Solar balloon

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solar balloon is a balloon that gets buoyant when the air inside is heated by solar radiation, usually with the help of black or dark balloon material. The hot air inside the sun balloon expands and has a lower density than the surrounding air. Thus, solar balloons are similar to hot air balloons. The use of solar balloons is mainly in the toy market, although it has been suggested that they are used in the investigation of Mars, and some solar balloons are large enough for human flight. Ventilation at the top can be opened to release hot air to descend and deflation.

Video Solar balloon

Operating theory

Generates lift power

Increasing the air temperature inside the envelope makes it less dense than the ambient air. The balloon floats because of the buoyant force given to it. This style is the same force that works on objects when in water and is explained by the principle Archimedes. The amount of lift (or buoyancy) provided by the blimp depends primarily on the difference between the air temperature inside the envelope and the air temperature outside the envelope.

The lifts produced by 100,000Ã, ftÃ,³ (2831.7 mÃ,³) from the dry air heated to various temperatures can be calculated as follows:

Air density at 20 ° C, 68 ° F, is about 1.2, kg/m,. Total lift for 100,000 cu ft balloon heated to (99 ° C, 210 ° F) will be 1595 lbf, 723.5 kgf. In fact, the air contained in the envelopes is not all the same, as the thermal image shows, and hence the calculation is based on the average.

For typical atmospheric conditions (20 ° C, 68 ° F), hot air balloons heated to (99 ° C, 210 ° F) require approximately 3.91 m m of volume of envelopes to lift 1 kilogram (62, 5 ft cu/lb). The exact amount of lift depends not only on the internal temperature mentioned above, but also the external temperature, the height above sea level, and the humidity of the surrounding air. On a warm day, the balloon can not lift as much on a cold day, as the temperature required for the launch will exceed the sustainable maximum for the envelope cloth. Also, in the lower atmosphere, the elevator provided by the hot air balloon is reduced by about 3% for every 1,000 meters (1% per 1,000 feet) of the height obtained.

Solar radiation

Insolation is a measure of the energy of solar radiation received at a certain surface area at a given time. This is usually expressed as the average radiation in watts per square meter (W/m2). Direct insulation is solar radiation measured at certain locations on Earth with surface elements perpendicular to sunlight, excluding diffusion insulation (solar radiation dispersed or reflected by atmospheric components in the sky). The direct insolation is equal to the solar constant minus the atmospheric loss due to absorption and scattering. While the solar constant varies with Earth-Sun distance and solar cycles, losses depend on the time of day (the length of the path of light through the atmosphere depends on the angle of the Sun's elevation), cloud cover, moisture content, and other impurities.

For a year the average solar radiation arrives at the peak of Earth's atmosphere of approximately 1.366 watts per square meter (see the solar constant). The power of radiation is distributed throughout the electromagnetic spectrum, although most of the power is in the visible part of the spectrum. Sunlight is attenuated as they pass through the atmosphere, thus reducing insolation on the Earth's surface to about 1,000 watts per square meter for surfaces perpendicular to sunlight at sea level on a clear day.

The black body absorbs all the radiation that attacks it. Real-world objects are gray objects, with their absorption equal to their emissivity. The black plastic may have an emissivity of about 0.95, which means 95 percent of all radiation that it hits will be absorbed, and the remaining 5 percent is reflected.

Estimating received energy

Jika balon dibayangkan sebagai bola, sinar matahari yang diterima oleh bola ini dapat dibayangkan sebagai penampang silinder dengan radius yang sama dengan bola ini, lihat diagram. Area lingkaran ini dapat dihitung melalui: ${\ displaystyle \ mathrm {\ pi} r ^ {2} \}  ÂÂ$

For example, the energy received by a ball, a 5 meter radius, a solar balloon with a black plastic envelope on a sunny day with a direct insolation of 1000 W/m ² , can be estimated by calculating the area of ​​the big circle:

${\ displaystyle \ mathrm {Area} = \ pi \ times (5m) ^ {2} \ approximately 78 {.} 54m ^ {2}} Â Â$

Then duplicate this with the emissivity of the plastic and insolation directly from the sun:

78,54 * 0,95 * 1000 = 74,613 Watt

At sea level at 15 ° C in ISA (International Standard Atmosphere), air has a density of about 1.22521 kg/m ³ . Air density decreases with higher temperatures, at a rate of about 20 grams per m ³ per 5 K. About 1 kilojoule of energy is required to heat 1 kilogram of dry air by one kelvin (see heat capacity). So, to increase the temperature of 1 m ³ air (at sea level and at 15 Â ° C) 5 Â ° C requires about 5 Â ° C * 1 kilojoule/(kilogram * kelvin) * 1,225 kilograms = 6,125 kilojoules. Thus, you have reduced the mass of 1 m ³ air to about 24 grams. On a sunny day with a black body surface of 1 m ² perpendicular to the sun and no heat is lost, it will take a little more than 6 seconds.

Estimating the energy level lost

Below is the energy balance equation of the energy level lost from the solar balloon when drawing the boundary line around the balloon. The Solar Balloon experiences heat transfer due to convection and heat transfer due to radiation.

? out = t ?? r ² (TS4-TF4) h? r ² (TS-TF)

Perkiraan Perubahan dalam Entropi

Tds = Your PDV

? s =? (cv/T) dT Rgasln (V2/V1)

? s = cvln (T2/T1)

Equilibrium

The system is in equilibrium when the energy lost from the balloon through convection, radiation and conduction, equals the energy received by radiation from the sun.

Maps Solar balloon

History

In 1972, Dominic Michaelis, a British architect and inventor of many solar utilities and projects, invented and built the first solar balloon, with a clear external surface and a dark internal wall and attracted attention.

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Manned flight

The first man to carry a pure solar balloon flight was made on May 1, 1973 by Tracy Barnes in his balloon 'Barnes Solar Firefly Tetrahedron'. This balloon is made of a spiral tube of fabric formed into a tetrahedron. Dominic Michaelis was noted to have had the first pure sun balloon in Europe. This balloon was flown by Julian Nott in the English Channel. The notes were prepared for the FAI show that on February 6, 1978, Frederick Eshoo from Iran also made a solar power flight in a balloon called Sunstat. It uses a standard balloon design, but uses clear plastic on one side, allowing solar radiation to reflect the inner surface, heating the air inside.

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First Antarctic airspace flight

The first 100% solar weather probe, named Ballon ORA, was launched from Antarctica's Dumont d'Urville French Station in January 2011 by a joint team of students, scientists and engineers. The idea is to assess the feasibility of using a solar balloon as a probe in a remote area, where storing the use of lifting gas, helium or hydrogen, would be valuable. The flight was a success, approaching 46,000 feet (14,000 m). Savings are not just about lifting the gas itself. ORA balloons relieve the need for transportation, in and out, heavy gas cylinders.

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Use in planetary exploration

The Jet Propulsion Laboratory of the California Institute of Technology has conducted research on the use of solar balloons on several planets and moons in the solar system, concluding that they are a viable option for Mars, Jupiter, and Saturn.

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Security

Planning permits and air space may be required by local or national air authorities.

Manned flights carry special risks. Unexpected clouds pose serious risks, similar to regular air balloons without spare fuel. The solar balloon can go down quickly when cooling occurs, making ballasts very important.

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Gallery

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References

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External links

• Current history and development of the solar balloon
• EOSS-43: "Mars Micro Balloon Probe" Study using a solar balloon on Mars
• Create and fly alone
• Register the solar balloon and print tracking tag
• French-language site with English content
• Popular April 1982 Mechanics Articles on flights over the English Channel

Source of the article : Wikipedia