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Apparatus and method for producing sustainable power and heat

Apparatus and method for producing sustainable power and heat description/claims

The present invention relates generally to the onsite production of heat and power from sustainable resources such as solar, waste heat and biomass system for the supply of electrical power, domestic hot water and space heating operating either in parallel or in isolation from the central grid, and more specifically, to a modular, scalable systems that enables maximum harvesting of solar energy, waste heat energy and heat from the combustion of fuel, to produce electrical power and useable heat in a closed loop heat engine cycle using a volatile organic working fluid in a system dynamically responsive to the source temperature, sink temperature, facility's electrical and thermal loads and ambient conditions.

In recent years, six major trends have emerged that are reshaping the energy industry. First, millions of consumers have experienced more frequent, more prolonged and more devastating electrical outages from failure of the central grid caused by more frequent, more severe and more costly hurricanes and storms and the increasing dependency of modern society on electrical devices including, computers, modems, televisions, and the like. Second, the cost of fossil fuel has spiked including gasoline, diesel fuel, natural gas and coal stimulated by the unprecedented demand for energy from emerging nations and the more severe storms. Third, the nearly universal acknowledgement of the detrimental impact caused by air pollution and specifically large fossil fuel plants in global warming. Fourth, the deregulation of the electrical industry has substantially reduced obstacles to interconnection by distributed generation resources. Fifth, substantial incentives from various governments spur more sustainable energy technologies. And, sixth, the increasing availability of real time pricing for all classes of electrical customers places a premium on technologies that can reduce grid electrical demand during high demand/high price situations.

Although there is an abundance of solar energy received by the Earth, its intensity at the Earth's surface is actually very low and varying with the time of day, time of year and the conditions of the Earth's atmosphere. Conventional heat engine cycles have been analyzed based on the on the ideal heat engine cycle Carnot disclosed in 1824 which postulates an infinite heat source and an infinite heat sink. In such hypothesized system, the efficiency of the power systems is determined by:

(i) the temperatures of the available heat source and sink;

(ii) the selection of the state points, thereby describing the adopted thermodynamic cycle;

(iii) the behavior of the working fluid used;

(iv) the irreversibility's in the mechanical systems involved; and,

(v) the temperature and pressure limitations of the materials used in the devices.

In a similar fashion the more practical Rankine and its associated organic Rankine cycles (ORCs) also assume infinite source and sink temperature and requires the evaporation and typically superheating of the working fluid in the heating device before entering the expander.

In 1977, S. S. Wilson & M. S. Radwan in “Appropriate Thermodynamics for Heat Engine Analysis and Design” disclosed a modified organic heat engine cycle, called the trilateral flash cycle (TFCs) based on the matching and optimization of heat source and sink, cycle, working fluid, expander and load characteristics which heats the liquid working fluid only to the point of boiling, saturation, and expands the heated high pressure saturated working fluid using positive displacement expanders in a cycle that optimizes the amount of the finite heat energy recoverable and electricity produced from a finite heat source. All previous disclosed closed loop heat engine systems utilizing a volatile organic working fluid were designed to operate in one of the two distinct modes, super heated, (ORC) or saturated liquid, (TFC) and did not contemplate the advantages or the ability to dynamically switch between the two modes in response to changing fuel load and operating conditions. Clearly, it is desirable to overcome the limitations and deficiencies of the ORC and TFC to provide a method which dynamical adjusts the heating of the working liquid only up to its boiling point, TFC or beyond its boiling point, ORC depending on the fuel, load, and ambient conditions.

During the expansion of volatile organic working fluid in an expander, almost invariably the working fluid leaves the expander in the superheated state and has to be cooled in the condenser or requires a recuperator heat exchanger to transfer the heat to preheat the relatively high pressure liquid. Everything else being equal the greater the superheat in the exhausted working fluid exiting the expander, the lower the efficiency of the mechanical/electrical generating heat engine cycle. Clearly dispensing with the need for a recuperator and producing more electrical energy from the same thermal energy is desirable through the injection of relatively high pressure liquid into the expansion volume of the expander and modulating the mass flow of the injected liquid such that the combined mass flow of the working fluid exits the expander in a saturated state and produces more net power.

Combined heat and power (CHP) systems using internal combustion engines, turbines, micro turbines, and fuel cells have been known for some time as a way to improve overall efficiency by an order of magnitude in energy production systems. In a typical CHP system, heat and electricity are produced from a combustion process engine that drives an electric generator, as well as heat water, or air. Although historically CHP systems tend to be rather large, because of the six forces outline above, micro CHP systems consuming fossil fuel are emerging technologies. Because of the dramatic increase in power outages and fossil fuel prices, there is a huge market for dispatchable, sustainable energy systems.

In view of the limitations of the existing art, the present invention fulfills the long felt need to optimize the production of electricity and heat in response to the varying availability of solar energy, waste heat and the varying load requirements of the facility, to dynamically optimize the electric power production by operating the system with a superheated working fluid entering the expander as in a Carnot or Rankine cycles or with a saturated liquid entering the expander in the trilateral flash cycle and minimizing the superheat of the working fluid exiting the expander and to provide a more reliable and secure source of electricity and heat not subject to the numerous power outages of central grid systems. The above and other objects and advantages of the present invention will become apparent from the following specifications, drawings and claims. It will be understood that the particular embodiments of the invention are shown by way of illustration only and not as limitation of the invention. The principle features of this invention may be employed in various embodiments without departing from the scope of the invention.

While the above-described systems fulfill their respective, particular objectives and requirements, the aforementioned systems do not describe a system that uses beneficial portions of the Rankine and Carnot cycles to produce electricity and heat at minimal amounts of energy. Therefore, a need exists for a new and improved apparatus and method for producing sustainable power and heat that in its structure allows for multiple fuels to generate heat. The present invention substantially fulfills this need. Further, the present invention substantially departs from the conventional concepts and designs of the prior art.

The present invention is an integrated system to provide both electric power and heat from various energy sources including solar, waste heat, biomass and fossil fuels. The combined heat and power system operates with a volatile organic working fluid that circulates in a variable speed heat engine type cycle, where the organic working fluid is heated to either its boiling point, a saturated state or past its boiling point, a superheated gas state, expanded through an expander, with relatively high pressure subcooled liquid working fluid injected into the expansion chambers of the expander such that the volatile organic working exiting the expander is in a saturated state, cooled in a condenser in thermal communication with the domestic hot water or space heating system, and pressurized and circulated by a pump. Heat exchange loops within the system define hot water production capability for use in space heating, domestic hot water, and/or process heat while the generator is coupled to the expander to produce electricity which is interconnected to the grid at fixed frequency and voltage in either a paralleling or island mode.

The foregoing has outlined, in general, the physical aspects of the invention and has served as an aid to better understanding the detailed description. Thus, the present invention is not limited to the method or detail of construction, fabrication, material, or application of use described and illustrated herein. Any other variation of fabrication, use, or application should be considered apparent as an alternative embodiment of the present invention.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.

Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the drawings. In this respect, before explaining the current embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and devices for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and the scope of the present invention.

It is therefore a principal object of the present invention to provide a method and apparatus which will maximize the overall energy efficiency of the energy process of harvesting and converting solar energy to usable electrical power and heat, while overcoming the disadvantages and drawbacks of known methods of solar photovoltaic, solar thermal electric, and solar thermal systems.

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