Power plants – Motive fluid energized by externally applied heat – Process of power production or system operation
Reexamination Certificate
2001-03-13
2003-02-25
Nguyen, Hoang (Department: 3748)
Power plants
Motive fluid energized by externally applied heat
Process of power production or system operation
C060S671000, C062S087000
Reexamination Certificate
active
06523347
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to heat engines that utilize bottoming and topping cycles and binary working fluid, and more particularly to a thermodynamic power system utilizing a binary working fluid and having a low-temperature bottoming cycle and an open or closed modified Brayton topping cycle.
2. Brief Description of the Prior Art
It is known that any thermodynamic system operating on a cycle and receiving heat while doing work must also have a heat-rejection process as part of the cycle. A statement called Carnot's Maxim says: “Heat should be added at the highest temperature and rejection at the lowest possible temperature if the greatest amount of work is to be gained and the highest thermal efficiency is to be realized”. Hot gases of combustion are produced in a combustion chamber by burning fuel in air and a maximum temperature of about 2000° is attained. The hot gases obtained from the process are the finite heat reservoir for a thermodynamic cycle. Today's engine design options have both theoretical and practical limits that may be described as follows. The maximum amount of heat that can be transferred from this heat reservoir would be obtained by cooling the gases from the maximum temperature to the atmospheric temperature. Note that cooling goes only to the atmospheric temperature, but not less. Theoretically, this is the “lowest permissible level” of temperature.
This theoretical restriction is a barrier that inhibits the development of energy technology. However, Kelvin's statement of the Second Law of Thermodynamics does not state or imply this restriction. The development of the Second Law of Thermodynamics is based primarily on heat engine analysis. The gist of Kelvin's statement of the Second Law Of Thermodynamics is that no cyclic process is possible whose sole result is a flow of heat from a single reservoir and the performance of equivalent work. Thus, the basic Statement of the Second Law of Thermodynamics determines only that a heat engine cannot convert into work all of the heat supplied to the working fluid; it must reject some heat.
For a hydroelectric station, the “lowest permissible level” of temperature is restricted by the level of the ocean. For the working process of a heat engine, the “lowest permissible level” of the air temperature may be significantly below the temperature of the “air ocean”. Furthermore, the heat engine may use the heat of that “air ocean” as a reservoir for producing power and cool refrigerated air simultaneously because the working fluid gas has an ability to alter its physical parameters depending on the pressure and temperature differentiate of the liquid.
Most prior art systems having thermodynamic cycles require two external heat reservoirs for the heat-addition and heat-rejection processes. however, a heat-rejection process may be made up in closed cycles without an external heat reservoir, provided that the working medium is a combined mixture of a non-condensable first gas such as helium or hydrogen and a fine dispersed low-temperature non-freezable lubricating liquid such as nitrogen, oil, water with antifreeze, etc., wherein the low-temperature liquid is used as an internal cold reservoir to carry out the heat-rejection process and the non-condensable first gas is cooled during adiabatic expansion producing useful work and serves as a coolant to heated liquid recovering from an initial condition of the gas/liquid mixture. Therefore, it is possible to construct a heat engine which will do work and exchange heat using a single external heat reservoir for the heat-addition process only. The conversion of the heat energy into another form is appreciably enhanced by employing a binary working fluid in the low-temperature closed bottoming cycle and for cooling of the working fluid of the open or closed modified Brayton topping cycles before its compression.
Heat engines are known in the art which have combined cycles such as a combination of Brayton and Rankin cycles. Fruschi, U.S. Pat. No. 5,386,685 discloses a method and apparatus for a combined cycle power plant. Simpkin, U.S. Pat. No. 5,431,016 discloses a high efficiency power generation engine. One of the principal shortcomings of these combined cycle systems is that they are not capable of cooling air before or during its compression in the topping Brayton cycle.
The present invention is distinguished over the prior art, and is a significant advance over our commonly owned previous patent application Ser. No. 09/448,557. pending and U.S. Pat. Nos. 6,161,392, and 5,996,355, which are incorporated herein by reference. A major distinction is that, in the present invention, conversion of the heat energy into another form is appreciably enhanced by employing a binary working fluid in a low-temperature closed bottoming cycle for cooling of the working fluid of the open or closed modified Brayton topping cycles during the continuous compression process. The working process of the present invention produces a cooled first gas at a cryogenic temperature in the bottoming cycle which is significantly less that the temperature of ambient air which is cooled by being drawn through a heat exchanger of the bottoming cycle and then compressed. Thus, the work of compression is significantly reduced and the amount of power is significantly increased.
The present thermodynamic power system embodiment with an open modified Brayton topping cycle using a high-temperature heat source can generate a large amount of specific power to achieve a high thermal efficiency. The present thermodynamic power system embodiment with a closed modified Brayton topping cycle can be effectively utilized as an engine for a space station using a solar heat source. Such a space energy device has significant advantages over conventional devices because it utilizes a heat-rejection process without an external heat exchanger. It also allows use of an inexpensive fuel source.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a thermodynamic power system that can generate a large amount of specific power to achieve a high actual thermal efficiency.
It is another object of this invention to provide a thermodynamic power system that is inexpensive to manufacture in mass production and is inexpensive to operate, service, and repair.
Another object of this invention is to provide a thermodynamic power system that has applicability as an engine in industry, as well as applications for outer space.
Other objects of the invention will become apparent from to time throughout the specification and claims as hereinafter related.
The above noted objects of the invention are accomplished by a thermodynamic power system that utilizes a cryogenic refrigeration bottoming cycle operating on a two-phase (binary) working fluid (gas/liquid mixture) in combination with several different topping cycles. In a first embodiment the topping cycle is an open modified Brayton topping cycle using a high temperature heat source and, in a second embodiment, the topping cycle is a closed modified Brayton topping cycle. The low-temperature bottoming cycle functions to cool the working fluid of the toppings cycles.
The apparatus of the bottoming cycle includes a sliding-blade gas/liquid compressor and expander unit, a vortex separator, a heat exchanger, a plurality of liquid atomizers, a pump, gas and liquid storage tanks, temperature and pressure sensors, and control means for adjustably controlling the volume of fluids in the system contained within a thermally insulated housing. In the operation of the bottoming cycle, rotation of the gas/liquid compressor and expander rotor draws a first gas (helium or hydrogen) from the expander operating chamber into the gas/liquid compressor operating chamber.
Simultaneously, a fine dispersed low-temperature lubricating liquid (such as nitrogen, oil, water with antifreeze, etc.) is injected into the operating chamber of the gas/liquid compressor through the plurality of liquid atomizers
Jirnov Alexei
Jirnov Mikhail A.
Nguyen Hoang
Roddy Kenneth A.
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