RO134665A2 - Thermo-electric generator of high power and efficiency, with pulsed operation - Google Patents

Abstract

The invention relates to a thermoelectric generator of high power and efficiency, pulsating operation. The generator according to the invention consists of a heating source (1), a thermoelectric unit (2) formed by a plurality of thermally rechargeable capacitors, electrically connected in series and thermally connected in parallel, a cooling device (3), a device for the ultra-fast discharge of the thermally rechargeable capacitor in the primary consisting of a single coil of a transformer and a means for converting the ultra-fast DC pulses into AC.

Description

Thermoelectric generator of high power and efficiency, pulsating operation

Thermoelectric generator of high power and efficiency, pulsating operation, with applications in the electrical fields (efficiency of conversion of thermal energy into electricity) and space, refers to a new type of thermoelectric generator obtained by substantially increasing the dimensional factor, surface / thickness pleasant thermoelectric, (A / l), operated stationary (pulsating) with a high power per generator but also a substantial improvement of the efficiency of conversion of thermal energy into electricity by avoiding thermal dissipation of electrical pulse energy with very short life.

Thermoelectric generators traditionally manufactured by mounting in series from an electrical point of view and in thermal parallel of a number N of thermoelectric elements n and p alternatively, operated continuously (DC) and characterized by an open circuit voltage, Voc and a resistance are known. internal, Ri. With the thermoelectric materials used so far, the delivered power / module does not exceed 20-30W and the maximum efficiency varies around 5-6% for temperature differences of the order of 250C.

In order to remove the disadvantages listed above, the present invention proposes a thermoelectric conversion unit using a so-called "thermally rechargeable capacitor" which by substantially increasing at least 100 times the dimensional factor A / L can be a current source of very high current. high (-1000A) and low voltage (~ 3V), a unit that requires a fast pulse operation to avoid the dissipation of the pulse energy in the mass of the thermoelectric plates and their unnecessary overheating.

The present invention proposes the use of common thermoelectric materials, widely used in the profile industry (Bi2Te3 doped n or p) but does not exclude any other present or future thermoelectric material.

The technical problem solved by the invention consists in providing a method of substantial increase of the electric power debited by the thermoelectric source simultaneously with a major improvement of the conversion efficiency of thermal energy into electric energy, keeping all the other advantages of thermoelectric generators.

The thermoelectric generator proposed as an invention solves all the disadvantages listed above for the thermoelectric field by redesigning the thermoelectric unit so as to increase the electric power tens or even hundreds of times and solve the problem of conversion efficiency by taking these ^- huge milks of current and transfer their temporary in a magnetic field in less time than the time of 2019 00336

05/06/2019 life of these pulses. The use of energy transferred in the magnetic field of high frequency ferrites is part of a so-called "up converter" is a method known in the art.

The proposed semiconductor material, BizTes, has certain physical characteristics that dictate the operating frequency and filling factor and the A / L dimensional factor of the semiconductor plates used can be varied depending on the power needs to be provided by this generator.

In the present invention, the frequency, f, and the filling factor, τ = τ _οη / (τ _οη + w) are correlated with, τ = RiC, the time constant of the «thermal rechargeable capacitor» according to the requirement of a maximum operating efficiency . The various assembly assemblies of the generator in fig. 3 which are the subject of the present invention consist of:

A heating source (1) that can use any heat source,

A thermoelectric unit (2) formed by a plurality of “thermally rechargeable capacitors” connected in electrical series and in thermal parallel with dimensional factor, A / l> 100 cm,

A cooling device (3) which may be air-to-air or liquid-to-liquid,

A device for the periodic discharge of the plurality of "thermally rechargeable capacitors" in a single loop of the primary of a transformer (up converter),

A means of consuming the electricity supplied by the secondary of this "up converter" of direct voltage.

To charge these "thermally rechargeable capacitors" the thermal energy is taken from the heater continuously. The loading and unloading times are strictly correlated with the physical parameters and the thickness of the thermoelectric plates used, through the relation τ = RiCi, where Ri is the internal resistance of the thermoelectric unit and C, is the capacitance of the same thermoelectric unit. Because the A / l ratio of the basic capacitor is the same as the internal resistance of the basic thermoelectric plate, τ = ε / σ and in this case the dimensional factor, A / l, can be designed according to the needs of electric power and the operating frequency being the one that controls the conversion efficiency.

Using an electronic switch, the capacitor can be discharged with a given frequency preferably between 100kHz and 500kHz, and a filling factor preferably between 1% and 10%. The ratio of the number of turns in the primary / the number of turns in the secondary depends on the ratio of the obtained voltage ρΈ Thermoelectric Lineage / the desired operating voltage. The term “thermally rechargeable capacitor” is used to identify a combination of heat take-up plate - semiconductor plate - capacitor cooling plate with ultra-fast charging-discharging capacity. This capacitive unit has an inversely proportional capacity and an internal resistance directly proportional to the number of connected capacitors.

and 2019 00336

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The heat source can be any solid liquid or gaseous fuel. Very good electrical and thermal contacts are required between the metal plates that take heat from the hot source and dissipate heat to the cold source so as to obtain the largest possible temperature differences between the hot and the cold face of the thermoelectric material. The heat transfer plates for the hot face and the heat dissipation plates for the cold face are made of copper. In order to avoid the diffusion of copper in the thermoelectric material, both the copper plates and the ones made of thermoelectric material are covered with a Nickel barrier layer or a Nickel-Iron alloy obtained by electroplating using or not electric current when depositing.

The thermoelectric generator according to the invention has the following advantages:

the electric power delivered by the generator can be controlled by the variation in design of the dimensional factor, A / l, depending on the power needs of the thermoelectric generator.

it is thus possible to start manufacturing thermoelectric generators with very high powers never seen before in the field of thermoelectricity.

the conversion efficiency of thermal energy into electricity can be controlled from the operating frequency and the filling factor.

this opens the perspective of the transition of thermoelectric generators from the niche stage of the market to consumer products.

An embodiment of the invention is given below, in connection with Figures 1 to 3, which represent:

Figure 1. Pleasant thermoelectric.

Figure 2. "Thermally rechargeable capacitor" acting as a thermoelectric generator.

Figure 3. Possible arrangement for assembling the "thermally rechargeable condensers" together with the heating and cooling unit. Any other arrangement is not excluded by the present invention.

The images in fig. 1 represents a thermoelectric plate represented from the front and profile with the surface A = 2cm x 2cm = 4cm ² and the thickness of 0.1 cm. This results in a dimensional factor A / l = 40 cm, ie about 400 times larger than traditionally used. The thermoelectric parameters of the B'i2Te3 plate are approximately ~200pV / K and σ ~ ΙΟΟΟΩ ^ οπτ ¹ . The internal resistance of such a plate is R = l / axl / A = 10 ' ³ Ωοπίχ 1/40 cm ^-1 = 25 μ Ω. Assembling 4 subassemblies of 10 pairs of thermoelectric plates as in Figs. 3 in series from an electrical and thermal parallel point of view results in a thermoelectric unit consisting of 40 pairs of rechargeable capacitors of 2019 00336

05/06/2019 thermal. This unit will have an resulting internal resistance Ri = 80 plates x 25 μ Ω / plate = 2 mQ. If between the hot part and the cold part of the thermoelectric unit a temperature difference of 200C is achieved, an open circuit voltage of V = 80 pairs x 200pV / K x 200K results. = 3.2V. The short circuit current of such a unit would be Le - 3.2V / 2m Ω = 1600 A. The power of such a unit is P = V ² / 4Ri = (3.2 ² ) V ² / (4 x 2m Ω) = 1.28 kW in case of stationary operation and P = V ² / Ri = (3.2 ² ) V ² / (2m Ω) = 5.12 kW in case of non-stationary operation.

The difference is made by the unsteady take-up of the current pulses.

Claims (1)

Claim Thermoelectric generator of high power and efficiency, operated pulsating (in pulses), is characterized in that the device is composed of: a heating device, a thermoelectric unit consisting of a multitude of "thermally rechargeable capacitors" connected in series and in parallel, a cooling device, a device for the ultra-fast discharge of the "thermally rechargeable capacitor" in the primary consisting of a single turn of a transformer (up converter) and a means for converting ultra-fast DC pulses into domestic DC 2, and the device according to claim 1 which maintains continuous thermal contact and extracts electricity from the device by pulsating, ultrafast discharge of the "thermally rechargeable capacitor".