CROSS REFERENCE OF RELATED APPLICATION

The present invention claims priority under 35 U.S.C. 119(a-d) to CN 202010087252.8, filed Feb. 11, 2020.

BACKGROUND OF THE PRESENT INVENTION

Field of Invention

The present invention relates to the field of low-temperature heat source power generation technology, and more particularly to a power generation device and method using organic working fluid for circulation without pump and valve, namely a flash jet natural cycle.

Description of Related Arts

Thermal energy is the most widely used form of energy in the national economy and people's lives. In recent years, many scholars have done a lot of research on the utilization of various low-temperature thermal energies. They are various industrial waste heat, solar energy, geothermal energy, biomass energy, etc., and the total amount is huge.

At present, the main utilization methods of low-temperature thermal energy are organic Rankine cycle, Kalina cycle and supercritical carbon dioxide cycle. The above methods have the problems of complex structure, low efficiency and high cost. Therefore, a new power generation device is proposed which is driven by the combination of flash force and gravity without pump and valve. It can be referred to as flash jet natural cycle.

SUMMARY OF THE PRESENT INVENTION

The present invention provides a power generation device and method using organic working fluid for circulation without pump and valve. Instead of using a working fluid pump and a turbine, the flash injection tube and the upper magnetic sphere are employed to drive the cycle and convert electricity in the power generation device provided by the present invention. Notably, the lower magnetic sphere and the upper magnetic sphere are able to replace the valves in some pumpless organic Rankine cycle. Therefore, the power generation device has advantages of simple structure, low cost and high efficiency.

Accordingly, the power generation device using organic working fluid for circulation without pump and valve comprises a flash injection tube, a magnetic sphere motion tube, a storage tank, a working fluid descent tube, a lower nozzle, a lower magnetic sphere, an upper nozzle, an upper magnetic sphere, a conical expansion part, a finned tube, a concentric outer tube, a heat source, a linear generator coil, a rectifier circuit, and a load, wherein the flash injection tube, the magnetic sphere motion tube, the conical expansion part, a lower portion of the storage tank and the working fluid descent tube are connected with each other in sequence to form a main loop; an upper portion of the storage tank, the finned tube and the lower portion of the storage tank are connected with each other for forming a cooling loop; the lower nozzle and the lower magnetic sphere are provided at a lower end of the flash injection tube, which forms a one-way valve to restrict fluid to move upwardly only; the upper nozzle and the upper magnetic sphere are provided at an upper end of the flash injection tube, which forms a flash nozzle to drive the upper magnetic sphere to move upwardly through the fluid; the upper magnetic sphere is able to move in the magnetic sphere motion tube; the flash injection tube and the concentric outer tube form a tube and shell heat exchanger; the heat source is used to provide shell side fluid of the tube and shell heat exchanger and transfer heat to tube side fluid to cause the fluid flashing; the conical expansion part is provided at an upper end of the magnetic sphere motion tube away from the flash injection tube; the linear generator coil is wound around the magnetic sphere motion tube, the linear generator coil is connected with the rectifier circuit, the rectifier circuit is connected with the load; the upper magnetic sphere, the magnetic sphere motion tube, the linear generator coil and the rectifier circuit form a linear generator.

Preferably, the main loop is filled with the organic working fluid with low boiling point.

Preferably, both the lower nozzle and the upper nozzle are converging-diverging nozzles.

Preferably, both the upper magnetic sphere and the lower magnetic sphere are neodymium iron boron magnetic spheres.

Preferably, a diameter of the lower magnetic sphere and the upper magnetic sphere is smaller than an inner diameter of the flash injection tube and the magnetic sphere motion tube, respectively.

Preferably, the finned tube is used for condensation of the working fluid by the method of air cooling or water cooling.

Also, a power generation method of the power generation device using organic working fluid for circulation without pump and valve is provided, the power generation method, namely a flash jet natural cycle, comprises the steps of:

increasing temperature and pressure of a part of the working fluid in the flash injection tube by heating the flash injection tube with the heat source, the part of the working fluid in the flash injection tube pushing away the upper magnetic sphere when the pressure overcomes gravity of the upper magnetic sphere and a part of the working fluid in the magnetic sphere motion tube, wherein the pressure of the part of the working fluid in the flash injection tube suddenly drops; simultaneously, the part of the working fluid in the flash injection tube experiences a quasi-isothermal rapid expansion process and quickly approaches initial pressure of the power generation device;

since the initial pressure of the power generation device is lower than saturated steam pressure of the part of the working fluid in the flash injection tube after heated, the part of the working fluid in the flash injection tube will gradually overheat; the superheated working fluid undergoing a phase transition and producing a large number of bubble nucleus, resulting in rapid gasification, that is, producing a lot of bubbles, namely flashing;

the bubbles expanding rapidly till bursting, wherein the expansion and bursting process produces a strong flash force, ejecting the upper magnetic sphere upwardly under an action of the flash force; the upper magnetic sphere moving upwardly in the magnetic sphere motion tube, wherein in order to control a motion height of the upper magnetic sphere, the conical expansion part is provided at an upper end of the magnetic sphere motion tube away from the flash injection tube; wherein after driving the upper magnetic sphere to move upwardly, the part of the working fluid in the flash injection tube undergoes a spontaneous process from a quasi-steady state to a steady state, which is from formation and growth of the bubble nucleus to a gas-liquid two-phase state;

the upper magnetic sphere falling back to an initial position under an action of gravity since a cross section from the magnetic sphere motion tube to the conical expansion part is increased and the steam rises up and flows to the storage tank, a velocity of the part of the working fluid in the magnetic sphere motion tube is decreased, a thrust applied to the upper magnetic sphere is decreased, wherein during above steps, the lower magnetic sphere acts as a one-way valve for completely applying a flash force of the part of the working fluid in the flash injection tube to drive the upper magnetic sphere to move upwardly and allowing a part of the working fluid in the storage tank entering the flash injection tube again;

after gas-liquid mixture in the part of the working fluid in the flash injection tube entering the storage tank, gas-phase separation taking place; since a density of gas-phase working fluid is smaller than a density of liquid-phase working fluid, the gas-phase working fluid flowing towards an upper portion of the storage tank, dissipating heat through the finned tube, condensed fluid flowing back to the storage tank, flowing into the flash injection tube again under an action of gravity, and starting a new cycle;

wherein linear reciprocating movement of the upper magnetic sphere causes a magnetic flux change in the linear generator coil; according to Faraday's law of electromagnetic induction, an induced current in the linear generator coil is produced and is able to be used by the load after modulated by the rectifier circuit.

The power generation method for low-temperature heat energy, provided by the present invention, has innovations as follows.

(1) Compared with the traditional organic Rankine cycle (ORC) power generation system, the power generation device provided by the present invention adopts natural circulation in the main loop and cooling loop, replaces the booster pump of ORC power generation system with the flash injection tube which reduces the power consumption of the pump. What's more, the upper magnetic sphere and the magnetic sphere motion tube replace the expander which avoids the sealing problem.

(2) Compared with the pumpless ORC power generation system, the upper and lower magnetic spheres arranged at the upper and lower ends of the flash injection tube in the present invention play the same role as the valves installed before the evaporator and the expander.

(3) Compared with the usual power generator device, the upper magnetic sphere and the magnetic sphere motion tube are like the mover and stator of linear generator, which replace the indispensable electric generator.

Due to the special design, the power generation device provided by the present invention has advantages of high efficiency, simple structure and low cost. It is able to be used in the fields such as small generators, distributed power generation systems, and low-temperature industrial waste heat recovery.

