| There are many types of freezers out there, most likely, the type you're familiar with is either the one in your refrigerator, or the deep freeze you may have in your basement, but when it comes to commercial mass production, many businesses use what's called a tunnel freezer. These freezers are either straight tunnels, or spiral freezers, straight tunnels are long freezers that run the product in a straight line through the freezer. Spiral freezers are generally larger in volume, but don't take up so much length. The product runs through the freezer up one spiral and down another, increasing the time that it is exposed to the cold temperatures, which generally results in a more thoroughly frozen product.
One of the differences between such commercial freezers and the type that keeps your burritos cold, is the medium used as a coolant, most commercial freezers use anhydrous ammonia as a coolant, and require it to be fed in from the outside. This has to do with the fact that ammonia is cheaper to get and is good at carrying away heat.
Note: Tunnel Freezers are considered a confined space and as such, it would be an extremely bad idea to walk into one while the conveyor is running (you should probably lock that out first). | 
