TWI805965B - Thermal energy conversion system and method for controlling a working fluid thereof - Google Patents

Abstract

A thermal energy conversion system is provided to solve the problem of kinetic energy loss of the conventional thermal energy conversion system adjusting the circulation flow and the rotating speed of the generator. The system comprises a starter generator with a drive shaft, two permanent magnet drivers respectively connected to the two ends of the drive shaft, an expander, a compressor, an evaporator, and a condenser. Each permanent magnet driver comprises an air gap with adjustable size. The expander and the compressor are respectively connected to the two permanent magnet drivers. The expander converts the internal energy of a working fluid with gaseous state into rotational kinetic energy. The compressor converts the rotational kinetic energy into kinetic energy of the liquid working fluid. The evaporator receives the liquid working fluid from the compressor and evaporates the working fluid, then imports the gaseous working fluid into the expander. The condenser receives the gaseous working fluid from the expander and condenses the working fluid, then imports the liquid working fluid into the compressor. A method for controlling the working fluid of the thermal energy conversion system is also provided.

Description

Thermoelectric power generation system and its working fluid flow control method

The invention relates to a renewable energy power generation technology, in particular to a thermoelectric power generation system that improves energy conversion efficiency and is suitable for low-temperature waste heat and a method for regulating the flow of working fluid.

The thermoelectric power generation system uses the principle of heat exchange. The working fluid with a low boiling point is evaporated into a gaseous state by heat supply from a heat source, and the expansion pressure of the gaseous working fluid is used to drive the turbine to generate electricity, and then the cooling source absorbs heat to condense the working fluid into a liquid state. The cycle of repeated expansion and compression of the working medium continues to generate electricity.

The known thermoelectric power generation technology uses stable and large-scale cold and heat sources, such as deep low-temperature seawater and surface normal-temperature seawater, which can provide temperature differences that do not change with seasons or time, so that the generator can output stable power and energy conversion Efficiency can meet economic benefits. However, when the heat source of thermoelectric power generation is discontinuous heat energy, such as industrial waste heat, geothermal heat or biomass heat, etc., in order to maintain stable power generation, pumps and throttle valves must be added to the circulation pipeline to adjust the flow of working fluid, or The use of frequency converters to control the generator speed causes the thermoelectric power generation system to consume extra power, reducing the overall energy conversion efficiency, which is not conducive to the promotion and application of low-temperature waste heat reuse technology.

In view of this, it is necessary to improve the conventional thermoelectric power generation system.

In order to solve the above problems, the object of the present invention is to provide a thermoelectric power generation system, which is The rotational kinetic energy can be fully utilized to reduce additional energy consumption.

The second object of the present invention is to provide a thermoelectric power generation system that can adjust the transmission torque between the various devices.

Another object of the present invention is to provide a method for regulating the flow of working fluid in a thermoelectric power generation system, which can control fluid circulation and stabilize power generation.

Another object of the present invention is to provide a method for regulating the flow of working fluid in a thermoelectric power generation system, which can be applied to low-temperature waste heat environments with discontinuous heat sources.

The elements and components described throughout the present invention use the quantifier "a" or "an" only for convenience and to provide the usual meaning of the scope of the present invention; in the present invention, it should be interpreted as including one or at least one, and singular The notion of also includes the plural unless it is obvious that it means otherwise.

The thermoelectric power generation system of the present invention comprises: a starter generator with a transmission shaft; two permanent magnet governors connected to the two ends of the transmission shaft respectively, each of the permanent magnet governors has two rotating discs, and the two rotating An adjustable air gap is formed between the disks, one of the rotating disks is coaxially connected to the transmission shaft; an expander is connected to the other rotating disk of the permanent magnet governor opposite to the transmission shaft, and the expander will The internal energy of a gaseous working medium is converted into rotational kinetic energy; a compressor is connected to the other rotating disk of the permanent magnet governor relative to the transmission shaft, and the compressor converts the rotational kinetic energy into the liquid working medium cyclic kinetic energy, the compressor has a power element, the rotating shaft of the power element is connected to the permanent magnet governor, and the power element pushes the liquid working fluid to flow; an evaporator is respectively connected to the expander and the compressor, The evaporator receives the liquid working fluid from the compressor, and the working fluid evaporates into a gaseous state and then introduces the expander; a condenser is connected to the expander and the compressor respectively, and the condenser receives the gaseous working fluid from the expander. The working fluid, the working fluid is condensed into a liquid state and then introduced into the compressor; a sensing unit, the sensing unit detects the pressure and temperature of the working fluid entering the expander; and a processing unit receives and based on the sensing The pressure and temperature detected by the unit to adjust the air gap of the permanent magnet governor size.

The working fluid flow control method of the thermoelectric power generation system of the present invention includes: a motor starting step, the starter generator receives an applied current, the starter generator starts to rotate and gradually increases the speed; a working medium flow step, the starter generator The air gap between the first permanent magnet governor and the compressor changes from large to small, the starter generator transmits torque to the compressor, the compressor starts to rotate and gradually accelerates, and the compressor drives the working fluid Start the cycle; a turbine rotation step, the gaseous working medium does work on the expander, and the expander starts to rotate; a power generation step, the second permanent magnet governor between the starter generator and the expander The air gap changes from large to small, the expander transmits torque to the starter generator, the speed of the starter generator increases and switches to the power generation state; and a fine-tuning step, detecting the pressure and temperature of the working fluid entering the expander, According to the saturation temperature condition of the working fluid, the size of the air gap of the first permanent magnet governor is adjusted to change the rotating speed of the compressor to adjust the flow of the working fluid.

Accordingly, the thermoelectric power generation system of the present invention and the method for regulating the flow of working fluid thereof can make full use of the rotational kinetic energy and reduce additional energy consumption, and by changing the size of the air gap of the two permanent magnet governors, the speed of the starter generator and the compressor can be adjusted, which has the functions of controlling the fluid circulation and stabilizing the power generation, and is applicable In the low-temperature waste heat power generation technology with unstable heat source supply, in addition, the power element can convert the rotational kinetic energy into the kinetic energy of the liquid working medium, which has the effect of adjusting the flow rate and flow rate of the working medium.

Wherein, the disk surfaces of the two rotating disks of each permanent magnet governor are opposite and do not directly contact each other. The rotating shaft of one of the rotating disks is connected to a telescopic piece, and the rotating disk moves axially through the telescopic piece to adjust the air gap. size. In this way, the smaller the air gap, the greater the torque generated by the permanent magnet governor, which has the effect of adjusting torque and rotating speed.

Wherein, the expander has a turbine and a cavity, the turbine divides the cavity into a high-pressure section and a low-pressure section, and the gaseous working fluid enters the low-pressure section from the high-pressure section and drives the turbine Rotate, the shaft of the turbine is connected to the permanent magnet governor. In this way, the working medium can do work on the turbine, which has the effect of driving the turbine and the permanent magnet governor to rotate.

It also includes a recuperator, which is located at the outlet of the expander to collect the waste heat of the gaseous working fluid. In this way, the recuperator can use waste heat to preheat the liquid working fluid entering the evaporator, which has the effect of improving heat exchange efficiency and reusing waste heat.

Wherein, the fine-tuning step adjusts the size of the air gap of the second permanent magnet governor, and changes the rotation speed of the starter generator to adjust the power generation. In this way, the fine-tuning step can avoid overload or shortage of the power generation of the starter generator, and has the effect of stabilizing the power generation.

Wherein, the fine-tuning step detects the rotation speed and power generation of the starter generator, and adjusts the size of the air gap of the second permanent magnet governor according to the speed and power generation of the starter generator. In this way, the fine-tuning step can adjust the torque of the starter generator driven by the expander in real time, and has the effect of maintaining the rotation speed and power generation of the starter generator.

1: Start the generator

11: Drive shaft

2: Permanent magnet governor

2a: The first permanent magnet governor

2b: The second permanent magnet governor

21: Rotating disk

22: Telescopic piece

3: Expander

31:Turbo

32: Cavity

33: High pressure section

34: Low pressure section

4: Compressor

41: Power components

5: Evaporator

6: Condenser

G: air gap

S1: Motor start step

S2: Working fluid flow step

S3: Turbine rotation step

S4: power generation step

S5: Fine-tuning steps

[Fig. 1] A system block diagram of a preferred embodiment of the present invention.

[Fig. 2] An enlarged view of a partial structure of a preferred embodiment of the present invention.

[Fig. 3] A partial perspective view as shown in Fig. 2.

[Fig. 4] is a diagram of the steps of the preferred embodiment of the present invention.

[Fig. 5] It is a graph showing the variation of the rotational speed of each element in each step as shown in Fig. 4.

In order to make the above-mentioned and other purposes, features and advantages of the present invention more obvious and understandable, the preferred embodiments of the present invention are specifically cited below, together with the accompanying drawings, and are described in detail as follows:

Please refer to Fig. 1, which is a preferred embodiment of the thermoelectric power generation system of the present invention, comprising a starter generator 1, two permanent magnet governors 2, an expander 3, a compressor 4, and an evaporator 5 and a condenser 6, the starter generator 1 is respectively connected to the expander 3 and the compressor 4 through the two permanent magnet governors 2, and the compressor 4 is connected to the evaporator 5, the expander 3 and the The condenser 6 is connected back to the compressor 4 to form a circulation path for a working fluid to circulate.

Please refer to Figure 2, the starter generator 1 has the function of combining the drive motor and the power generation device. When the current is input into a coil stator, it drives a permanent magnet rotor to rotate, and it can be used as a motor; when the external power acts on the When the permanent magnet rotor rotates relative to the coil stator, the coil stator generates induced current, which can be used as a generator. The starter generator 1 has a transmission shaft 11 which rotates synchronously with the permanent magnet rotor.

Please refer to Figures 2 and 3, the two permanent magnet governors 2 are respectively connected to the two ends of the drive shaft 11 of the starter generator 1, each of the permanent magnet governors 2 has two rotating discs 21, and the two permanent magnet governors 2 The disk surfaces of the rotating discs 21 are opposite and do not directly contact, so that an air gap G is formed between the two rotating discs 21. The two rotating discs 21 can be respectively permanent magnets and conductors. Law (Lenz's Law) Torque can be transmitted between the two rotating discs 21, when one of the rotating discs 21 actively rotates, the other rotating disc 21 can be driven to rotate passively through the torque, and the smaller the air gap G is, the more The greater the torque. Each of the permanent magnet governors 2 has a telescopic part 22 in addition, and the telescopic part 22 is connected to the rotating shaft of one of the rotating discs 21, and the rotating shaft of the other rotating disc 21 is connected to the transmission shaft 11, so that the two rotating discs 21 1. The telescopic part 22 and the transmission shaft 11 can rotate coaxially, and the telescopic part 22 can be extended or shortened in the axial direction, and the rotating disk 21 can be moved axially to adjust the size of the air gap G, which has the ability to adjust the torque and the effect of speed.

Please refer to Figure 2, the expander 3 has a turbine 31 and a cavity 32, the turbine 31 is located in the cavity 32, and the cavity 32 is divided into a high-pressure section 33 and a low-pressure section by the turbine 31 Section 34, by introducing high-temperature and high-pressure gaseous working fluid into the high-pressure section 33, making the working fluid pass through the The turbine 31 works on the turbine 31 to drive the turbine 31 to rotate, and the working fluid consumes energy to form a relatively low-temperature and low-pressure gaseous working fluid that enters the low-pressure section 34 . Please refer to Fig. 3 again, the rotating shaft of the turbine 31 is connected to the telescopic member 22 of the permanent magnet governor 2, so that the turbine 31, the telescopic member 22 and the rotating disk 21 connected to the telescopic member 22 can be coaxial rotate.

Please refer to the 2nd and 3 shown, the compressor 4 has a power element 41, the rotating shaft of the power element 41 is connected to the telescopic part 22 of the permanent magnet governor 2, so that the power element 41, the telescopic part 22 The rotating disk 21 connected with the telescopic member 22 can rotate coaxially. The power element 41 can be a pump impeller, and when the power element 41 rotates, energy can be transferred to the liquid working fluid passing through the compressor 4, so that the flow rate of the working fluid can be increased to obtain kinetic energy, or the temperature of the working fluid can be increased. The system obtains internal energy, and the compressor 4 series has the function of adjusting the flow rate of the working medium.

Please refer to Figure 1, the evaporator 5 exchanges heat with a heat source, the evaporator 5 receives the low-temperature liquid working fluid from the compressor 4, and the working fluid absorbs the heat provided by the heat source in the evaporator 5. Heat energy evaporates the working fluid into a gaseous state and raises the temperature and pressure, and the evaporator 5 then introduces the high-temperature and high-pressure gaseous working medium into the expander 3 .

The condenser 6 exchanges heat with a cold source. The condenser 6 receives the gaseous working medium from the expander 3. The cold source absorbs the heat energy of the working medium through the condenser 6 to condense the working medium into a liquid state. The condenser 6 then guides the liquid working medium into the compressor 4 .

The energy source of the thermoelectric power generation system of the present invention is an external current input to the starter generator 1 to drive the motor to rotate, and the expander 3 receives the internal energy of the working fluid and converts it into rotational kinetic energy, and then through the two permanent magnet governors 2 Transmit the rotational kinetic energy to the starter generator 1 and the compressor 4 in sequence, the starter generator 1 converts the kinetic energy into electrical energy for storage or use through the generator function, and the compressor 4 converts the rotational kinetic energy into the working fluid Kinetic energy and internal energy, and drive this working medium cycle; Again, this working medium absorbs heat energy in this evaporator 5 and changes from liquid state to gaseous state, then this working medium releases energy in this expander 3 and this condenser 6, and After the condenser 6 changes from the gaseous state to the liquid state, and the working fluid returns to the liquid state, the The compressor 4 controls the flow rate and re-inputs the working fluid into the evaporator 5 to form a cycle.

The thermoelectric power generation system of the present invention can also have a reheater, and the reheater can be located at the outlet of the expander 3 (not shown in the figure), and the waste heat discharged by the gaseous working medium in the gaseous state of the expander 3 can consume energy Collected by the reheater, the waste heat is used by the reheater to preheat the liquid working fluid entering the evaporator 5, and the waste heat can also be used for heating devices such as water heaters or heating.

The thermoelectric power generation system of the present invention can also have a sensing unit located in the expander 3 (not shown in the figure), the pressure and temperature of the working fluid entering the expander 3 are detected by the sensing unit, and sent back to a processing unit, the processing unit changes the size of the air gap G of the permanent magnet governor 2 according to the pressure and temperature changes of the working medium, and can control the flow of the working medium by adjusting the speed of the compressor 4 to Ensure that the working medium can be completely vaporized when it enters the expander 3, avoiding the coexistence of liquid and gas in the expander 3 and not being able to generate enough pressure to drive the expander 3 to rotate, and has the function of elastic self-adaptive regulation of the flow rate of the working medium.

Please refer to Figures 4 and 5, which is a preferred embodiment of the method for regulating the flow of working medium in the thermoelectric power generation system of the present invention, which includes a motor starting step S1, a working medium flowing step S2, a turbine rotating step S3, A generating step S4 and a fine-tuning step S5.

The step S1 of starting the motor is that the starter generator 1 receives an external current in a motor state, so that the starter generator 1 starts to rotate and gradually increases the speed.

The working fluid flowing step S2 is to transmit the torque of the starter generator 1 to the compressor 4 through the first permanent magnet governor 2a between the starter generator 1 and the compressor 4, so that the compressor 4 Start to rotate and gradually accelerate, the compressor 4 can drive the working fluid to start circulation, and the acceleration of the speed of the starter generator 1 slows down, when the speed of the starter generator 1 and the compressor 4 reaches a steady state, the The rotation speed of the starter generator 1 is greater than the rotation speed of the compressor 4 . In this embodiment, the air gap G of the first permanent magnet governor 2a is changed from large to small, so that the torque of the compressor 4 driven by the starter generator 1 increases gradually.

The turbine rotating step S3 is that the gaseous working fluid does work on the expander 3, so that the expander 3 starts to rotate. The flow rate of the working fluid passing through the expander 3 is positively correlated with the speed of the expander 3. When the flow rate of the working medium is stable, the expander 3 can rotate at a constant speed.

The power generation step S4 is to transmit the torque of the expander 3 to the starter generator 1 through the second permanent magnet governor 2b between the starter generator 1 and the expander 3, so that the starter generator 1 As the speed increases, the starter generator 1 can be switched from the motor state to the power generation state. Since the starter generator 1, the expander 3 and the compressor 4 rotate coaxially through the two permanent magnet governors 2a, 2b, the The rotation speed of the compressor 4 increases, and the expander 3 sequentially transmits torque to the starter generator 1 and the compressor 4 , which will cause the rotation speed of the expander 3 to decrease. In this embodiment, the air gap G of the second permanent magnet governor 2 b is changed from large to small, so that the torque of the starter generator 1 driven by the expander 3 increases gradually.

The fine-tuning step S5 is to control the rotating speed of the compressor 4 to change the flow rate of the working fluid by adjusting the size of the air gap G of the first permanent magnet governor 2a, so as to ensure that the working fluid enters the expander At 3 o'clock, it can be completely vaporized, avoiding the coexistence of liquid and gas in the working medium in the expander 3 and not being able to generate enough pressure to drive the expander 3 to rotate. In addition, when the rotation speed of the starter generator 1 is too high and the power generation is overloaded, the speed of the starter generator 1 can be reduced by increasing the air gap G of the second permanent magnet governor 2b; When the rotation speed of the starter generator 1 is too low to cause insufficient power generation, the rotation speed of the starter generator 1 can be increased by reducing the air gap G of the second permanent magnet governor 2b. Therefore, adjust the The size of the air gap G of the second permanent magnet governor 2b has the function of controlling the rotation speed of the starter generator 1 and supplying stable power generation.

In addition, the fine-tuning step S5 can also detect the pressure and temperature of the working fluid entering the expander 3, control the flow of the working fluid according to the saturation temperature of the working fluid, and detect the speed and power generation of the starter generator 1. To adjust the torque of the starter generator 1 driven by the expander 3 in real time. When the heat energy supplied by the heat source is unstable, the fine-tuning step S5 adjusts the two permanent magnet governors 2a, 2b, it can maintain the circulation of the working fluid and stabilize the power generation.

In summary, the thermoelectric power generation system and its working medium flow control method of the present invention can make full use of the rotational kinetic energy by coaxially connecting the starter generator, the expander and the compressor with the two permanent magnet governors, To reduce additional energy consumption, the temperature and pressure input to the expander can be detected in real time through the detector, and the value can be fed back to adjust the air gap size of the first permanent magnet governor, so that the compressor can be used without The flow rate of the working medium can be adjusted flexibly and adaptively, and the system can still operate stably and efficiently even if the heat source is unstable.

Although the present invention has been disclosed by using the above-mentioned preferred embodiments, it is not intended to limit the present invention. It is still within the scope of this invention for anyone skilled in the art to make various changes and modifications relative to the above-mentioned embodiments without departing from the spirit and scope of the present invention. The technical scope protected by the invention, therefore, the scope of protection of the present invention should be defined by the scope of the appended patent application.

1: Start the generator

2: Permanent magnet governor

3: Expander

4: Compressor

5: Evaporator

6: Condenser

Claims (7)

A thermoelectric power generation system, comprising: a starter generator with a transmission shaft; two permanent magnet speed regulators respectively connected to the two ends of the transmission shaft, each of the permanent magnet speed regulators has two rotating disks, and the two rotating disks An adjustable air gap is formed between them, one of the rotating discs is coaxially connected to the transmission shaft; an expander is connected to the other rotating disc of the permanent magnet governor opposite to the transmission shaft, and the expander converts the gaseous The internal energy of a working medium is converted into rotational kinetic energy; a compressor is connected to the other rotating disk of the permanent magnet governor relative to the transmission shaft, and the compressor converts the rotational kinetic energy into the liquid working medium. Circulating kinetic energy, the compressor has a power element, the rotating shaft of the power element is connected to the permanent magnet governor, and the power element promotes the flow of the working fluid in liquid state; an evaporator is respectively connected to the expander and the compressor, the The evaporator receives the liquid working fluid from the compressor, and the working fluid evaporates into a gaseous state and then introduces the expander; a condenser is connected to the expander and the compressor respectively, and the condenser receives the gaseous working fluid from the expander. Working fluid, the working fluid is condensed into a liquid state and then introduced into the compressor; a sensing unit, the sensing unit detects the pressure and temperature of the working fluid entering the expander; and a processing unit receives and according to the sensing unit The detected pressure and temperature are used to adjust the size of the air gap of the permanent magnet governor. The thermoelectric power generation system according to claim 1, wherein the surfaces of the two rotating disks of each permanent magnet governor are opposite and not in direct contact, and the shaft of one of the rotating disks is connected to a telescopic member, and the rotating disk passes through the telescopic member Move axially to adjust the size of the air gap. The thermoelectric power generation system according to claim 1, wherein the expander has a turbine and a cavity, and the turbine divides the cavity into a high-pressure section and a low-pressure section, and the gaseous working fluid is fed from the high-pressure The pressure section enters the low-pressure section and drives the turbine to rotate, and the rotating shaft of the turbine is connected to the permanent magnet governor. The thermoelectric power generation system according to Claim 1 further includes a recuperator, which is located at the outlet of the expander to collect the waste heat of the gaseous working medium. A method for regulating the flow rate of working fluid in a thermoelectric power generation system, using the thermoelectric power generation system according to any one of claims 1 to 4, including: a motor starting step, the starter generator receives an external current, and the starter generator starts Rotate and gradually increase the speed; a working fluid flow step, the air gap of the first permanent magnet governor between the starter generator and the compressor changes from large to small, the starter generator transmits torque to the compressor, The compressor starts to rotate and gradually accelerates, and the compressor drives the working medium to start circulating; a turbine rotation step, the gaseous working medium works on the expander, and the expander starts to rotate; a power generation step, the starting generator The air gap of the second permanent magnet governor between the expander and the expander is changed from large to small, and the expander transmits torque to the starter generator, and the speed of the starter generator is increased and switched to a power generation state; and a fine adjustment step, detecting the pressure and temperature of the working fluid entering the expander, adjusting the size of the air gap of the first permanent magnet governor according to the saturation temperature condition of the working fluid, so as to change the speed of the compressor to adjust the The flow of working fluid. The working fluid flow control method of a thermoelectric power generation system according to claim 5, wherein the fine-tuning step adjusts the size of the air gap of the second permanent magnet governor, and changes the speed of the starter generator to adjust the power generation. The method for regulating the flow of working fluid in a thermoelectric power generation system according to claim 6, wherein the fine-tuning step detects the speed and power generation of the starter generator, and adjusts the second permanent magnet speed regulation according to the speed and power generation of the starter generator The size of the air gap in the device.

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