Waste energy recovery method and waste energy recovery system

Abstract

An oil cooler for cooling hydraulic oil that has increased in temperature due to energy loss in a hydraulic circuit a radiator for cooling engine cooling water that has increased in temperature as a result of cooling an engine and an ATAAC for cooling engine intake air that has increased in temperature as a result of being compressed by a turbocharger, are provided with heat pipes for vaporizing low-boiling medium by absorbing heat from the oil cooler the radiator and the ATAAC. A power recovery turbine is rotated by energy provided by vaporized low-boiling medium is provided for the engine. A low-boiling medium circuit is provided so as to drive the turbine by feeding the low-boiling medium that has been vaporized by waste heat energy. The low-boiling medium circuit includes the heat pipes of the oil cooler the radiator, and the ATAAC, as well as the turbine.

Description

CROSS-REFERENCE TO PRIOR APPLICATION [0001] This is a U.S. National Phase Application under 35 U.S.C. §371 of International Patent Application No. PCT / JP2005 / 006628, filed Apr. 5, 2005, and claims the benefit of Japanese Patent Application No. 2004-273991, filed Sep. 21, 2004, both of which are incorporated by reference herein. The International Application has not published yet at the time of filing of this application.TECHNICAL FIELD [0002] 1. Field of the Invention [0003] The present invention relates to a waste heat energy recovery method and a waste heat energy recovery system for recovering waste heat energy generated from a hydraulic circuit or any other similar system. [0004] 2. Background Art [0005] A conventional construction machine typically has such a configuration that power is supplied from an engine, which is normally a diesel engine, to a main pump so that pressurized oil is fed from the main pump to actuator control valves. [0006] An actuator that has been supplied...

AI Technical Summary

Benefits of technology

[0017] The present invention provides a waste heat energy recovery method for recovering waste heat energy by using a low-boiling medium to absorb waste heat energy from hydraulic oil that has increased in temperature as a result of loss of energy in a hydraulic circuit that includes a pump adapted to be driven by an engine, as well as waste heat energy from another fluid that has increased in temperature as a result of operation of the engine, and rotating a power recovery turbine by utilizing the low-boiling medium that has vaporized as a result of absorbing the heat so as to boost the power of the engine by means of the turbine. By transferring waste heat energy to the low-boiling medium from the hydraulic oil that has increased in temperature as a result of loss of energy in the hydraulic circuit as well the other fluid that has increased in temperature as a result of operation of the engine, the hydraulic oil and the other fluid are cooled while the low-boiling medium is vaporized, so that the vaporized low-boiling medium rotates the turbine, which then provides a boost to the engine and thereby recovers the waste heat energy. As a part of the lost engine power, which would, in case of a conventional art, wastefully dissipate into the air as waste heat energy of the hydraulic oil and the other fluid, is effectively recirculated to the engine through the turbine, the energy use efficiency of the engine is improved.

[0018] The present invention also provides a waste heat energy recovery system having an oil cooler, another cooling means, a power recovery turbine, and a low-boiling medium circuit. The oil cooler serves to cool hydraulic oil that has increased in temperature as a result of loss of energy in a hydraulic circuit that includes a pump adapted to be driven by an engine. The other cooling means serves to cool another fluid that has increased in temperature as a result of operation of the engine. The aforementioned turbine is provided for the engine and adapted to be rotated by energy provided by a vaporized low-boiling medium. The low-boiling medium circuit serves to drive the turbine by providing the turbine with the low-boiling medium that has been vaporized by waste heat energy from the oil cooler and the other cooling means. With the configuration as above, by transferring waste heat energy to the low-boiling medium from the hydraulic oil that has increased in temperature as a result of loss of energy in the hydraulic circuit as well as the other fluid that has increased in temperature as a result of operation of the engine, the hydraulic oil and the other fluid are cooled while the low-boiling medium is vaporized. And by providing the turbine with the vaporized low-boiling medium through the low-boiling medium circuit in order to drive the turbine so that the turbine provides a boost to the engine and thereby recovers the waste heat energy. As a part of the lost engine power, which would, in case of a conventional art, wastefully dissipate into the air as waste heat energy from the oil cooler and the other cooling means, is effectively recirculated to the engine by means of the low-boiling medium circuit and the turbine, the energy use efficiency of the engine is improved.

[0019] According to another feature of the present invention, the aforementioned other cooling means of a waste heat energy recovery system is a radiator for cooling engine cooling water that has increased in temperature as a result of cooling the engine. With the configuration as above, by transferring waste heat energy from the hydraulic oil and engine cooling water to the low-boiling medium, the hydraulic oil and the engine cooling water are cooled while the low-boiling medium is vaporized. And by providing the turbine with the vaporized low-boiling medium through the low-boiling medium circuit in order to drive the turbine so that the turbine provides a boost to the engine and thereby recovers the waste heat energy. As a part of the lost engine power, which would, in case of a conventional art, wastefully dissipate into the air as waste heat energy from the oil cooler and the radiator, is effectively recirculated to the engine by means of the low-boiling medium circuit and the turbine, the energy use efficiency of the engine is improved.

Problems solved by technology

An oil cooler is provided to reduce the temperature of the hydraulic oil, because a rise in the temperature of the hydraulic oil causes thermal degradation of the oil as well as a decrease in its viscosity, resulting in damage to hydraulic equipment.

This presents the problem of substantial power loss of the engine 11, resulting in very poor energy use efficiency.

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