Materials: wire, magnets, nails, cardboard, batteries. Steps: 1. Cut a piece of cardboard of suitable size and fold it into a rectangular box shape. 2. Insert a nail into the center of the cardboard box so that the box can easily rotate around the nail. 3. Put the two magnets into the paper box. 4. Wrap 200 to 300 turns of wire around the box. 5. Remove the plastic wrapping both ends of the wire, then connect the two ends together. 6. Use a voltmeter and ammeter to test.
Thermoelectric power generation uses the difference in seawater temperature to produce electricity. There are large temperature differences between different layers of water in the ocean, with surface waters generally much warmer than deep or bottom waters. The principle of electricity generation is that after hot water flows into the evaporation chamber, sea water boilsunder low pressure and turns into steam or boil-off gas such as propane as a fluid, which drives the turbine to rotate and start the AC motor to produce electricity. ; the spent steam enters the condensation chamber and is absorbed by deep ocean water, cooled and condensed, and then circulates. It is estimated that differences in ocean temperatures can generate around 1.5 billion kilowatts of electricity per year.
The reasons for the low efficiency of thermoelectric energy production
Ocean thermal energy comes mainly from solar energy. The area of the world's oceans is vast and limitless, and the tropical oceans are also quite large. Ocean thermal energy can be replenished after use and is worth developing and using. According to calculations, as long as half of the ocean surface, between 20 degrees south latitude and 20 degreesnorth latitude, is used for electricity production and the sea water temperature drops on average only 1°C, 60 billion kilowatts of electrical energy can be obtained, which is equivalent to the current electricity production in the world. Experts estimate that the U.S. East Coast alone can get 75 times the electricity the U.S. needed in 1980 from warm current coming from the Gulf of Mexico.
How can we effectively use the energy of the seawater temperature difference to serve humanity? Arsène Arsonval of France first proposed the idea of generating electricity from ocean temperature differences in 1881. That is, the invention of a power plant that uses the temperature difference between the surface layer (heat source) and the deep layer (cold source) of sea water to produce electricity. Thus, in 1930, ClaudHe successfully used the energy of the ocean temperature difference to generate electricity for the first time off the coast of Cuba. However, because the water pumps in the power generation system consumed more energy than the electricity they produced, the net electricity production. the amount was negative. However, people were not discouraged. In 1979, Hawaii's MINI-OTEC power generation system generated a net power generation capacity of 15 kW for the first time [1]. Seawater temperature difference power generation technology uses surface seawater (25℃~28℃) heated by solar energy as a high temperature heat source, and uses the sea water (4℃~7℃) at a depth of 500 meters to 1,000 meters as a heat source. a low temperature heat source. It is made up of a heat engine. Power generation technologyricity using a thermodynamic cycle system. From a high temperature heat source to a low temperature heat source, it is possible to obtain efficient energy with a total temperature difference of approximately 15°C to 20°C. Ultimately, it is possible to obtain energy with technical significance from a temperature difference of 11°C.
As early as September 1881, the Parisian biophysicist de Assonval proposed the idea of using ocean temperature differences to produce electricity. In November 1926, the French Academy of Sciences created an experimental thermoelectric power station, which confirmed Asson's hypothesis.Val's idea. In 1930, Claude, a student of Assonval, built a seawater temperature difference power plant in the sea near Cuba.
In 1961, France built two 3,500-kilowatt seawater temperature differential power plants on the coast of West Africa. THEs The United States and Sweden jointly built a seawater temperature differential power plant with an installed capacity of 1,000 kilowatts on the Hawaiian Islands in 1979. The United States also plans to build a producing electricity at seawater temperature difference of 1,000,000 kilowatts in the 21st century and using the thermal energy of the Gulf Stream. Establish 500 ocean thermal power plants on the east coast, with a power generation capacity of 200 million kilowatts [3].
The reason for the efficiency of electricity generation at low temperature difference: the small temperature difference of sea water.
Compared with existing biochemical energy and nuclear energy, the main reason why ocean temperature difference energy cannot be commercially applied on a large scale is the low thermal efficiency of the cycle. The wayThe most effective way to improve the thermal efficiency of the OTEC system cycle is to increase the temperature difference between cold and warm sea water. The temperature difference between warm sea water and cold sea water must be at least 20 °C to achieve electricity production by ocean temperature difference.
Based on an average sea surface temperature of 25°C, cold sea water of around 5°C is typically sampled at a depth of around one kilometer in the ocean. If the temperature difference continues to widen, the depth will be deeper.
Change: When the temperature in the metal is unequal, free electrons at high temperatures have greater kinetic energy than free electrons at low temperatures. Like a gas, thermal diffusion occurs when the temperature is uneven. Therefore, free electrons diffuse from the high temperature end to the high temperature end.ity and accumulate at the low temperature end, thus forming an electric field in the conductor and causing an electric potential difference. at both ends of the metal rod. This diffusion of free electrons continues until the effect of the electric field strength on the electrons is balanced by the thermal diffusion of the electrons.
Detailed Information
In 1856, Thomson used the thermodynamic principles he created to conduct a comprehensive analysis of the Seebeck effect and the Peltier effect, and a connection is established between the Seebeck coefficient and the Peltier coefficient, originally unrelated to each other. Thomson believed that at absolute zero there is a simple multiple relationship between the Peltier coefficient and the Seebeck coefficient.
Based on this, he theoretically predicted a new thermoelectric effect, that is, when current passes through a conductiveur with uneven temperature, in addition to producing irreversible Joule heat, the conductor also absorbs or releases a certain amount. of heat (called Thomson heat).
Or conversely, when the temperatures at the two ends of a metal rod are different, a potential difference will form between the two ends of the metal rod. This phenomenon was later called the Thomson effect, becoming the third thermoelectric effect after the Seebeck effect and the Peltier effect.
Baidu Encyclopedia - Thermoelectric Power Generation
Baidu Encyclopedia - Ocean Thermoelectric Power Generation