JP4580247B2 - Engine system - Google Patents

Description

  The present invention relates to an engine system that is a combination of a gas engine as an internal combustion engine whose fuel is liquefied gas and a Stirling engine as an external combustion engine in a closed cycle.

  A Stirling engine is known as an engine that can use various heat sources (see Patent Document 1 and Patent Document 2).

  A Stirling engine is a type of external combustion engine. When a chamber with sealed working fluid is provided on both sides of a reciprocating piston, one chamber is heated and the other chamber is cooled. Power is obtained using the principle of moving to the side.

  The basic cycle configuration consists of isothermal compression-isothermal heating-isothermal expansion-isothermal heat dissipation. The part that converts thermal energy into mechanical energy consists of a displacer, a hot space, a heater, a regenerator, a cooler, and an output piston.

  Since the Stirling engine is a closed cycle, the working fluid is not directly exchanged with the atmosphere.

In the case of Patent Document 1, thermal energy possessed by exhaust gas from a diesel engine and thermal energy possessed by engine cooling water are used as a high-temperature heat source for a Stirling engine. In the case of Patent Document 1, waste heat from an incinerator or melting furnace or natural heat such as sunlight is used as a high-temperature heat source for a Stirling engine.
JP 01-294946 A Japanese Patent Laid-Open No. 2003-13805

  In the conventional Stirling engine, various thermal energies are used as the heat source of the heater as in Patent Document 1 and Patent Document 2, but the cooler releases the amount of heat taken from the working fluid to the atmosphere. Only radiators are used.

  As an energy supply system for operating a Stirling engine as an external combustion engine in a closed cycle, the present invention is combined with an internal combustion engine (gas engine with clean exhaust gas) that uses liquefied gas as a fuel, thereby achieving high efficiency and low pollution. It aims at providing the engine system of.

The invention comprises a gas engine as an internal combustion engine fuel is liquefied gas, a Stirling engine as the external combustion engine of the closed cycle, the working fluid of the Stirling engine by vaporization of the liquefied gas in the fuel supply system of the gas engine And means for cooling the working fluid of the Stirling engine, wherein the passage of the fuel supply system of the gas engine passes through the cooling section of the Stirling engine .

  In this invention, since the working fluid of the Stirling engine is cooled by the latent heat of vaporization of the liquefied gas of the gas engine, the pressure difference between the high temperature space and the low temperature space becomes large, and the output of the Stirling engine can be improved. On the other hand, in the fuel supply system of the gas engine, since the vaporization latent heat of the liquefied gas is given from the working fluid of the Stirling engine, it is possible to promote downsizing of the functional component (vaporizer) that vaporizes the liquefied gas.

  In FIG. 1, 16 is a gas engine as an internal combustion engine using liquefied natural gas (LNG) as fuel, and 10 is a Stirling engine as an external combustion engine in a closed cycle. In the case of a vehicle, the gas engine 16 is mounted as a prime mover of the vehicle, and the Stirling engine 10 is mounted as a driving device such as auxiliary equipment (for example, a driving device for a compressor of a refrigerator).

  Although not shown, the Stirling engine 10 is a 1 displacer-1 piston system, and a displacer and an output piston are accommodated inside a cylinder so as to be capable of reciprocating in the axial direction. A high temperature space is defined between the cylinder and the displacer, and a low temperature space is defined between the displacer and the output piston. The displacer is connected to the crankshaft, and the output piston is connected to the crankshaft with a predetermined phase difference from the displacer.

  A communication passage 15 (which constitutes an operation space together with the high temperature space and the low temperature space) that connects the high temperature space and the low temperature space is provided, and a certain amount of working fluid (for example, helium) is sealed in the operation space. In the communication path 15, a regenerator 13, a heater 12, and a cooler 14 are interposed.

  In the Stirling engine 10, when the displacer moves in the direction of compressing the high temperature space, the working fluid flows through the communication path 15 from the high temperature space to the low temperature space, and is cooled by the regenerator 13 and the cooler 14 at that time. Reduce the pressure. On the other hand, when the displacer returns in the direction of expanding the high-temperature space, the working fluid flows from the low-temperature space to the high-temperature space through the communication path 15 and is heated by the regenerator 13 and the heater 12 at that time. Raise. Thus, the reciprocating motion of the displacer creates a pressure difference between the high temperature space and the low temperature space, and the output piston reciprocates, so that output is obtained from the crankshaft of the Stirling engine 10.

  In the gas engine 16, the exhaust system passage 19 is piped through the heater 12 of the Stirling engine 10. The heater 12 includes a flow path 19a that constitutes a part of the passage 19 of the exhaust system and a flow path 15a that constitutes a part of the communication path 15, and surrounds the flow path 19a with the flow path 15a. Formed in the heat exchanger.

  In the gas engine 16, a fuel supply unit (fuel injection unit) is provided in an intake system passage, and a fuel supply system passage 18 that connects a fuel supply unit (not shown) and a fuel container 17 is formed. The passage 18 of the fuel supply system is piped so as to pass through the cooler 14 of the Stirling engine 10. The cooler 14 includes a flow path 18a constituting a part of the passage 18 of the fuel supply system and a flow path 15b constituting a part of the communication path 15, and the flow path 18a is surrounded by the flow path 15b. Formed in the heat exchanger.

  In heat exchangers 12 and 14, fins 20 that promote heat exchange are disposed on the outer periphery of flow path 19a and the outer periphery of flow path 18a. In the passage 18 of the fuel supply system of the gas engine 16, the heat exchanger 14 constitutes a functional component (vaporizer) for vaporizing the liquefied natural gas, and the upstream passage portion 18b (the fuel container 17 and the flow passage 18a). The piping connecting the two is covered with a heat insulating material so that the liquefied natural gas is not vaporized.

  With such a configuration, in the stroke in which the displacer moves in the direction of compressing the high temperature space, the working fluid flowing from the high temperature space to the low temperature space is cooled by the vaporization of the fuel of the gas engine 16 when passing through the cooler 14. In the process of expanding the high temperature space by the displacer, the working fluid flowing from the low temperature space to the high temperature space is heated by the heat energy of the exhaust of the gas engine 16 when passing through the heater 12. That is, not only the exhaust energy of the gas engine 16 is regenerated for heating the high temperature space, but also the latent heat of vaporization of the fuel of the gas engine 16 is used for cooling the low temperature space, so the output of the Stirling engine 10 can be increased. is there.

  In the gas engine 16, since the vaporization latent heat is received from the thermal energy of the working fluid of the Stirling engine 10, the functional component that vaporizes the liquefied natural gas can be reduced in size. Since the passage portion 18b from the fuel container 17 to the cooler 14 has heat insulation, the latent heat of vaporization can be concentrated from the working fluid passing through the cooler 14, so that the cooler 14 of the Stirling engine 10 functions effectively. be able to.

  As a result, the energy supply system for operating the Stirling engine 10 as an external combustion engine in a closed cycle is combined with the gas engine 16 as an internal combustion engine that uses liquefied natural gas as a fuel and has a clean exhaust gas, thereby improving the thermal efficiency. High and low pollution engine system can be realized at low cost.

  The configuration according to the present invention (means for cooling the working fluid of the Stirling engine by vaporizing the liquefied gas in the fuel supply system of the gas engine) is not limited to the case where the Stirling engine is a 1 displacer-1 piston system. The present invention is applicable even when the display salon pick type or the operation space is a two-piston type.

It is a schematic diagram of an engine system explaining an embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Stirling engine 12 Heater 13 Regenerator 14 Cooler 15 Communication path 16 Gas engine (LNG engine)
17 Fuel container 18 Fuel supply passage 19 Exhaust passage 20 Fin

Claims (5)

A gas engine as an internal combustion engine fuel is liquefied gas, a Stirling engine as the external combustion engine of the closed cycle, and means for cooling the working fluid of the Stirling engine by vaporization of the liquefied gas in the fuel supply system of the gas engine And the means for cooling the working fluid of the Stirling engine is piped so that the passage of the fuel supply system of the gas engine passes through the cooling part of the Stirling engine . A gas engine as an internal combustion engine in which the fuel is liquefied gas, a Stirling engine as an external combustion engine in a closed cycle, and means for cooling the working fluid of the Stirling engine by vaporizing liquefied gas in the fuel supply system of the gas engine; An engine system comprising: means for heating the working fluid of the Stirling engine by heat energy of exhaust of the gas engine . The engine system according to claim 2, wherein the means for heating the working fluid of the Stirling engine is piped so that a passage of an exhaust system of the gas engine passes through a heating unit of the Stirling engine . It said means for cooling the working fluid of the Stirling engine, the engine system according to claim 2, characterized in that the passage of the fuel supply system of the gas engine is plumbed so as to pass through the cooling portion of the Stirling engine. 5. The engine system according to claim 1, wherein the passage of the fuel supply system of the gas engine has a heat insulating property in a passage portion from a fuel container that stores liquefied gas to a cooling unit of the Stirling engine. .