Heat storage substances face a critical issue: they tend to leak. As phase change materials gain energy by liquefying, they frequently spill out of their containers, causing equipment malfunctions and diminishing efficiency. This basic physical principle has restricted their application in various fields, from temperature-moderating buildings to solar energy applications. A novel method employs carbon derived from crustacean shells to contain the liquid while enhancing the thermal conductivity of the material.
Researchers from Shenyang Agricultural University have reported that a carbon aerogel made from chitin can stabilize stearic acid, a widely investigated organic phase change material, stopping leakage during its melting phase while retaining a high heat storage capacity. The findings, published December 29 in Sustainable Carbon Materials, transform seafood processing byproducts into a robust thermal energy storage element.
Pores and nitrogen keep the liquid contained
Chitin is a structural polymer present in crab shells, shrimp shells, and the walls of fungi. It is plentiful, renewable, and has a high nitrogen content. The team dissolved chitin in sodium hydroxide and urea, then freeze-dried this mixture to create an extremely lightweight aerogel. This aerogel was carbonized at regulated temperatures, resulting in a porous framework with connected cavities ranging from nanometers to multiple micrometers.
When molten stearic acid is infused into this carbon matrix, capillary forces within the pores effectively retain the liquid. Nitrogen-rich sites on the carbon surface create hydrogen bonds with stearic acid molecules, chemically anchoring them. This combination prevents fluid movement even when the material is heated beyond the melting threshold.
The composite contained 60 percent stearic acid by weight without any observable leakage. Thermal assessments indicated a melting enthalpy of around 118 joules per gram, surpassing many previously reported biomass-based phase change composites. Thermal conductivity was enhanced by 61 percent compared to pure stearic acid, indicating that the material can absorb and release heat more rapidly.
“Our aim was to create a low-cost and eco-friendly support that can securely hold substantial amounts of phase change material without leakage,” states corresponding author Hui Li. “Chitin is plentiful, renewable, and rich in nitrogen, making it particularly appealing for this application.”
100 cycles without deterioration
After 100 cycles of heating and cooling, the material preserved over 97 percent of its initial heat storage capacity. The phase change temperature remained mostly constant, and structural examinations revealed no chemical degradation or breakdown of the carbon structure. The carbon aerogel increased the activation energy required for the melting and solidification of stearic acid, indicating improved thermal stability due to nanoscale confinement and hydrogen bonding.
Given that chitin can be sourced from seafood processing waste, this method presents a pathway to transform organic byproducts into energy storage materials. The same approach might be adapted for other phase change materials and fine-tuned to suit different temperature ranges based on specific application requirements. Phase change materials store and release energy by melting and solidifying at designated temperatures, making them suitable for building climate control, solar energy storage, and electronic thermal regulation.
The findings imply that merging natural polymers with engineered carbon structures could tackle energy efficiency issues while decreasing reliance on fossil-derived substances. The nitrogen content in chitin, previously merely a chemical detail, becomes a practical benefit when the material is carbonized and utilized as a thermal storage framework.