Power plants – Combustion products used as motive fluid – External-combustion engine type
Reexamination Certificate
2002-01-04
2002-11-05
Nguyen, Hoang (Department: 3748)
Power plants
Combustion products used as motive fluid
External-combustion engine type
C060S512000, C060S515000
Reexamination Certificate
active
06474058
ABSTRACT:
BACKGROUND
1. Field of Invention
The present invention relates to mechanization of the “Warren Cycle”. The “Warren Cycle” is: cooled compression, stored heat released from a regenerator and heat added to the working fluid at constant volume, heated expansion, and heat stored in a regenerator and heat removed from the working fluid at constant volume. The resulting engine is a thermally regenerated, reciprocating, two stroke external combustion engine that stores the spent heat and returns it to the engine cycle to do work.
2. Description of Prior Art
Thermal regeneration is the capturing of waste heat from a thermodynamic cycle, and the utilization of that energy within the cycle or engine to improve the cycle or engine's performance. This is commonly done with many heat engines including Stirling engines, gas turbines, and Rankine cycle devices. In the Stirling cycle engine, the fluid is moved about in the engine by a displacer piston or a regenerator acting as a displacer piston. In a gas turbine the exhaust heat coming out of the exhaust is transferred to the fluid leaving the compressor and going into the combustor. This way it is not necessary to add as much heat (fuel) in the combustor to raise the fluid temperature to the desired turbine inlet temperature. This means that the same work is accomplished but less fuel is used.
The approach taken by most inventors who attempted to incorporate regeneration into reciprocating external combustion engines was to try to improve existing cycles. In the gas turbine and Brayton cycles, heat is added at constant pressure. This results in a pressure difference across the regenerator that must be sealed. The gas turbines use high speed rotating devices that are costly. The piston type Braton engines need valves in the high temperature working fluid paths. The Stirling cycle engines use a displacer piston or a regenerator that acts as a displacer piston. They also have difficulty getting the heat from the heater into the working fluid and from the working fluid into the cooler. They also have problems timing the heating and cooling with the position of the power piston.
The Warren cycle engine is a piston engine. It has no high speed rotating parts. Heat is added at constant volume. There is a slight pressure difference across the regenerator that requires minimum sealing. The Warren cycle engine has no displacer piston, and the regenerator does not act like a displacer piston. In addition, the engine moves the fluid to be heated through the regenerator, heater, or cooler each time the fluid is to be heated or cooled. The Warren cycle engine has perfect timing between the power piston position and when heat is added or removed. Other differences exist between the engines and the regenerated engine disclosed herein. All of these are discussed in greater detail in the section entitled “Detailed Description of the Invention”.
SUMMARY
This invention is a two stroke, regenerated, external combustion, reciprocating engine made up of a number of similar working units. Each working unit is comprised of a cylinder that is closed at one end by a cylinder head and contains a heater, cooler, regenerator, and a power piston that is connected to a power output means. The regenerator, heater, and cooler can move between the power piston and the cylinder head, and means are provided to accomplish this movement at the appropriate times during the engine's operating cycle. The regenerator is an alternating flow heat exchanger. The movement of the regenerator, heater, and cooler is such that the cooling stroke (the regenerator is heating) begins when the power piston is at about 85% of the way from the cylinder head, and ends when the power piston is about 15% of the way towards the cylinder head. (This is cooling at constant volume). The compressed fluid heating stroke (the regenerator is giving up heat) begins at about 85% of the power piston's stroke towards the cylinder head, and ends at about 15% of downward travel of the power piston's expansion stroke. (This is heating at constant volume). Means are provided for the introduction of heat into the working fluid during the heating and expansion cycles. Means are provided for the removal of heat from the working fluid during the cooling and compression cycles.
Objects and Advantages
Several objects and advantages of the Warren cycle engine are:
(a) The engine compresses the fluid in the same cylinder that the engine expands the fluid in.
(b) The engine cools the fluid during compression.
(c) The engine saves the heat from the spent fluid and releases the heat to the compressed fluid.
(d) The engine has no valves.
(e) The engine has no displacer piston
(f) The heater supply and exit pipes can be sized so that there is no compression during the heating cycle.
(g) The engine can be operated so that the charge is almost fully expanded.
REFERENCES:
patent: 4074533 (1978-02-01), Stockton
patent: 4077221 (1978-03-01), Maeda
patent: 4511805 (1985-04-01), Boy-Marcotte et al.
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