Ocean thermal power plant and method of operation

Abstract

The application discloses a marine temperature difference power generation device and a working method, and belongs to the field of marine energy utilization. The device comprises a thermal shrinkage and cold expansion body, a rope and a generator. The thermal shrinkage and cold expansion body is connected with the rope, and the rope is connected with the generator. The thermal shrinkage and cold expansion body is in a shrinkage state in the upper sea water close to the sea surface which is relatively hot, and the difference between the gravity and the buoyancy is relatively large. The thermal shrinkage and cold expansion body is in an expansion state in the deep sea water which is relatively cold, and the difference between the gravity and the buoyancy is relatively small. The rope is unbalanced in stress and moves, thereby driving the rope to pull the generator to generate electricity. In another structure, the device further comprises a fixed pulley. The fixed pulley is arranged on the sea level or the sea bottom. The rope is wound around the fixed pulley. The fixed pulley is connected with the generator. The rope drives the fixed pulley to rotate, thereby realizing power generation. The whole inventive concept of the application is novel, the structure design is ingenious, the engineering transformation value is huge, and the utilization efficiency of energy is high.

Description

Technical Field

[0001] This invention belongs to the field of marine energy utilization, and more specifically, relates to a marine thermal energy conversion device and its operating method. Background Technology

[0002] As is well known, the temperature of ocean water varies with depth, especially in low latitudes where the surface temperature is higher and decreases with depth. At a depth of 200 meters, the water temperature is often more than 10°C lower than the surface temperature. As early as 1880, the Frenchman Dassonfa proposed that the temperature difference of ocean water could be used to generate electricity, and many scientists have since conducted extensive research and experimentation in this field.

[0003] Currently, the main approach to generating electricity using seawater temperature differences remains the traditional method of using the evaporation of a liquid working fluid to drive a turbine. Specifically, there are basically two types of power generation devices:

[0004] 1. Closed-loop system: A closed-loop circulating system uses a low-boiling-point working fluid as the working medium. Its main components include an evaporator, condenser, turbine, working fluid pump, and warm and cold seawater pumps. Because the working fluid system circulates within a closed system, it is called a closed-loop circulating system. The warm seawater pump draws up warm seawater and transfers its heat source to the working fluid in the evaporator, causing it to evaporate. The evaporated working fluid expands adiabatically in the turbine, driving the turbine blades to generate electricity. The working fluid after power generation is introduced into the condenser, where it transfers its heat to the cold seawater drawn from deep water. It is cooled by the cold seawater and returns to liquid form, then is pumped back to the evaporator by the circulating pump, forming another cycle. The working fluid can be repeatedly recycled and can be high-density, high-vapor-pressure gaseous refrigerants such as ammonia, butane, and chlorofluorocarbons. Ammonia and chlorofluorocarbons are the most likely working fluids. The energy conversion efficiency of a closed-loop circulating system is 3.3%–3.5%. If the energy consumption of the pumps is deducted, the net efficiency is 2.1%–2.3%. (Yang Pengcheng, Zhang Xuelai, Wang Wenguo, et al. Ocean thermal energy conversion technology [J]. Shanghai Electric Power, 2009(01):38-41.)

[0005] 2. Open-loop system: The open-loop system does not use a working fluid as a working medium, but directly uses warm seawater. First, the warm seawater is introduced into a vacuum evaporator to partially evaporate it, and its vapor pressure is about 3 kPa (25℃), which is equivalent to 0.03 atmospheres. The water vapor undergoes adiabatic expansion in the low-pressure turbine, and after completing its work, it is introduced into the condenser and cooled into liquid by the cold seawater. There are two methods of condensation: one is that the water vapor is directly mixed into the cold seawater, which is called direct contact condensation; the other is to use a surface condenser, in which the water vapor does not directly contact the cold seawater. The latter is the method of producing fresh water incidentally. Although the energy conversion efficiency of the open-loop system is higher than that of the closed-loop system, the power generation capacity is small due to the uncertainty of the efficiency of the low-pressure turbine and the low density and pressure of the water vapor, making it unsuitable for large-capacity power generation. (Wang Li, Shi Linxing, Lu Dianqing. Optimization design of marine thermal power generation system in East China coastal area [J]. Renewable Energy, 2010(01):134-136.)

[0006] Overall, traditional seawater temperature difference power generation devices that rely on the evaporation of working fluid generally suffer from drawbacks such as requiring a large temperature difference (at least 20°C), low power generation efficiency, and insufficient durability of materials in seawater, which are far from large-scale commercial operation.

[0007] Therefore, there is a need to develop a new device or method for generating electricity using ocean temperature differences that has higher power generation efficiency. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to design a novel device and operating method for generating electricity using ocean thermal differences. Based on a novel concept, it utilizes the thermal expansion and contraction effect of a specific material to change its volume, thereby causing a change in buoyancy. This change in buoyancy is then converted into mechanical energy to generate electricity. The concept is ingenious and has a very high energy utilization efficiency.

[0009] To achieve the above objectives, the present invention provides an ocean thermal energy conversion device, comprising thermally contractible and scalable bodies, a rope, and a generator. Thermally contractible and scalable bodies are located at both ends of the rope, which is connected to the generator. In the warmer upper seawater near the surface, the thermally contractible and scalable bodies are in a contracted state, resulting in a larger difference between their weight and buoyancy. In the colder, deeper seawater, they are in an expanded state, resulting in a smaller difference between their weight and buoyancy. During operation, the volume of the thermally contractible and scalable bodies at both ends of the rope varies with the seawater depth, causing changes in the difference between the weight and buoyancy at both ends of the rope. This movement of the rope drives the generator, thereby generating electricity.

[0010] According to another aspect of the present invention, an ocean thermal energy conversion device is also provided, comprising a fixed pulley, a thermally contractible and expandable body, a rope, and a generator. Identical thermally contractible and expandable bodies are respectively provided at both ends of the rope. The rope passes over and moves along the fixed pulley. The fixed pulley is connected to the generator. The thermally contractible and expandable bodies are in a contracted state in the warmer upper seawater near the surface, where the difference between their weight and buoyancy is large; and in the colder, deeper seawater, they are in an expanded state, where the difference between their weight and buoyancy is small. During operation, the thermally contractible and expandable bodies on both sides of the rope have different differences in weight and buoyancy due to their different temperatures, thereby driving the rope to move, which in turn drives the fixed pulley to rotate, thus generating electricity.

[0011] Furthermore, the density of the thermally shrinking and expanding body is greater than that of seawater. The fixed pulley and generator are positioned above and near the sea level. During the initial power generation process, the thermally shrinking and expanding bodies on both sides of the rope are located at the ocean surface and the ocean depth, respectively. The thermally shrinking and expanding body on one side of the rope is located at the higher temperature of the ocean surface. After sufficient heat exchange, it reaches a relatively high temperature state, shrinks in volume, and reduces its buoyancy. The thermally shrinking and expanding body on the other side of the rope is located at the ocean depth. After sufficient heat exchange, it reaches a relatively low temperature state, expands in volume, and increases its buoyancy. This imbalance of forces on both sides of the rope causes the rope to move, thus generating electricity. This process repeats, allowing the rope to rise and sink repeatedly, achieving continuous power generation.

[0012] Furthermore, the generator is placed on the seabed, with a fixed pulley connected to the generator's rotor. Identical thermally expandable and contractible bodies are installed at both ends of the rope. These bodies have a density less than that of seawater. During the initial power generation process, the thermally expandable and contractible bodies at both ends of the rope are located at the ocean surface and deep ocean layers, respectively. The thermally expandable and contractible body at one end of the rope, located at the higher temperature of the ocean surface, reaches a relatively high temperature state after sufficient heat exchange, causing its volume to shrink and its buoyancy to decrease. The thermally expandable and contractible body at the other end of the rope, located at the deeper ocean layer, reaches a relatively low temperature state after sufficient heat exchange, causing its volume to expand and its buoyancy to increase. This imbalance of forces on both sides of the rope causes it to move, driving the fixed pulley to rotate and generate electricity. This process repeats, allowing the rope to rise and sink repeatedly, achieving continuous power generation.

[0013] Furthermore, the thermally expandable and contractible bodies on both sides of the rope form a piston assembly structure. This piston assembly includes a sealed piston, a water-permeable piston, crossbeams, and hollow steel balls. Both the sealed and water-permeable pistons are arranged parallel to and perpendicular to the two crossbeams, with their piston rods fixed to the same crossbeam. The bottoms of both pistons are also fixed to another crossbeam. The piston chamber of the sealed piston is either a vacuum or filled with gas, while the piston chamber of the water-permeable piston contains a temperature-sensitive polymer. This polymer exhibits the property of absorbing water and swelling at relatively low temperatures and dehydrating and shrinking at relatively high temperatures. The hollow steel balls are located at the top of one of the crossbeams. By controlling the volume of the hollow steel balls, the density of the entire piston assembly structure is designed to be less than the density of seawater. The advantage of this design is that the generator is fixed to the seabed, and the generated electricity can be directly output via a submarine cable, eliminating the need for an additional platform above sea level.

[0014] Furthermore, the thermally shrinking and expanding bodies on both sides of the rope are piston assembly structures. The piston assembly structure includes a sealed piston, a water-permeable piston, a crossbeam, and a spring. The sealed piston, the water-permeable piston, and the spring are all arranged parallel to each other between the two crossbeams and perpendicular to the crossbeams. The piston rods of the sealed piston and the water-permeable piston are both fixed on the same crossbeam. The bottoms of the sealed piston and the water-permeable piston are also fixed on another crossbeam. The piston chamber of the sealed piston is a vacuum or a gas chamber. The piston chamber of the water-permeable piston contains a temperature-sensitive polymer. This temperature-sensitive polymer has the characteristic of absorbing water and swelling at relatively low temperatures and dehydrating and shrinking at relatively high temperatures.

[0015] Furthermore, the thermally shrinking and expanding bodies on both sides of the rope are made of gallium-indium alloy. The mass fraction of indium in the gallium-indium alloy is 5% to 19%, the melting point is between 5°C and 25°C, and during the melting process of the gallium-indium alloy, there is a volume shrinkage of about 3%, and the solidification process is reversible.

[0016] Furthermore, the temperature-sensitive polymer is a crosslinked copolymer of N-isopropylacrylamide and N-tert-butylacrylamide, and is in the form of gel particles.

[0017] Furthermore, there are two permeable pistons and two springs. The two permeable pistons are respectively arranged on both sides of a sealed piston, and the two springs are also respectively arranged on both sides of the sealed piston, and located between the sealed piston and the permeable piston.

[0018] Furthermore, the bottom of the permeable piston has small holes to allow seawater to pass through. A porous ceramic permeable layer is also provided at the bottom of the permeable piston. The porous ceramic permeable layer covers the small holes and is used to isolate the temperature-sensitive polymer in the piston cavity of the permeable piston from the marine environment. The pore diameter of the porous ceramic permeable layer is smaller than the diameter of the temperature-sensitive polymer particles.

[0019] Furthermore, the piston chamber diameter of the sealed piston is larger than that of the permeable piston.

[0020] Furthermore, the rope is made of polyethylene fishing line.

[0021] According to a third aspect of the present invention, a method for operating the ocean thermal energy conversion device as described above is also provided.

[0022] S1: Place the thermally shrinkable and expandable element on one side of the rope at the ocean surface and the thermally shrinkable and expandable element on the other side at the ocean depth. Fix the pulley and wait for the set time.

[0023] S2: Measure the tension in the ropes on both sides of the fixed pulley. After the tension on both sides stabilizes, release the fixed pulley to allow it to rotate freely under the action of the ropes, thus performing the first cycle of power generation.

[0024] S3: After the rope completes one full movement, the first cycle of power generation is completed. The thermal expansion and contraction bodies on both sides of the rope are swapped at their seawater positions. The fixed pulley is then fixed and left to stand for a set time until the tension on the rope on both sides of the fixed pulley remains constant.

[0025] S4: Release the fixation on the fixed pulley, the rope moves, and the second cycle of power generation begins.

[0026] Repeat steps S2 and S3 to achieve continuous power generation.

[0027] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0028] This invention features a novel concept, utilizing the unique effect of thermal expansion and contraction. An object contracts in surface seawater, reducing buoyancy and causing it to sink; conversely, it expands in deeper water, increasing buoyancy and causing it to rise. This cycle repeats, generating work. A fixed pulley and rope are designed, with thermally expandable and contractible materials on both sides of the rope. The work done by the rising and falling due to the volume change of these materials is transferred to a generator via the pulley, resulting in electricity generation. The structure is simple and the power generation efficiency is high. A cross-linked copolymer of gallium-indium alloy and N-isopropylacrylamide and N-tert-butylacrylamide is cleverly chosen as the thermally expandable and contractible material, making it well-suited for use in ocean environments with varying temperatures at different depths. In conclusion, this invention boasts a novel concept, ingenious structural design, and significant engineering transfer value. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the thermal expansion and contraction process when the thermally shrinking and expanding body in the marine thermal power generation device of Embodiment 1 of the present invention is made of gallium-indium alloy;

[0030] Figure 2 This is a schematic diagram showing the specific composition of the piston assembly structure in the marine thermal thermal power generation device of Embodiment 2 of the present invention, where the thermally shrinking and cold-expanding body adopts a piston assembly structure and the generator is located near the sea surface.

[0031] Figure 3 This is a schematic diagram of the structure of the ocean thermal power generation device in Embodiment 3 of the present invention when the generator is installed on the seabed;

[0032] Figure 4 This is a schematic diagram showing the specific composition of the piston assembly structure used in the marine thermal thermal power generation device in Embodiment 3 of the present invention.

[0033] In the above figures, the same reference numerals denote the same structures or elements throughout, wherein,

[0034] 1-Thermal shrinking and expanding body; 2-Rope; 3-Fixed pulley

[0035] 4-Water-permeable piston; 5-Sealed piston; 6-Crossbeam

[0036] 7-Thermosensitive polymer; 8-Porous ceramic permeable layer; 9-Permeable pores

[0037] 10-Spring 11-Hollow steel ball Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] This invention presents a novel concept for ocean thermal energy generation, distinct from traditional methods. It utilizes the "thermal contraction and expansion" effect of one or more special substances or structures, causing these substances to repeatedly rise and fall in seawater, thereby driving a generator to produce electricity. An object exhibits thermal contraction and expansion characteristics in the temperature range corresponding to the surface and deep layers of seawater. In the surface seawater, it contracts, its buoyancy decreases, and it sinks; in the deep seawater, it expands, its buoyancy increases, and it rises. This cycle repeats, thus generating electricity.

[0040] The device for generating electricity using ocean thermal differences of the present invention includes a thermally shrinking and expanding body. In the warmer ocean surface layer, the thermally shrinking and expanding body undergoes heat exchange, reaching a high-temperature state, with a small volume and low buoyancy, and performs work W1 during its descent. After sinking to the cooler ocean depth layer, the body undergoes heat exchange, reaching a low-temperature state, expanding in volume, and increasing buoyancy, consuming work W2 to propel it back to the ocean surface. Therefore, W1 > W2. This up-and-down reciprocating motion generates net energy output, driving a generator to produce electricity.

[0041] The device of this invention, for example, comprises at least two thermally expandable and contractile bodies whose average density is always greater than that of seawater (even in the deep ocean, when they expand due to cold, their average density is still greater than that of seawater; and at the ocean surface, when they shrink due to heat, their average density is also greater than that of seawater). The two thermally expandable and contractile bodies are connected by a rope, which is connected to a fixed pulley on the sea surface so that the pulley can rotate during the rope's ascent or descent; as one thermally expandable and contractile body rises, the other descends simultaneously. The fixed pulley is connected to a generator, converting the mechanical energy of the pulley's rotation into electrical energy, thereby driving the generator to produce electricity. In fact, as long as the weight minus buoyancy of the thermally expandable and contractile body at high temperature is greater than the weight minus buoyancy of the thermally expandable and contractile body at low temperature, the fixed pulley can be driven to move. It is not necessary for the average density of the thermally expandable and contractile body at low temperature to be less than that of seawater for it to float and drive the fixed pulley. In this invention, the density of both thermally expandable and contractile bodies is greater than that of seawater, whether at the ocean surface or in the deep ocean.

[0042] The key to this invention lies in selecting materials with significant thermal expansion and contraction characteristics between 5°C and 25°C. Gallium-indium alloys with an indium content between 5% and 19% in pure materials meet the requirements, possessing a melting point between 5°C and 25°C, and exhibiting approximately 3% volume shrinkage during melting and reversible solidification. Specifically, a gallium-indium alloy with an indium content of 10% can be selected, having a melting point of 20°C, exhibiting 3% volume shrinkage during melting and 3% volume expansion during solidification.

[0043] However, gallium-indium alloys are very expensive and unlikely to be used on a large scale. Many polymer materials swell or dehydrate between 5°C and 25°C due to changes in their hydrophilic or hydrophobic properties. For example, crosslinked copolymers of N-isopropylacrylamide and N-tert-butylacrylamide exhibit hydrophobic properties at higher temperatures, resulting in smaller overall polymer particle volume, while at lower temperatures, the polymer chains exhibit hydrophilic properties, causing the polymer particles to swell and significantly increase in volume. This polymer swelling process differs from the thermal contraction and expansion near the melting point of gallium-indium alloys. It involves the exchange of substances with the external environment and does not cause a significant change in the difference between buoyancy and gravity within the polymer gel itself. However, the swelling force can be used to pull additional structures to expand in volume, causing a significant increase in the difference between buoyancy and gravity. This design can also realize the concept of this invention.

[0044] Specifically, the thermally shrinking and expanding body includes a sealed piston, a water-permeable piston, a crossbeam, a spring, and a temperature-sensitive polymer. The sealed piston is connected to the water-permeable piston at both ends via a crossbeam, forming a linked structure. A spring is installed between the crossbeams at both ends of the piston to facilitate the contraction of the sealed and water-permeable pistons on the ocean surface. The movement of the water-permeable piston drives the sealed piston to move synchronously. The water-permeable piston is filled with a temperature-sensitive polymer, which allows seawater to pass through without leaking. The temperature-sensitive polymer is in a gel-like particle state, absorbing water and swelling at low temperatures, and dehydrating and shrinking at high temperatures. The sealed piston has excellent sealing properties, and its interior is a vacuum or gas. In the deep ocean, the temperature-sensitive polymer absorbs water and swells, causing the permeable piston to expand. This, in turn, pulls the piston cap of the sealed piston, increasing its volume and thus increasing the buoyancy of the thermally shrinking and expanding body. In the ocean surface, the temperature-sensitive polymer dehydrates and shrinks, causing the spring to rebound and shrink the permeable piston. This, in turn, pulls the piston cap of the sealed piston, reducing the volume of the internal vacuum or gas cavity of the sealed piston. This reduces the volume of the thermally shrinking and expanding body and decreases its buoyancy.

[0045] In fact, the generator can also be placed on the seabed. When placed on the seabed, the piston assembly structure needs to be improved simultaneously. The density of the entire piston assembly structure needs to be less than the density of seawater. A hollow steel ball of appropriate size can be placed in the original piston assembly structure to reduce the density of the entire piston assembly structure, so that its overall density is less than the density of seawater.

[0046] To illustrate the device of the present invention in more detail, the following description is provided in conjunction with specific embodiments.

[0047] Example 1: Seawater Temperature Difference Power Generation Device Utilizing the Thermal Expansion and Contraction of Gallium-Indium Alloy

[0048] like Figure 1The apparatus shown consists of two 1 kg gallium-indium alloy blocks (A and B) encased in sealed plastic films, each containing 10% indium and with a melting point of 20°C. The rope (2) is a 0.2 mm diameter PE fishing line with a total length of 202 meters, 2 meters of which are exposed above the sea surface. The sea surface temperature is 29°C, while the temperature at a depth of 200 meters is 15°C. Thermo-indium A is submerged at a depth of 200 meters, while molar B is suspended above the ocean surface. A fixed pulley (3) is connected to a small DC generator. Initially, the pulley is locked. After 30 minutes of rest, a spring scale shows that the tension in the fishing line on the side of molar B is 0.05 N greater than that on the side of molar A. The pulley is then released, causing molar B to sink and molar A to rise, rotating the pulley and generating electricity to power a 1 milliwatt LED bulb. After 68 seconds, the thermally shrinkable and cold-expanded body A floats to the surface. Its temperature is still very low, with only a small amount of gallium-indium alloy melting on the surface. The fixed pulley is locked. After 30 minutes, the gallium-indium alloy in the thermally shrinkable and cold-expanded body A has completely melted. The tension of the fishing line on the side of the thermally shrinkable and cold-expanded body A is 0.05 N greater than that on the side of the thermally shrinkable and cold-expanded body B. After that, the fixed pulley is released, and power generation can be resumed.

[0049] Example 2: Seawater Temperature Difference Power Generation Device Utilizing the Thermosensitive Swelling Properties of Crosslinked Poly(N-isopropylacrylamide)

[0050] The overall structure of the device remains the same. Figure 1 As shown, we still define two thermally shrinkable and cold-expandable bodies as A and B. However, these two thermally shrinkable and cold-expandable bodies become as follows: Figure 2 The structure is shown. Each thermally shrinkable and expandable body comprises two permeable pistons 4 with an inner diameter of 10 cm, a sealed piston 5 with an inner diameter of 12 cm, two springs, and two crossbeams 6 made of No. 5 channel steel. Both ends of all pistons are welded and fixed between the two crossbeams. The two ends of the springs 10 are also connected to the two crossbeams to create additional tension between them. The bottom of the permeable piston has 12 permeable holes 9 with a diameter of 1 mm, covered with an 8 mm thick porous ceramic permeable layer 8, with an average pore size of 1 μm. The interior of the permeable piston is filled with cross-linked copolymer particles of N-isopropylacrylamide and N-tert-butylacrylamide, which serve as a temperature-sensitive polymer 7. The specific preparation method is as follows:

[0051] N-tert-butylacrylamide monomer and N-isopropylacrylamide monomer were mixed at a molar ratio of 1:9 and dissolved in a certain volume of water to prepare a solution with a total monomer concentration of 3 mol / L. Then, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone and N,N-methylenebisacrylamide, a crosslinking agent, were added to the monomer solution. The molar ratio of monomer to initiator was 1:0.001; the molar ratio of monomer to crosslinking agent was 1:0.01. The prepared solution was subjected to UV-initiated polymerization for 2 hours in a sealed, oxygen-free, transparent container to obtain a thermally shrinking and cold-expanding crosslinked copolymer bulk hydrogel. Finally, the prepared bulk gel was crushed into hydrogel particles with an average particle size of approximately 200 μm using a crusher.

[0052] The above copolymer particles undergo a sudden change in hydrophilicity and hydrophobicity at 25℃; above 25℃, they dehydrate and shrink, while below 25℃, they absorb water and swell. Each permeable piston is filled with 1 kg of cross-linked copolymer particles of N-isopropylacrylamide and N-tert-butylacrylamide. The rope is made of 0.3 mm diameter, 8-strand PE fishing line with a total length of 202 meters.

[0053] The test was conducted in the ocean near the Xisha Islands at 113°E, 17°N, with a surface temperature of 29°C and a depth of 200 meters of water of 15°C. Thermally shrinkable and expandable object A sank to a depth of 200 meters, while thermally shrinkable and expandable object B remained suspended at the ocean surface. A small DC generator was connected to a fixed pulley. Initially, the pulley was locked, and after 30 minutes of rest, a spring scale showed that the tension of the fishing line on the side of thermally shrinkable and expandable object B was 40 N greater than that on the side of thermally shrinkable and expandable object A. The pulley was then released, causing thermally shrinkable and expandable object B to sink and thermally shrinkable and expandable object A to rise, driving the pulley to rotate and generating electricity with an output of approximately 90 W. After 72 seconds, thermally shrinkable and expandable object A floated to the surface, still at a very low temperature and with a relatively large volume. With the fixed pulley locked, after 30 minutes of heat exchange, the cross-linked copolymer particles of N-isopropylacrylamide and N-tert-butylacrylamide in thermal shrinkable and expandable body A dehydrate and shrink. Under the action of the spring, both the permeable piston and the sealed piston shrink. At this time, the tension of the fishing line on the side of thermal shrinkable and expandable body A is 40 N greater than the tension of the fishing line on the side of thermal shrinkable and expandable body B. After that, the fixed pulley is released, and power generation can be resumed.

[0054] Example 3: Seawater thermal energy conversion device with generator placed on the seabed

[0055] Figure 3 This is a schematic diagram of the structure of the ocean thermal power generation device in Embodiment 3 of the present invention when the generator is installed on the seabed. Figure 4 This is a schematic diagram illustrating the specific composition of the piston assembly structure used in the marine thermal expansion and contraction device of Embodiment 3 of the present invention. Figure 3 and Figure 4As shown, the generator is placed on the seabed at a depth of 300 meters in the South China Sea, and its rotor is connected to a fixed pulley. A rope passes around the fixed pulley and connects to two identical thermally shrinkable and expandable bodies, still defined as thermally shrinkable and expandable body A and thermally shrinkable and expandable body B. In this embodiment, the thermally shrinkable and expandable body is based on embodiment 2, except that the spring is removed, and an incompressible hollow steel ball 11 is welded to the top crossbeam 6 to provide additional buoyancy, ensuring that the buoyancy of the thermally shrinkable and expandable body is always greater than its weight. See details below. Figure 4 As shown.

[0056] The temperature at a depth of 10 meters below the sea surface is 28°C, and the seabed temperature is 13°C. Thermally shrinkable and expandable body A is suspended 10 meters below the sea surface, while thermally shrinkable and expandable body B is suspended 1 meter above the seabed. Initially, the fixed pulley is locked. After 30 minutes of stillness, the tension of the fishing line on the side of thermally shrinkable and expandable body B is 40 N greater than that on the side of thermally shrinkable and expandable body A. The fixed pulley is then released, causing thermally shrinkable and expandable body B to rise and thermally shrinkable and expandable body A to sink, driving the fixed pulley to rotate and generating electricity, with an output power of approximately 90 W. After 82 seconds, thermally shrinkable and expandable body B rises to a depth of 10 meters below the sea surface, where its temperature is still very low and its volume is still relatively large. The fixed pulley is locked again. After 30 minutes of heat exchange, the cross-linked copolymer particles of N-isopropylacrylamide and N-tert-butylacrylamide in thermally shrinkable and expandable body B dehydrate and shrink. Under water pressure, both the permeable piston and the sealed piston contract. At this point, the tension of the fishing line on side A of the thermally shrinking and expanding body is 40 N greater than the tension of the fishing line on side B of the thermally shrinking and expanding body. After that, the fixed pulley is released, and the power can be generated again.

[0057] In fact, in the piston assembly structure of this invention, when the piston chamber of the sealed piston is evacuated, a spring is not required. When the piston assembly structure moves to the sea level, after a sufficiently long period of time, the volume of the temperature-sensitive polymer body shrinks, and the volume of the sealed piston naturally decreases under the action of external atmospheric pressure, thus reducing the overall buoyancy.

[0058] The gallium-indium alloy and temperature-sensitive polymer of the present invention require a sufficiently long time for heat exchange. The time required for the thermally shrinkable and expandable body to float or sink in seawater is much shorter than the time required to complete the heat exchange. Therefore, the change in volume of the thermally shrinkable and expandable body during the floating or sinking process can be ignored.

[0059] The average density mentioned in this invention is obtained by dividing the total mass by the total volume.

[0060] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A marine thermal energy conversion device, characterized in that, It includes a fixed pulley, a thermally expandable / contractor, ropes, and a generator. The rope has identical thermally expandable and contractible bodies connected to both ends. The rope passes over a fixed pulley and drives its rotation. The pulley is connected to a generator. In the warmer, upper layers of seawater near the surface, the thermally expandable and contractible bodies are in a contracted state, resulting in a larger difference between their weight and buoyancy. In the colder, deeper layers of seawater, they are in an expanded state, resulting in a smaller difference between their weight and buoyancy. The thermally expandable and contractible elements on both sides of the rope form a piston assembly structure. The piston assembly structure includes a sealed piston, a water-permeable piston, a crossbeam, and a spring. The sealed piston, water-permeable piston, and spring are all arranged parallel to each other between two crossbeams and perpendicular to them. The piston rods of both the sealed piston and the water-permeable piston are fixed to the same crossbeam, and the bottoms of both are fixed to another crossbeam. The piston chamber of the sealed piston is a vacuum or gas chamber. The piston chamber of the water-permeable piston contains a temperature-sensitive polymer. This temperature-sensitive polymer has the property of absorbing water and swelling at relatively low temperatures and dehydrating and shrinking at relatively high temperatures. The piston assembly structure includes a sealed piston, a permeable piston, a crossbeam, and a hollow steel ball. Both the sealed and permeable pistons are arranged parallel to each other between two crossbeams and perpendicular to them. The piston rods of both pistons are fixed to the same crossbeam, and the bottoms of both pistons are fixed to another crossbeam. The piston chamber of the sealed piston is either a vacuum or filled with gas. The piston chamber of the permeable piston contains a temperature-sensitive polymer that absorbs water and swells at relatively low temperatures and dehydrates and shrinks at relatively high temperatures. The hollow steel ball is located at the top of the upper crossbeam. By controlling the volume of the hollow steel ball, the average density of the entire piston assembly structure is designed to be less than the density of seawater. During operation, the thermal expansion and contraction of the two ends of the rope result in different values ​​of gravity minus buoyancy due to their different temperatures, which in turn drive the rope to move and in turn drive the fixed pulley to rotate, thereby generating electricity.

2. The ocean thermal energy conversion device as described in claim 1, characterized in that, The average density of thermally expandable and contractible bodies is always greater than that of seawater. The fixed pulley and generator are located above and close to the sea level. During the initial power generation process, the thermally expanding and contracting bodies at both ends of the rope are located at the ocean surface and the deep ocean, respectively. The thermally expanding and contracting body on one side of the rope is located at the ocean surface where the temperature is higher. After sufficient heat exchange, it reaches a relatively high temperature state, shrinks in volume, and reduces its buoyancy. The thermally expanding and contracting body on the other side of the rope is located at the ocean depth. After sufficient heat exchange, it reaches a relatively low temperature state, expands in volume, and increases its buoyancy. This imbalance of forces on both sides of the rope causes the rope to move, thus generating electricity. This process repeats, allowing the rope to rise and sink repeatedly, enabling continuous power generation.

3. The ocean thermal energy conversion device as described in claim 1, characterized in that, The generator is placed on the seabed, with a fixed pulley connected to the generator's rotor. Identical thermally expandable and contractible materials are installed at both ends of the rope; the average density of these materials is always less than the density of seawater. During the initial power generation process, the thermally expandable and contractible bodies at both ends of the rope are located at the ocean surface and the deep ocean, respectively. The thermally expandable and contractible body at one end of the rope is located at the ocean surface where the temperature is higher. After sufficient heat exchange, it reaches a relatively high temperature state, shrinks in volume, and reduces its buoyancy. The thermally expandable and contractible body at the other end of the rope is located at the ocean depth where the thermally expandable and contractible body is located at a relatively low temperature state after sufficient heat exchange, and expands in volume, increasing its buoyancy. By utilizing the imbalance of forces on both sides of the rope, the rope moves, which drives the fixed pulley to rotate and generate electricity. This process is repeated, allowing the rope to rise and sink repeatedly, thus achieving continuous power generation.

4. The ocean thermal energy conversion device as described in claim 1, characterized in that, The thermosensitive polymer is a crosslinked copolymer of N-isopropylacrylamide and N-tert-butylacrylamide, and is in the form of gel particles.

5. The ocean thermal energy conversion device as described in claim 1, characterized in that, The device has two permeable pistons and two springs. The two permeable pistons are respectively positioned on both sides of a sealed piston, and the two springs are also respectively positioned on both sides of the sealed piston, between the sealed piston and the permeable piston. A small hole is provided at the bottom of the permeable piston to allow seawater to pass through. A porous ceramic permeable layer is also provided at the bottom of the permeable piston. The porous ceramic permeable layer covers the small holes and is used to isolate the temperature-sensitive polymer in the piston cavity of the permeable piston from the marine environment. The pore diameter of the porous ceramic permeable layer is smaller than the diameter of the temperature-sensitive polymer particles.

6. The method of operating the ocean thermal energy conversion device as described in any one of claims 1-5, characterized in that, S1: Place the heat-shrinkable and cold-expandable element at one end of the rope on the ocean surface and the heat-shrinkable and cold-expandable element at the other end of the rope in the deep ocean. Fix the pulley and wait for the set time. S2: Measure the tension in the ropes on both sides of the fixed pulley. After the tension on both sides stabilizes, release the fixed pulley to allow it to rotate freely under the action of the ropes, thus performing the first cycle of power generation. S3: After the rope completes one full movement, the first cycle of power generation is completed. The thermal expansion and contraction bodies on both sides of the rope are swapped at their seawater positions. The fixed pulley is then fixed and left to stand for a set time until the tension on the rope on both sides of the fixed pulley remains constant. S4: Release the fixation on the fixed pulley, the rope moves, and the second cycle of power generation begins. Repeat steps S2 and S3 to achieve continuous power generation.

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