GB2589670A

GB2589670A - Solar heating system

Info

Publication number: GB2589670A
Application number: GB2011917.8A
Authority: GB
Inventors: Squire John; Hick Karl
Original assignee: LARKFLEET Ltd
Current assignee: LARKFLEET Ltd
Priority date: 2019-08-01
Filing date: 2020-07-31
Publication date: 2021-06-09
Anticipated expiration: 2040-07-31
Also published as: WO2021019251A1; GB2618930A; GB202312959D0; WO2021019198A1; GB201910997D0; EP4007872A1; GB2589670B; GB202011917D0; GB2586062A; GB2586062B; GB2618930B

Abstract

A solar heating system 1 for heating a fluid has a chassis 17 and at least one arm support 19 mounted on the chassis. An arm 21 is pivotally attached to the at least one arm support such that it can pivot relative to the arm support about a generally horizontal axis. A tubular fluid receiver (5 Fig 13) is mounted to the arm, and in use, at least one lens array 3a, 3b, which is also mounted on the arm, focuses light from a lens 9 onto the tubular receiver. A drive system (8 Fig 16), which may include a sliding scissor lift (22 Fig 10), is arranged to pivot the arm about the generally horizontal axis (X-X), and also to adjust the position of the lens array. The drive system is controlled by a control system 10, and the control and drive system may move the solar heating system between a non-deployed and deployed position, and in the non-deployed position, the solar heating system can fit within a 40-foot shipping container.

Description

SOLAR HEATING SYSTEM

TECHNICAL FIELD

The present invention relates to a solar heating system, and a steam generation plant, a desalination plant, a waste treatment plant, an electrical generator plant, a water treatment plant, and a cooling system, each of which include a solar system according to the invention. In particular, the solar heating system includes a lens array, such as a Fresnel lens array, that is arranged to heat fluid in a tubular receiver.

BACKGROUND TO THE INVENTION

The utilisation of thermal radiation from the sun, referred to herein as solar radiation, for heating water in a tube for the purposes of producing steam and, subsequently used in various processes is generally known. For example, W02010097637 (Boyle) discloses an apparatus with a Fresnel lens mounted on a frame for selectively directing solar radiation onto a thermosensitive member and a generator means for converting the resulting thermal expansion/contraction into electrical power. While expansion/contraction of the thermosensitive member is the main drive means for the generator, this document also describes an embodiment where sunlight is focussed through an array of Fresnel lenses onto a tube carrying water for the purposes of producing steam capable of powering an electrical generator, and also for utilisation as a desalination process. A pictorial representation of this apparatus is provided as Figure 1 in the attached drawings.

In particular, the prior art embodiment of Figure 1 describes a rod 402, a water source 406, a pair of steam accumulators 408, 408', a pair of steam "engine rooms" 410,410', a corresponding motor 412, 412' and a plurality of condensing areas 414. The rod 402 is supported by a frame and, in turn, is used as a pivot axis for a Fresnel lens (not seen) with a focal line centred on the rod. Water is injected into the rod 402 at a central location such that, by the time it reaches the respective ends of rod 402, it has turned to steam for collection by the steam accumulators 408/408' whereupon the high pressure is used for power generation.

There is often a need to for solar heating systems by communities who essentially live off grid. For example, some rural communities, possibly living in more remote parts of the world. Accordingly there is a need for a solar heating system that is easily transportable to such communities, and in particular that is capable of fitting into a standard shipping container. Such shipping containers can be transported by ship and by lorry. Furthermore, it is desirable that solar heating systems are efficient, robust, and can be set up in a relatively straightforward manner when removed from the shipping container. It may also be necessary to move the solar heating system to a new destination after a period of use, and therefore it is also desirable that the solar heating system can be easily reinserted into the shipping container (or a new equivalent standard shipping container) for transportation to the new destination, subsequent removal from the shipping container and set up for use in the new destination in a relatively straightforward manner.

In at least some situations, it is desirable that the solar heating system is arranged to generate hot water and/or steam in an efficient manner. The hot water and/or steam can be used in a variety of applications, including for use as drinking water, 25 washing and for agricultural purposes. Other applications are envisaged.

SUMMARY OF THE INVENTION

Accordingly the present invention seeks to mitigate at least one of the above-mentioned problems, or to at least provide an alternative to known solar heating 5 systems. Accordingly, an object of the invention is to provide a solar heating system that can be transported within a standard shipping container to its place of use, and preferably a standard 40-foot (12.19m) high cube shipping container. Another object of the present invention is to provide a solar heating system that can be set up in a relatively straightforward manner when removed from the shipping 10 container. Another object of the present invention is to provide a solar heating system that is able to generate hot water and/or steam in a reasonably efficient manner.

According to one aspect there is provided a solar heating system according to claim 1. The solar heating system is arranged to produce steam and/or hot water in an efficient and cost-effective manner. The solar heating system can be arranged to produce high temperature steam, for example at greater than or equal to 150°C, preferably greater than equal to 180°C, and more preferably greater than equal to 200°C; or hot water, for example at around at greater than or equal to 70°C, preferably greater than or equal to 80°C, and more preferably greater than or equal to 90°C. The steam and/or hot water produced can be used for many different applications, for example many industrial and commercial uses such as in dairies for pasteurisation processes, in the food industry for steam cooking, in agriculture for the treatment of waste water, in hotels for hot water, water treatment, drinking water, washing. Many other applications are also envisaged such as desalination of water, general treatment of wastewater, cooling systems, and electricity generation.

According to another aspect there is provided a solar heating system.

The solar heating system can include a chassis.

The solar heating system can include at least one arm support mounted on the chassis. The solar heating system can include a plurality of arm supports. The arm supports can be mounted towards one end of the chassis. The arm supports can be 5 spaced apart from one another.

The solar heating system can include an arm. The arm can be pivotally attached to the or each arm support. The arm can be arranged to pivot relative to the or each arm support about a generally horizontal axis.

The solar heating system can include a tubular receiver. The tubular receiver can be 10 mounted to the arm. The tubular receiver can be and arranged to pivot about the generally horizontal axis with the arm The tubular receiver can have an internal cavity arranged to receive fluid.

The solar heating system can include at least one lens array, and preferably a plurality of lens arrays. The at least one lens array is arranged to, in use, direct sunlight on to the tubular receiver to heat fluid contained within the tubular receiver. The at least one lens array can be mounted on the arm. The at least one lens array can be arranged to pivot about the generally horizontal axis with the arm and tubular receiver.

The solar heating system can include a drive system. The drive system can be 20 arranged to pivot the arm about the generally horizontal axis. The drive system can be arranged to adjust a position of the at least one lens array. The drive system can be arranged to adjust an orientation of the at least one lens array.

The solar heating system can include a control system. The control system can be arranged to control operation of the drive system.

The drive system can include a drive assembly arranged to adjust a separation between the at least one lens array and the tubular receiver. The drive assembly can be arranged to move the at least one lens array translationally to adjust the separation. For example, the drive assembly can be arranged to move the at least one lens array in a direction that is generally perpendicular to a longitudinal axis of the tubular receiver. The drive assembly can be arranged to move the at least one lens array in a generally radial direction relative to the tubular receiver.

The drive assembly can be arranged to move the at least one lens array from a retracted position to a deployed position. In the deployed position, at least some of the lenses focus light on to the tubular receiver. When the or each lens array is in the deployed position, the overall height of the solar heating system is greater than when the lens array is in the retracted position. Having a retracted position enables the solar heating system to be inserted into a standard shipping container.

The drive assembly can include at least one linear actuator, and preferably a plurality 15 of linear actuators. At least one linear actuator can be located at each end of the lens array.

Each linear actuator can comprise a hydraulic ram.

The longitudinal axis of the tubular receiver can be arranged co-axially, or parallel, with a longitudinal axis of the arm.

The drive system can include a drive assembly arranged to adjust the angular orientation of the lens array about a longitudinal axis of the lens array. Adjusting the angular orientation of the lens array about a longitudinal axis of the lens array adjusts the overall width of the solar heating system. The solar heating system has a maximum width when the or each lens array has a horizontal orientation. By inclining the orientation of a lens array about the axis its longitudinal axis reduces the overall width of the solar heating system. This helps the solar heating system to fit within a standard shipping container, while in use provides a relatively wide lens array to direct light on to the tubular receiver.

The at least one lens array can include a second lens arrays.

The drive assembly can be arranged to adjust the angular orientation of the first lens array about a longitudinal axis of the first lens array. The drive assembly can be arranged to adjust the angular orientation of the second lens array about a longitudinal axis of the second lens array. Typically, each lens array can be pivoted through a limited angle. The angle is typically less than or equal to 90 degrees, preferably less than or equal to 70 degrees, and more preferably less than or equal to 50 degrees.

The drive assembly can be arranged to pivot the first and second lens arrays in different rotational directions. For example, the drive assembly can be arranged to pivot the first lens array in a clockwise direction about its longitudinal axis. The drive assembly can be arranged to pivot the second lens array in an anti-clockwise direction about its longitudinal axis.

The drive assembly can be arranged to adjust the angular orientations of the first and second lens arrays between generally horizontal orientations for solar heating operations, and inclined orientations for transportation. In some embodiments, an innermost longitudinal edge the first lens array can be positioned higher than an outermost edge of the first longitudinal array when in the inclined orientation. In some embodiments, an innermost longitudinal edge the second lens array can be positioned higher than an outermost edge of the second longitudinal array when in the inclined orientation.

The drive assembly can include at least one motor. The at least one motor can comprise a hydraulic motor. The at least one motor can comprise an electric motor.

The drive system can include a drive assembly arranged to adjust the angular orientation of the arm about the generally horizontal axis. Rotating the arm about the generally horizontal axis adjusts the pitch angle of the arm, and hence the pitch angle of the tubular receiver and the pitch angle of the lens array. This can adjust the amount of solar energy focussed on to the tubular receiver.

The drive assembly arranged to adjust the angular orientation of the arm about the generally horizontal axis can include at least one linear actuator. The linear actuator 10 can comprise a hydraulic ram.

The drive assembly arranged to adjust the angular orientation of the arm about the generally horizontal axis can include a sliding scissor lift.

The sliding scissor lift can include a first support pivotally attached to the chassis. The first support can be pivotally attached to the chassis at a first end of the first 15 support. The sliding scissor lift can include a second support pivotally attached to the arm at a first end of the second support by means of a sliding pivot.

The first and second supports can be pivotally attached to one another at their second ends.

A first end of the at least one linear actuator can be pivotally attached to the chassis. 20 A second end of the at least one linear actuator can be pivotally attached to the second support.

The drive system can include a drive assembly arranged to adjust the angular orientation of the at least one lens array about the longitudinal axis of the tubular receiver. The longitudinal axis of the tubular receiver can be considered a roll axis.

The drive assembly enables the at least one lens array to pivot about the tubular receiver to track the sun, for example in an east-west direction. This enables light to be focused on to the tubular receiver while tracking movement of the sun. This helps to provide an efficient solar heating system. Typically, the drive assembly can be arranged to pivot the at least one lens array about the longitudinal axis of the lens array through a limited range of angles. Typically the limited range of angles can be ±60 degrees from an axis extending perpendicularly outwards from the longitudinal axis of the tubular receiver.

The drive assembly can be arranged to rotate the lens arrays and the linear actuators 10 used to adjust the separation between the lens arrays and the tubular receiver, as a unit, about the longitudinal axis of the tubular receiver.

The drive assembly arranged to adjust the angular orientation of the at least one lens array about the longitudinal axis of the tubular receiver can include at least one motor and a transmission system. The transmission system can be arranged to communicate drive from the at least one motor to the lens array. The at least one motor can comprise a hydraulic motor.

The arm can include a first support post. The first support post can be located towards a first end of the arm. The arm can include a second support post. The second support post can be located towards a second end of the arm. The first and 20 second support posts can be arranged to support the tubular receiver.

The solar heating system can include a frame pivotally attached to the first and second support posts. The frame supports the linear actuators arranged to adjust the separation between the lens array and the tubular receiver. The transmission system can include a gear that engages the support frame. The gear can be arranged to pivot the support frame, linear actuators and the lens array about the longitudinal axis of the tubular receiver.

The gear can be a ring gear. The ring gear can be mounted co-axially with the longitudinal axis of the tubular receiver. The tubular receiver can extend through an aperture formed the gear.

The solar heating system can include a solar tracking device. The control system can be arranged to receive signals from the solar tracking device. The control system can be arranged to automatically control operation of the drive system in response to signals received from the solar tracking device, to orient the lens array towards the sun.

The control system can be arranged to operate the drive system to pivot the arm 10 about the generally horizontal axis in response to signals received from the solar tracking device.

The control system can be arranged to operate the drive system to pivot the lens array about the longitudinal axis of the tubular receiver in response to signals received from the solar tracking device.

The or each lens array can comprise an array of Fresnel lenses.

Each lens can comprise a Fresnel lens assembly. The lens assembly can include a supporting substrate. The lens assembly can include a film applied to a surface of the supporting substrate. The film can have at least one lens formed therein, and preferably at least one Fresnel lens formed therein.

In use, the lens assembly directs light to the tubular receiver. The light heats a fluid in the tubular receiver to increase the temperature of the fluid, and in some instances to change the state of the fluid, for example from a liquid to a gas.

The film can comprise a plastics material, and preferably a thermoplastic material such as Polymethyl methacrylate (PM MA).

The film can have a maximum thickness that is greater than or equal to 30 microns. The film can have a maximum thickness that is less than or equal to 250 microns.

The lens can be formed in the film by a casting drum.

The supporting substrate can comprise a plastic material, and preferably a 5 thermoplastic material such as Polymethyl methacrylate (PMMA), thermoplastic polyurethane (TPU), polyethylene terephthalate (PET) and/or polycarbonates (PC).

The at least one lens can have a focal length that is greater than or equal to lm. The at least one lens can have a focal length that is less than or equal to 2m. Preferably the at least one lens can have a focal length in the range 1.2m to 1.8m, and is 10 preferably around 1.65m.

The lens array can include a plurality of lens assemblies, and preferably a plurality of Fresnel lens assemblies. Each lens assembly can include a supporting substrate. Each lens can include a film applied to at least one surface of the supporting substrate. Each film can have a lens formed therein, and preferably a Fresnel lens formed therein. Each lens assembly can be arranged according to any configuration described herein.

The lens array can be planar. A plurality of lens assemblies can be arranged in an array. For example, the array can include at least one row of Fresnel lens assemblies, and preferably a plurality of rows of Fresnel lens assemblies.

The tubular receiver can include a tubular absorber. The tubular absorber can be metallic, and is preferably made from steel. The tubular absorber can be coated with an absorber coating to minimise heat loss, for example infrared heat loss. The coating can comprise a nano-coating. Nano-coatings are particularly effective at reducing heat loss. The coating can be a dark colour, such as black.

The tubular receiver can include an optically transparent casing housing at least part of the tubular absorber. This provides a very efficient arrangement. A receiver arranged in this manner has been found to have an efficiency of around 984%. The optically transparent casing helps to prevent light escaping. The optically transparent casing can be coaxial with the tubular absorber. The casing can be made from glass. The casing can have an antireflective coating to increase solar transmittance.

The tubular receiver can be arranged to include a space between the optically transparent casing and the tubular absorber. Air can be evacuated from said space 10 to create a vacuum. The vacuum reduces or prevents gas heat conduction between the transparent casing and the tubular receiver, which can improve performance.

The tubular receiver can include an annular member mounted on the tubular absorber co-axially therewith. The annular member can be arranged to support a first end of the optically transparent casing.

The annual member can include a first annular part sealably attached to the tubular absorber. The annual member can include a second annular part sealably attached to the optically transparent casing. The tubular receiver can include an expandable flexible member folded in a concertina arrangement. The expandable flexible member is attached to the first annular part and the second annular part. The expandable member accounts for differences in thermal expansion between the tubular receiver and the optically transparent casing. The expandable flexible member can be sealed to the first annular part. The expandable flexible member can be sealed to the second annular part.

The tubular receiver can include a second annular member mounted on the tubular 25 receiver co-axially therewith. The second annular member can be arranged to support a second end of the optically transparent casing. The second annual member can include a first annular part sealably attached to the tubular absorber. The second annual member can include a second annular part sealably attached to the optically transparent casing. The tubular receiver can include an expandable flexible member folded in a concertina arrangement.

The system can include an elongate reflector mounted parallel with the tubular receiver on a side of the tubular receiver that is opposite to the side facing towards the lens array. The reflector redirects light towards the tubular receiver.

The frame can include first and second parts.

The second part can be arranged to support the tubular receiver. The second part 10 can be arranged to pivot about the second axis.

The first part can support the lens array. The first part can be arranged to pivot relative to the second part about the first axis. The tubular receiver can be arranged co-axially with the first axis. Thus the lens array can be pivoted about the tubular receiver.

The control system can include a wind protection mode. The control system can include wind speed measurement means and the processor is arranged to receive signals from the wind speed measurement means. The control system can be arranged to move the lens assembly to a safe orientation in response to receiving a signal from the wind speed measurement means that indicates that the wind speed is greater than or equal to a threshold value. Typically the safe orientation is a horizontal orientation. When the lens assembly is in the horizontal orientation, typically the first part of the frame is in a vertical orientation.

The system can include a fluid supply system. The fluid supply system supplies a thermal transfer fluid to the tubular receiver.

The fluid supply system can be arranged to supply the fluid in a liquid state to the tubular receiver. The lens array can be arranged to heat the tubular receiver to a sufficiently high temperature to generate gas from the liquid.

The fluid supply system can include a header tank. The header tank can be arranged to store fluid in a liquid state.

The fluid supply system can include a condenser arranged to condense gas to liquid. The liquid can be recycled back to the header tank. In general, if water is not used for other purposes (e.g. drinking water) then water from the system is recyclable back to the header tank.

The fluid supply system can include a de-ionizer arranged to de-ionize the fluid, such as water.

The fluid system can include at least one pump. The fluid system can include at least one pump arranged to pump the fluid into the tubular receiver. Typically, the pump can be arranged to pump a liquid into the tubular receiver. The fluid supply system 15 can include at least one pump arranged to pump fluid to the header tank.

The fluid supply system can include a blowdown tank. The blowdown tank is arranged to store the fluid in gaseous form.

The fluid supply system can include an energy storage tank. The energy storage tank is a larger and/or lower pressure vessel than the blowdown tank and is arranged to store a larger volume of fluid in liquid and/or gaseous form. The energy storage tank can include an output, for example an output pipe, that supplies the second fluid, such as hot water and/or steam, to a downstream process or user. The output pipe can include at least one valve to control the flow of the second fluid from the energy storage tank.

The fluid supply system can include an absorption chiller. The absorption chiller can be a lithium bromide absorption chiller. The absorption chiller includes a refrigeration system that is driven by heat taken from the fluid. The fluid is typically supplied to the absorption chiller at a temperature in excess of 60°C.

The fluid supply system can include at least one filter arranged to filter fluid in the system. The fluid supply system can include a plurality of filters, the arrangement being such that one of the filters can be changed without having to shut down the solar heating system.

The fluid supply system can include at least one additional tank for storing the 10 thermal transfer fluid.

The system can include at least one temperature sensor arranged to monitor a fluid temperature in the fluid supply system. A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the header tank, for example at an output side of the header tank. A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the tubular receiver, for example at an output side of the tubular receiver. A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the heat exchanger, for example at an output side of the heat exchanger. A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the blowdown tank, for example at an input side of the blowdown tank. A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the condensate tank, for example at an input side of the condensate tank. A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the energy storage tank, for example at an input side of the energy store tank. A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the absorption chiller, for example at an input side of the absorption chiller.

The system can include a controller arranged to receive signals from at least one temperature sensor.

The controller can be arranged to send a control signal to the tracking system to adjust the position of the lens array in response to receipt of a signal from at least 5 one temperature sensor, for example a signal indicating that the temperature has reached a threshold value.

The control system can be arranged to adjust the position of the lens array in response to receipt of the control signal from the controller. For example, the control system can be arranged to move the lens array to a position that decreases the amount of solar energy directed on to the receiver. In one embodiment the control system can be arranged to move the lens array to a position wherein the lens array faces away from the sun. This provides the solar heating system with a safety arrangement to prevent components from overheating.

The fluid supply system can include at least one flow meter.

The fluid supply system can include a primary circuit having a first thermal transfer fluid. The primary circuit can include the tubular receiver.

The fluid supply system can include a secondary circuit having a second thermal transfer fluid. Typically the second thermal transfer fluid is different from the first thermal transfer fluid.

The fluid supply system can include a heat exchanger arranged to transfer heat from the first thermal transfer fluid to the second thermal transfer fluid. The heat exchanger can be part of the primary and secondary circuits.

The primary circuit can include a header tank. The header tank can store the first fluid, typically in a liquid state.

The primary circuit can include the tubular receiver.

The header tank, tubular receiver and heat exchanger can be arranged in series. The primary circuit can be a closed loop circuit.

The primary circuit can include a first filter system. Preferably the second filter system 5 includes first and second filters. The first filter system can be located between the heat exchanger and the header tank.

The primary circuit can include at least one pump. At least one pump can be arranged to pump the first fluid to the to the tubular receiver. The first fluid is typically in a liquid state went it enters the tubular receiver. The at least one pump 10 can be arranged to pump the first fluid to the header tank.

The primary circuit can include at least one valve. A check valve can be located between the header tank and the receiver tube. A check valve can be located between the heat exchanger and the header tank.

The primary circuit can include at least one temperature sensor, and preferably a IS plurality of temperature sensors, arranged to measure the temperature of the first fluid. A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the header tank, for example at output side of the header tank. A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the tubular receiver, for example at an output side of the tubular receiver.

A temperature sensor can be arranged to monitor the fluid temperature in and/or adjacent the heat exchanger.

The primary circuit can include at least one flow meter. A flow meter can be located between the header tank and the receiver tube.

The secondary circuit can include a header tank. The header tank is arranged to store the second fluid, preferably in a liquid state.

The secondary circuit can include the blowdown tank. The blowdown tank is arranged to store the second fluid in gaseous form. The blowdown tank can be a 5 steam tank.

The secondary circuit can include the condenser. The condenser is arranged to condense the second fluid from a gaseous state to a liquid state.

The secondary circuit can include the energy storage tank. The secondary circuit can include the absorption chiller.

The secondary circuit can include a second filter system. Preferably the second filter system includes first and second filters. The filter system can be located between the blowdown tank and the condenser.

The secondary circuit can be a closed loop circuit.

In the secondary circuit, the header tank, heat exchanger, blowdown tank and 15 condenser can be arranged in series. In the secondary circuit, the header tank, heat exchanger, blowdown tank, and absorption chiller can be arranged in series.

The energy storage tank can be arranged in parallel with the absorption chiller.

The secondary circuit can include at least one pump. At least one pump can be arranged to pump the second fluid in a liquid state from the header tank to the heat 20 exchanger. At least one pump can be arranged to pump the second fluid in a liquid state to the header tank.

The secondary circuit can include at least one valve. A check valve can be located between the header tank and the heat exchanger. A check valve can be located between the condenser and the absorption chiller. A diverter valve can be located between the blowdown tank and the condensate tank. The diverter valve can be arranged to control the flow of fluid from the blowdown tank to the condensate tank. The diverter valve can redirect the output from the blown tank to the energy storage tank.

The secondary circuit can include at least one temperature sensor, and preferably a plurality of temperature sensors, arranged to measure the temperature of the second fluid. A temperature sensor can be arranged to monitor the fluid temperature in the header tank, at an input side of the header tank and/or an output side of the header tank. A temperature sensor can be arranged to monitor the fluid temperature in the heat exchanger, at an input side of the heat exchanger and/or an output side of the heat exchanger. A temperature sensor can be arranged to monitor the fluid temperature in the blowdown tank, at an input side of the blowdown tank and/or an output side of the blowdown tank. A temperature sensor can be arranged to monitor the fluid temperature in the condenser, at an input side of the condenser and/or an output side of the condenser. A temperature sensor can be arranged to monitor the fluid temperature in the energy store, at an input side of the energy store and/or an output side of the energy store. A temperature sensor can be arranged to monitor the fluid temperature in the absorption chiller, at an input to the absorption chiller and/or an output to the absorption chiller.

The secondary circuit can include at least one flow meter. A flow meter can be located between the header tank and the heat exchanger.

According to another aspect there is provided a steam generator plant, including a solar heating system according to any configuration described herein. The steam, or 25 other gas, generated by the solar heating system can be used for any suitable purpose.

According to another aspect there is provided a desalination plant, including a solar heating system according to any configuration described herein. The steam, or other gas, generated by the solar heating system can be used in a desalination process.

According to another aspect there is provided a waste treatment plant including a 5 solar heating system according to any configuration described herein. The steam, or other gas, generated by the solar heating system can be used in a waste treatment process.

According to another aspect there is provided an electrical generator plant including a solar heating system according to any configuration described herein. The steam, or other gas, generated by the solar heating system can be used in an electrical generator plant to generate electricity. For example, the steam, or other gas, can be used to drive turbine to generate electricity.

According to another aspect there is provided a water treatment plant including a solar heating system according to any configuration described herein.

According to another aspect there is provided a cooling system, including a solar heating system according to any configuration described herein. The cooling system can include an absorption chiller unit According to another aspect there is provided a solar heating system including a tubular receiver having an internal cavity arranged to receive fluid; at least one lens array arranged to, in use, direct sunlight on to the tubular receiver to heat fluid contained within the tubular receiver; a drive system and a control system for controlling operation of the drive system, wherein the drive system includes a drive assembly arranged to adjust a separation between the at least one lens array and the tubular receiver to move the at least one lens array from a retracted position to an operational position, wherein in the operational position the tubular receiver is spaced apart from at least some of the lenses by a distance equal to the focal length of the lenses. The arrangement adjusts the height of the solar heating system for ease of insertion into a shipping container.

According to another aspect there is provided a solar heating system including a 5 tubular receiver having an internal cavity arranged to receive fluid; first and second lens arrays arranged to, in use, direct sunlight on to the tubular receiver to heat fluid contained within the tubular receiver; a drive system and a control system for controlling operation of the drive system, wherein the drive system includes a drive assembly arranged to adjust the angular orientation of the first lens array about a 10 longitudinal axis of the first lens array, and to adjust the angular orientation of the second lens array about a longitudinal axis of the second lens array. The arrangement adjusts the width of the solar heating system for ease of insertion into a shipping container. Preferably the drive assembly is arranged to pivot the first and second lens arrays in different rotational directions.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described with reference to the following drawings by way of example only:

Figure 1 illustrates a view of a prior art system;

Figure 2 is an end view of a solar heating system according to the invention in a non-operational configuration, ready for transportation; Figures 3 is a side view of the solar heating system of Figure 2 in the nonoperational configuration; Figure 4 is an isometric view of the solar heating system of Figure 2 in a transitional configuration, with the lens arrays in a horizontal orientation but non-elevated position; Figure 5 is an end view of the solar heating system of Figure 2 in the transitional configuration; Figure 6 is side view of the solar heating system of Figure 2 in the transitional configuration; Figure 7 is an isometric view of the solar heating system of Figure 2 in an operational configuration, with the lens arrays in a horizontal orientation, and in an elevated position; Figure 8 is an end view of view of the solar heating system of Figure 2 in the operational configuration of Figure 7; Figure 9 is an isometric view of the solar heating system of Figure 2 in a second operational configuration, with a support arm elevated at one end thereby tilting the lens arrays towards the sun; Figure 10 is a side view of the solar heating system of Figure 2 in the second operational configuration shown in Figure 9; Figure 11 is an isometric view from a left side of the solar heating system of Figure 2 in a third operational configuration, with a support arm elevated at one end and the lens array rotated about a longitudinal axis of the support arm, thereby tilting the lens arrays towards the sun; Figure 12 is an isometric view from a right side of the solar heating system of Figure 2 in the third operational configuration of Figure 11; Figure 13 is a side view of the solar heating system of Figure 2 in the first operational configuration shown in Figure 7, and showing a tubular receiver, the position of a transmission system, and wheeled screw jacks; Figure 14 is a diagrammatic representation of the transmission system shown in Figure 13; Figure 10 is a cross-sectional detailed view of end part of the tubular receiver shown in Figure 13; Figure 16 is a diagrammatic representation of a solar tracking system, programable logic controller and hydraulic system used in the solar heating system of Figure 2; Figure 17 is a diagrammatic representation of the hydraulic system of Figure 16; Figure 18 is an enlarged diagrammatic view of a part of a lens included in the embodiment of Figure 2; Figure 19 is a schematic view of a lens arrangement in the embodiment of Figure 2; Figures 20 to 22 are examples of circuits including the solar heating system of Figure 2, which is represented by the receiver tube of Figure 13.

DETAILED DESCRIPTION OF THE INVENTION

Figures 2-19 illustrate the main components of a solar heating system 1 according to an embodiment of the invention. The solar heating system 1 includes first and second lens arrays 3a,3b; a tubular receiver 5 arranged to receive solar energy from the lens arrays 3a,3b; a support assembly 7 for supporting the lens arrays 3a,3b; a drive system 8 for adjusting the position and/or orientation of the lens arrays 3a,3b; and a control system 10 for controlling operation of the drive system 8.

The solar heating system 1 is suitable to heat a fluid, such as water, and is designed 5 to fit within a standard 40-foot high cube shipping container. The internal dimensions of that type of container are: 39' 6" (12.03m) long x 7 9" (2.35m) wide x 810" (2.59m) high, and it has a usable capacity of 76m3.

Each lens array 3a,3b includes a plurality of lenses 9, and preferably a plurality of Fresnel lens 9. Each lens array 3a,3b can include any practicable number of lenses 9.

Typically each lens array 3a,3b includes 1 to 20 lenses 9. In Figure 4, each lens array 3a,3b has twelve lenses 9 arranged in a longitudinal row. The number of lenses is selected according to the heating requirements, and how easy and cost effective it is to manufacture and assemble a given size of lens 9.

For embodiments including Fresnel lenses 9, each Fresnel lens 9 includes a substrate 11 and a film 13. The substrate 11 provides support for the film 13. The substrate typically comprises a panel, and preferably a planar panel. Typically the panel is rectangular in plan view. The panel is typically made from a plastic material, and preferably a thermoplastic material, such as polymethyl methacylate (PMMA), thermoplastic polyurethane (TPU), polyethylene terephthalate (PET) or polycarbonates (PC). The substrate 11 preferably comprises a PMMA panel.

The film 13 includes an arrangement of lens elements 15 formed therein. Each lens element 15 typically comprises a micro-prism. The overall arrangement of the lens elements 15 produces the Fresnel lens 9. The film 13 typically has a thickness in the range 30-250 microns. The film 13 is typically made from polymethyl methacrylate (PMMA). The film 13 is applied to a major surface of the substrate 11. The film 13 is preferably bonded to the substrate 11, for example by a solvent such as methyl chloride.

The film 13 is produced by forming a lens pattern into a curved surface of a casting drum. The casting drum can be made from copper or high phosphorus nickel, the 5 lens pattern is typically cut into the drum using diamond cutters that are computer controlled according to a program arranged to provide a lens with a specific focal length. The casting drum is mounted in a roll to roll UV casting machine. A web of film material is fed over the casting drum and the lens pattern on the casting drum forms the arrangement of lens elements 15 in the web of film material. The film 13 10 is then cut to size and each film portion is mounted on to a respective substrate 11. Each Fresnel lens is approximately 1.2m long 0.7m wide. Each lens has a specific focal length, which is typically in the range lm to 2m, preferably 1.2m to 1.8m, and is typically around 1.65m.

Optionally, a transparent wear film or coating can be applied to the film 13 to protect 15 the optical surfaces.

The control system 10 is an electronic control system 8 that is suitable for controlling operation of the drive system 8. The control system 10 can include at least one controller that is suitable for controlling operation of drive system 8 apparatus, for example can include at least one programmable logic controller (PLC).

The support assembly 7 includes a chassis 17, arm supports 19, and a pivotable arm 21.

Each lens array 3a,3b includes an elongate support frame 23a,23b. The lenses 9 in each lens array 3a,3b are mounted to the support frame 23a,23b, and are fixed thereto. The lenses 9 in each array are arranged in a 1 row by 12 column array. The 25 lenses 9 extend along the elongate support frame, as shown in Figure 4.

The lens arrays 3a,3b are arranged parallel to one another, and long sides of the support frames 23a,23b are aligned with one another so that there are 2 rows of 12 lenses 9. At a first end of the lens arrays 3a,3b, each support frame 23a,23b is connected to a first transverse member 25a. The first transverse member 25a is arranged perpendicular to the longitudinal axes of the support frames 23a,23b. At a second end of the lens arrays 3a,3b, each support frame 23a,23b is connected to a second transverse member 25b. The second transverse member 25b is arranged perpendicular to the longitudinal axes of the support frames 23a,23b. Each support frame 23a,23b is connected to the first and second transverse members 25 in a pivotable manner, for example by means of an axel mounted in a bush or bearing, and each support frame 23a,23b is able to rotate about a longitudinal axis of the support frame 23a,23b. This enables each lens array 3a,3b to pivot about its longitudinal axis from an orientation which is generally parallel to the chassis 17 to orientation that is inclined to the chassis 17. Adjusting the orientations of the lens arrays 3a,3b changes the effective width of the solar heating system 1. That is, when the lens arrays 3a,3b are in an orientation that is generally parallel with the chassis 17 (generally horizontal orientation) (see Figures 4 to 6) the width of the solar heating system 1 is such that it will not fit into a standard 40-foot (12.19m) high cube shipping container. That is, the width of the solar heating system 1 exceeds 2.35m. However, by inclining the orientation of the lens arrays 3a,3b to the chassis 17 (see Figures 2 and 3a,3b), the overall width of the solar heating system 1 is reduced to a value that is less than 2.35m, thereby allowing the system 1 to be placed into the standard high cube shipping container. The arrangement allows relatively large lenses 9 to be used in the system 1 to focus more sunlight during a heating operation, and therefore the design constraint of the system having to fit into a shipping container does not significantly affect the optical effectiveness of the system.

When moving between horizontal and inclined orientations, the lens arrays 3a,3b typically rotate in opposite directions from one another. That is, one lens array 3a,3b rotates in a clockwise direction and the other lens arrays 3a,3b rotates in an anticlockwise direction. Typically, when moving from the horizontal orientation to the inclined orientation, inner longitudinal edges 23aIE,23bIE of the support frames 23a,23b rotate in a generally upwards direction from the horizontal, and outer longitudinal edges 23a0E,23b0E of the support frames rotate in a generally downwards direction from the horizontal. Typically, when moving from inclined orientations to horizontal orientations, inner longitudinal edges 23aIE,23bIE of the support frames 23a,23b rotate in a generally downwards direction towards the horizontal, and outer longitudinal edges 23a0E,23b0E of the support frames tend to rotate in a generally upwards direction towards the horizontal.

The drive system 8 includes at least one motor that is arranged to adjust the rotational orientation of the first and second lens arrays 3a,3b. The motor can be a hydraulic motor. Alternatively, motor can be an electric motor. The motor is arranged to adjust the rotational orientation of the first and second lens arrays 3a,3b from an inclined orientation to a generally horizontal orientation, in response to a first control signal received from the control system 10. The motor is arranged to adjust the rotational orientation of the first and second lens arrays 3a,3b from a horizonal orientation to an inclined orientation, in response to a second control signal received from the control system 10. When the solar heating system 1 is removed from the shipping container, a user is able to reorient the lens arrays 3a,3b from the inclined orientations to horizontal orientations by actuating a control on a control panel 12. When the solar heating system 1 is to be inserted into the shipping container, a user is able to reorient the lens arrays 3a,3b from the horizontal orientations to inclined orientations by actuating the control on the control panel 12.

The drive system 8 includes four first hydraulic rams 27. The first transverse member 25a is mounted on a first pair of the first hydraulic rams 27. The second transverse member 25b is mounted on a second pair of the first hydraulic rams 27. The control system 10 is arranged to adjust the elevation of the lens arrays 3a,3b, by controlling operation of the first hydraulic rams 27. The control system 10 is arranged to move the lens arrays 3a,3b between retracted and deployed positions. The lens arrays 3a,3b are positioned in the retracted positions when the solar heating system 1 is not in use, for example at a time when operation of the system 1 is not required, or when the system is to be transported in the shipping container. The lens arrays 3a,3b are positioned in the deployed positions, when the solar heating system 1 is being operated. In the deployed position, the lens arrays 3a,3b are positioned at a height that is arranged to focus light from the lens 9 on to the tubular receiver 5, which is preferably 1.65m above the tubular receiver 5. In the deployed positions the lens arrays 3a,3b are arranged parallel with the tubular receiver 5. A user is able to move the lens arrays 3a,3b between the deployed and retracted positions by operating a control on the control panel 12. The control system 10 can include at least one sensor arranged to determine when the lens arrays 3a,3b are in the deployed and retracted positions. When the lens arrays 3a,3b are in their operational positions, the height of the solar heating system 1 exceeds the internal height of the 40-foot shipping container (2.59m). By moving the lens arrays 3a,3b to their non-deployed positions, the overall height of the solar heating system is less than 2.59m, which allows the solar heating system 1 to be inserted into the 40-foot high cube shipping container.

The overall length of the solar heating system 1 is less than 12m, and is typically in 25 the range 10m to 11.5m.

The chassis 17 provides a base for the solar heating system 1.

The arm supports 19 comprises support pillars. The arm supports 19 are located towards a first end of the chassis. The arm supports 19 are spaced apart. The arm 21 is pivotally attached the arm supports 19 by a pivot pin 20. The arm 21 pivots about a horizontal pivot axis X-X. The arm 21 comprises a space-frame arrangement for strength and providing a relatively light weight arm for the overall length.

The tubular receiver 5 is mounted on to the arm 21. The tubular receiver 5 is elongate. The tubular receiver 5 runs along a central longitudinal axis of the arm 21, along substantially the full length of the arm 21. The tubular receiver 5 is supported at each end by a support member 32 and has a protective frame 34, that partly surrounds the tubular receiver 5 in a manner wherein at least an upper surface of the tubular receiver 5 is exposed to the lenses 9.

The tubular receiver 5 is located at a focal line of the lenses 9. In use, the lenses 9 focus solar energy onto the tubular receiver 5 to heat a fluid therein. Figure 19 illustrates diagrammatically the lenses 9 focusing light towards the tubular receiver 5.

The tubular receiver 5 comprises a thermally conductive absorber tube 49, which is typically made from metal, such as steel (see Figure 15), and preferably stainless steel. The absorber tube 49 has a transparent outer casing 51, which is typically made from glass, and preferably crystal glass. The outer casing 51 is arranged co-axially with the absorber tube 49. The outer casing 51 has a larger diameter that the absorber tube 49 such that the inner surface of the outer casing 51 is spaced apart from the outer surface of the absorber tube 49. The space between the outer casing 51 and the absorber tube 49 is evacuated to create a vacuum. The vacuum supresses gas heat conduction, and convection within the space. Each end of the tubular receiver 5 has end assembly 53. The end assembly 53 includes a ring assembly 55, which separates the outer casing 51 from the absorber tube 49 and a bellows assembly 57 which allows for differences in the rates of thermal expansion and contraction between the absorber tube 49 and the outer casing 51. The ring assembly 55 comprises a first part 55a sealed to the absorber tube 49. The metal ring 55 includes a second part 55b sealed to the outer casing 51. The bellows assembly 57 is sealed to both the first and second parts of the ring. The receiver 5 can include getter material in order to maintain the vacuum in the receiver. The getter material is arranged to absorb free gases in the space between the outer casing 51 and the absorber tube 49. In use, the absorber tube 49 carries a fluid, such as water or an oil, which is heated up by the solar energy directed on to it by the lenses 9. The heat generated can be sufficient for the fluid to change state, for example the fluid can be inserted into the absorber tube 49 in the form of a liquid and can change state to a gas. For example, liquid water can be changed to steam.

Tubular connector portions 47 are arranged co-axially with the tubular receiver 5. Each tubular connector portion 47 is connected to a respective end of the absorber tube 49 and is in fluid communication therewith. The tubular connector portions 47 extend through respective support members 32. The tubular connector 47 connect the tubular receiver 5 to a fluid circuit, such as a steam circuit (see Figures 20 and 21), for example by attaching flexible pipes or hoses to the tubular connector portions 47.

The outer diameter of the outer casing 51 is typically around 100mm to 150mm and is preferably around 125mm. The outer diameter of the tubular absorber is typically in the range 50mm to 100mm, and is preferably around 70mm. The absorber is typically between 9m and llm long, and may comprise two shorter lengths welded together end to end. The tubular receiver is very efficient at converting solar energy to heat the fluid. The arrangement has an efficiency of 98.4%.

The absorber tube 49 can include a coating to promote heat absorption. For example, the absorber tube 49 can include a coating of nanoparticles to promote heat absorption. The outer casing 51 can include an anti-reflective coating to reduce the amount of light reflected by the casing 51.

A reflector 52 is shown in diagrammatically in Figure 19 which is in the form of a semi-cylindrical element coaxial with the receiver, providing a reflective surface to direct light and heat energy back upon tubular receiver 5 towards the underside of the receiver 5. The reflector 52 can include a highly polished Alanod film, which has a 98% reflectivity.

Cross members 38a,38b are mounted on respective tubular connector portions 47a,47b. The cross members are arranged transversely to the longitudinal axis Y-Y of the tubular receiver 5. The cross members 38a,38b support respective pairs of first hydraulic rams 27. Each pair of first hydraulic rams 27 is fixedly attached to their respective cross member 38a,38b. The frame 34 includes longitudinal members 40, which are arranged parallel with the longitudinal axis Y-Y of the tubular receiver 5 and which connect together the cross members 38a,38b. The frame 34 thus forms a unit with the cross members 38a,38b and first hydraulic rams 27.

The frame 34 also includes a further longitudinal member 42, which is arranged parallel with the longitudinal axis Y-Y of the tubular receiver 5. The longitudinal 20 member 42 is typically located below the tubular receiver 5.

The drive system 8 includes a transmission 44, which is shown diagrammatically in Figures 13 and 14. The transmission 44 includes a ring gear 46, which is supported by planetary gears 48, and two further gears 50,52, which transmit drive from hydraulic motors 54,56 to the ring gear 46. The tubular receiver 5 extends through the central aperture 72 in the ring gear 46, is preferably arranged co-axially with the ring gear 46. The further longitudinal member 42 engages the ring gear 46. For example, the further longitudinal member 42 can pass through a small hole made in a peripheral portion of the ring gear 46. Alternatively, the further longitudinal member 42 can be split into two parts, wherein an end of each part is bolted to the peripheral portion of the ring gear 46. In either case, the arrangement is such that when the hydraulic motors 54,56 are actuated and the ring gear 46 rotates, the frame 34, cross members 38a,38b, first hydraulic rams 27 and lens arrays 3a,3b rotate about the longitudinal axis Y-Y of the tubular receiver with the ring gear 46. When in a rotated condition, the distance between the lenses 9 and the tubular receiver 5 is maintained such that light is always focused on to the tubular receiver 5. The ring gear 46, and hence the lens arrays 3a,3b can be pivoted about the longitudinal axis Y-Y of the tubular receiver 5 through an angle in the range ±55° (see Figures 11 and 12). 0 degrees is when the lens arrays 3a,3b are in horizontal orientations.

The drive system 8 includes a sliding scissor lift 22. The sliding scissor lift 22 is mounted on the chassis 17. The sliding scissor lift 22 includes first and second parts.

A first end of the first part 24 is pivotally attached to the chassis 17. A first end of the second part 26 is pivotally attached to the arm 21, via a slidable pivot that is able to move axially along the arm 21, in a longitudinal direction, within a limited range. The first and second parts 24,26 are pivotally attached to one another at their second ends. The scissor lift 22 includes at least one second hydraulic ram 28 that is arranged to adjust the angular separation between the first and second parts 24,26 and thereby pivoting the arm 21 with respect to the chassis 17 about the pivot pin 20. In a non-deployed position, the arm 21 is in a generally horizontal orientation (see Figure 6) and is generally parallel with the chassis 17. The control system 10 controls operation of the second hydraulic ram to adjust the angular deployment of the arm 21 (see Figures 9 and 10). The arm 21 can be deployed to any given angle within an allowable range of angles. A typical range of angles is 1 to 60 degrees from the horizontal non-deployed orientation. Since the tubular receiver 5 is attached to the arm 21, angularly deploying the arm 21 also angularly deploys the tubular receiver 5. Accordingly, the control system 10 is arranged to adjust an angle of inclination of the longitudinal axis Y-Y of the tubular receiver 5, with respect to the horizontal non-deployed orientation, about the horizontal axis X-X.

The system 1 includes a solar tracking system 59. The tracking system 59 is arranged to provide signals to the control system 10, to enable the control system 10 to automatically adjust the orientation of the lenses 9 to track the position of the sun, thereby increasing the amount of solar energy directed to the tubular receiver 5. Any suitable solar tracking system 59 can be used, for example the SIMATIC 57-1200 tracking system sold by Siemens e.

The control system 10 is arranged to control operation of the second hydraulic ram 28, and hence the sliding scissor lift 22, in accordance with signals received from the solar tracking device 59, to automatically adjust the angular deployment of the arm 21 during a solar heating operation. Pivoting the arm 21 about the horizonal axis X-X enables the lens arrays 3a,3b to track changes in altitude of the sun during a solar heating operation.

The control system 10 is arranged to control operation of the hydraulic motors 54,56 in accordance to signals received from the solar tracking device 59, to automatically adjust the angular deployment of the lens arrays 3a,3b about the longitudinal axis of the Y-Y of the tubular absorber 5 during a solar heating operation. Pivoting the lens arrays 3a,3b about the longitudinal axis of the Y-Y of the tubular absorber 5 enables the lens arrays 3a,3b to track changes in east-west positioning of the sun during a solar heating operation. In some arrangements, the control system can be bespoke for controlling operation of the motors.

Tracking the sun about the X-X and Y-Y axes ensures that the lenses 9 are always oriented towards the sun during a solar heating operation to maximise the solar gain, and hence the efficiency of the solar heating system 1.

Due to the two axes of movement of the lenses 9, the lenses 9 may track the 5 movement of the sun during daylight hours in both elevation and from East to West.

The hydraulic elements of the drive system Bare shown in Figure 17. Figure 17 shows an illustrative hydraulic circuit 58 that can be used to drive movement of the lens arrays 3a,3b and arm 21. The circuit 58 includes a hydraulic power pack 60 and pumps 62,64. The circuit 58 includes the first hydraulic rams 27 and a suitable manifold 66. The circuit 58 includes the second hydraulic rams 28 and a suitable manifold 68. The circuit 58 includes the hydraulic motors 54,56 and a suitable manifold 70.

Optionally, the control system 10 can include a wind protection system that is arranged to move the lens arrays 3a,3b into a safe orientation in the event of high winds. The control system 10 can include a wind speed measurement device, or at least be arranged to receive an input from a separate device. The control system 10 is arranged to monitor the wind speed. When the control system 10 determines that the wind speed is greater than or equal to a threshold value, in response the control system 10 moves the lens arrays 3a,3b into a safe orientation, for example by actuating at least one of: the first hydraulic rams 27, the hydraulic motors 54,56, and the second hydraulic ram 28. A safe orientation is when the lens array 3 is in a generally horizontal orientation.

Optionally, the solar heating system 1 can include at least one rechargeable cell (not shown), and typically includes 4 to 10, and preferably 6 to 8, 12 Volt high capacity 25 truck batteries, which are configured to provide a 24 Volt electrical system. The solar heating system can include at least one renewable source of electricity for recharging the rechargeable cell, such as a photovoltaic cell or an array of photovoltaic cells (not shown). Electricity from the rechargeable cell(s) can be used to power at least some of the electrical and electronic devices used in the system 1, such as the control system 10 and solar tracker 59, and typically all of the electrical and electronic systems in the system 1. This enables the solar heating system 1 to be energy independent, that is, it is not necessary to plug the apparatus into a national grid system for it to operate.

Optionally, the solar heating system 1 can include an arrangement of screw jacks 74 attached to the chassis 17 (shown diagrammatically in Figure 13). This enables the chassis 17 to be raised and lowered. For example, the chassis 17 can be raised above the ground for transportation purposes, to make it easier for the system 1 to be moved into the shipping container. The chassis 17 can be lowered to engage the ground The solar heating system 1 can include a fluid supply system that is arranged to 15 supply fluid to the receiver 5. The fluid supply system can include a fluid supply circuit. Figures 20 and 21 are examples of such circuits.

Figure 20 shows a fluid supply system that can be used for generating high temperature steam, for example at 200C + and/or hot water, for example at 90C. The arrangement is capable of providing high temperature steam for example for the treatment of wastewater, brackish water, saline water, industrial and commercial uses, textiles, chemicals, agriculture, dairies for water treatment and pasteurisation, food-steam cooking, agriculture, and hospitals.

Alternatively the arrangement is cable of providing hot water for lower temperature applications, for example for use in various industrial facilities, such as factories, and 25 commercial facilities, such as hotels, and other organisations such as hospitals, schools, etc. The fluid supply system includes a first water tank 65, a second water tank 67 (also referred to as a steam condenser), a heat radiator 69, a steam tank 71 and the receiver tube 5. The fluid supply system can include several valves V1-V12, such as ball valves, and check valves. The fluid supply system can include one or more pumps MU -MT4. The table in Figure 14 illustrates how the state of the valves (open/closed) and operation of the pumps can effect circuit functions, for example to fill the second water (condenser) tank 67, recirculation for steam generation, agitation between tanks for temperature equalization, download to the first water tank 65, and closing the radiator 69.

Water fed to the receiver tube 5 is heated to a sufficiently high temperature by the solar gain from the Fresnel lenses 9 to generate the required steam. The steam generated can be used for any application requiring steam and/or hot water.

Optionally, the solar heating system 1 can include at least one sensor, and preferably a plurality of sensors. For example, the solar heating system 1 can include one or more temperature sensors T1...Tn arranged to monitor a fluid temperature in the fluid supply system. The solar heating system 1 can include a controller 73 that is arranged to receive signals from the temperatures sensors T1...Tn. If at least one of the temperature sensors T1...Tn reaches a threshold value, the controller 73 is arranged to send a control signal to the tracking system 59 to adjust the position of the Fresnel lenses 9, for example to decrease the solar energy directed on to the receiver 5. The tracking system 59 can be arranged to move the Fresnel lenses 9 to a position where they no longer face towards the sun, thereby reducing the solar energy falling on the receiver 5. This provides a safety system to prevent components in the solar heating system 1 from overheating.

Optionally, the fluid supply system can include at least one filter arranged to filter a fluid, such as water, in the fluid supply system. Preferably the fluid supply system includes a duplex filter system. The duplex filter system allows one of the filters to be exchanged with a new filter without having to shut down the solar heating system 1.

Optionally, the circuit can include a de-ionizer.

It is envisaged that the invention can be used for the purpose of solar thermal irrigation, tea plantations, horticulture, and solar thermal cooling by integrating an "absorption chiller" system.

At least some of the equipment such as tanks and piping, may include insulation. The insulation can include AluZinc insulation.

Figure 21 relates to a power generation circuit. A preferred form of the system will include temperate and pressure gauges to monitor operation at critical points of the system. Furthermore, condensate can be returned to the header tank. In the circuit of Figure 21 air vents may be fitted at any high points in the circuit as required. Likewise, drain points (e.g. DN15) may be fitted at low points. If a temperature gauge 126 on header tank 128 is not easily visible to an operator, a temperature transmitter can be considered, to be received by a control unit (not seen).

Preferably water is drawn from a low level of the tank 128 by a pump 130, passed through a strainer 132 and ultimately returned via line DN32 to a higher level. Referring to Figure 15, any power generation apparatus would be located downstream of receiver tube 5, e.g. within line DN32. A plurality of valves 134, 132 may be installed for control of flow through the circuit. Similarly, thermocouples may activate an emergency shut down in the event that operating parameters are exceeded.

Lagging/insulation of pipe work may not be required in all applications, particularly 25 since it is desirable that the steam, after power generation, should return to a liquid state before return to header tank 128, or as use for purified drinking water etc. However, where insulation is used in the circuit, for example for tanks and piping, the insulation can include AluZinc insulation.

Unlike the prior art system (Figure 1) it is intended to introduce liquid water at one 5 end of tubular receiver 5, where it will be turned to steam and pressurised as it travels along tubular absorber 49. However, alternative configurations are possible, such as a central or multiple injection points.

The lenses 9 are designed to focus solar radiation onto a line that is substantially coaxial with the tubular receiver 5 or its wall surface.

Figure 22 is an example of a system having a primary circuit 100 and a secondary circuit 200. The primary circuit 100 is connected to the secondary circuit 200 by means of a heat exchanger 300.

The primary 100 circuit includes a header tank 165 that stores a thermal transfer fluid in a liquid state. The thermal transfer fluid is preferably an organic thermal transfer fluid such as a thermal oil. For example, Marlotherm® XC can be used as the thermal transfer fluid. It has a suitable operating temperature range for pressurised systems of: -90°C to 300°C. Alternatively, the thermal transfer fluid can in the primary circuit comprise water. The thermal transfer fluid enables the primary circuit 100 to operate at higher temperatures than a water circuit normally would. For example, the thermal transfer fluid can be heated to around 220°C to 240°C. The header tank 165 includes a low-level meter 166. A temperature sensor 168 measures the temperature of the thermal transfer fluid on an output side of the header tank 165. An output side of the header tank 165 is connected to an input side of the receiver tube 5. A check valve 101 and a flow meter 102 are located between the header tank 165 and the receiver tube 5. A pump 103 is arranged to pump the thermal transfer fluid from the header tank 165 through the tubular receiver 5. An output side of the receiver tube 5 is connected to an input side of the heat exchanger 300. An output side of the heat exchanger 300 is connected to an input side of the header tank 165. A check valve 105 is located between the heat exchanger 300 and the header tank 165. A pump 107 is arranged to pump the thermal transfer fluid back to the header tank 165. A filter 108 is located between the heat exchanger 300 and the header tank 165 to filter the thermal transfer fluid. The header tank 165, tubular receiver 5 and heat exchanger are preferably arranged in series.

A temperature sensor 111 measures the temperature of the thermal transfer fluid at an output side of the tubular receiver 105. A control system monitors output signals from the temperature sensors 168,111 and can control the position of the lens array 3 in response to the output signals thereby adjusting the amount of solar energy directed to the tubular receiver 5. For example, if at least one of the temperature sensors 168,111 indicates that the temperature of the thermal transfer fluid exceeds at threshold value, and therefore is too high, the control system controls operation of the linear actuator 49 and/or slew ring 31 to adjust the position of the lens array 3 to reduce the amount of solar energy falling on the tubular receiver 5, for example by orienting it away from the sun.

The secondary circuit 200 includes the heat exchanger 300, a blowdown tank 271, a condensate tank 250, a header tank 265 and a filtration system 260. The header tank 265 typically stores water. The header tank 265 includes a low-level meter 266. The header tank 265 is connected to an input side of the heat exchanger 300 and supplies liquid water thereto. The water supplied to the input side of the heat exchanger is typically at a temperature of around 6C to 20C. A pump 201 pumps water from an output side of the header tank 265 to an input side of the heat exchanger 300. A check valve 203 and flow meter 204 are located between the header tank 265 and the heat exchanger 300. The blowdown tank 271 is connected to an output side of the heat exchanger 300. A temperature sensor 211 measures the temperature of the water at an output side of the heat exchanger 300 / input side of the blowdown tank 271. Typically, the water is in the form of steam or very hot liquid water as it exits the heat exchanger 300 and enters the blowdown tank 271. Typically, the water temperate is in the range 90C to 120C. An output side of the blowdown tank 271 is connected to a diverter valve 272. The diverter valve 272 is arranged to direct hot liquid water / steam to at least one of an energy storage tank 270 (sometimes referred to as an energy store) and a condensate tank 250, according to the setting of the diverter valve 272. The diverter valve 272 can be manually operated or can be controlled by a control system. The energy storage tank 270 is arranged to store hot liquid water / steam until required for a useful purpose. An output side of the energy storage tank is connected to a gate valve 274, typically via a gate valve 276. A user or a process can extract hot liquid water / steam from the energy storage tank 271 via gate valve 276. The condensate tank 250 is arranged to cool hot liquid water / steam received from the blowdown tank 271, typically to around 60C to 90C. The filter system 260 is located between the blowdown tank 271 and the condensate tank 250. A pump 262 is arranged to transfer water from the blowdown tank 271 to the condensate tank 250. An output side of the condensate tank 250 can be connected to an absorption chiller 280. The absorption chiller 280 can be used in a cooling process, for example as an air-conditioning unit. An output side of the absorption chiller 280 is connected to an input side of the header tank 265. A valve 205 is located between the condensate tank 250 and the absorption chiller 280. Preferably the header tank 265, filtration system 260, heat exchanger 300, blowdown tank 271 and condensate tank 250 are arranged in series.

The absorption chiller 280 can be a lithium bromide absorption chiller 280. Water supplied from the condensate tank 250C to the absorption chiller 280 is typically at a temperature in the range 60C to 90C. The absorption chiller 280 uses the hot water to drive a refrigeration process and, as a consequence, removes heat from the water. For example, water leaving an output side of the absorption chiller 280 can have a temperature of around 6°C to 20°C. Water leaving the absorption chiller 280 is returned to the header tank 265. Preferably the condensate tank 250, absorption chiller 280 and header tank 265 are arranged in series.

A temperature sensor 209 measures the temperature of the water at an output side of the header tank 265. A temperature sensor 211 measures the temperature of the water at an output side of the heat exchanger 300 and/or an input side of the blowdown tank 271. A temperature sensor 213 measures the temperature of the water at an input side of the energy storage tank 270. A temperature sensor 215 measures the temperature of the water at an input side of the condensate tank 215. The control system monitors output signals from the temperature sensors 209,211,213,215 and is arranged to control the position of the lens array 3 in response to the output signals thereby adjusting the amount of solar energy directed to the lens array. For example, if at least one of the temperature sensors indicates that the temperature of the water exceeds at threshold value, and therefore is too high, the control system 10 controls operation of at least one of: the first hydraulic rams 27, the hydraulic motors 54,56, and the second hydraulic ram 28 to adjust the position of the lens arrays 3a,3b to reduce the amount of solar energy falling on the tubular receiver 5, for example by orienting it away from the sun.

Preferably at least one of the filters 108,260 comprises a double filter system. The double filter system allows one of the filters to be exchanged with a new filter without having to shut down the solar heating system 1.

In use, the lens arrays 3a,3b directs solar energy onto the tubular receiver 5, which 25 heats the thermal transfer fluid to a temperature around 220°C to 240°C and turns it into a vapour and/or gas. The receiver tube 5 is connected to the heat exchanger 300. The vapour and/or gas passes through the heat exchanger 300 and condenses back to a liquid thereby providing heat to the secondary circuit 200. The heat exchanger 300 receives liquid water from the header tank 265. Heat provided from the primary circuit 100 causes the liquid water to turn to steam, which is supplied to 5 the blowdown tank 271. Hot liquid water / steam can be supplied from the blowdown tank 271 to energy store 270 for later use by a process or user. For example, the hot liquid water/steam can be used for sterilization purposes, for cleaning, washing, etc. Hot liquid water/steam can be supplied from the blowdown tank 271 to the condensate tank 250 and then to the absorption chiller 280 to drive 10 the refrigeration process. The refrigeration process can be used for many purposes, such as air conditioning, chilling food, chilling medical products, etc. Where insulation is used in the primary and secondary circuits, for example for tanks and piping, the insulation can include AluZinc insulation.

It will be appreciated that the above examples can be modified while still falling 15 within the scope of the invention. For example, a different number of lenses 9 can be included in the array. The lenses 9 can have a different focal length. The lens panels can have a different size and/or shape.

At least one electric motor can be used instead of hydraulic motors 54,56. The electric motor is controlled by the control system 10.

At least one dedicated electric motor can be used to adjust the orientation of the lens arrays 3a,3b with respect to support frames 23a,23b. The electric motor is controlled by the control system 10.

Claims

CLAIMS: 1 A solar heating system, including: a chassis; at least one arm support mounted on the chassis; an arm pivotally attached to the at least one arm support, wherein the arm is arranged to pivot relative to the at least one arm support about a generally horizontal axis; a tubular receiver mounted to the arm, the tubular receiver having an internal cavity arranged to receive fluid; at least one lens array mounted to the arm; a drive system arranged to pivot the arm about the generally horizontal axis, and to adjust at least one of a position of the lens array and an orientation of the lens array with respect to the tubular receiver; and a control system arranged to control operation of the drive system.
2. The system of claim 1, wherein the drive system includes a drive assembly arranged to adjust a separation between the at least one lens array and the tubular receiver, thereby adjusting the position of the at least one lens array.
3 The system of claim 2, wherein the drive assembly is arranged to move the at least one lens array from a retracted position to a deployed position, wherein in the deployed position at least some of the lenses in the lens array focus light on to the tubular receiver.
4. The system of claim 2 or 3, wherein the drive assembly includes at least one linear actuator, and preferably a plurality of linear actuators.
5. The system of claim 4, wherein each linear actuator comprises a hydraulic ram.
6. The system of any one of claims 2 to 5, wherein the drive assembly is arranged to move the at least one lens array in a direction that is generally perpendicular to a longitudinal axis of the tubular receiver.
7. The system of any one of any one of the preceding claims, wherein drive system includes a drive assembly arranged to adjust the angular orientation of the at least one lens array about a longitudinal axis of the lens array.
8. The system of claim 7, wherein the at least one lens array includes a second lens array, and the drive assembly is arranged to adjust the angular orientation of the second lens array about a longitudinal axis of the second lens array.
9. The system of claim 8, wherein the drive assembly is arranged to rotate one of the lens array and the second lens array in a clockwise direction about its longitudinal axis and to rotate the other of the lens array and the second lens array in an anti-clockwise direction about its longitudinal axis.
10. The system of claim 8 or 9, wherein the drive assembly is arranged to adjust the angular orientations of the lens arrays between generally horizontal orientations for solar heating operations, and inclined orientations for transportation.
11. The system of any one of claims 7 to 10, wherein the drive assembly includes at least one motor.
12. The system of any one of any one of the preceding claims, wherein drive system includes a drive assembly arranged to adjust the angular orientation of the arm about the generally horizontal axis.
13. The system of claim 12, wherein the drive assembly includes at least one linear actuator.
14. The system of claim 13, wherein the linear actuator comprises a hydraulic ram.
15. The system of any one of claims 12 to 14, drive assembly includes a sliding scissor lift.
16. The system of claim 15, wherein the sliding scissor lift includes a first support pivotally attached to the chassis, and a second support pivotally attached to the arm by means of a sliding pivot.
17. The system according to claim 16, wherein the first and second supports are pivotally attached to one another.
18. The system according to claim 15 or 16, when dependent on claim 14, wherein the at least one linear actuator is pivotally attached to the chassis and the at least one linear actuator is pivotally attached to the second support.
19. The system of any one of any one of the preceding claims, wherein drive system includes a drive assembly arranged to adjust the angular orientation of the at least one lens array about the longitudinal axis of the tubular receiver.
20. The system of claim 19, wherein the drive assembly is arranged to pivot the at least one lens array and the linear actuators used to adjust the separation between the lens array and the tubular receiver, as a unit, about the longitudinal axis of the tubular receiver.
21. The system of claim 19 or 20, wherein the drive assembly includes at least one motor and a transmission system, wherein transmission system communicates drive from the at least one motor to the lens array.
22. The system according to claim 21, wherein the arm includes first and second supports arranged to support the tubular receiver, and including a frame pivotally attached to the first and second support posts, wherein the frame supports the linear actuators arranged to adjust the separation between the at least one lens array and the tubular receiver, and wherein the transmission system includes a gear that engages the support frame and is arranged to pivot the support frame, and the linear actuators mounted on the support frame and the at least one lens array, about the longitudinal axis of the tubular receiver.
23. The system of claim 22, wherein the gear comprises a ring gear mounted co-axially with the longitudinal axis of the tubular receiver, with the tubular receiver extending through an aperture formed the gear.
24. The system of any one of the preceding claims, including a solar tracking device, wherein the control system is arranged to receive signals from the solar tracking device and to automatically control operation of the drive system in response to signals received from the solar tracking device, to orient the at least one lens array towards the sun.
25. The system according to claim 24, wherein the control system is arranged to operate the drive system to pivot the arm about the generally horizontal axis in response to signals received from the solar tracking device; and/or the control system is arranged to operate the drive system to pivot the lens array about the longitudinal axis of the tubular receiver in response to signals received from the solar tracking device.
26. The system of any one of the preceding claims, wherein the at least one lens array can comprise an array of Fresnel lenses.
27. The system of claim 26, wherein each Fresnel lens includes a supporting substrate and a film applied to a surface of the supporting substrate, the film has at least one lens formed therein.
28. The system of claim 26 or 27, wherein the film can comprise a plastics material, and preferably a thermoplastic material such as Polymethyl methacrylate (PM MA).
29. The system of any one of claims 26 to 28, wherein the supporting substrate can comprise a plastic material, and preferably a thermoplastic material such as Polymethyl methacrylate (PMMA), thermoplastic polyurethane (TPU), polyethylene terephthalate (PET) and/or polycarbonates (PC).
30. The system of any one of the preceding claims, wherein at least some of the lenses in the lens array have a focal length that is greater than or equal to lm.
31. The system of any one of the preceding claims, wherein at least some of the lenses in the lens array have a focal length that is less than or equal to 2m.
32. The system of any one of the preceding claims, wherein, in use, the lens array directs light to the tubular receiver, the light heats a fluid in the tubular receiver to increase the temperature of the fluid.
33. The system of any one of the preceding claims, wherein the tubular receiver includes a tubular absorber coated with an absorber coating to minimise heat loss.
34. The system of claim 33, wherein the coating comprises a nano-coating.
35. The system of claim 33 or 34, wherein the tubular receiver includes an optically transparent casing, which houses at least part of the tubular absorber.
36. The system of claim 35, wherein the casing is made from glass.
37. The system of claim 35 or 36, wherein the casing has an antireflective coating to increase solar transmittance.
38. The system of any one of claims 35 to 37, wherein the tubular receiver includes a space between the optically transparent casing and the tubular absorber, and air is evacuated from said space to create a vacuum.
39. The system according to claim 38, wherein the tubular receiver includes an annular member mounted on the tubular absorber co-axially therewith, the annular member is arranged to support a first end of the optically transparent casing; the annual member includes a first annular part sealably attached to the tubular absorber, a second annular part sealably attached to the optically transparent casing, and the tubular receiver includes an expandable flexible member folded in a concertina arrangement, which is attached to the first annular part and the second annular part and is arranged to account for differences in thermal expansion between the tubular receiver and the optically transparent casing.
40. The system of any one of the preceding claims, including an elongate reflector mounted parallel with the tubular receiver on a side of the tubular receiver that is opposite to the side facing towards the lens array.
41. The system of any one of the preceding claims, including a fluid supply system arranged to supply a thermal transfer fluid, such as water, to the tubular receiver.
42. The system of claim 41, wherein the fluid supply system includes a header tank, arranged to store fluid in a liquid state.
43. The system of claim 41 or 42, wherein the fluid supply system includes a condenser arranged to condense gas to liquid.
44. The system of any one of claims 41 to 43, wherein the fluid supply system includes a de-ionizer arranged to de-ionize the fluid, such as water.
45. The system of any one of claims 41 to 44, wherein the fluid system includes at least one pump arranged to pump the fluid into the tubular receiver.
46. The system of any one of claims 41 to 45, wherein the fluid system includes at least one pump arranged to pump fluid to the header tank.
47. The system of any one of claims 41 to 46, wherein the fluid system includes at least one pump arranged to supply fluid to a blowdown tank, wherein the blowdown tank is arranged to store the fluid in gaseous form.
48. The system of any one of claims 41 to 47, wherein the fluid system includes an energy storage tank.
49. The system of any one of claims 41 to 48, wherein the fluid system includes an absorption chiller.
50. The system of any one of claims 41 to 49, wherein the fluid system includes at least one filter arranged to filter fluid in the system.
51. The system of any one of claims 41 to 50, wherein the fluid system includes at least one additional tank for storing the thermal transfer fluid.
52. The system of any one of claims 41 to 51, wherein the fluid system includes at least one temperature sensor arranged to monitor a fluid temperature in the fluid supply system.
53. The system according to claim 52, wherein the control system is arranged to receive signals from at least one temperature sensor, and the control system is arranged to adjust the position of the lens array in response to receipt of a signal from at least one temperature sensor, for example a signal indicating that the fluid temperature has reached a threshold value.
54. The system according to claim 53, wherein the control system is arranged to move the lens array to a position that decreases the amount of solar energy directed on to the tubular receiver.
55. The system of any one of claims 41 to 54, wherein the fluid system includes at least one flow meter.
56. The system of any one of claims 41 to 55, wherein the fluid system includes a primary circuit having the tubular receiver and a first thermal transfer fluid; a secondary circuit having a second thermal transfer fluid; a heat exchanger arranged to transfer heat from the first thermal transfer fluid to the second thermal transfer fluid.
57. A desalination plant, including a solar heating system of any one of the preceding claims.
58. A waste treatment plant, including a solar heating system of any one of claims 1 to 56.
59. An electrical generator plant, including a solar heating system of any one of claims 1 to 56.
60. A water treatment plant, including a solar heating system of any one of claims 1 to 56.
61. A cooling system, including a solar heating system of any one of claims 1 to 56.