Next in importance to the direct utilization of refrigeration for cooling perishable products is artificial ice making. While there are a number of systems which may modify present methods, practically all ice produced today is made by either the can or the plate system.
The Can System involves immersing cans of water in brine tanks and using distilling apparatus to purify water before freezing it into ice blocks. Distilled water is crucial as impurities affect ice quality and purity. The process includes boiling out air and other gases, ensuring no contact with air post-boiling to prevent discoloration or corrosion.
<Callout type="important" title="Purity of Ice">The transparency of ice does not accurately reflect its purity; pure ice may appear opaque due to trapped air bubbles.</Callout>
Freezing times vary based on brine temperature and ice size. For example, a 6-inch block takes approximately 14.9 hours compared to an 11-inch block taking around 50 hours.
The Plate Ice System uses metal plates submerged in tanks with raw water that is frozen against the plate surface. Agitation helps remove air bubbles and impurities. This system produces ice less brittle than can ice, making it easier to store without breaking.
<Callout type="risk" title="Agitation Importance">Increased agitation is crucial for removing both solid and gaseous impurities in the plate system.</Callout>
The Center-Freeze System improves upon the plate method by freezing ice radially from vertical brine pipes, reducing freezing time significantly.
Evaporators and vacuum distilling apparatus are used to maintain full capacity when sweet water is insufficient. Combined can and plate plants maximize efficiency in large-scale operations.
Key Takeaways
- The purity of ice depends on the quality of water used, requiring distillation or purification processes.
- Agitation is crucial for removing air and impurities in plate ice systems to ensure marketable product quality.
- Combining can and plate ice-making methods maximizes efficiency and capacity.
Practical Tips
- Use high-quality water sources to minimize the need for extensive distillation or purification processes.
- Regularly inspect and maintain agitation mechanisms in plate ice systems to prevent impurity buildup.
- Consider combining both can and plate systems for larger operations to optimize resource utilization.
Warnings & Risks
- Improper handling of ammonia refrigerants poses significant safety risks, including toxicity and flammability.
- Failure to properly agitate water during the freezing process in plate ice systems can result in poor-quality ice with impurities.
Modern Application
While this chapter focuses on early 20th-century mechanical refrigeration techniques for ice production, many of its principles remain relevant today. Understanding these historical methods provides a foundation for modern survival scenarios where electricity and advanced technology may be unavailable or unreliable.
Frequently Asked Questions
Q: What are the two main systems used in artificial ice making?
The two primary systems discussed are the can system, which involves freezing water in cans submerged in brine tanks, and the plate system, where raw water is frozen against metal plates.
Q: Why is agitation important in the plate ice system?
Agitation helps remove air bubbles and other impurities from the freezing water, ensuring that the resulting ice is of high quality and free from discoloration or cloudiness.
Q: How does the center-freeze system improve upon traditional methods?
The center-freeze system uses vertical brine pipes to freeze ice radially, reducing freezing time significantly compared to conventional plate systems. This method is claimed to be more efficient and faster in producing ice.