Patent Application
20050268955
The present invention relates to diesel-electric locomotives, and more particularly to a locomotive waste energy recovery system including a thermoelectric device.
In most modern railroad diesel-electric locomotives, the diesel engine drives an electric generator which in turn provides electrical power to motors which are mechanically geared to the locomotive wheels. The diesel engine is typically turbocharged. The turbocharger provides charge air for the diesel engine fuel combustion. In this regard, combustion exhaust gas provides work of expansion across a turbine section of the turbocharger which, in turn, provides rotational energy to the compressor section of the turbocharger so as to produce the charge air for combustion. The exhaust gas from the turbocharger is discharged into the atmosphere, wherein the heat thereof is dumped to the atmosphere.
In operation, the locomotive is typically operated at a set of throttle notches, each of which defines a specific engine load and speed. As the engine operates, the combustion process generates waste heat which must be removed from the engine. In this regard, locomotive diesel engines have a coolant system in which a liquid coolant is circulated within the engine so as to transport heat from engine components (as, for example, cylinder liners, heads, oil coolers, etc.) to radiators where the heat is discharged to the atmosphere (surrounding air).
An increasing awareness of energy conservation and preservation of the environment has renewed interest in applications of thermoelectric devices because thermoelectric devices can transform heat directly into electrical energy and can also act as solid state refrigerators.
Historically, due to its low cooling coefficient of performance and energy conversion efficiency, thermoelectric technology has seen limited use. The efficiency characteristics of a thermoelectric device are determined by the thermoelectric material's figure of merit, ZT.
Prior to 1990, the highest ZT values of all thermoelectric materials remained below one. The combination of increased U.S. government funding and private enterprise research and development have led to significant increases in ZT values in recent years which has stimulated interest in thermoelectric technology applications. There has now emerged a large variety of new high efficiency thermoelectric materials that cover a wide temperature range, thereby allowing further design flexibility for locomotive applications.
Accordingly, what remains needed in the art is to devise some way that thermoelectric devices could help to increase the ability of locomotive diesel engines to convert diesel fuel combustion waste heat into useful work, thereby minimizing waste heat rejected to the atmosphere, and increasing locomotive fuel efficiency by as much as 10 percent.
The present invention is a system which recovers waste heat generated by a locomotive diesel engine by utilization of a thermoelectric device connected to a source of waste heat of the engine to thereby convert this waste heat into additional electricity or other useful work (as, for example, air conditioning) to the locomotive.
The present invention is a locomotive diesel engine waste heat recovery system consisting of a thermoelectric module thermally interfaced with the waste heat of the engine and electrically interfaced with selected electrical components. Any source of waste heat of the diesel engine serves as a high temperature heat source for the thermoelectric module, and any source of cooler temperature serves as the low temperature heat source for the thermoelectric module, wherein the difference in temperatures therebetween powers the thermoelectric module to provide conversion of the waste heat into useful work, particularly electricity.
In the most preferred embodiment, the thermoelectric module is preferably located adjacent to, or integral with, the turbocharger exhaust gas duct such that the high temperature exhaust gas exiting therefrom is directed through a first chamber of the thermoelectric module, thus providing a high temperature heat source for the thermoelectric module. The atmosphere ultimately provides the low temperature heat source for the thermoelectric device, most preferably by the diesel engine coolant circuit having a loop passing through a second chamber of the thermoelectric module. The temperature differential provided between the hot and low temperature heat sources, the hot exhaust gas and the cooler liquid coolant, provides energy to drive the thermoelectric process at the thermoelectric module so as to output therefrom electrical energy which is used for powering selected components of the locomotive. For example, the electrical energy is routed to the locomotive power management module where it is then conditioned for use in powering locomotive electrical equipment such as fans, blowers, and other ancillary equipment, and/or for powering locomotive traction power drives.
Accordingly, it is an object of the present invention to provide a waste heat recovery system for a locomotive diesel engine utilizing a thermoelectric module to convert waste heat of the engine into useful work, particularly electricity.
This and additional objects, features and advantages of the present invention will become clearer from the following specification of a preferred embodiment.
Referring now to the drawings, wherein in the various views like numbers refer to like functioning components,
Referring now to
In order to remove the waste heat from the diesel engine 12, a coolant system 14 is provided, which includes liquid coolant 16 which flows through coolant conduits 18 at the urging of a pump 20 so that the coolant flows through predetermined passages within the engine and also through a radiator 22, whereat heat QR is rejected to the atmosphere 24. Thus, at the engine the coolant 16 (see detail inset circle A) absorbs heat of combustion from the engine 12 and rejects heat QR at one or more radiators 22 to the atmosphere 24.
The combustion process of the diesel engine 12 also produces hot exhaust gas 26. This hot exhaust gas 26 is conventionally dumped to the atmosphere, preferably after going through a turbine section of a turbocharger 28. However, the locomotive diesel engine waste heat recovery system 10′, 10″ according to the present invention utilizes this hot exhaust gas 26 as a source of high temperature which provides a high temperature heat source TH for a thermoelectric module 30.
The turbocharger 28 provides charge air for fuel combustion in the diesel engine 12. In this regard, the exhaust gas 26 is piped 25 (see detail inset circle B) to provide work of expansion across a turbine section of the turbocharger which, in turn, provides rotational energy to the compressor section of the turbocharger so as to produce the charge air for combustion. The thermoelectric module 30 is preferably located adjacent to, or integral with, an exhaust gas duct 32 connected 34 to the turbocharger 28, and is connected 36 to a first chamber 38 of the thermoelectric module (see detail at
The atmosphere 24 ultimately provides a source of low temperature for the low temperature heat source TL for extracting heat Q3 from the thermoelectric module 30. It is preferred to provide the low temperature heat source TL by utilization of the coolant 16 of the coolant system 14 having a connection to a second chamber 42 of the thermoelectric module 30 (see detail at
As best seen at
The temperature differential provided between the hot and low temperature heat sources TH, TL (the hot exhaust gas 26 and the cooler liquid coolant 16), drives the thermoelectric process at the thermoelectric module 30 so as to provide a work output W′ such as refrigeration or electrical energy, wherein in the preferred form of electrical energy, the electricity is used for powering locomotive electrical equipment. For preferable example, the electrical energy is routed, via an electrical connection 46, to the locomotive power management module 48, where it is then conditioned for use in powering locomotive electrical equipment 50, such as for example fans, blowers, and other ancillary equipment, and/or locomotive tractive power devices, via electrical connections 52.
Any waste heat source of the locomotive diesel engine 12 may be utilized for operating the thermoelectric module, as per the example of
To those skilled in the art to which this invention appertains, the above described preferred embodiment may be subject to change or modification. Such change or modification can be carried out without departing from the scope of the invention, which is intended to be limited only by the scope of the appended claims.
The present patent application claims the benefit of provisional patent application Ser. No. 60/577,966, filed on Jun. 8, 2004.
| Number | Date | Country | |
|---|---|---|---|
| 60577966 | Jun 2004 | US |
