EP2044318A1

EP2044318A1 - Energy supply system

Info

Publication number: EP2044318A1
Application number: EP07763757A
Authority: EP
Inventors: James Richard Hunt
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-07-26
Filing date: 2007-07-06
Publication date: 2009-04-08
Also published as: AU2007278810A1; WO2008011656A1

Abstract

An energy supply system, particularly for converting waste heat energy into useful energy, comprising a closed refrigerant fluid circuit (12). A heat exchanger (16) is provided for transferring heat to the fluid in the circuit to convert the fluid to a high pressure. Energy converting mechanism such as a generator (30) is provided for receiving the high pressure fluid to drive the mechanism to supply output energy.

Description

ENERGY SUPPLY SYSTEM

Field of the Invention

This invention relates to an energy supply system for converting heat energy and, in particular, waste heat energy, into useful energy such as electrical energy or mechanical energy.

Background of the Invention

The conversion of waste heat energy produced by industrial machines and generators to useful energy sources has been known for some time. However, most conventional systems which are available to do this are not particularly efficient and often do not lend themselves to application in small environments , such as vehicles and the like .

Summary of the Invention

The object of the present invention is to provide an energy supply system which is relatively efficient and which can be adapted for use in small environments such as vehicles as well as in larger commercial environments such as power networks and the like.

The present invention may be said to reside in an energy supply system comprising: a closed fluid circuit for containing a refrigerant fluid; a heat exchanger for transferring heat to the fluid in the circuit so that heat is absorbed by the fluid to convert the fluid to a high pressure fluid; an energy converting mechanism in the circuit for receiving the high pressure fluid and producing output energy from the high pressure fluid, thereby converting the high pressure fluid to a low pressure fluid; and — O —

a pump for supplying the low pressure fluid in the circuit back to the heat exchanger .

Providing a closed fluid circuit which contains a refrigerant, heat exchange to the refrigerant, and heat release from the refrigerant fluid to drive the energy converting mechanism to supply the output energy, is extremely efficient. The reason for this is that the refrigerant readily and quickly absorbs a great deal of heat and holds that heat energy, and also readily releases the energy when the high pressure fluid is applied to the energy converting mechanism. Furthermore, since the system comprises a closed fluid circuit, a heat exchanger and a pump, the system can be made relatively small and therefore, used in small environments such as vehicles as well as larger environments such as power supply networks .

Preferably the closed fluid circuit has a restrictor for dividing the circuit into a high pressure part and a low pressure part, so the high pressure fluid can pass through the restrictor to the energy converting mechanism, whereupon expansion of the fluid can take place so that release of energy drives the energy converting mechanism to produce the output energy and allows the fluid to condense to a liquid phase so the pump can supply the liquid- phase back to the heat exchanger to heat the fluid and produce the high pressure fluid.

Preferably the circuit includes a reservoir for receiving liquid refrigerant and storing liquid refrigerant for supply to the heat exchanger .

The energy converting mechanism may comprise a piston engine for providing output mechanical energy, a turbine for driving a generator to produce electrical output energy, a Stirling cycle, or an air conditioning system. In one embodiment the heat exchanger is for receiving heated exhaust gas and for transferring heat from the heated exhaust gas to the fluid in the circuit so that the exhaust gas is discharged as a cooled exhaust gas .

In another embodiment the heat exchanger comprises a solar energy collector for collecting solar energy and transferring heat from the solar energy collector to the fluid.

In a still further embodiment the heat exchanger may be a heat exchanger for transferring heat from ambient hot air to the fluid in the circuit.

Waste heat generated by an air conditioning system may be used to supply hot air, in effect using a buildings waste heat for power generation.

The invention may also be said to reside in a drive system for a vehicle comprising: an internal combustion engine; a transmission for receiving rotary power from the internal combustion engine and for driving at least one wheel of the vehicle; an exhaust gas outlet from the internal combustion engine for exit of hot exhaust gas; a closed fluid circuit containing a refrigerant fluid; a heat exchanger on the circuit for receiving the hot exhaust gas and for transferring heat from the hot exhaust gas to the refrigerant in the circuit; and a heat converting mechanism for receiving high pressure fluid in the circuit and producing secondary output power for supply to at least one of the wheels of the vehicle .

Preferably the circuit includes a pump for circulating fluid through the circuit.

Preferably the pump is for receiving liquid refrigerant which has condensed from the high pressure fluid and for supplying the condensed liquid refrigerant to the heat exchanger .

Preferably the closed fluid circuit has a restrictor for dividing the circuit into a high pressure part and a low pressure part, so the high pressure fluid can pass through the restrictor to the energy converting mechanism, whereupon expansion of the fluid can take place so that release of energy drives the energy converting mechanism to produce the output energy and allows the fluid to condense to a liquid phase so the pump can supply the liquid phase back to the heat exchanger to heat the fluid and produce the high pressure fluid.

Preferably the circuit includes a reservoir for receiving liquid refrigerant and storing liquid refrigerant for supply to the heat exchanger.

Preferably the energy converting mechanism comprises a generator for producing electricity and an electric motor driven by the electricity produced by the generator to provide the secondary output power .

Preferably the transmission is a dual input transmission for receiving input rotary power from the internal combustion engine and the secondary output power from the electric motor, the transmission having an output coupled to at least one of the wheels of the vehicle for driving the at least one of the wheels of the vehicle .

Preferably the system includes an electricity storage element for storing electrical energy produced by the generator and/or electrical energy generated during braking of the vehicle.

Preferably the storage element comprises at least one capacitor .

The electrical energy stored in the storage element may be used to drive an ancillary electrical device.

In one embodiment the ancillary electrical device may comprise the pump.

In another embodiment the device may comprise a condenser for facilitating condensing of the refrigerant fluid to a liquid state for resupply to the heat exchanger.

Preferably the refrigerant fluid comprises liquid petroleum gas or other suitable refrigerant.

Brief Description of the Drawings

Preferred embodiments of the invention will be described, by way of example, with reference to the accompanying drawings , in which :

Figure 1 is a diagram illustrating one embodiment of the invention ;

Figure 2 is a diagram illustrating application of the embodiment of Figure 1 to a vehicle;

Figure 3 is a view of a second embodiment of the invention; and Figure 4 is a flowchart explaining heat transfer and energy supply according to embodiments of the invention .

Detailed Description of the Preferred Embodiments

With reference to Figure 1, an energy supply system 10 is shown which comprises a closed circuit 12 containing a refrigerant fluid such as liquid petroleum gas . The circuit 12 has a restrictor 14 and a part 12c which passes through a heat exchanger 16 which may comprise an exhaust pipe for receiving exhaust gas from an internal combustion engine 20. The exhaust gas is supplied from the engine 20 via an exhaust manifold (not shown) and an exhaust pipe 21 and the heat exchanger 16 may be configured by locating part 12c of the circuit 12 in the exhaust pipe 21 so that that part of the circuit and the refrigerant in that part of the circuit is heated by heat transfer from the hot exhaust gas .

The restrictor 14 divides the circuit 12 into a high pressure part 12a between the pump 24 and clockwise to the restrictor 14, and a low pressure part 12b between the restrictor 14 and the pump 24.

The high pressure part 12b has a refrigerant reservoir 22 and a pump 24. The pump 24 may be located between the condenser 26 and the reservoir 22.

A condenser 26 may be provided between the restrictor 14 and the reservoir 22 for facilitating complete condensing of the fluid in the circuit 12 after the fluid has been used to drive an energy converting mechanism 30.

The energy converting mechanism 30 may comprise a generator which is driven by a turbine 31 located in the circuit 12 so as to produce electrical energy for powering an electric motor 34. However, in other embodiments, other heat engines such as a piston engine, Stirling cycle or the like may be used as the energy converting mechanism 30 instead of a generator.

Liquid petroleum gas has a low boiling point and is generally in a gaseous phase at room temperature and pressure. In order to convert the liquid petroleum gas to a liquid phase it is generally necessary to cool the gas .

The liquid petroleum gas in the circuit 12 is heated by heat exchange in the heat exchanger 16. The liquid petroleum gas is able to absorb large amounts of heat energy very quickly from the heat exchanger 16, thereby substantially increasing the pressure of the liquid petroleum gas in the branch 12a.

The exhaust gas which leaves the exhaust pipe 21 leaves the exhaust pipe as a cooled exhaust gas which has significant environmental advantages, as will be discussed below.

The high pressure liquid petroleum gas in the branch 12a is supplied to the restrictor 14 and passes through the restrictor 14 to the turbine 31 to drive the turbine 31 to in turn drive the generator 30. As the high pressure liquid petroleum gas passes through the restrictor 14, it is able to expand, thereby giving up its heat which drives the turbine 31 and at the same time, the pressure and temperature of the liquid petroleum gas decreases significantly so that the gas condenses to a liquid state .

The condenser 26 may be provided after the generator 31 in the flow direction of the liquid petroleum gas so that if any liquid petroleum gas does remain in the vapour state, heat is withdrawn from the gas to condense the gas to the liquid phase. The condenser 26 may be a fan for blowing cool air on the part 12b of the circuit 12.

The pump 24 circulates the refrigerant through the part 12b of the circuit 12 from the reservoir 22 for supply to the heat exchanger 16 for again heating and pressurising the refrigerant for supply to the part 12a of the circuit 12. Because the liquid petroleum gas is able to very quickly absorb large amounts of heat and is also able to quickly release that heat energy upon expansion, the energy transfer between the hot exhaust gas supplied to the heat exchanger 16 to the liquid petroleum gas refrigerant, and from the liquid petroleum gas refrigerant to the turbine 31, is able to happen very quickly and very efficiently, thereby producing a substantial amount of energy for driving the energy converting mechanism, such as the generator 30, or some other mechanism such as a piston engine, Stirling cycle or any other heat engine.

The restrictor 14 may comprise a throttle which is microprocessor controlled so as to open the throttle to a prescribed degree to allow high pressure refrigerant to pass from the part 12a of the circuit 12 for supply to the turbine 31 of the generator 30. Thus, by controlling the restrictor 14, the amount of output power produced by the mechanism 30 can be controlled.

Instead of using exhaust gas to provide heat to part 12c of the circuit so waste heat created during air conditioning of the building can be used to provide power generation .

Further still, parts of the circuit 12 can be used at the heat exchanger to cool air to provide air conditioned air for use in a building or the like .

Figure 4 is a flowchart showing heat transfer according to the system of Figure 1. With reference to Figure 4 , liquid petroleum gas in the reservoir 22 is generally at a relatively low pressure of about 100 psi. The pump 24 moves the liquid petroleum gas to the heat exchanger 16 when the liquid petroleum gas is heated and has its pressure increased to about 1000 psi because of the restricted release of the liquid petroleum gas through restrictor 14. Heat is absorbed by the liquid petroleum gas as it converts to a vapour in the heat exchanger 16.

Thus, heat input at the heat exchanger 16 increases the pressure of the liquid petroleum gas so that the liquid petroleum gas in the part 12a of the branch 12 is a high pressure and temperature vapour. The vapour passes through the restrictor 14 to drive the turbine 31 of the generator 30. The energy to drive the turbine 31 is produced from the hot liquid petroleum gas vapour and therefore heat is given up from the liquid petroleum gas vapour which cools the gas. This, together with expansion of the gas downstream of the restrictor 14, causes the liquid petroleum gas to condense back to the liquid phase for supply back to the reservoir 22.

When the generator 30 is driven, output electrical energy is produced for supply to electric motor 34 shown in Figure 1.

Electrical energy to drive the pump 24 may be supplied from the generator 30.

The condenser 26, if provided, may also be powered with electricity produced by the generator 30. Alternatively, the liquid petroleum gas may be allowed to condense simply by its expansion in the part 12b of the branch 12 and due to heat being withdrawn from the liquid petroleum gas when the turbine 31 is driven.

Thus , as shown by the arrows A in Figure 4 , heat flows out of the system into the turbine 31 to create shaft power for conversion into electricity. The control of the throttle controls the amount of power output and the pump 24 moves condensed liquid from the low pressure reservoir

22 to the high pressure zone of the heat exchanger 16. The electric motor 34 may be connected to an electrical energy storage element 36 which may comprise one or more capacitors for storing electrical energy for use in the system. Energy can be stored if excess energy is supplied to the motor or when the motor is turned in reverse (and therefore acts as a generator itself) during braking of a vehicle or even in reverse motion of the vehicle. The electrical energy stored in the capacitor 36 may be used to power the electrical components of the system, such as the pump 24 and condenser 26 if provided, as previously described, or used to recharge batteries (not shown) .

Figure 2 is a schematic view of a vehicle using the embodiment of Figure 1. As shown in Figure 2 , the system 10 produces electrical energy which is supplied to motor 34 which in turn is supplied to a transmission 40 for driving rear wheels 42 of the vehicle. The internal combustion engine 20 is used to supply conventional output rotary power to the transmission 40 which also drives the wheels 42. The transmission 40 is a dual input transmission which can receive rotary input power both from the electrical motor 34 and from the crank shaft (not shown) of the engine 20 so that the transmission 40 is driven either by rotary power from the engine 20, rotary power from the electric motor 34, or rotary power from both the engine 20 and the electric motor 34.

In the embodiment of Figure 2, additional systems 10 (not shown) can be provided in conjunction with other heat generating areas of the vehicle, such as the vehicle brakes for converting heat generated by the vehicle brakes into electrical energy for supply to the capacitor 36 or the electrical motor 34.

Figure 3 is a still further embodiment of the invention in which heat exchanger 16 is in the form of a solar energy collector or the like in which solar energy is converted to heat to heat the liquid petroleum gas refrigerant in the circuit 12 and for producing electricity from the generator 30 for supply to a power grid or to an electrical power circuit of a building, etc.

In still further embodiments, heat exchangers which merely capture heat energy from ambient air and transfer that energy to the liquid petroleum gas in the circuit 12 may also be used.

Apart from the fact that the preferred embodiments can convert waste heat (from engines) and solar energy, such energy not previously utilised greatly reduces the use of fuels and further reduce the cost of electricity to housing and businesses generally. The other aspect of this, which is as equally important, is the environmental benefit both as to reduced emissions and the global cooling benefit. It is well known that the exhaust temperature of an engine used to power vehicles will be around 400°C and using this technology, this will be reduced to something nearer 40°C. Moreover the conversion of solar energy, using this technology, will produce cool air, on a large scale, venting back to atmosphere.

Thus, the various embodiments of the present invention will have significant environmental impact because of the reduction of hot waste gases to the environment and also reducing greenhouse gases .

Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this invention is not limited to the particular embodiment described by way of example hereinabove .

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication , the word "comprise" , or variations such as "comprises" or "comprising", is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention .

Claims

1. An energy supply system comprising: a closed fluid circuit for containing a refrigerant fluid; a heat exchanger for transferring heat to the fluid in the circuit so that heat is absorbed by the fluid to convert the fluid to a high pressure fluid; an energy converting mechanism in the circuit for receiving the high pressure fluid and producing output energy from the high pressure fluid, thereby converting the high pressure fluid to a low pressure fluid; and a pump for supplying the low pressure fluid in the circuit back to the heat exchanger.

2. The system of claim 1 wherein the closed fluid circuit has a restrictor for dividing the circuit into a high pressure part and a low pressure part, so the high pressure fluid can pass through the restrictor to the energy converting mechanism, whereupon expansion of the fluid can take place so that release of energy drives the energy converting mechanism to produce the output energy and allows the fluid to condense to a liquid phase so the pump can supply the liquid phase back to the heat exchanger to heat the fluid and produce the high pressure fluid.

3. The system of claim 1 wherein the circuit includes a reservoir for receiving liquid refrigerant and storing liquid refrigerant for supply to the heat exchanger .

4. The system of claim 1 wherein the energy converting mechanism comprises a piston engine for providing output mechanical energy, a turbine for driving a generator to produce electrical output energy, a Stirling cycle, or an air conditioning system.

5. The system of claim 1 wherein the heat exchanger is for receiving heated exhaust gas and for transferring heat from the heated exhaust gas to the fluid in the circuit so that the exhaust gas is discharged as a cooled exhaust gas .

6. The system of claim 1 wherein the heat exchanger comprises a solar energy collector for collecting solar energy and transferring heat from the solar energy collector to the fluid.

7. The system of claim 1 wherein the heat exchanger is a heat exchanger for transferring heat from ambient hot air to the fluid in the circuit.

8. A drive system for a vehicle comprising: an internal combustion engine; a transmission for receiving rotary power from the internal combustion engine and for driving at least one wheel of the vehicle; an exhaust gas outlet from the internal combustion engine for exit of hot exhaust gas ; a closed fluid circuit containing a refrigerant fluid; a heat exchanger on the circuit for receiving the hot exhaust gas and for transferring heat from the hot exhaust gas to the refrigerant in the circuit; and a heat converting mechanism for receiving high pressure fluid in the circuit and producing secondary output power for supply to at least one of the wheels of the vehicle .

9. The system of claim 8 wherein the circuit includes a pump for circulating fluid through the circuit.

10. The system of claim 9 wherein the pump is for receiving liquid refrigerant which has condensed from the high pressure fluid and for supplying the condensed liquid refrigerant to the heat exchanger.

11. The system of claim 8 wherein the closed fluid circuit has a restrictor for dividing the circuit into a high pressure part and a low pressure part, so the high pressure fluid can pass through the restrictor to the energy converting mechanism, whereupon expansion of the fluid can take place so that release of energy drives the energy converting mechanism to produce the output energy and allows the fluid to condense to a liquid phase so the pump can supply the liquid phase back to the heat exchanger to heat the fluid and produce the high pressure fluid.

12. The system of claim 8 wherein the circuit includes a reservoir for receiving liquid refrigerant and storing liquid refrigerant for supply to the heat exchanger .

13. The system of claim 8 wherein the energy converting mechanism comprises a generator for producing electricity and an electric motor driven by the electricity produced by the generator to provide the secondary output power .

14. The system of claim 8 wherein the transmission is a dual input transmission for receiving input rotary power from the internal combustion engine and the secondary output power from the electric motor, the transmission having an output coupled to at least one of the wheels of the vehicle for driving the at least one of the wheels of the vehicle .

15. The system of claim 8 wherein the system includes an electricity storage element for storing electrical energy produced by the generator and/or electrical energy generated during braking of the vehicle .

16. The system of claim 15 wherein the storage element comprises at least one capacitor.

17. The system of claim 8 wherein the refrigerant fluid comprises liquid petroleum gas or other suitable refrigerant .