Thermoses (Vacuum Flasks) and Spacecraft Heat Dissipation

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Spacecraft Heat Dissipation

Many wonder how a spacecraft cools down in space, given that a vacuum is a great insulator. The answer is that heat dissipation is an important part of spacecraft design. Spacecrafts accumulate heat from their electronics, rocket engines, fuel cells, and incoming solar radiation, among other sources. Failure to dissipate this heat could lead to overheating. However, a spacecraft is floating in the largest thermos in the world, outer space. So, how does it dump its excess heat?

The answer lies in the spacecraft’s design. For instance, Skylab had a gold coating to reflect infrared radiation from the sun and a large radiator to dissipate heat. Since space radiators only use infrared heat radiation to dissipate heat, they must be larger than Earth’s radiators, where convection plays a significant role in the cooling process. Radiators line the inside of the space shuttle’s cargo bay doors. Once the shuttle is in orbit, the crew opens these doors to allow heat to radiate away.

Despite being a vacuum and a good insulator, astronauts experience cold fingers on space walks. This problem is fascinating and addressed in this article.

For more information on thermoses and related topics, visit the links below.

Related HowStuffWorks Links

  • How Refrigerators Work
  • How Air Conditioners Work
  • How Car Cooling Systems Work

Other Great Links

  • Scientific American: A furnace in a Thermos
  • Ask A Scientist: Thermos Physics
  • Solar Thermos Bottle manufacturer
  • The Thermal Resistivity of Straw Bales for Construction – measurement of R values in insulation


1. What is a thermos?

A thermos, also known as a vacuum flask, is a container designed to keep the temperature of its contents stable for an extended period. It consists of two glass or plastic walls separated by a vacuum, which prevents heat transfer by conduction and convection. The inside wall is usually coated with a reflective material to minimize radiation heat transfer.

2. How does a thermos work?

A thermos works by reducing heat transfer between its contents and the external environment. The vacuum between the two walls of the thermos prevents heat transfer by conduction and convection, while the reflective coating on the inside wall minimizes radiation heat transfer. As a result, the temperature of the contents remains nearly constant for several hours.

3. What are the benefits of using a thermos?

The main benefit of using a thermos is that it keeps the temperature of the contents stable for an extended period, which is particularly useful for keeping hot beverages hot or cold beverages cold. It also reduces the need for reheating or refrigeration, which saves energy and time. Additionally, a thermos is portable and easy to use, making it ideal for outdoor activities or traveling.

4. What types of materials can be stored in a thermos?

A thermos can store a variety of materials, including hot and cold beverages, soups, stews, and even ice cream. However, it is important to ensure that the material is safe for storage in a thermos and that it does not react with the container’s materials, which can affect the taste or cause contamination.

5. How long can a thermos keep its contents hot or cold?

The duration that a thermos can keep its contents hot or cold depends on various factors, such as the initial temperature, the volume of the contents, and the external temperature. In general, a well-insulated thermos can keep hot beverages hot for up to 12 hours and cold beverages cold for up to 24 hours.

6. How do you clean a thermos?

To clean a thermos, first, rinse it with hot water to remove any residue. Then, fill it with a mixture of warm water and dish soap and let it sit for a few minutes. Use a soft-bristled brush or sponge to scrub the inside of the thermos, paying particular attention to the bottom and corners. Rinse it thoroughly with hot water and let it air dry. Avoid using abrasive cleaners or harsh chemicals, as they can damage the thermos.

7. How do you maintain a thermos?

To maintain a thermos, it is essential to follow the manufacturer’s instructions for use and care. Avoid exposing the thermos to extreme temperatures or impacts, as this can damage the vacuum seal. Additionally, do not store the thermos with its lid closed when not in use, as this can cause moisture buildup and odors. Regular cleaning and inspection can also help prolong the thermos’s lifespan.

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