Power plants – Fluid motor means driven by waste heat or by exhaust energy... – Fluid motor means is expansible chamber type with movable...
Patent
1996-12-19
1999-04-27
Kamen, Noah P.
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
Fluid motor means is expansible chamber type with movable...
60659, 60668, 60712, 60713, F02G 300
Patent
active
058967460
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention refers to an engine assembly that includes an internal combustion engine and a steam engine connected to a driving assembly, for instance, by a common driving axle, and further includes a heat exchanged by which heat losses, from exhaust gases or cooling water, or both, from the internal combustion engine are utilized for generating steam to the steam engine.
2. Description of the Related Art
It is conventional to utilize combustion gases from an internal combustion engine in order to improve its efficiency, an internal combustion engine referring here to otto-cycle and diesel engines. The most common device presently in use is an exhaust driven turbo turbine driving a turbo compressor for supercharging the intake combustion air, which improves the performance of the engine at high shaft speeds. In large ships it is also customary to use steam turbines in order to utilize the heat from the exhaust gases of diesel engines. It has also been proposed to use exhaust gas heat from an internal combustion engine in a Rankine cycle process for the purpose of increasing engine efficiency. However, in conventional steam technology, the steam engine with its auxiliary system is too bulky and heavy. Therefore, these conventional systems have not been considered as a realistic alternative for vehicles in which weight and space demands are of great importance.
From a thermodynamic point of view, a piston steam engine could be a possible solution for utilizing the heat losses of an internal combustion engine. However, in such a case, the weight and space demands of the system must be considerably reduced compared to that provided by present steam technology.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an engine assembly of the previously discussed type, having smaller dimensions and less weight to optimize the flexibility afforded by a reasonable steam engine system.
This objective is achieved according to the present invention because the steam engine is a displacement type engine with a built-in engine braking capability. The excess steam from the heat exchanger is not directly used for driving the steam engine but is instead fed to a steam buffer which is designed to supply steam for short periods to the steam engine with a high power density.
The present invention is directed on the utilization of a steam buffer of the type described in detail in a co-pending U.S. application Ser. No. 08/750,833 entitled "Steam Buffer For A Steam Engine Plant", to which reference is here made regarding the details about the steam buffer. This steam buffer is equipped with a high temperature connection for steam, preferably with a temperature about 500.degree. C. with a pressure of about 250 bar, and a low temperature connection for feed water. A solid heat exchanging structure with a large number of pressure resistant flow channels having a hydraulic diameter less than 0.5 mm for the steam and feed water is located between the two connections. It has been found that an energy density output of at least 500 kJ/kg and a power density output of 100 kW/kg is possible with this design, compared to a lead-acid battery having an energy density output of 100 kJ/kg and a power density output of only 100 W/kg.
Typically, vehicle engines are used at a very low power output as compared to its maximum power output, which should be available for some situations mostly during short periods of time. Fuel consumption for a vehicle will therefore be determined by its efficiency at these normal low loads. The present invention also relies on the knowledge that an internal combustion engine has its highest efficiency at high loads whereas a steam engine of the displacement or piston type has its highest efficiency at low loads. A diesel engine having an efficiency of 45% at these low load conditions will get an increase in efficiency by 10-15 percentage points from the steam engine, through which the total efficiency of the assembly can be incre
REFERENCES:
Patent Abstracts of Japan, vol. 7, No. 283, M-263 58-158304 (NIPPON KOKAN K.K.) Sep. 20, 1983.
Kamen Noah P.
Ranotor Utvecklings AB
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