FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2006
COMPLETE
Specification
(See Section 10 and Rule 13)
A SYSTEM FOR GENERATING ENERGY
THERMAX LIMITED
an Indian Company
of D-13, MIDC Industrial Area, R.D. Aga Road,
Chinchwad, Pune-411 019,
Maharashtra, India.
Inventors: 1. PANNEERSELVAM BABU 2. RANADE MUKUND.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF DISCLOSURE
The present disclosure relates to a system for generating energy.
Particularly, the present disclosure relates to a system for generating energy
using an improved organic rankine cycle having high efficiency.
BACKGROUND
Energy is a prime mover of economic growth and is vital to the sustenance of a modern economy. In case of developing countries, the energy sector assumes critical importance in view of the ever-increasing energy needs, requiring huge investments to meet them. This makes imperative to use all forms of energy efficiently. Turbines are commonly used in power plants, industrial plants, process plants, and commercial installations for generating useful electricity/work, which can be used for commercial purposes such as to drive electric generators, pumps, blowers, compressors, shredders, mills and machinery or for domestic purposes.
Generally, a steam rankine cycle is used to generate power, where steam is produced using fossil fuels such as coal, gas, petroleum products, and the like; this steam is then converted into energy by using a turbine. In the present condition, where the need for more power at a cheaper rate is growing faster than ever, there is felt a need for newer technologies that use low-grade waste heat and/or solar energy to produce useful electricity. An organic rankine cycle (ORC) has been more recently introduced to enable the use of low-grade heat or waste heat for generating electricity/power.

In the organic rankine cycle, condensers coupled to the exhaust of the turbines return condensate to the power cycle and generator. The surface-type condensers are provided with either once-through or recirculated water as the cooling medium. Hence, there is always a requirement of make-up water. Also, the thermodynamic properties of water are not very ideal. Further, this system has other drawbacks like water freezing problems, generation of water vapor plumes, high system maintenance costs and an added concern over water-pollution. When air is used as the cooling medium, the ORC system efficiency is reduced by about 5-7 %. Since, an ORC already has a lower efficiency compared to the rankine cycle due to the low-grade energy used, any further decrease in the efficiency is not feasible.
Therefore, there is felt a need for an improved organic rankine cycle which will overcome the above-listed drawbacks of the known organic rankine cycles. Also, there is need for a working fluid with better thermodynamic properties than water, so as to increase the efficiency of the organic rankine cycle.
OBJECTS
Some of the objects in the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object in the present disclosure is to provide a system for generating power from low-grade waste heat energy such as exhaust.
Another object in the present disclosure is to provide an organic rankine cycle which prevents water-freezing, water vapor plumes and water-pollution.

Still another object in the present disclosure is to provide an organic rankine cycle which is economical and efficient.
Yet another object in the present disclosure is to provide an organic rankine cycle which reduces the operating costs as compared to the known organic rankine cycles.
One more object in the present disclosure is to provide an organic rankine cycle which reduces CO2 emissions.
Still one more object in the present disclosure is to provide an organic rankine cycle which is easy to maintain, flexible in operation and which can operate at relatively low temperature and pressure.
Other objects and advantages in the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.
SUMMARY
In accordance with the present invention, there is envisaged a system for generating energy which combines an organic rankine cycle and a vapor compression cycle, said system comprising:
■ an evaporator for vaporizing a condensed secondary refrigerant by extracting heat from low pressure primary refrigerant vapors, to provide secondary refrigerant vapors and a condensed primary refrigerant;

■ an absorber for absorbing said secondary refrigerant vapors in a concentrated Li-Br solution, giving a weak Li-Br solution;
■ a primary generator for concentrating said weak Li-Br solution by using a heat input, to provide said concentrated Li-Br solution and hot secondary refrigerant vapors;
■ a secondary generator for extracting heat from said hot secondary refrigerant vapors in said condensed primary refrigerant, to provide high pressure primary refrigerant vapors and said condensed secondary refrigerant which is conveyed to said evaporator; and
■ a turbine for expanding said high pressure primary refrigerant vapors for driving a generator to generate energy, the expansion resulting in said low pressure primary refrigerant vapors which are conveyed to said evaporator to complete the cycle.
Typically, said system comprises an economizer for cooling said low pressure primary refrigerant vapors prior to condensation in said evaporator by transferring heat to said condensed primary refrigerant.
Preferably, said system comprises a low temperature heat exchanger for heating said weak Li-Br solution prior to concentration in said primary generator by extracting heat from said concentrated Li-Br solution leaving said primary generator.
Additionally, said system comprises a heat reclaimer for further heating said weak Li-Br solution prior to concentration in said primary generator by extracting left-over heat from said heat input.

In accordance with the present invention, there is provided a method for generating energy using an organic rankine cycle and a vapor compression cycle, said method comprising the steps of:
■ vaporizing a condensed secondary refrigerant by extracting heat from low pressure primary refrigerant vapors in an evaporator, to obtain secondary refrigerant vapors and a condensed primary refrigerant;
■ absorbing said secondary refrigerant vapors in a concentrated Li-Br solution sprayed in an absorber to obtain a weak Li-Br solution;
■ concentrating said weak Li-Br solution in a primary generator by using a heat input to obtain said concentrated Li-Br solution and hot secondary refrigerant vapors;
■ extracting heat from said hot secondary refrigerant vapors in said condensed primary refrigerant in a secondary generator to provide high pressure primary refrigerant vapors and said condensed secondary refrigerant which is conveyed to said evaporator; and
■ expanding said high pressure primary refrigerant vapors in a turbine for driving a generator to generate energy, resulting low pressure primary refrigerant vapors are conveyed to said evaporator to complete the cycle.
Typically, said method includes the step of using R245FA as said primary refrigerant and water as said secondary refrigerant.
Preferably, said method includes the step of heating said weak Li-Br solution in a low temperature heat exchanger by extracting heat from said concentrated Li-Br solution leaving said primary generator prior to concentration.

Additionally, said method includes the step of further heating said weak Li-Br solution in a heat reclaimer by extracting left-over heat from said heat input.
Typically, said method includes the step of cooling said low pressure primary refrigerant vapors prior to condensation in said evaporator by transferring heat to said condensed primary refrigerant.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The disclosure will now be described with the help of the accompanying drawing, in which,
FIGURE 1 illustrates a schematic of the system for generating energy in accordance with the present disclosure.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWING
The disclosure will now be described with reference to the accompanying drawing which does not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The present disclosure envisages a system for generating energy from low-grade heat source or waste heat such as exhaust gases. The system of the present disclosure eliminates water-related problems including water-freezing, formation of water vapor plumes, and water pollution issues, associated with a conventional organic rankine cycle. Further, the system of the present disclosure is easy to maintain, flexible to operate, energy efficient, and reduces CO2 emissions.

Referring to FIGURE 1, therein is illustrated a schematic of the system of the present disclosure; the system is generally represented by numeral 100 in FIGURE 1. The system 100 combines an organic rankine cycle and a vapor compression cycle. The system 100 mainly comprises a primary evaporator 102, a low pressure absorber 104, a primary generator 106, a secondary generator 108, and a turbine 114. A liquid refrigerant typically water, also referred to as a secondary refrigerant, is sprayed in the evaporator 102. In the evaporator 102, this liquid refrigerant is vaporized by extracting heat from a low pressure vapor refrigerant conveyed through the evaporator 102 tubes. The low pressure vapor refrigerant is generally referred to as a primary refrigerant and is preferably R245FA, gets condensed.
The evaporator 102 is provided in operative communication with the absorber 104, wherein a concentrated Li-Br solution having concentration between 60 -65 % is sprayed in the absorber 104. The secondary refrigerant vapors so released in the evaporator 102 are subsequently absorbed in the concentrated Li-Br solution sprayed in the absorber 104. As a result, the concentrated Li-Br solution gets diluted to a concentration between 55-57 %, this solution is referred as a weak Li-Br solution. During the absorption process, heat of dilution is generated in the absorber 104. This heat of dilution is extracted by water having temperature in the range of 50 - 60 °C circulated through the absorber 104 tubes. The weak Li-Br solution leaving absorber 104 is conveyed to a low temperature heat exchanger 110.
In the low temperature heat exchanger 110 the weak Li-Br solution exchanges heat with a concentrated Li-Br solution leaving the primary generator 106. The concentrated Li-Br solution leaving primary generator 106 after losing heat in

low temperature heat exchanger 110 is sprayed in the absorber 104 for initiating a new cycle. The heated weak Li-Br solution from the low temperature heat exchanger 110 is fed to a heat reclaimer 112. The heat reclaimer 112 is adapted to receive at least partly heated exhaust gases from the primary generator 106, where, in the heat reclaimer 112 these exhaust gases are cooled by exchanging heat with the heated weak Li-Br solution. The further heated weak Li-Br solution is then fed to the primary generator 106, where, by using a direct heat input 118 such as fuel firing, exhaust gases, and the like, the further heated weak Li-Br is boiled and thereby concentrated to 60 - 65 %. This concentrated Li-Br solution is fed to the absorber 104 via the low temperature heat exchanger 110.
The secondary refrigerant vapors released in primary generator 106 due to the boiling process, are conveyed to the secondary generator 108 as a heat source. In the secondary generator 108, the secondary refrigerant vapors exchange heat with the condensed primary refrigerant from the evaporator 102, thereby generating high pressure primary refrigerant vapors. The condensed secondary refrigerant is returned to the evaporator 102 to initiate a new cycle. Unlike conventional power plants, where a substantial portion of heat is wasted as the condensate rejects the heat in an external condenser, the system 100 uses more than 50% of the condensate heat for internal heating, therefore reducing the heat input required. The high pressure primary refrigerant vapors generated in the secondary generator 108 are fed to the turbine 114. In the turbine 114, a pressure drop is effected and the high pressure primary refrigerant vapors are expanded to generate energy. Thus, a single heat input is used to operate both, viz., the vapor compression cycle and the organic rankine cycle. Therefore, the heat input required to obtain a certain power output is considerably less when

using the system of the present disclosure as compared to a conventional power plant. This reduction in the amount of heat input (fuel firing required) gives a corresponding reduction in the CO2 emissions.
In the turbine 114 during the expansion process the temperature and pressure of the refrigerant vapors is reduced. The low pressure primary refrigerant vapors are then fed to an economizer 116. In the economizer 116, the low pressure primary refrigerant vapors exchange heat with the condensed primary refrigerant leaving the evaporator 102. The low pressure primary refrigerant vapors are subsequently returned to the evaporator 102 where they condense after exchanging heat with the secondary refrigerant to form the condensed liquid primary refrigerant. The condensed primary refrigerant is then recycled to the secondary generator 108 via the economizer 116, thereby completing the cycle.
The system 100 requires a higher initial capital investment as compared to a convention power plant; however, the system 100 is more efficient and largely effective over a longer period as the operating costs are low, the heat input required is low, and the generated power output is high.
TECHNICAL ADVANTAGES
A system for generating energy which combines an organic rankine cycle and a vapor compression cycle, as described in the present disclosure has several technical advantages including but not limited to the realization of:
■ uses low-grade waste heat energy such as exhaust;
■ prevents water-freezing, water vapor plumes and water-pollution;
■ economical and efficient;

■ reduces the operating costs as compared to the known organic rankine cycles;
■ reduces C02 emissions; and
■ easy to maintain, flexible in operation and operates at relatively low temperature and pressure.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters,

dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
In view of the wide variety of embodiments to which the principles of the present disclosure can be applied, it should be understood that the illustrated embodiments are exemplary only. While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principle of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

WE CLAIM;
1. A system (100) for generating energy which combines an organic
rankine cycle and a vapor compression cycle, said system comprising:
■ an evaporator (102) for vaporizing a condensed secondary refrigerant by extracting heat from low pressure primary refrigerant vapors, to provide secondary refrigerant vapors and a condensed primary refrigerant;
■ an absorber (104) for absorbing said secondary refrigerant vapors in a concentrated Li-Br solution, giving a weak Li-Br solution;
■ a primary generator (106) for concentrating said weak Li-Br solution by using a heat input (118), to provide said concentrated Li-Br solution and hot secondary refrigerant vapors;
■ a secondary generator (108) for extracting heat from said hot secondary refrigerant vapors in said condensed primary refrigerant, to provide high pressure primary refrigerant vapors and said condensed secondary refrigerant which is conveyed to said evaporator (102); and
■ a turbine (114) for expanding said high pressure primary refrigerant vapors for driving a generator to generate energy, the expansion resulting in said low pressure primary refrigerant vapors which are conveyed to said evaporator (102) to complete the cycle.
2. The system as claimed in claim 1, wherein an economizer (116) is
provided for cooling said low pressure primary refrigerant vapors prior to
condensation in said evaporator (102) by transferring heat to said
condensed primary refrigerant.

3. The system as claimed in claim 1, wherein a low temperature heat exchanger (110) is provided for heating said weak Li-Br solution prior to concentration in said primary generator (106) by extracting heat from said concentrated Li-Br solution leaving said primary generator (106).
4. The system as claimed in claim 3, wherein a heat reclaimer (112) is provided for further heating said weak Li-Br solution prior to concentration in said primary generator (106) by extracting left-over heat from said heat input (118).
5. A method for generating energy using an organic rankine cycle and a vapor compression cycle, said method comprising the steps of:

■ vaporizing a condensed secondary refrigerant by extracting heat from low pressure primary refrigerant vapors in an evaporator, to obtain secondary refrigerant vapors and a condensed primary refrigerant;
■ absorbing said secondary refrigerant vapors in a concentrated Li-Br solution sprayed in an absorber to obtain a weak Li-Br solution;
■ concentrating said weak Li-Br solution in a primary generator by using a heat input to obtain said concentrated Li-Br solution and hot secondary refrigerant vapors;
■ extracting heat from said hot secondary refrigerant vapors in said condensed primary refrigerant in a secondary generator to provide high pressure primary refrigerant vapors and said condensed secondary refrigerant which is conveyed to said evaporator; and
■ expanding said high pressure primary refrigerant vapors in a turbine for driving a generator to generate energy, resulting low pressure

primary refrigerant vapors are conveyed to said evaporator to complete the cycle.
6. The method as claimed in claim 5, which includes the step of using R245FA as said primary refrigerant and water as said secondary refrigerant.
7. The method as claimed in claim 5, which includes the step of heating said weak Li-Br solution in a low temperature heat exchanger by extracting heat from said concentrated Li-Br solution leaving said primary generator prior to concentration.
8. The method as claimed in claim 7, which includes the step of further heating said weak Li-Br solution in a heat reclaimer by extracting leftover heat from said heat input.
9. The method as claimed in claim 5, which includes the step of cooling said low pressure primary refrigerant vapors prior to condensation in said evaporator by transferring heat to said condensed primary refrigerant.