JP2009541662A - Closed cycle engine - Google Patents

Abstract

A closed cycle engine system comprises an engine unit operable to combust fuel with combustion supporting gas, and a gas circuit providing fluid communication between the intake and the exhaust of the engine unit. In operation, the engine unit produces exhaust gases. The gas circuit is provided with an absorber to at least partially absorb the exhaust gases and a flow resistance. The flow resistance is located between the absorber and the intake, and is arranged such that the pressure at the intake is less than the pressure at the exhaust. Such an arrangement improves the efficiency of the absorber, and thus the overall efficiency of the engine. A method of operating such an engine system, and vehicles comprising such an engine system, are also disclosed.

Description

  The present invention relates to an improved closed cycle engine system. Closed cycle engine systems can operate regardless of the atmosphere, are particularly useful in places where the atmosphere is not freely available, and are often used for underwater applications.

  A closed cycle engine is known, for example, in European Patent Publication No. 0118284. This engine has a circulation path, and is piped so that a certain amount of exhaust gas discharged from the combustion chamber returns to the combustion chamber through the circulation path. Oxygen mixed with an inert carrier gas is provided to the combustion chamber where fuel is burned with oxygen along with other combustion products to produce carbon dioxide.

  This circulation path has an adsorption device, in which the exhaust gas is treated with water in order to remove carbon dioxide from the exhaust gas.

  Unfortunately, the absorption of carbon dioxide gas from the exhaust requires a lot of energy and therefore causes a lot of parasitic power loss to the engine. In order to improve the overall efficiency of the engine, it is essential to reduce this parasitic loss. In the prior art, since the absorption efficiency increases as the partial pressure of carbon dioxide increases, it is recognized that it is important to increase the partial pressure of carbon dioxide in the adsorption device. Therefore, in European Patent Publication No. 0118284, a technique is proposed in which the exhaust gas is compressed before the exhaust gas reaches the adsorption device, and then the exhaust gas from the adsorption device is expanded. Such expansion is essential to reduce the pressure at the intake manifold of the engine to a pressure that is within engine operating constraints. However, as disclosed in European Patent Publication No. 0118284, compression of exhaust gases requires additional parasitic energy losses to power the compressor. Without this additional compression, the maximum absorption pressure must be the maximum intake manifold pressure allowed by the engine. This limitation is because the engine peak cylinder pressure is directly affected by the intake manifold pressure that is sealed against the absorption pressure in a system that is configured to minimize energy loss. Engine pot life is directly affected by engine peak cylinder pressure. That is, the pot life is shortened by the high peak cylinder pressure.

European Patent Publication No. 0118284

  Therefore, there is a need for a more efficient closed cycle engine system with less parasitic losses. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a closed cycle engine system that at least partially meets this need, and a closed cycle engine system that at least partially solves the above-described problems of conventional closed cycle engine systems. It is to be.

  The present invention is a sealed type in which a differential pressure is generated between an intake manifold and an exhaust manifold during operation of the engine, and a larger pressure on the exhaust port side of the engine is used to improve exhaust gas absorption efficiency. The concept is that of a cycle engine system. By incorporating flow resistance into the gas circuit connecting the exhaust to the intake, such a differential pressure is achieved, thereby improving carbon dioxide absorption efficiency and thus reducing parasitic losses. Thus, despite the additional resistance expected to increase energy loss in the engine system is introduced into the gas circuit flow, the overall efficiency of the system is improved. Furthermore, these advantages are achieved without the use of a compressor.

In accordance with a first aspect of the present invention, a closed cycle engine system is provided, which is an engine unit operable to burn fuel together with a combustion supplemental gas, whereby exhaust gas is generated, the engine unit being an intake port And an engine unit having an exhaust port, and a gas circulation path that performs fluid transmission between the intake port and the exhaust port, the gas circulation path at least partially absorbs exhaust gas and flow resistance. Since the flow resistance is placed between the adsorption device and the intake port, the pressure at the intake port is lower than the pressure at the exhaust port, and the flow resistance depends on the pressure at the intake port. It can be adjusted. The installation of flow resistance between the adsorber and the intake port ensures that the adsorber is at a lower intake pressure or higher exhaust pressure. Since the pressure in the adsorber increases without the need for additional power consuming components such as a compressor, the additional flow resistance to the gas circuit improves the efficiency of the engine system. Increasing the pressure in the adsorber increases the efficiency of CO ₂ absorption and therefore reduces the parasitic losses associated with the adsorber. As parasitic losses are reduced, the exhaust power of the system for a given engine shaft power increases.

  By including flow resistance, the closed cycle system can use the natural capacity of the engine unit to allow the differential pressure between the intake manifold and the exhaust manifold. Also, certain types of engine units, such as diesel engines that are provided with an exhaust-driven turbocharger, are designed to operate with a differential pressure between the inlet and exhaust. By removing the turbocharger, this differential pressure is used to increase the absorption efficiency. Furthermore, because of the differential pressure between the intake manifold and exhaust manifold of the engine unit, a wide variety of engine units can be used in a closed cycle engine system. Previously, the limit defined by the highest allowable intake manifold pressure reduced the number of engine units that could be used in a closed cycle engine system. This problem is alleviated by the present invention because the flow resistance can be selected according to the engine unit desired to be used in a given closed cycle engine system.

  Advantageously, the flow resistance can be adjusted according to the pressure at the inlet, so that it is ensured that the intake pressure is kept within an acceptable range for the engine, while the adsorption device maintains a high pressure. Is also possible. In addition, the presence of an adjustable flow resistance allows the system to account for any transient increase in inlet pressure. On the other hand, such a transient state exceeds the maximum pressure that the inlet can tolerate.

  The flow resistance includes a throttle valve, such as an orifice plate, or a portion of a shortened diameter pipe. The use of an orifice plate provides a simple method that is preferred to achieve flow resistance, which can be quickly and cost-effective and can be incorporated into existing closed cycle engine systems, or It can also be incorporated into existing designs for closed cycle engine systems. In certain embodiments described below, the flow resistance further comprises a pressure reducing valve that is responsive to the intake pressure. At that time, the pressure in the intake manifold of the engine unit is adjusted so that the most efficient pressure value is selected.

  Further, the combustion auxiliary combustion gas (or combustion support gas) is supplied to the gas circulation path between the orifice plate and the pressure reducing valve. Once the bulk pressure reduction is performed by the orifice plate, it is easy to introduce gas supply. The combustion support gas is preferably a mixture of oxygen and an inert carrier gas from a separate gas supply bottle, for example argon, which is introduced by the introduction of these gases before the flow passes through the pressure reducing valve. The gas components are well mixed before entering the intake manifold.

  The flow resistance preferably has power extraction means to extract power from the flow in the gas circuit. Power extraction from the flow in the gas circuit further increases the efficiency of the closed cycle engine system. The power extraction means has a turbine. Alternatively, the power extraction means comprises a vane or other positive displacement motor.

  The pressure at the intake port can be controlled independently of the pressure at the exhaust port. By such independent control means, the pressure in the engine system is adjusted to increase efficiency.

  In accordance with a second aspect of the present invention, there is provided a method for driving a closed cycle engine system, the system having an engine unit having an inlet and an exhaust, and a gas circulation path comprising the exhaust and the intake. The fluid is transmitted to and from. The driving method includes operating the engine to generate exhaust gas discharged into the gas circulation path at the exhaust port, absorbing the exhaust gas at least partially in the adsorption device, and intake air lower than the pressure at the exhaust port. Adjusting the pressure at the mouth and providing a flow resistance to the gas circuit defined between the adsorber and the inlet.

  The present invention extends to a submersible having a closed cycle engine system as described above. Such submersibles are, for example, in the form of submarines or underwater vehicles that require motive means.

  For a better understanding of the present invention, specific embodiments will now be described, by way of example only, with reference to the accompanying drawings.

It is a schematic diagram of an embodiment of the present invention.

  An argon circulating closed cycle diesel engine system 100 according to an embodiment of the present invention is schematically illustrated in FIG. The system 100 includes a diesel engine unit 110 having an intake manifold 112 and an exhaust manifold 114. The exhaust manifold is connected to the adsorption device 120 via an appropriate duct or pipe, and the adsorption device 120 is connected in order via a separator 130, an orifice plate 140, and a pressure reducing valve 150, and an engine unit. 110 is connected to the intake manifold 112. Therefore, a gas circulation path connecting the exhaust manifold to the intake manifold is defined. Between the orifice plate 140 and the pressure reducing valve 150, intake ports 144 and 146 for supplying argon and oxygen to the circulation path are provided. An inlet (not shown) for supplying fuel to the engine unit 110 is also provided. Oxygen and argon supplies are provided from gas bottles or other suitable gas storage devices.

System 100 can operate in a closed cycle. The engine unit 110 is sucked together with a combustion auxiliary gas having a mixture of argon and oxygen supplied from the intake ports 144 and 146. By combining the fuel and oxygen in the engine unit 110, exhaust gas containing carbon dioxide (CO ₂ ) is generated. Some CO ₂ is absorbed into the chamber 120.

Similar to conventional known closed cycle engines, the adsorber 120 has a rotor with a wire mesh or other material with a large surface area relative to the volume ratio through which water is fed by centrifugal force. The exhaust gas is thrown out in the radial direction by the air, so that the exhaust gas flows backward in the meantime. By changing the amount of water passing through the adsorption device 120 using a variable speed water pump, the amount of CO ₂ absorbed and the resulting pressure at the adsorption device 120 and the exhaust port 114 are controlled.

  Thereafter, the gas processed at that time passes through the separator 130 that removes water from the gas flow and flows to the orifice plate 140. The orifice plate 140 cooperates with the pressure reducing valve 150 to help control the pressure in the intake manifold of the engine unit 110. Since the pressure reducing valve 150 is controlled according to the pressure at the intake port 112, it is certain that the pressure at the intake port will not increase beyond the maximum intake pressure allowed by the engine unit 110. This is schematically shown in FIG. 1 by a dotted line 155 connecting the inlet 112 to the pressure reducing valve 150. Therefore, the pressure at the inlet 112 is controlled independently of the pressure at the outlet 114.

  The engine unit 110 is usually a conventional diesel engine of the same type, to which an exhaust-driven turbocharger is attached. When operating in a normal aerobic configuration, such an engine is comprised of an engine 110 and sufficient turbines to drive a turbine that compresses the inlet to a predetermined pressure. Configured to operate with a differential pressure therebetween. Therefore, the exhaust pressure is higher than the generated intake pressure. The engine unit is adapted for use in the system 100 by removal of the turbocharger and direct joining of the inlet 112 and exhaust 114 to the engine 110.

  Therefore, in a closed cycle operation, when the turbocharger is removed, the possible output of an engine operating with a differential pressure that exceeds the possible output of the engine increases the absorption efficiency by increasing the pressure in the adsorber 120. On the other hand, the possible output of the engine maintains the pressure in the intake manifold 112 at a value within the allowable range of the engine unit 110.

Initially, the system is at a constant pressure and the differential pressure occurs after the initial startup of the engine unit 110. Since the partial pressure of CO ₂ in this system is very low at start-up, the absorption capacity is also low. As the engine continues to operate, a partial pressure of CO ₂ is produced and the efficiency of the adsorber increases until equilibrium is reached. The differential pressure increases between the intake manifold and the adsorber by the action of additional flow resistance including the orifice plate 140 and pressure reducing valve 150. This difference can maintain a constant value consistent with the maximum pressure that the intake manifold can accept when in equilibrium. On the other hand, the difference is to maintain the pressure in the adsorption device 120 at a pressure higher than the pressure in the exhaust manifold 114. Therefore, the adsorber efficiency is increased. By increasing the absorption efficiency, parasitic losses in the engine are reduced, and therefore the overall efficiency of the engine is improved by introducing an orifice plate and pressure reducing valve into the gas circuit.

  Changes and modifications to the above-described embodiments are possible as will be readily apparent to those skilled in the art. For example, in the above, the use of a combination orifice plate and pressure reducing valve for restricting flow and controlling intake pressure is described, but several other structures may be used. Such other structures can use shortened diaphragm pipes or active and passively controlled throttle valves known to those skilled in the art. In a particularly simple construction, the flow resistance has only an orifice plate rather than including a pressure reducing valve as described above. If the exact differential pressure required during engine system operation is known during manufacture, such flow resistance is appropriate and no further control is necessary. It is also recognized that devices that can use energy from the vacuum, such as gas turbines and expanders, or any type of positive displacement motor, can be used to provide additional power to the plant. ing. Finally, it should be noted that such changes and modifications will be readily apparent to those skilled in the art and are possible without departing from the scope of the invention as defined in the appended claims. It is understood that.

Claims (12)

An operable engine unit having an intake port and an exhaust port and generating exhaust gas by burning fuel together with combustion auxiliary gas; and
An adsorbing device for transferring fluid between the intake port and the exhaust port and at least partially absorbing the exhaust gas and the flow resistance is provided, and the flow resistance is between the adsorber and the intake port. And the pressure at the intake port is lower than the pressure at the exhaust port, and the flow resistance is adjustable according to the pressure at the intake port; and
A closed cycle engine system comprising:   The engine system according to claim 1, wherein the flow resistance includes a throttle valve.   The engine system according to claim 1, wherein the flow resistance includes an orifice plate.   The engine system according to claim 3, wherein the flow resistance further includes a pressure reducing valve corresponding to the intake pressure.   The engine system according to claim 4, wherein the combustion auxiliary combustion gas is supplied between the orifice plate and the pressure reducing valve.   2. The engine system according to claim 1, wherein the flow resistance includes power extraction means for extracting power from the flow in the gas circulation path.   The engine system according to claim 6, wherein the power extraction unit includes a turbine.   The engine system according to any one of claims 1 to 7, wherein the pressure at the intake port is controllable independently of the pressure at the exhaust port.   A closed cycle engine system substantially as herein described with reference to the accompanying drawings.   The submersible craft according to any one of claims 1 to 9, comprising a closed cycle engine system. An operation method of a closed cycle engine system comprising an engine unit having an intake port and an exhaust port, and a gas circulation path for transmitting fluid between the exhaust port and the intake port,
a) operating the engine to generate exhaust gas discharged into the gas circulation path at the exhaust port;
b) at least partially absorbing the exhaust gas in the adsorber;
c) providing a flow resistance to the gas circulation path that is adjusted to the pressure at the intake port lower than the pressure at the exhaust port and defined between the adsorber and the intake port;
d) adjusting the flow resistance in accordance with the pressure at the intake port, and a method for operating a closed cycle engine system.   A method of operating a closed cycle engine system as substantially described herein with reference to the accompanying drawings.

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