Radiatively Heated Hot Fluid Reservoir

Abstract

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Description

Details of original application No.: 40 The following statement is a full description of this invention, including the best method of performing it known to me 45 2025271160   21 Nov 2025 Radiatively Heated Hot Fluid Reservoir Technical field 5 The present invention relates to a radiatively heated, hot fluid reservoir, for electricity generation from so l a r rad i ative heating. Background Australian Bureau of Meteorology data shows Australian daily solar irradiation as up to 10   37 MJ per square meter per day, this compares to petroleum at 35 MJ per litre. The earth’s oceans cover 70% of the planet. Solar radiation warms the ocean surface which thus becomes earth’s largest solar collector. To extract this thermal energy and produce electricity heat engines are required. 15 This conversion process is known as OTEC, Ocean Thermal Energy Conversion. Heat engines operate between two thermal reservoirs, one hot and one cold. Classic OTEC designs operate in areas where the ocean surface temperatures exceed 24 degrees Celsius, this surface sea water acts as a massive hot reservoir. An equally massive cold water reservoir is found at a depth of 1000 meters where the sea 20 temperature is approximately 4 degrees Celsius. OTEC electricity generation provides electricity without the requirement of battery backup! Unfortunately, experimental prototypes and mathematical modelling, show that the energy required to pump the cold water from a depth of 1000 meters to the surface is 25 approximately equal to the energy produced by the OTEC process. An objective of this invention is to increase the temperature of a body of a hot fluid reservoir beyond the temperature of surface sea water, this results in an increase in the Carnot thermal efficiency of heat engines used for electricity generation. The percentage of work required for pumping is thus less and electricity generation 30 becomes achievable, in this manner, electricity may be produced that is: Clean, renewable and sustainable, with no battery requirement. 2025271160   21 Nov 2025 Summary of invention In a first aspect of the invention there is provided a Radiatively Heated Hot Fluid Reservoir. (RHHFR). The RHHFR comprising a fluid, contained within a vessel, the walls 5 and floor of which are thermally insulated, to prevent heat egress to the environment. Above the body of hot fluid, are a series of, thin polymer windows which cover the body of hot fluid. The polymer has a high transmittance coefficient for solar energy between the wavelengths of 400nm - 1100nm 10 In an embodiment, between two layers of polymer windows, rotating mirrors form a reflective barrier, which may be open or closed to nominated angles, by electric motors, under supervisory computer and data acquisition processor (SCADA). Solar Radiation Gate The rotating mirrors when closed, form an infra-red radiation gate, blocking the egress 15 of infra-red radiation from the hot fluid, and when open enable solar radiation entry to heat the hot fluid. Above the rotating mirrors, a second polymer window which is of high strength, woven and impervious to gas migration with high solar radiation transmittance. Between the two polymer IR windows a gas, with high solar radiation transmittance, 20 forms an insulated barrier to thermal conductivity. In the manner described above: - Hot fluid heat loss from thermal conductivity, is substantially blocked with thermal insulation. - Hot fluid has convective heat loss blocked by solar radiation transparent gas 25         contained between polymer windows. - Hot fluid has radiative heat flow loss blocked by rotating mirrors, IR gates, at low light levels and night. 2025271160   21 Nov 2025 In a second aspect there is provided a video camera which maps sky luminance above the Hot Fluid Reservoir. The temperature of the Hot Fluid is measured by thermocouples the output being fed into the SCADA system, which enables the host processor to decide if there will be a net 5 heat loss or heat gain if the rotating mirrors form a solar radiation gate that is either open, closed or at an intermediate position. Generally, if the sky luminance provides less energy per square meter than the emitted infra-red emitted from the hot fluid, as calculated from the temperature of the hot fluid, the rotating mirrors, as an infra - red gate, should be closed to prevent IR transmittance into space. If the sky has a high LUX 10 reading, and the solar radiation energy is greater per unit area than the infra-red emission per unit area is, the rotating mirror IR gate should remain open permitting solar radiation to heat the hot fluid Carnot Theorem and thermal efficiency of OTEC Systems The extraction of useful work from the thermal energy of a fluid is limited in terms of 15 efficiency by the Carnot theorem: Nc = 1 - Tc / Th Where Tc = Cold Reservoir temperature in Kelvin Th = Hot Reservoir temperature in K If a large body of sea water, with a temperature of 24 C Is used as a hot reservoir and the cold fluid, pumped from 1000 meter, ocean depth is 4 C the maximum thermal energy efficiency is: 20 For warm seawater, 24 C, cold sea water 4 C: Nc = 1- (273+4) / (273+24) = 6.73% Mathematical modelling and extensive “real world” experimentation has shown that the energy required to pump the cold sea water in an OTEC system, from a depth of 1000 meters is approximately equal to any useful electrical output. 25 If a fluid, other than sea water is heated with solar radiation, as a hot reservoir, experimentation has shown temperatures of up to 90 C. Under these circumstances the Carnot thermal efficiency is: 30 Hot fluid, 90 C, cold sea water 4C: Nc = 1 - (273+4) / (273 + 90) = 23.69% The useful electrical production increasing to 3.5 times the cold sea water pump requirements. Clean, renewable, sustainable electricity generation without batteries. 2025271160   21 Nov 2025 Dimensions A one gigawatt system, equal to the power of a nuclear reactor, or ten million solar 5 panels, requires an area of 3km x 3km, however, unlike solar panels, no battery backup is required and construction cost is a fraction of the cost of either PV solar or nuclear power. Brief Description of the Figures Embodiments of the invention will now be described with reference to the accompanying 10 drawings which are not drawn to scale and which are exemplary only and in which: Fig. 1 is a cross sectional figure of a Radiatively Heated, Hot Fluid Reservoir. Fig.2 is a cross sectional figure of a rotating mirror, infra-red gate. Fig.3 is a cross sectional figure of a land based Radiatively Heated Hot Fluid 15 Reservoir. Fig. 4 is a cross sectional figure of a sea based Radiatively Heated Hot Fluid Reservoir. 20 Fig. 5 is block diagram of the gas and fluid pathways. Detailed Description of Embodiments of the Invention Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, 25 which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed method, structure or system. Further, the terms and phrases are not intended to be limiting, but rather to provide an 30 understandable description of the invention. In the preferred embodiment there is provided a RHHFR which is designed to capture solar radiation and increase the temperature of a hot thermal fluid reservoir. 2025271160   21 Nov 2025 Fig. 1 illustrates one embodiment of a Radiatively Heated Hot Fluid Reservoir of the present invention. In this embodiment, a hot fluid 101, is contained within an insulated vessel,102. Entry of warm fluid to hot fluid reservoir, via 103, exit of hot fluid via 104. 5 In a preferred form, sea water may constitute the hot fluid. Sea water has a boiling temperature of 102 Celsius, if sodium chloride in the form of sea salt is added to the sea water, the boiling temperature may increase beyond 108 C. The insulated vessel, 102 is preferably lined with rubber from reconstituted car tyres, in the form of rubber bladders, preferably filled with argon gas. 10 The Radiatively Heated Hot Fluid Reservoir has gaseous insulation 111, between two polymer IR transparent windows,105 &106. The gas employed to provide the insulation needs to have high transmittance of short wave radiation, 400nm - 1100nm and low thermal conductivity. Nitrogen 78% of atmosphere, Oxygen 20%, Argon 1% each are suitable with Argon having the best 15 overall performance, however for large scale implementation dry air, air with moisture vapour removed, offers the most economical solution. The thermal conductivity of air is 0.026 W / m. K The air drying is achieved by passing the air through a chiller which has a temperature less than the dew point resulting in the air losing moisture as a condensate, captured and removed by condensate trough, 112.The dried air then re-enters the space 20 between the polymer windows 105,106. Video Camera, 109, maps the luminosity of the sky above the Radiatively Heated Hot Fluid Reservoir, the sky LUX is compared with the hot fluid temperatures by thermocouples 110, immersed in the hot fluid. Rotating mirrors 107, are electrically driven to rotate about axis 108. 25 The rotating mirrors form a solar radiation gate, blocking egress of infra-red during night time and opening for incoming solar radiation during daylight hours, as measured by the LUX reading from video camera 109, and as determined by the SCADA (supervisory computer and data acquisition) processor. To rival nuclear power, an OTEC heat engine requires power delivery in excess of a one 30 gigawatt nuclear power system. The area for heating from the rotating mirrors needs to be in excess of 10 million square meters. This may be achieved when rotating mirrors cover an area of 3.162 Km x 3.162 Km. 2025271160   21 Nov 2025 Figure 2 illustrates the rotating mirror mechanism in greater detail. Each rotating mirror is constructed from ultra-thin metallized polymer, fig 2, 201. The metallized polymer is reflective to 97% of solar radiation. The ultrathin metallized polymer is supported between two cables, 202. These cables, 5 are up to 1 km long and are held in high tension by springs, 203, the springs are attached via screw thread eye bolts to rotating arms 204. Magnetic thrust bearings 205, have SCADA power on brake release function. When power applied the thrust bearings, 205, enable easy rotation of rotating arms 204. When power off, the thrust bearings become brakes 10 Single pole, double throw, magnetic reed switches, 206, provide datum reference points for angular positioning optical encoder, 207 SCADA input. Low power, DC motor, with reverse functionality, 208, drives rotation of mirror assembly, 15 from each end of cable assembly, via rotating arms 204, SCADA output. Support stand 209, in a preferred embodiment is a galvanised steel I beam, set in concrete slab 210, for land based systems. 20 Fig. 3 is a cross sectional view of land based RHHFR. The advantage of large scale land based RHHFR is simplicity of construction, particularly in desolate coastal areas such as the gulf of Carpentaria, of Australia. Fig.3 expands on the description of fig.1 and depicts the application of low height walls, Fig.3, 312 The most significant factor, that determines the strength of the walls, and 25 hence cost, is the pressure on the walls, Fig.3 P, which is entirely dependent on the depth of the fluid contained within the walls and the density of the cold fluid herein contained by the walls, not the volume of fluid contained, in this manner, large volume RHHFR may be constructed at minimal cost, as the containment walls Fig.3, 312, cost, reduces as a function of scale, particularly for circular RHHFR walls, whereby the 30 heating area is a function of the square of the radius with a cost proportional to the radius. As shown in fig.3, the “roof” 306, a rugged, solar radiation transparent, UV stable, gas impermeable, woven polymer. 35 The rotating mirrors, as described in Fig.2 201, are depicted in Fig.3 307. 2025271160   21 Nov 2025 Fig. 3,305 is also a rugged, solar radiation transparent, UV stable, gas impermeable, woven polymer, the volume of gas, trapped between Fig 3. 306 and Fig.3 305, becomes thermal insulation between the atmosphere and the RHHFR hot fluid, Fig.3,301. The gas 5 being a dry gas mix, admitted through entry port Fig.3, 310 and exiting via exit port Fig.3, 311 following initial gas purge on start-up, inhibits thermal convection. Warm fluid, which is to be radiatively heated, is admitted to the RHHFR through fluid pathway Fig.3, 303 with hot fluid exit to hot fluid application / s via Fig.3, 304. To enable solar radiation transmission through the gas volume contained between the 10 surface of the hot fluid Fig3., 301 and polymer Fig.3, 305 this gas contains minimum moisture, the dry gas enters through gas pathway Fig.3, 308 and exits via gas passage Fig.3, 309, the gas pathway being shown in detail in block diagram Fig.5 The hot fluid Fig 3., 301 of RHHFR is insulated from beneath and the side walls by preferably dry air, filled bladders Fig 3., 302 fabricated from recycled car tyres. 15 Alternatively, polyurethane expanded foam in lieu of dry air. The bladders have metalized interiors to reflect radiant infrared heat. The metallization from vacuum sputtering. As a land based system the RHHFR sits upon levelled ground Fig.3, 313. A moderate sized system, comparable to a 1 gigawatt nuclear reactor requires 20 approximately 9 square kilometres of land area. To power Australia, the required land area would be approximately 50 x larger, 450 square kilometres, occupying an area approximately 21.2 Km. x 21.2 Km. A significant land area. The oceans of the world cover 70% of the planet. Australia has an Exclusive Economic 25 Zone extending 200 nautical miles off shore equal to 370 Km out to sea. In total this represents an area of 8.1 million square kilometres = 8.1 x 10A6 sq. km. An area of radiative heating = 450 sq. km. is required to power Australia. = 4.5 x 10A2 sq.km As a percentage of the Australian Exclusive Economic Zone this is: 30 4.5 x 10A2 / 8.1 x 10A6 = 0.555 x 10A-4 x 1x10A2= 0.555x10A-2 = 0.00555% of, Australian Exclusive Economic Zone to power Australia For this reason, a sea based RHHFR takes the form as depicted in Fig.4 2025271160   21 Nov 2025 Fig. 4 is a cross sectional figure of a sea based radiatively heated hot fluid reservoir. The sea based RHHFR, Fig. 4, is designed as a variant of the land based RHHFR to contain and heat a hot fluid reservoir. 5 The hot fluid Fig.4, 401 is contained by thermally insulative walls Fig.4, 402, which also act as flotation devices, having an overall density less than the surrounding water, enables the hot fluid reservoir to float within the sea. In a preferred form the walls Fig.4, 402 are constructed from preferably bladders which are dry air, filled with metalized interiors to block infra-red radiative cooling. The 10 bladders being formed from reconstituted rubber car tyres. Alternatively, polyurethane expanded foam in lieu of dry air, may be contained within the bladders. Warm fluid, which is to be radiatively heated, is admitted to the RHHFR through fluid pathway Fig.4, 403 with hot fluid exit to hot fluid application / s via Fig.4, 404. 15 To enable solar radiation transmission through the gas volume contained between the surface of the hot fluid Fig4., 401 and polymer Fig.4, 405 this gas has moisture removed, and enters through gas pathway Fig.4, 408 and exits via gas passage Fig.4, 409, the gas pathway being shown in detail in block diagram Fig.5 20 As shown in fig.4, the “roof” Fig.4, 406 a rugged, solar radiation transparent, UV stable, gas impermeable, woven polymer. Video cameras, placed above the sea based RHHFR, not shown, create LUX luminosity 25 maps which are used to determine which angular position the rotating mirrors Fig.4, 407 should each be in, for optimum heating of hot fluid. The rotating mirrors, Fig.4, 407 having been described and shown in Fig.2 201. are housed within the insulative body of dry gas, contained within polymer windows, Fig.4, 30   406 and Fig.4, 405. With dry gas entering through Fig.4, 410 and exiting from Fig.4,411 for processing and recycling as per block diagram Fig.5 2025271160   21 Nov 2025 Salinity and Hot fluid convection currents In a preferred form, highly saline sea water may constitute the hot fluid. Sea water has a boiling temperature of 102 Celsius, sodium chloride in the form of sea salt may be 5 added to the water, if sea water is used as the hot fluid and the concentration of salt increased to 23% by weight, then the boiling temperature is increased up to 108 Celsius. When the salinity is maximum, convection within the fluid is minimised with the denser hot fluid at the bottom of the RHHFR, and cooler less dense, less saline fluid at the 10 surface of the hot fluid. This is the reverse of fresh water heating, and ensures maximum heating of deeper saline solution and less energy for evaporation at surface. The increase in salinity can be achieved through a process of solar evaporation. Fig. 5 is block diagram of the gas and fluid pathways. 15 System Commissioning, Salinity Increase, Start Up The following is a system start up procedure, commissioning of system To achieve solar evaporation, the temperature of the hot fluid reservoir, the is achieved in the following manner: 20       (i) Gas valve Fig. 5, 505 is opened to atmosphere. (ii) Gas Valve Fig. 5, 507 is opened to atmosphere (iii) Pump Fig.5, 502 pumps sea water into hot fluid reservoir, Fig 5,504 (iv) To appropriate depth, of RHHFR reservoir Fig5,504. (v) The LUX measurement camera, Fig.1, 109 outputs data to SCADA processor. 25       (vi) Rotating mirrors, as solar radiation / infra-red gates are angular positioned for optimum solar heating of hot fluid. (vii) Centrifugal gas pump Fig.5, 506 pumps fluid vapour to atmosphere, increasing salinity of remaining fluid. 30 The above process is repeated until desired salinity (for boiling point) is reached, with hot fluid reservoir at preferred volume. 2025271160   21 Nov 2025 Radiative Heating and moisture removal To facilitate the radiative heating of hot fluid Fig.5, 504, the gas volumes Fig. 5, 511 and Fig.5, 512, have water vapour reduction to minimise attenuation of solar radiation transmission into the hot fluid body, which is heated to approx. 90 C, 5 When the desired salinity has been achieved, normal operation is as follows: (i) Valve to atmosphere Fig.5,505 is closed. (ii) Valve Fig.5, 507 is selected from purge mode to moisture remove cycle. (iii) Vapour containing moisture, from above hot fluid reservoir Fig.5, 512 is pumped by pump Fig.5, 506 through valve Fig.5, 507 then through chiller assembly 10              Fig.5, 509 & 510 where distilled water becomes a by-product of the process. Applications The Radiatively Heated Hot Fluid Reservoir has multiple applications: (i)     Electricity production by OTEC process. 15       (ii)     Storage of thermal energy, eliminating need for batteries. (iii)    Supply of distilled, desalinated water. (iv) Absorption of used car tyres, recycled plastic in construction. (v)    Supply of thermal energy for industrial processes. (vi)    Supply of thermal energy for home and office heating. 20       (vii) The hot fluid reservoir complements the new generation of organic Rankine cycle working fluids, that are referred to as advanced materials which are: Non Toxic, Non Flammable, No Global warming potential, non ozone depleting. (viii) The radiatively heated hot fluid reservoir complements OTEC systems, from 25              an environmental standpoint, enabling OTEC systems to provide electricity generation that is: Clean, Renewable and Sustainable without the requirement of batteries or fuel.

Claims

1. A radiatively controlled thermal energy storage system comprising:a reservoir containing a body of heat-storage fluid;one or more solar radiation transparent cover layers positioned above the body of heat-storage fluid;a plurality of metallised reflective elements positioned above the body of heat-storage fluid and rotatable about at least one axis;at least one actuator configured to rotate the reflective elements;a plurality of optical sensors configured to generate a spatial map of measured solar illuminance above the reservoir;at least one temperature sensor configured to measure a thermal condition of the body of heat-storage fluid; anda control system configured to:(i) receive data from the optical sensors and the temperature sensor;(ii) generate a spatial distribution of the measured solar illuminance across the reservoir;(iii) continuously adjust the angular orientation of the reflective elements in response to the spatial distribution of the measured solar illuminance and the measured thermal condition of the body of heat-storage fluid,wherein the control system regulates the net radiative heat transfer of the reservoir by controlling the angular orientation of the reflective elements to selectively admit incoming solar radiation and inhibit the escape of outgoing infrared radiation.

2. The system of claim 1, wherein the reflective elements form adjustable radiative gates.

3. The system of claim 1 or claim 2, wherein the reflective elements comprise lightweight metallised polymer films.

4. The system of any one of claims 1 to 3, wherein the reflective elements are mounted between solar radiation transparent polymer sheets.

5. The system of any one of claims 1 to 4, wherein the reflective elements are supported by high-tensile cables connected to rotating arms.

6. The system of claim 5, wherein the rotating arms are driven by electric motors or pneumatic motors.

7. The system of any one of claims 1 to 6, wherein the control system comprises a supervisory control and data acquisition system.

8. The system of claim 7, wherein rotational position sensors provide angular position data of the reflective elements to the control system.

9. The system of any one of claims 1 to 8, wherein the optical sensors are distributed across the reservoir to provide real-time spatial mapping of measured solar illuminance.

10. The system of any one of claims 1 to 9, wherein the control system compares the spatial distribution of measured solar illuminance with the measured thermal condition of the body of heat-storage fluid to determine an optimum angular configuration of the reflective elements for regulating the net radiative heat transfer of the reservoir.

11. The system of any one of claims 1 to 10, further comprising thermal insulation arranged beneath and along sides of the reservoir.

12. The system of claim 11, wherein the thermal insulation comprises gas-filled polymer bladders.

13. The system of claim 12, wherein the gas comprises argon or dry air.

14. The system of claim 12 or 13, wherein internal surfaces of the polymer bladders are2025271160   04 Aug 2026metallised to reflect infrared radiation.

15. The system of any one of claims 1 to 14, wherein the heat-storage fluid comprises saline water.

16. The system of claim 15, wherein the salinity is increased to elevate the boiling point of the heat-storage fluid.

17. The system of claim 15 or claim 16, wherein ethylene glycol is added to the heat-storage fluid.

18. The system of any one of claims 1 to 17, wherein multiple solar radiation transparent cover layers define insulating gas spaces therebetween.

19. The system of any one of claims 1 to 18, wherein the control system continuously optimises the angular orientation of the reflective elements in response to the spatial distribution of measured solar illuminance and the measured thermal condition of the body of heat-storage fluid.

20. The system of any one of claims 1 to 19, wherein the system operates without direct conductive heat input.

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