JPS5857514B2 - Suisohatsuseihosyuusouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrogen generation and collection device that generates hydrogen gas by electrolyzing seawater using the power generated by a thermoelectric generator that uses solar radiant energy as a heat source.

Most of the energy sources currently used by humans are fossil energy resources such as coal, oil, and natural gas.

However, when these coals, petroleum, etc. are burned, they produce large amounts of carbon dioxide gas, sulfur dioxide gas, and other harmful substances, causing air pollution, and natural gas extraction causes many problems, such as causing ground subsidence.

Furthermore, it is clear that if mining continues at the current rate, the fossil energy resources mentioned above will be exhausted in the near future, and there is now an urgent need to save energy and develop next-generation energy.

Hydrogen gas is one of the promising energies of the future, and it can be easily obtained by electrolyzing seawater, which is abundant on the earth, and its quantity is inexhaustible.

It is clear that the use of hydrogen gas as a fuel provides a completely harmless energy source, which is extremely important and appropriate.

The DC power sources necessary to obtain such hydrogen gas include various chemical batteries, rectifiers, and DC generators, but these are extremely difficult to use for long periods in remote areas or at sea due to maintenance constraints and are not practical. The current situation is that progress is slow.

The present invention has been made in view of the above-mentioned points, and is made by absorbing solar radiation energy by the heat absorption surface of the high temperature junction of a thermoelectric generator to obtain a high temperature, and by immersing the radiator of the low temperature junction in seawater to radiate the heat. A hydrogen generation and collection device that obtains a low temperature by using a radiator, and uses the generated electric power to electrolyze seawater to generate hydrogen gas, and collect and store this hydrogen gas. This is what we are trying to provide.

The present invention will be described in detail below based on one embodiment of the accompanying drawings.

In the figure, Pl, P2,...P6 and N1,
N2, ..., N6 are P-type and N-type semiconductor thermoelectric elements (hereinafter referred to as thermoelectric elements), 31-36.41-4, respectively
7 is a high-temperature bonding metal piece and a low-temperature bonding metal piece, and each of the above P-type thermoelectric elements and N-type thermoelectric element is bonded to form a thermocouple, and at the same time, each thermocouple P1-N□, P2-N2... ..., P6
-N6 are connected in series to form one thermoelectric generator with a large electromotive force.

Note that the respective joining metal pieces 31 to 36 and 41 to 47 are electrically insulated from each other.

Each of the high-temperature bonded metal pieces 31 to 36 is thermally bonded to the heat absorbing plate 5 via a melter 2 filled with a suitable heat storage agent 6.

The heat storage agent 6 is a mixture of, for example, NaK, K, halogen compounds, or nitrates, and is used to store solar energy during sunshine and to prevent large changes in temperature at the PN junction of the thermoelectric element.

The surface of the heat absorbing plate 5 is coated with black or treated with black copper oxide, silicon oxide, etc. to have a suitable transverse absorption surface in order to improve heat absorption and prevent heat radiation.

Furthermore, the heat absorbing plate 5 is covered with a transparent plate 7, such as a plastic plate or a glass plate, in order to reduce heat loss due to air convection and re-radiation and improve absorption efficiency.

The thermoelectric generator, heat absorption plate 5, transparent plate 7, etc. are housed in the storage container 1 as described above.

A condenser 8, such as a lens, is for condensing and projecting sunlight onto a heat absorbing surface, and is disposed at a suitable position above the transparent plate 7.

The condenser 8 may include a condenser mirror or Fresnel in addition to the lens, and may be used as appropriate depending on the conditions of use.

In this way, the high temperature junction of the thermoelectric generator can absorb solar radiant energy with sufficient efficiency and obtain a high temperature.

The low-temperature bonding metal pieces 41 to 47 are electrodes 9a1 that also serve as radiators.
9b, respectively, and furthermore, thermoelectric elements P□,
N6 is electrically connected to electrodes 9a and 9b through bonding metal pieces 41 and 47, so that electrode 9a becomes an anode and electrode 9b becomes a cathode.

The electrodes 9a19b are separated by a suitable partition 10, such as asbestos cloth, to prevent hydrogen gas and oxygen gas generated at both electrodes from mixing.

A suitable slope 11 is provided on the upper part of the twisted electrodes 9a and 9b so that the floating hydrogen gas and oxygen gas are led out of the container 1.

The hydrogen gas generated and floated on the electrode 9b is once collected by a collection pipe 12 and then introduced into a tank 14 via a pipe 13 and stored therein.

The hydrogen generation and collection device configured as described above is installed in a suitable flotation device 1.
5. For example, the thermoelectric generator and the tank 14 are floated on the sea using a squid or a buoy, and the electrode 9a
, 9b are immersed in seawater 16.

The Seebeck coefficient at the operating temperature of a pair of thermoelectric elements is α
(77℃), electrical resistance R (Ω), thermal coefficient K (W/
'C), when thermal energy of Qa (W) is given to the high temperature side, the high temperature junction is TH (0K) and the low temperature junction is T
c ('K) and a current of I (A) flows through the external load. On the other hand, the thermal energy Qd (w) released to the low temperature side is as follows.

Therefore, the electrical output is P.

(W), then P.

, η are efficient η (knowledge It is expressed as

Now, for example, the cross-sectional area A (crit) and length L of each element
N of B12To3 system with ratio A/L = 0.08 (cm )
type, P type thermoelectric element has a high temperature junction temperature TH = 523 (
'K), cold junction temperature T.

When operated at −293 ('K), the Seebeck coefficient α, electrical specific resistance ρ, and thermal conductivity γC of the pair of elements are as follows.

Therefore, the electric resistance R and thermal coefficient of a pair of elements are respectively becomes.

Therefore, when the electrical resistance between the electrodes of seawater is 1 (Ω), in-begence matching is obtained with 25 element pairs, and at this time the electrical output condition is maximum, and the above equations (1), (2),
From (3) and (4), the absorbed energy Qa of the heat absorption surface is Qa
= 30.35 (W) and closed circuit output voltage 1.5 (V)
, a current of 1.5 (A) can be obtained, and the output Po =
The efficiency is 2.25 (W) yl = 7.4 (%), and about 6.3 (A) of hydrogen can be obtained in standard conditions in 10 hours.

Therefore, if this device, which uses 4,500 thermoelectric generators (UNIS) formed from 25 pairs of the above-mentioned elements, is floated on the ocean and its floating position can be moved, solar energy can be effectively used throughout the year. Approximately 10
It is possible to obtain kW of electricity and collect approximately 10,000 - of hydrogen gas per year.

Incidentally, although the above embodiment describes the case where a semiconductor is used as the thermoelectric element, the present invention is not limited to this, and it goes without saying that other thermoelectric elements such as semi-metals may be used.

Next, an experiment was attempted to demonstrate the present invention.

Figure 2 shows the prototype thermoelectric generator;
The table shows the modules.

The thermoelectric elements N and P used are B i ”T e
-8e, B1-Te-8b system, its average operating temperature 1
The Seebeck coefficient at 00℃ is αPn=500μ■/
The a specific electrical resistance is Pn = Pp = 1.5 x 10-
30-, the thermal conductivity is Kn = Kp = 2.2X
10-2 W/cm'C.

At this time, the maximum power output expected from the design is approximately 2.2 W.
1 internal resistance is approximately 1Ω, and thermoelectric conversion efficiency is approximately 4.9%.

In the actual operation test of the thermoelectric module with
At 0°C and 25°C on the low temperature side, it exhibited characteristics of an open circuit voltage of 3°02cm and an internal resistance of 1.050, which satisfied the design conditions.

Solar energy was collected using a Fresnel lens made of highly transparent acrylic resin with an effective area of 60 x 40 cm.

Using this concentrating thermoelectric power generation module, we conducted a minimum-scale experiment assuming a hydrogen generation raft on the ocean.

In this experiment, a 60 x 60 x 50 cfl iron container was filled with approximately 1,007 liters of seawater (approximately 3.4% salinity) collected from Tokyo Tsutsu (Mutsuura Coast), and a heat sink that also served as the electrode on the low temperature side of the thermoelectric module was submerged in the seawater. Manually track the sun with the Fresnel lens system, focus the light on the high temperature surface of the thermoelectric module, and record the high temperature side temperature Th, low temperature side temperature Tc, and terminal voltage V1 current (3). As shown in the figure.

The apparent resistance between the electrodes in seawater is approximately 10Ω, the voltage between the terminals during maximum solar radiation is approximately 2.7 V, and the electrical output is approximately 0.8 W.
The amount of hydrogen gas generated was approximately 100 cc per hour.

The reason why this example's output was lower than the expected maximum output of 2.2 W is that while the designed internal resistance of the thermoelectric module is approximately 1 Ω, the apparent resistance between the electrodes is approximately 10 Ω, and the resistance values of both are matched. This is because it significantly deviated from the maximum output conditions for thermoelectric power generation that should be achieved.

However, this point can be resolved by setting the thermoelectric element cross-sectional area, length, and logarithm used, which determine the internal resistance of the thermoelectric module, and the electrode area and distance between electrodes, which determine the apparent resistance between the electrodes. .

In addition, in this example, a condensing thermoelectric power generation module using a Fournel lens was used; however, the present invention is not limited to this, and the effective area of the high temperature surface of the thermoelectric module may be appropriately selected to provide a flat plate type thermoelectric module with selective absorption properties. good.

Note that the former has the advantage that high temperatures can be obtained with a small heat-receiving surface, while the latter does not need to constantly track the sun.

Incidentally, although the salinity of seawater varies somewhat regionally, its composition remains constant, with salinity ranging from 3.2% to 3.6% and chlorine content from 18% to 20%, as shown in Table 2. , its specific electrical resistance is within 20Ω as shown in Table 3.

As described above, according to the present invention, it is possible to efficiently convert solar energy directly into electricity without the need for power transportation or maintenance, and to generate and store hydrogen from the earth's abundant seawater resources. It has excellent effects.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the hydrogen generation and collection device according to the present invention, Fig. 2 is a perspective view of a thermoelectric generator used in experiments with the device of the present invention, and Fig. 3 is the solar radiation hours per day. It is a graph showing records of high temperature side temperature Th, low temperature side temperature T c % terminal voltage V and current ■ in the band. DESCRIPTION OF SYMBOLS 1... Storage container, 2... Container, 31-36... High-temperature bonding metal piece, 41-47... Low-temperature bonding metal piece, 5...
...Heat absorption plate, 6...Heat storage agent, 7...Transparent plate, 8.
... Lens, 9a, 9b... Electrode, 10... Partition wall, 12... Collection tube, 14... Tank, 15...
flotation device.

Claims (1)

[Claims] 1. A thermoelectric generator, a heat absorption plate that is thermally in close contact with the high-temperature junction of the thermoelectric generator and absorbs solar energy, and a heat-absorbing plate that is thermally in close contact with the low-temperature junction of the thermoelectric generator and that is in contact with the electrode for electrolysis and heat dissipation. a hydrogen collection tank; and a flotation device that levitates the thermoelectric generator and the hydrogen collection tank above the ocean while the electrode plates are immersed in the sea.
A hydrogen generation and collection device that electrolyzes seawater using the power generated by the thermoelectric generator to generate and store hydrogen gas.