Calcium chloride as a de-icing agent

Calcium chloride is found in small quantities, along with other salts, in seawater and in many mineral springs [۱]. Calcium chloride is highly soluble in water over a wide temperature range, with maximum solubility of approximately ۷۵% at temperatures above۱۷۵ ۰C. Anhydrous calcium chloride and the lower hydrates emit a large amount of heat when dissolved in water; this may cause a temperature rise great enough to boil water. Mixing of calcium chloride with water is an exothermic reaction [۲]. Thus, when by addition of calcium chloride to water, the solution heats. Salts hydrates are the result of an anhydrous salt forming a solid crystalline structure in the presence of water in specific molar ratios. Depending on the ionic structure of the salt, there is a finite number of hydrates that can form and often only one or two is thermodynamically stable. Calcium chloride (CaCl۲) forms four hydrates crystal structure. The hexahydrate (CaCl۲·۶H۲O) and tetrahydrate (CaCl۲·۴H۲O have different melting temperatures that depend on the water content; the hexahydrate (CaCl۲·۶H۲O) has a melting point of around ۳۰°C whereas the tetrahydrate (CaCl۲·۴H۲O) has a melting point of around ۴۴°C. These compounds. These compounds are important in the Thermal energy storage [۳]. Calcium chloride was considered a waste product until uses for it were developed some years later. Its importance has grown continuously to the extent that it is now invaluable for various uses, including ice and dust control, oil well drilling, refrigeration, coal thawing, and food processing. Calcium chloride’s versatility is related to its unique combination of physical properties, moisture attraction and retention, high solubility, high heat of solution, and freezing point depression of solutions. Calcium chloride melts ice at temperatures as low as -۵۱ ۰C. Because it liberates heat when exposed to moisture, ice is melted quickly, usually within ۱۵–۳۰ min of application. Calcium chloride is most widely known for its de-icing and dust-controlling abilities. The largest market for calcium chloride, ۳۰% of total production is for de-icing of roads, side-walks [۴].

کلیدواژه ها:

Calcium chloride ، De-icing ، Phase change material ، Hydrated salts