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Hoshizaki's Evaporator Plate Provides Great Advantages

 

[posted December 30, 2011]

Sometimes things aren't always what they seem in the ice making industry. There may be not better example of this than with Hoshizaki. First, despite the Japanese-sounding name, Hoshizaki is not a foreign company - their ice machines that are bought and sold in the United States are manufactured by Hoshizaki America in Peachtree City, GA. Second, they make ice in a way unlike any other ice machine company. Hoshizaki makes some of the most efficient, durable ice makers on the market, and they do this through methods that go deep into the most basic principles of ice making and commercial refrigeration. To look at it one way, forget everything that you know about the way commercial ice makers work, and read on to learn how innovation and simplicity will save you potentially thousands of dollars in long term operating costs. While there are a myriad of topics to discuss here, for today, we are going to focus on the heart of the ice machine - the evaporator plate.

In general, the more parts any machine has, the better the chances are that something can go wrong. Simple machines tend to last longer. Hoshizaki ice makers seem to work on this principle. By focusing on the process of ice making and not on thousands of computerized controls and attempts to reinvent their wheel, Hoshizaki has been very successful. Traditional ice makers freeze ice by running filtered water across what is known as an "evaporator plate" that freezes the ice. The way this works is relatively simple. The water enters the machine into a reservoir that has been sized to hold the exact, correct amount of water needed to create a batch of ice. Then this water is pumped over the evaporator repeatedly as it gets colder and colder with each pass. Only pure water freezes at 32 degrees Fahrenheit so as the water runs across the plate the ice freezes in increments, basically growing the ice cubes. The evaporator plate on a traditional ice machine is almost exactly like your ice cube tray at home, except that it is made of copper that is plated in nickel or tin. As we all know, copper is a fantastic conductor, and nickel and tin have properties that allow them to effectively freeze the ice in the sheet necessary to create the "cubes" as the ice falls into the bin below.

A Hoshizaki evaporator plate is actually made of stainless steel, not copper. While some may think that this would be worse for ice making, the stainless steel evaporator plate actually provides some great benefits. True, stainless steel is not as good a conductor as copper, but it is more durable, resistant to contamination and corrosion, and easier to maintain. Also, the construction of the stainless steel evaporator plate is quite different. As mentioned above, the traditional copper evaporator plate is like our ice cube trays at home, a waffle-like grid, and a mold in which ice cubes can grow. This leaves thousands of tiny corners for bacteria to grow in, areas for sediment to settle in, and delicate metal fins that are more susceptible to cracks or breaks. Not to mention, the lack of tenacity in the coating around the copper plate that, if not kept in a perfect and pristine environment, will eventually deteriorate and chip off, reducing the life of your ice machine.

If we can get slightly off topic for a second, let's look at what is behind the evaporator plate, and where it got its name. Refrigeration works on a few basic principles - many of the same principles that a lot of the aspects of our physical reality are governed by. Without going into any serious discussions of thermodynamics, we do need to talk about the nature of refrigeration a little bit. The ice making process works like this, basically a continuous cycle of compression and expansion:

1. Compression: An aptly named "compressor" is a machine within your ice machine that pressurizes the hot refrigerant while it is in its gaseous state. When pressure is increased, naturally, so is the temperature.
2. Condensation: At this stage the gas, under pressure, moves along to the coils, like in your car's radiator. The gas moves through a system of narrow tubes known as coils which are attached to fan blades that help remove the heat. While the heat is drawn away, it condenses into a liquid.
3. Evaporation: Now, this cooled liquid is evaporated (turned back into a gas) by going through an expansion valve and into a series of larger pipes. During this part of the process, it is the nature of the refrigerant to draw any heat away from its surroundings. So, the ice machine has this part of the process built in to the evaporator.
4. Repeat.
Overall, it's a pretty simple procedure. Most traditional ice makers, have the expansion tubes on the rear side of the evaporator plate. Hoshizaki ice makers, because the evaporators are flat sheets of stainless steel, have one evaporator plate on each side of the refrigerated tubing. In other words, because of the nature of thermodynamics, Hoshizaki ice makers are able to produce twice as much ice per cycle than a traditional ice maker. This means that a Hoshizaki ice maker works is required to do half the work as a traditional machine. For example,, competitor X's machine cycles every fifteen minutes with a new batch of ice. Hoshizaki makes the same amount in one batch every half hour equal to two batches of the competitor in the same half hour. This means that the Hoshizaki uses less power as it runs less often, which saves you money.

Let's get back to the flat evaporator plate. Hoshizaki eschews the confines of convention and opts not for a ridiculously intricate waffle-shaped ice maker, but rather a nearly flat plate of stainless steel. Behind this thin plate are the expansion tubes removing heat from the evaporator on their way back to the compressor. These tubes are lined perfectly so that as the water flows down, across the evaporator (which is not completely flat, it does have small, vertical channels to prevent the ice from freezing in sheets) ice cubes grow over the tubes in perfect crescent shaped cubes.

These cubes fall independently as the machine uses all of the water in its reservoir for that cycle. It then skips the coils on one cycle, and heats the evaporator for a few seconds to around 45 degrees which is enough to allow the cubes to neatly slide off into the bin below.

I know that we are talking about a lot here, but in order to paint the best picture of the brilliance of Hoshizaki ice makers, all of these details are necessary. Not only does the stainless steel evaporator work better by producing more ice at once, but as we discussed, stainless steel is better for its durability. In the end, my favorite thing to do is to ask the tech. Here at Ice Machines Plus, we have had a very close relationship over the last thirty years with an ice machine rental and refrigeration repair company. Any time we talk to the owner he always chides us when he finds out we sold anything else. He loves getting service calls, but for his own personal accounts, he buys nothing but Hoshizaki. When asked why, he replied simply, "Because I never have to do anything except clean them!" Hoshizaki's evaporator plate is truly a step above the rest. Check out all of the Hoshizaki ice machines available at Ice Machines Plus and find out how one can better your establishment.

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