System for conversion of heat energy

Abstract

The invention relates to engines with an external heat supply and provides for more efficient heating of a gaseous working fluid. A system for the conversion of heat energy comprises a closed loop containing a gas as a working fluid and a liquid as a piston. Said loop comprises, in series, a positive displacement compressor, a liquid cooler, at least one heater with an external heat supply, and an expander. The heater is configured in the form of annular tubular loops which surround with clearance a housing of the gas heater with an external heat supply. Said annular tubular loops are mounted with clearance relative to one another, and each annular tubular loop has an inlet channel and an outlet pipe. The axis of the inlet channel lies along a tangent to the longitudinal axis of an annular channel that passes through the inside of the annular tubular loop.

Description

[0001] Thermal energy conversion system

[0002] The invention pertains to thermal power engineering, specifically to heat engines, and in particular to installations and devices that convert thermal energy from an external source into another form of energy, thereby performing useful work. It can be used in engines with an external heat supply. It can also be applied in power plants, shipbuilding, and gas energy companies.

[0003] A method for converting thermal energy is known according to Russian patent for invention RU2773086, F01K27 / 00, 2022. The method for converting thermal energy involves using a working fluid consisting of a mixture of components in a closed cycle, compressing the working fluid, heating the working fluid, expanding the working fluid to perform work, and cooling the working fluid. The first component is an inert gas, and the second is a low-boiling liquid. The number of components is selected by calculation such that the ratio of the quantity of the first component to the quantity of the second component by mass is within the range from 1:0.055 to 1:6.25. Compression of the components is carried out, during which evaporation and condensation of the second component occur along the saturation line. Heating of the resulting gas mixture to 100-150°C is carried out. Expansion of the working fluid is carried out, after which the working fluid is cooled with the release of the second component into the liquid phase.The method utilizes a compressor, heater, expander, and condenser connected in series. A disadvantage is the complexity of the method, due to the use of a two-component working fluid, the need to select the component ratio, the four stages of the cycle, the need for liquid injection, and the need for a condenser to condense one of the components.

[0004] A hot-air thermal power plant and its operating method are known from Russian patent RU2705687, F02B 37 / 20, 2019. The hot-air thermal power plant comprises a turbocharger, a check valve, a receiver, a valve, a motor, a heat exchanger, and a heater. The thermal power plant's components are connected in series: the turbocharger compressor, a check valve, a receiver, a valve, a motor, a chamber for the heated medium, a turbocharger turbine, a heater, and / or a chamber for the heating medium of the heat exchanger. The heater can be any known heating solution, such as various types of burners, an electric heater, etc., but a liquid fuel burner is preferred. The disadvantages of the plant are its low power and low operating efficiency.

[0005] An engine with an external heat supply is known under Russian patent for invention RU2246021, F01K 25 / 00, 2005. An engine with an external heat source comprises a coolant tank containing a heat exchanger with a working fluid chamber. The tank is connected to a radiator and a coolant heater to form closed hot and cold coolant circuits. The actuator is designed as a cylinder with a constant-pressure cavity and a working-pressure cavity connected to the working fluid chamber. The heat exchanger is designed as tubes, the openings of which are connected to the coolant tank. The hot coolant circuit includes a heater, a hot coolant supply control unit, and pipelines. The cold coolant circuit includes a radiator, a cold coolant supply control unit, and pipelines. Water is used as the coolant, and oil is used as the working fluid.The disadvantages are the large weight of the engine with its relatively low power, low heating efficiency, and large dimensions.

[0006] The closest analogue to the claimed invention is the thermal energy conversion system according to Russian patent RU 2806951, F01K 27 / 00, 2023. The system comprises a closed loop with two components: one is a gas, and the other is a liquid. The loop consists of a positive-displacement compressor, a heater (designed as an externally heated tank), and an expander. The working fluid in the closed loop is the gas, and the liquid acts as pistons in the compressor and expander. The compressor is designed as two tanks partially filled with liquid, the compressor tanks being connected by upper and lower communication lines. Both communication lines between the compressor tanks are connected to the compressor's cooling device.A hydraulic pump is installed in the lower communication line between the compressor tanks, connected via hydraulic distributors to the inlet of the compressor's cooling device. The outlet of this cooling device is connected via a hydraulic distributor to the upper communication line between the compressor tanks, the ends of which are connected to liquid diffusers located inside the compressor tanks at their upper ends. The closed circuit between the compressor and the expander is designed with a branch into two lines, each of which has its own heater with an external heat supply connected to the expander. The heaters are designed to alternately supply heated gas to the expander. The expander is designed as two tanks partially filled with liquid, with a hydraulic motor installed in the communication line between the expander tanks. A disadvantage is low heating efficiency and a low specific weight per unit of power, which is the ratio of the unit's weight to its power.

[0007] The technical objective of the claimed invention is to expand the range of means related to energy conversion systems.

[0008] The technical result is to ensure the specified purpose by creating an energy conversion system with an external heat supply, with high efficiency of heating the gaseous working fluid.

[0009] The technical result is achieved due to the fact that in a thermal energy conversion system containing a closed circuit with two components inside, where one component is a gas and the second component is a liquid, a volumetric compression compressor, at least one heater with an external heat supply and an expander are connected in series into the circuit, the working fluid in the closed circuit is gas, and the liquid is used as pistons in the compressor and expander, according to the invention, the heater is made in the form of annular tubular circuits that enclose with a gap the body of the gas heater, made with an external supply of fuel gas, the annular tubular circuits are installed with gaps relative to each other, each annular tubular circuit is a section of the closed circuit and has an inlet channel and an outlet branch pipe, wherein the axis of the inlet channel is located tangent to the longitudinal axis of the annular channel passing inside the annular tubular circuit.

[0010] The technical result is achieved by a heater design with an external heat supply. The heater includes a section of annular tubular circuits, which are sections of a closed-loop thermal energy conversion system. The use of annular circuits in the heater allows for the creation of high-velocity gas flows within them, circling an external heat source. The external heat source is a gas heater, whose design ensures uniform heating of all annular tubular circuits located externally around it. By achieving high gas velocity during heating, the intensity of heat exchange between the surface of the gas heater and the gas flow passing through the internal channel of the annular tubular circuit is increased, thereby increasing the Nusselt number. This increased heat exchange intensity significantly increases the gas heating rate and reduces the time required for heating.Each annular tubular heater circuit, designed with its own inlet and outlet, maintains a constant high velocity of the heated gas within the circuit. The inlet allows for the introduction of a new portion of gas, pre-compressed in the compressor and with a high initial velocity at the inlet, to replace the previous portion of gas, whose velocity has decreased due to losses during flow through the annular internal channel. The outlet also maintains a high flow velocity by allowing the gas portion that has passed through the annular channel to be released, allowing a new portion to be heated. Furthermore, the inlet channel, connected to the compressor outlet, allows gas to be supplied to the annular tubular circuit under pressure, ensuring its high velocity during heating.The inlet channel axis positioned tangentially to the longitudinal axis of the annular channel, which runs within the annular tubular circuit, allows for high flow velocity of the heated gas by creating a directed, annular, unimpeded gas flow. This avoids loss of mechanical energy and pressure, eliminating local resistance to flow. All this ensures maximum flow velocity, significantly increasing the intensity of gas heating in a heater with external heat input and achieving high heating rates.The installation of annular tubular circuits with a gap relative to the outer surface of the gas heater's cylindrical body, and the installation of parallel annular tubular circuits with a gap relative to each other, allow the heat flow from the gas heater to transfer most fully to the surface of the annular tubular circuits. Hot air flowing around them from all sides reduces heat loss and increases the efficiency of gas heating within the closed circuit. Thus, the heater design with external heat supply ensures the highest possible gas heating rate within the heated circuit, reduces heat loss from the external heat source, and increases the efficiency of gas heating within the heat conversion system. Increased heating efficiency and gas heating rate improve the efficiency of the expander and the entire heat conversion system.

[0011] Figure 1 shows a general diagram of an energy conversion system with external heat supply.

[0012] Figure 2 shows a general view of a heater with external heat supply.

[0013] Figure 3 shows a ring-shaped tubular circuit of a heater with external heat supply.

[0014] An energy conversion system with an external heat supply comprises a closed circuit 1, which comprises a compressor 2, a heater 3 with an external heat supply, and an expander 4, all connected in series. The closed circuit contains a working fluid, which may be any noble monatomic gas; for example, argon or mixtures of such gases may be used. Compressor 2 consists of two vertically oriented containers 5 and 6. The containers of compressor 2 are partially filled with liquid 7, which may be hydraulic oil. Alternatively, depending on the stage of the thermal energy conversion process, one of the containers 5 or 6 may be completely filled with liquid, while the other may not contain liquid at the same time. Containers 5 and 6 are connected at the bottom by a pipeline 8, with liquid bypass devices installed thereon and a hydraulic pump 9 installed thereon. Containers 5 and 6 are equipped with liquid diffusers connected to a cooler for the liquid coming from hydraulic pump 9.In closed circuit 1, compressor 2 outlet is connected to inlet channels 10 of annular tubular circuits 11 of heater 3 with external heat supply. Outlet pipes 12 of annular tubular circuits 11 of heater 3 are connected to expander 4 inlet. Annular tubular circuits 11 are arranged around gas heater casing 13 to form a gap between outer surface of casing 13 and sides of annular tubular circuits 11 facing this surface. Annular tubular circuits 11 are arranged around casing 13 in parallel rings, with a gap relative to each other between adjacent circuits 11. A section of one heater 3 may contain several annular tubular circuits 11. Gas heater casing 13 is provided with fuel gas supply pipe 14 and air supply pipes 15. Natural gas, such as methane, or other low-calorie fuel with the ability to heat the working fluid to 300 °C can be used as fuel gas.In the housing 13 of the gas heater 14, gas burners (not shown in the drawing) can be installed, uniformly heating the entire surface of the housing 13. The axis of each inlet channel 10 is located tangentially to the longitudinal axis of the annular channel, passing inside the annular tubular circuit 11. Valves 16 are installed on the inlet channels 10, valves 17 are installed on the outlet pipes 12. The outlets of the annular tubular circuits 11 are connected to the inlet of the expander 4. A liquid piston expander is used as the expander 4. The expander 4 consists of two vertically oriented tanks 18 and 19. The tanks of the expander 4 are partially filled with hydraulic oil 7, which acts as a liquid piston. Or, depending on the stage of the thermal energy conversion process, one of the tanks 18 or 19 can be completely filled with liquid, while the second one at this time may not contain liquid. Expander 4 is in a vacuum for thermal insulation (not shown in the drawing).Tanks 18 and 19 are connected at the bottom by a pipeline 20, in which a hydraulic motor 21 is installed. Each of the tanks 18 and 19 is connected to the gas supply line from the heater 3. The outlet of each of the tanks 18 and 19 is connected to the main line of the closed circuit 1. Check valves are installed at the gas inlets and outlets from the tanks 18 and 19.

[0015] The thermal energy conversion system with external heat works as follows.

[0016] When the system is started, the pressure is uniform across all its components. During the operating cycle, a monatomic gas, such as argon, is compressed, heated, expanded, and performs work. To compress the gas, it is directed into compressor 2 and hydraulic pump 9 is activated. Hydraulic pump 9 transfers hydraulic oil 7 from tank 6 to tank 5, passing it through a cooling device. In tank 5, the cooled oil is sprayed through a liquid diffuser, passes vertically through tank 5 in the form of jets and drops, cooling the gas inside, and settles to the bottom of tank 5. As the oil accumulates, its level rises, the gas above oil 7 is compressed, its pressure increases, and the gas is forced through a valve into closed-loop line 1 at a pressure of 137 bar.Oil 7 reaches the upper level in tank 5, then the level sensor switches the operation of hydraulic pump 9 in the opposite direction, while the pump shaft 9 maintains the direction of rotation, but pumps liquid 7 in the opposite direction - from tank 5 to tank 6. The process is repeated in the reverse direction. The direction of rotation of the shaft is ensured by the operation of the control system of hydraulic pump 9. Then, the gas compressed in compressor 2 is directed to heater 3 and through valves 16 is supplied to the inlet channels 10 of the annular tubular circuits 11 of heater 3 of closed circuit 1 at a temperature of -63 °C. Fuel gas, for example methane, is supplied to fuel gas supply pipes 14, located on the casing 13 of the gas heater, air is supplied to pipes 15. Inside the casing 13, combustion of the fuel gas occurs, passing through gas burners (not shown in the drawing), uniformly distributed in the internal space.Uniform heating of the housing 13 surface and of all annular tubular circuits 11, which encircle the housing 13 with a gap, occurs. Argon, the working fluid in closed circuit 1, enters under pressure tangentially to the axes of the annular tubular circuits 11 and moves within the annular channels at high speed. Heating of the gas to a temperature of 300°C is achieved in 1 - 1.14 seconds. Gas is fed into the annular tubular circuits 11 through valves 16 on the inlet channels 10, the gas makes several turns during heating along the annular channels inside the annular tubular circuits 11, then the gas is released through valves 17 of the outlet pipes 12 into the pipeline of the closed circuit 1 and the heated gas is fed to the expander 4. Valves 16 are opened again and a new portion of argon is fed into the annular tubular circuits 11, which quickly heats up to the required temperature when moving at high speed.Moreover, due to the rapid change of portions in the ring circuits, the heating rate of argon does not decrease, thereby significantly increasing the efficiency of gas heating in the system and the efficiency of the entire thermal energy conversion system. The heated working fluid is then fed to the expander 4, alternately opening the valves 17 of the outlet pipes 12 and releasing the heated gas from each ring tubular circuit 11 at a certain calculated frequency. The gas, heated to 300°C, entering the tank 18 of the expander 4, begins to compress the hydraulic oil 7 through the pipeline 20 into the tank 19, thereby causing the rotation of the shaft of the hydraulic motor 21. As the level of oil 7 in tank 18 decreases, the gas pressure decreases. The volume of tank 18 is calculated such that when the oil 7 reaches the lower level, the gas pressure drops from 350 bar to 25 bar.When the lower oil level in tank 18 is reached, the corresponding valves are switched to release gas into closed circuit line 1 with a pressure of 25 bar and to supply gas under a pressure of 350 bar to tank 19. The gas supplied under pressure forces the oil into tank 18, performing work on rotating the shaft of hydraulic motor 21. In this case, the shaft of hydraulic motor 21 does not change the direction of rotation, but when a control signal is supplied from the control system, the direction of the liquid flow 7 changes. In the expander 4, the gas pressure is converted into mechanical work. Then the working cycle is repeated. During operation of the system, intensive heat exchange occurs between the body 13 of the gas heater and the surface of the annular tubular circuits 11. At the same time, the Nusselt number, characterizing the intensity of convective heat exchange between the surface of the body and the gas flow, increases significantly, which makes it possible to reduce the specific mass of the system per unit of power to a value of 8 kg / kW at a power of 500 kW.Thus, the claimed invention makes it possible to expand the arsenal of means related to energy conversion systems by creating an energy conversion system with an external heat supply, with high efficiency of heating the gaseous working fluid.

Claims

CLAUSES OF THE INVENTION A thermal energy conversion system comprising a closed circuit with two components inside, one component being a gas and the second component being a liquid, the circuit sequentially including a positive displacement compressor equipped with a liquid cooler, at least one heater with an external heat supply and an expander, the working fluid in the closed circuit being a gas, and the liquid being used as pistons in the compressor and expander, characterized in that the heater is made in the form of annular tubular circuits enclosing with a gap the body of the gas heater made with an external fuel gas supply, the annular tubular circuits are installed with gaps relative to each other, each annular tubular circuit is a section of the closed circuit and has an inlet channel and an outlet branch pipe, wherein the axis of the inlet channel is located tangent to the longitudinal axis of the annular channel passing inside the annular tubular circuit.

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