DIY Supermaterial Could Save You From Heatstroke: Salt based PCMs

Summary

This video explores the creation and application of phase change materials (PCMs) using salts and water, focusing on materials like calcium chloride and sodium acetate. The creator demonstrates how PCMs can regulate temperature, particularly for building panels and solar panels, by absorbing and releasing heat. They also highlight the challenges of using high-temperature PCMs, such as corrosion and humidity concerns. Sodium acetate is examined for personal heating, but the process of making it at home is risky. Overall, the video showcases the potential of low-cost, non-flammable PCMs for a variety of uses, with an emphasis on practical applications and safety.

Takeaways

• 😀 Phase Change Materials (PCMs) can regulate temperature by absorbing and releasing heat at specific transition temperatures.
• 😀 Calcium chloride is used to create a PCM with a transition temperature of 85°F (29°C), which can be sealed into materials like cellulose insulation for building temperature regulation.
• 😀 Xanthan gum is added to PCMs to increase viscosity and prevent the crystals from settling, enhancing performance.
• 😀 Solar panels can benefit from PCMs by maintaining their optimal temperature and improving efficiency by absorbing excess heat during the day and releasing it at night.
• 😀 The primary concern when using PCMs for buildings is managing humidity, as these materials reduce temperature swings that help drive off moisture in traditional constructions.
• 😀 Sodium acetate trihydrate is another high-temp PCM with a melting point of 140°F (58°C), useful in hand warmers and solar heat storage.
• 😀 Sodium acetate can be supercooled far below its freezing point, and crystallization can be triggered with a metal disc, instantly releasing heat.
• 😀 Making sodium acetate yourself is difficult and dangerous due to its high temperature and crystallization properties, making it safer to buy pre-made products.
• 😀 Hydrocarbon-based PCMs, like molten wax, are tunable for various temperatures but may lose heat-carrying capacity when mixed with additives like oil.
• 😀 Salt- and water-based PCMs are advantageous due to low cost, zero flammability, and easier accessibility compared to hydrocarbon-based PCMs.
• 😀 Support for the channel through Patreon helps make science accessible to the public, and the creator engages with viewers through live streams and comments.

Q & A

What is a phase change material (PCM) and how does it work?

A phase change material (PCM) is a substance that absorbs or releases heat when it transitions between solid and liquid states. During melting or freezing, it can store or release energy, which helps in regulating temperature.

How is the PCM in the video created?

The PCM is created by dissolving calcium chloride in water. The solution is heated until most of the calcium chloride is dissolved. Then, a small amount of xanthan gum is added to increase viscosity and prevent crystals from settling.

What is the purpose of adding xanthan gum to the PCM mixture?

Xanthan gum is added to the PCM mixture to increase its viscosity, which helps to prevent the crystallization of the material and ensures that the PCM remains in liquid form during use.

What is the transition temperature of the PCM created in the video?

The PCM created in the video has a transition temperature of approximately 85°F (29°C). This means it absorbs or releases heat when the temperature reaches this point.

What are the potential uses for the PCM created in the video?

The PCM can be used to regulate the temperature of buildings by being absorbed into materials like shop rags or insulation panels. It can also enhance solar panel performance by absorbing excess heat to maintain optimal efficiency.

How does the PCM help improve solar panel performance?

The PCM helps solar panels by absorbing excess heat, preventing them from overheating. Since solar panels are most efficient at around room temperature, the PCM helps maintain that optimal temperature by absorbing heat during the day and releasing it at night.

What is one major concern when using PCMs for building temperature regulation?

One major concern is humidity. Modern buildings often rely on temperature swings to drive off humidity. With a PCM-regulated building, temperature fluctuations are reduced, which could lead to increased humidity levels and the need for dehumidifiers.

What is the difference between calcium chloride and sodium sulfate as PCMs?

Calcium chloride is more corrosive to metals, requiring better sealing to prevent leaks, while sodium sulfate is less corrosive, making it a safer option for use in applications where corrosion is a concern.

What is sodium acetate trihydrate and how is it used as a PCM?

Sodium acetate trihydrate is a high-temperature PCM with a melting point of 140°F (58°C). It is commonly used in hand warmers and for solar heat collection. It has the ability to supercool, and when triggered, it crystallizes rapidly, releasing heat.

What are the dangers of handling sodium acetate when making it yourself?

One danger of handling sodium acetate is that it can be extremely hot when crystallizing. If spilled on skin, it can stick and crystallize rapidly, causing a burning sensation. The presenter shares a personal experience of the terrifying sensation when it unexpectedly heated upon contact with skin.