste as in nuclear power production, and without producing pollutant
emissions including greenhouse gases as in fossil fuel power production.
Solar power production is independent of fluctuating fuel costs and does
not consume non-renewable resources.
Solar power generators generally employ fields of controlled mirrors, to
gather and concentrate sunlight on a receiver to provide a heat source for
power production. A solar receiver typically takes the form of a panel of
tubes conveying a working fluid therethrough. Previous solar generators
have used working fluids such as molten salt because it has the ability to
store energy, allowing power generation when there is little or no solar
radiation, such as at night time. The heated working fluids are typically
conveyed to a heat exchanger where they release heat into a second
working fluid such as air, water, or steam. Power is generated by driving
heated air or steam through a turbine that drives an electrical generator.
Such conventional methods and systems for solar power generation have
generally been considered satisfactory for their intended purpose.
However, there is still a need in the art for systems and methods for solar
power generation that allow for improved efficiency and decreased heat
loss.
SUMMARY
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system that includes one or more primary
reflectors wherein the one or more primary reflectors which are arranged
in parallel to each other.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system that includes one or more primary
reflectors which are arranged in parallel to each other, and further the
one or more primary reflectors are laterally connected to each other by at
least a connecting arm and tracking arm of a ganged tracking assembly.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy collector system and a linear cavity receiver, for
generating direct high temperature super-heated steam, wherein the
linear cavity receiver (LCR) houses a steel support structure, a
secondary reflector (SR), and an evacuated tube collector (ETC) with
solar selective absorber coating.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy collector system that includes one or more primary
reflectors and a linear cavity receiver for generating direct high
temperature super-heated steam, using a compound parabolic secondary
reflector and an evacuated tube collector.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy collector system and a linear cavity receiver, for
generating direct high temperature super-heated steam, using a
compound parabolic secondary reflector made of glass with high
temperature protective silver coating, and is clamped with provision for
thermal expansion.
According to an embodiment of the present invention there is provided a
linear fresnel reflector solar energy collector system and a linear cavity
receiver, for generating direct high temperature super-heated steam,
wherein the profile of the secondary reflector is designed such that the
reflected sunlight from the one or more primary reflectors is reflected on
to the absorber tube throughout the day.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy collector system and a linear cavity receiver, for
generating direct high temperature super-heated steam, wherein the
linear cavity receiver support structure is designed to hold the secondary
reflector and the absorber tube in place such that the spatial coordinates
are maintained during operation. In an embodiment, the secondary
reflector and the absorber tube has provision for accommodating thermal
expansion.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy collector system and a linear cavity receiver
wherein an array of sensors disposed across a cross-section of the linear
cavity receiver.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy collector system and a linear cavity receiver
wherein an array of sensors disposed across a cross-section of the linear
cavity receiver. A feedback circuit is provided comprising an electronic
controller wherein the electronic controller receives a feedback signal
from the array of sensors and then the intensity of sunlight distribution is
adjusted on the evacuated tube collector based on the feedback signal
received from the array of sensors.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system that includes one or more primary
reflectors that are preset with respect to each other at pre-defined/ preset
tilt angles, and wherein the pre-defined/ preset angles are driven by a
combination of at least one gear box and at least one motor.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system that includes a ganged tracking
assembly which is connected to a feedback circuit including an electronic
controller wherein the electronic controller receives a feedback signal
from at least one tilt sensor attached to at least one of the one or more
primary reflectors.
According to an embodiment of the present invention there is a direct
saturated and superheated steam generating linear fresnel reflector solar
energy boiler system that includes one or more primary reflectors and a
ganged tracking assembly. The ganged tracking assembly along with an
electronic controller and at least one tilt sensor operate in a closed loop,
and thereby maximizes the optical efficiency during operation.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler that includes one or more primary reflectors
that are mounted on one or more axles wherein the one or more axles
rest on one or more rollers that facilitates and supports axial rotation.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system that includes one or more primary
reflectors that are mounted on one or more axles. Each of the one or
more axles includes axle plates and wherein the axle plates of each of
the one or more axles are configured to accommodate a tracking arm for
each row of the one or more primary reflectors. The tracking arms for
each row of the one or more primary reflectors further have a slot
provision around the axle for setting the tilt angle for each row of the one
or more primary reflectors.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system that includes at least one linear cavity
receiver housing a single evacuated tube collector and one or more
primary reflectors, wherein the one or more primary reflectors
concentrates the sunlight on to an ETC and thereby increasing the
concentration ratio.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system wherein an ETC is clamped such that
the position of the ETC is fixed in the cross sectional plane and allowed
to expand due to thermal expansion in a longitudinal direction along the
length of the ETC.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system for generating useful heat in the form
of saturated or/and superheated steam by concentrating sunlight on to a
single row of one or more evacuated receiver tube collectors housed
along with one or more primary reflectors inside a receiver support
structure.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system wherein the sunlight is focused
continuously by the one or more primary reflectors on to the one or more
evacuated collector tubes. Further, the one or more primary reflectors are
placed close to the ground which tracks the sun by a mechanical system
connected to the electronic controller which receives feedback signal
from the array of sensors disposed across the linear cavity receiver and
the at least one tilt sensor attached to the one or more primary reflectors.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system that includes a configuration having a
single row of evacuated receiver tube collectors and one or more
secondary reflectors that increases the concentration ratio (Total mirror
aperture width to absorber tube aperture width) and hence the operation
parameters (Temperature and pressure of steam).
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system that includes an absorber tube that is
maintained in vacuum during operation hence the heat loss is reduced
and the efficiency is increased considerably.
According to an embodiment of the present invention there is provided a
direct saturated and superheated steam generating linear fresnel
reflector solar energy boiler system that includes a single row of
evacuated receiver tube collector configuration that simplifies the process
line and instrumentation thereby reducing the cost and operation
procedure.
These and further aspects which will be apparent to the expert of the art
are attained by a direct saturated and superheated steam generating
linear fresnel reflector solar energy boiler system in accordance with the
main claim.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the present
invention can be understood in detail, a more particular description of the
invention, briefly summarized above, may be had by reference to
embodiments, some of which are illustrated in the appended drawings. It
is to be noted, however, that the appended drawings illustrate only typical
embodiments of this invention and are therefore not to be considered
limiting of its scope, for the invention may admit to other equally effective
embodiments.
Figure 1 illustrates a perspective view of a Linear Fresnel Reflector (LFR)
system according to an embodiment of the present invention;
Figure 2 illustrates the configuration of a Linear Fresnel Reflector (LFR)
system according to an embodiment of the present invention;
Figure 3 illustrates a sectional view of the ganged tracked assembly of
the Linear Fresnel Reflector (LFR) system according to an embodiment
of the present invention; and
Figure 4 illustrates a perspective view of a microcontroller in a Linear
Fresnel Reflector (LFR) system according to an embodiment of the
present invention.
To facilitate understanding, identical reference numerals have been used,
where possible, to designate identical elements that are common to the
figures. It is to be noted, however, that the appended drawings illustrate
only typical embodiments of this invention and are therefore not to be
considered limiting of its scope, for the invention may admit to other
equally effective embodiments.
DETAILED DESCRIPTION OF THE DRAWINGS
Figure 1 to 4 illustrates various views of a Linear Fresnel Reflector (LFR)
system according to an embodiment of the present invention. The Linear
Fresnel Reflector (LFR) based concentrated solar thermal system 100
includes a linear cavity receiver 102 housing a secondary reflector of one
or more secondary reflectors 104 and evacuated absorber tube collector
(single tube collector) 106, one or more primary reflectors 108 , a ganged
tracking assembly, and a feedback circuit.
In an embodiment, the one or more primary reflectors 108 are arranged
in parallel with respect to each other, and each of the one or more
primary reflectors 108 are placed at a proximate distance (a gap) with
respect to the ground. The gap is so chosen that the shadow of the one
or more primary reflectors 108 is not casted on adjacent primary
reflectors of the one or more primary reflectors 108 at least for a
particular hour angle.
The linear cavity receiver support structure is designed to hold the
secondary reflector 104 and the evacuated tube collector 106 in place
such that the spatial coordinates of the secondary reflector 104 and the
evacuated tube collector 106 are maintained during operation. The
secondary reflector 104 and the evacuated tube collector 106 are further
designed to have a provision for accommodating thermal expansion.
In an embodiment, the profile of the secondary reflector 104 is designed
such that the reflected sunlight from the one or more primary reflectors
108 is reflected on to the absorber tube throughout the day. Further the
secondary reflector 104 is not rigidly clamped but held in position by
supports from the support structure of the linear cavity receiver 106 such
that the secondary reflector 104 material is allowed to freely move during
thermal expansion. The support structure is provided with bulk heads at
both the ends for fastening multiple receivers longitudinally. Further, the
angle supports are also welded to the bulk head for clamping on to the A
frame 110.
The one or more primary reflectors 108 are mounted on corresponding
one or more axles 302. The one or more axles 302 rest on corresponding
one or more rollers for supporting axial rotation. The one or more rollers
are coupled laterally using a steel hollow section (connecting arm) 304
and connected by one or more levers (tracking arm) 306. Each of the one
or more axles 302 comprises an axle plate which is configured to
accommodate the corresponding one or more tracking arms 306 for each
row of the one or more primary reflectors 108. The axle plates are
configured to rest on a roller v-block and further clamped from its top
portion with another set to aid rotation and support during upward loads
due to wind.
In an embodiment, each of the one or more tracking arms 306 further
includes a provision for a slot around each axle of the one or more axles
302 for setting the tilt angle for each row of the one or more primary
reflectors 108. According to one embodiment of the present invention, the
angle of tilt for each primary reflector of the one or more primary
reflectors 108 is preset and fixed. The one or more primary reflectors 108
is then driven laterally by a single motor connected to a gear box and
thus reducing the power consumption and cost. In an embodiment the
motor is a stepper motor but in any other embodiment of the present
invention any motor may be used without moving out of the scope of the
disclosed embodiments.
Further, a tilt sensor attached to one of the primary reflectors of the one
or more primary reflectors 108 is used to set the connected set from the
one or more primary reflectors 108 to the required angle. The signals
from the tilt sensor are fed to the feedback circuit. The feedback circuit
comprises an electronic controller 402 and when the signals is received
by the electronic controller 402, the electronic controller 402 in turn sets
the stepper motor in to motion. The stepper motor then laterally drives
the one or more primary reflectors 108 in order to adjust the one or more
primary reflectors 108 to the desired angle.
The Linear Fresnel Reflector (LFR) based concentrated solar thermal
system 100 further comprises an array of sensors 404. The array of
sensors 404 are disposed along the cross-section of the linear cavity
receiver 102. The array of sensors 404 are connected to an array of
photodiodes 406 via a glass optic fiber cable array 408. The array of
sensors 404 transmit the signals to the electronic controller 402 of the
feedback circuit via the glass optic fiber cable array 408 and the array of
photodiodes 406. The electronic controller 402 is a microcontroller.
Based on the feedback from the microcontroller 402, the intensity of
sunlight distribution across the ETC 106 is qualitatively measured by the
PLC, and subsequently the stepper motor is adjusted for maximum
output.
In an embodiment of the present invention the ganged tracking system
depicted in above figures facilitates the decrease in the errors and the
cost per module as the number of the plurality of primary reflectors 108
and an area covered by the one mechanical tracking system is higher
compared to the previous configuration. Further, Linear Cavity receiver
102 structure houses the secondary reflector 104 and the evacuated tube
collector 106 and is fixed at an optimum height from the secondary
reflector 104. Also, the Linear Cavity receiver 102 is stationary and is
internally provided with a mechanism for allowing thermal expansion of
the evacuated tube collector 106.
While the foregoing is directed to embodiments of the present invention,
other and further embodiments of the invention may be devised without
departing from the basic scope thereof, and the scope thereof is
determined by the claims that follow.

CLAIMS
What is claimed is:
1. A linear fresnel reflector solar energy boiler system comprising:
one or more primary reflectors, wherein the one or more primary reflectors are arranged in parallel to each other; a linear cavity receiver, wherein the linear cavity receiver comprises at least one secondary reflector and an evacuated tube collector; an array of sensors disposed across a cross-section of the linear cavity receiver; and a feedback circuit comprising an electronic controller, wherein the electronic controller receives a feedback signal from the array of sensors, and wherein an intensity of sunlight distribution is adjusted on the evacuated tube collector based on the feedback signal received from the array of sensors.
2. The linear fresnel reflector solar energy boiler system of claim 1
comprising a ganged tracking assembly, wherein the ganged tracking assembly comprises at least a connecting arm and a tracking arm.
3. The linear fresnel reflector solar energy boiler system of claim 2, wherein the ganged tracking assembly facilitates adjustment of the angles of the one or more primary reflectors.
4. The linear fresnel reflector solar energy boiler system of claim 1, wherein the electronic controller and the array of sensors operate in a closed loop to maximize the optical efficiency during operation of the linear fresnel reflector solar energy boiler system.
5. The linear fresnel reflector solar energy boiler system of claim 1 comprising at least one tilt sensor that is attached to at least one
of the one or more primary reflectors.
6. The linear fresnel reflector solar energy boiler system of claim 9, wherein a signal from the tilt sensor is fed to the electronic
controller which in turn sets up a motor that laterally drives the one or more primary reflectors to set the one or more primary reflectors
at a desired angle.
7. The linear fresnel reflector solar energy boiler system of claim 1, wherein the one or more primary reflectors that are mounted on one or more axles,
8. The linear fresnel reflector solar energy boiler system of claim 7, wherein the one or more axles rest on one or more rollers that
facilitates and supports axial rotation.
9. The linear fresnel reflector solar energy boiler system of claim 8,
wherein each of the one or more axles comprises axle plates, and wherein the axle plates of each of the one or more axles are configured to accommodate a tracking arm for each row of the one
or more primary reflectors.
10. The linear fresnel reflector solar energy boiler system of claim 2,
wherein the tracking arms for each row of the one or more primary
reflectors has a slot provision around each axle of one or more corresponding axles for setting the tilt angle for each row of the
one or more primary reflectors.