Dry Ice
Technology Term Definition
Dry Ice
Dry Ice
Definition 1: Solid carbon dioxide (CO2), white. Under -78.5°C and atmospheric pressure, it sublimates into a gas. It is widely used as a cloud-seeding agent in artificial weather modification.
Applied Disciplines: Atmospheric Sciences (First-level Discipline); Atmospheric Physics (Second-level Discipline)
Definition 2: Solid carbon dioxide.
Applied Disciplines: Aquaculture (Level 1 Discipline); Freshwater Product Preservation and Processing (Level 2 Discipline)
Molecular Weight 44.01
Density (solid) 1560 kg/m³ (-78°C)
Melting Point -57℃
Freezing Point -78.5℃
Molecular Model of Dry Ice
Three-phase point - 56.6°C, 5.17*10^5 Pascals
Critical Point 31℃ 7.37 x 10^6 Pascals
Properties
Colorless and odorless gas with an acidic taste.
Dissolution Condition
Soluble in water (1:1 by volume), partially forming carbonic acid.
Liquid to Gas Ratio: 8.726 SCF (gas)/LB (liquid -17.8°C, pressure 21 kg/cm²)
Liquid to Solid Ratio: 0.46 (-17.8℃) 0.57 (-48℃)
Dry ice is the solid form of carbon dioxide, which is an odorless, colorless gas under normal conditions and naturally present in the air. Although carbon dioxide constitutes a relatively small volume percentage in the air (about 0.03%), it is one of the important gases we recognize. Dry ice is highly volatile, sublimating into a non-toxic, odorless gas that is 1000 times larger in surface area than the solid carbon dioxide. Therefore, dry ice should not be stored in airtight, small-volume containers as it can easily explode. It is important to keep dry ice in a well-ventilated area to allow the gas produced by its sublimation to dissipate safely.
At room temperature and under a pressure of 6079.8 kPa, carbon dioxide is condensed into a colorless liquid, which then rapidly evaporates under low pressure, forming tightly packed solid substances resembling ice and snow.
Its temperature is -78.5°C, which is dry ice. Dry ice has more than 1.5 times the refrigeration capacity of water ice, absorbs heat and sublimates into carbon dioxide gas, leaving no residue, toxicity, or odor, and has sterilizing properties. It is affected by heat
Dry ice sublimates directly without liquefying. It is the solid form of carbon dioxide, and due to its extremely low temperature of -78.5°C, it is often used to maintain objects in a frozen or低温 state.
At room temperature, when carbon dioxide gas is pressurized to approximately 101325 Pa, and a portion of the vapor is cooled to around -56°C, it will freeze into a snowy solid form of carbon dioxide. The sublimation heat of solid carbon dioxide is veryAt -60°C, it measures 364.5 J/g, and when it sublimates under normal pressure, it can lower the surrounding temperature to around -78°C, without producing any liquid, hence the name "dry ice."Dry ice can also be used for artificial rainmaking. When placed in the air, it rapidly absorbs a large amount of heat, causing the surrounding temperature to drop quickly and the water vapor to condense into tiny droplets, thus achieving the purpose of precipitation. Additionally, substances like silver iodide (AgI) are also utilized.Share similar properties.
Application Scope
Dry ice applications in the electronics industry
Clean internal oils and dirt from cleaning robots and automated equipment; remove soldering flux, contaminated coatings, resins, solvent coatings, protective layers, and photosensitive corrosion inhibitors on printed circuit boards; applications of dry ice in the field of refrigerated transportation.
Low-temperature transportation for medical uses, as well as special medications such as plasma and vaccines.
Electronics low-temperature materials, and long-distance transportation of precision components.
Transportation of fresh preservation for high-end food products such as premium beef and mutton.
Due to these properties of dry ice, it has been increasingly used by some computer overclock enthusiasts to cool down and overclock CPU/GPU processors in recent years. Impact record.
Price
Prices vary as dry ice is a common refrigerant, with specialized chemical factories in major cities offering it at 10 to 15 yuan per kilogram, which is still acceptable for enthusiasts. There are various types of dry ice, including culinary, medical, and industrial. Culinary dry ice is commonly used for cooling food, widely employed in bars and restaurants, and is slightly more expensive than industrial dry ice. If industrial dry ice is unavailable, you can purchase culinary dry ice from food sales departments. Marketed dry ice is typically in block, granular, or powdered form, with granular or powdered dry ice used for overclocking. Avoid buying blocks, as they are very hard and difficult to break.
Be cautious when handling dry ice at all times and always use thick cotton gloves or other protective materials to touch it! Prolonged direct contact with the skin can cause cellular freezing and injuries similar to minor or severe burns. Do not use dry ice in areas like car interiors or ship cabins, as the sublimated carbon dioxide can displace oxygen, potentially leading to shortness of breath or even asphyxiation!
Do not let children handle dry ice alone!!
2. Dry ice is extremely cold; do not place it in your mouth, and prevent frostbite at all costs!!
3. Always use thick cotton gloves, clamps, or other protective items when handling dry ice (plastic gloves are NOT effective as barriers!!)
4. Use dry ice in well-ventilated areas. Never place dry ice in an enclosed space with it!!
Do not mix dry ice with liquids.
Warning: Proper and safe handling of dry ice to avoid injury.
During overclocking, be aware that dry ice sublimates very quickly at normal temperature and pressure. If not used promptly, it can disappear quickly, especially during summer when a 20 kg box of dry ice can completely sublime after 24 hours in a room at normal temperature. Before using dry ice for cooling during overclocking, there are two important reminders: first, maintain good ventilation in the room, and second, wear protective gloves. Dry ice is a low-temperature substance, so safety must be ensured during use as frostbite can be as painful as burns. Additionally, be cautious with the amount of dry ice added. Many believe that filling the entire chamber with dry ice provides better cooling, but it leads to a lot of condensation, which can cause accidents when water droplets land on the circuit boards. In reality, after the processor enters a stable operating state, there is a temperature balance point for cooling and heat dissipation. Adding excessive dry ice won't lower the processor temperature further. Experienced overclockers can effectively control this balance point, achieving good cooling results with minimal dry ice.
Frostbite Symptoms and Treatment Measures
Frostbite Definition
Frostbite refers to injury to a body part due to prolonged exposure to cold temperatures, resulting in damage to the skin and tissue.
Symptoms
The skin will feel very cold and may turn a bit red before it freezes.
The skin will first lose its color, but as frostbite gradually forms, it may turn white or grayish yellow, or white with spots.
May blister. It might be a bit painful, or you might not even realize you're frostbitten.
Initial symptoms at frostbitten areas (frostnip) are tingling, followed by numbness and stiffness, with the affected area appearing pale; warming it up can lead to complete recovery. If the initial frostbite is not treated, it may progress to superficial frostbite, where the skin and subcutaneous tissue have already necrotized, the skin remains pale or slightly gray, feeling cold but soft; after thawing, it may become red and painful, and large blisters similar to second-degree burns may form within one to several days; after a few more days, the blisters dry up and form black eschar, which, if no infection occurs, will eventually be replaced by new skin.
Cold Injuries Treatment Measures
Move to a warm area and keep the affected area in a warm, dry environment. Remove any constrictive items to prevent them from being difficult to remove during swelling. Keep the area warm by placing it in gradually adjusted warm water (38.8~40.5°C). Do not expose dry ice to cold temperatures again; elevate the affected area to reduce pain and swelling, then wrap the area with clean gauze and seek medical attention; the purpose of first aid is to restore the frozen body fluids to normal. Therefore, if the surrounding area of the affected area can be warmed, healing can occur quickly. Do not immerse the affected area directly in hot water or use fire to warm the area, as this may worsen the frostbite. Since massage can cause complications, refrain from massaging the affected area.
Caution --- Do not massage, bake, or puncture blisters to prevent infection of the affected area.
As we know, dry ice cleaning is also referred to as dry ice blast cleaning, CO2 cleaning, or low-temperature cleaning. The characteristics of dry ice cleaning technology differentiate it from other cleaning processes. The significant benefits include the applicability, environmental friendliness, practicality, cost-effectiveness, and safety of the customized dry ice cleaning solutions for clients.
Dry Ice Cleaning Technology Applications
Dry ice cleaning technology involves rapidly freezing the item to be cleaned, causing it to form micro-cracks, and then forcing dry ice into these cracks where it rapidly expands, forcing the item to be cleaned to shed adhered materials. As such, it is classified as a "physical cleaning method." Therefore, theoretically, dry ice cleaning technology can replace traditional physical cleaning processes such as sandblasting, water jetting, and wiping.
Dry ice cleaning technology can also replace certain "mixed cleaning techniques," such as traditional methods like using degreasing agents to clean dirt, acid washing to remove rust from metal surfaces, and diluting paint with solvents.
However, from an industrial practicality standpoint, the application of dry ice cleaning technology is related to national environmental awareness and legal requirements; that is, when traditional processes fail to meet environmental standards, dry ice cleaning can replace conventional cleaning methods. From a process perspective, the principle of any cleaning process is to ensure that the cleaned parts are not damaged, and to maintain the integrity of the parts. Dry ice cleaning must also adhere to this principle. Dry ice cleaning involves atomizing dry ice particles onto the surface of the parts, which must withstand a certain wind pressure. If the part surface cannot bear this wind pressure, dry ice cleaning cannot be used.
Dry ice cleaning is widely used in the nuclear power, metallurgy, casting, petroleum, chemical, rubber, plastic, shipping, automotive, food, pharmaceutical, machinery, printing, power, and electronic industries...
Cost of dry ice cleaning
A crucial question regarding whether dry ice cleaning technology can replace traditional cleaning processes is the cost issue. This necessarily ties into the consumption of dry ice, pressure levels, and flow rate, as well as the resulting cost concerns. However, the process cost of any cleaning method is directly related to the original condition of the item being cleaned and the required cleaning precision. Different levels of cleaning precision and varying cleaning conditions lead to significant cost discrepancies.
Firstly, the main materials for dry ice cleaning are dry ice and compressed air, with an unlimited supply of compressed air that requires no transportation, thus eliminating procurement and transportation costs for raw materials. The primary material is dry ice. The cost of dry ice is calculable, as 3.0 tons of liquid carbon dioxide can produce 1 ton of high-quality dry ice.
The consumption of dry ice is a major concern for users. In fact, the amount of dry ice used is closely related to the cleaning conditions and precision. For heavy oil污, such as paint, scale, carbon deposits, and slag, which have strong adhesion, they must be removed by deep freezing and effective impact, causing the material to crack and detach layer by layer. Consequently, the ice consumption necessarily increases, along with higher air pressure requirements and increased costs. However, for oil污 with less adhesion, strong compressed air is not needed, and low-pressure cleaning can be employed, significantly reducing the dry ice consumption and lowering costs accordingly.
Additionally, the key feature of dry ice cleaning is its speed. Dry ice has a high volatility, making slow operations impossible, and it also boasts high stripping speed, thus achieving rapid cleaning. Secondly, dry ice cleaning is a "dry cleaning" method that does not produce any conductive medium, preventing any residual conductive medium from damaging devices. Therefore, it is the preferred process for items that are not suitable for "wet cleaning." Most importantly, dry ice cleaning does not generate secondary pollution, eliminating the need for recovery and treatment of cleaning media, which can significantly reduce costs.
As for the final destination of the material being removed, since dry ice cleaning is a physical cleaning process, in principle, the cleaned material is merely stripped off the object and cannot disappear.
Where does the material removed during dry ice cleaning go?
