science

Slurry ice

Slurry ice is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Slurry ice rather than just read about it. In short: Slurry ice is a phase changing refrigerant made up of millions of ice "micro-crystals" (typically 0.1 to 1 mm in diameter) formed and suspended within a solution of water and a freezing point depressant. Some compounds used in the field are salt, ethylene glycol, propylene glycol, alcohols like isobutyl and ethanol, and sugars like sucrose and glucose.

Key takeaways

Slurry ice belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Slurry ice to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Slurry ice from memory before moving on to harder problems.

Reference excerpt

Slurry ice is a phase changing refrigerant made up of millions of ice "micro-crystals" (typically 0.1 to 1 mm in diameter) formed and suspended within a solution of water and a freezing point depressant. Some compounds used in the field are salt, ethylene glycol, propylene glycol, alcohols like isobutyl and ethanol, and sugars like sucrose and glucose. Slurry ice has greater heat absorption compared to single phase refrigerants like brine, because the melting enthalpy (latent heat) of the ice is also used.

Characteristics The small ice particle size results in greater heat transfer area than other types of ice for a given weight. It can be packed inside a container as dense as 700 kg/m3, the highest ice-packing factor among all usable industrial ice. The spherical crystals have good flow properties, making them easy to distribute through conventional pumps and piping and over product in direct contact chilling applications, allowing them to flow into crevices and provide greater surface contact and faster cooling than other traditional forms of ice (flake, block, shell, etc.). Its flow properties, high cooling capacity, and flexibility in application make a slurry ice system a substitute for conventional ice generators and refrigeration systems, and offers improvements in energy efficiency: 70%, compared to around 45% in standard systems, lower freon consumption per ton of ice, and lower operating costs.

Application fields Slurry ice is commonly used in a wide range of air conditioning, packaging, and industrial cooling processes, supermarkets, and cooling and storage of fish, produce, poultry and other perishable products.

Slurry ice can boost by up to 200% the cooling efficiency of existing cooling or freezing brine systems without any major changes to the system (i.e. heat exchanger, pipes, valves), and reduce the amount of energy consumption used for pumping.

Advantages Slurry ice is also used in direct contact cooling of products in food processing applications in water resistant shipping containers. It provides the following advantages:

Product is cooled faster – the smooth round shape of the small crystals ensures maximum surface area contact with the product and as a result, faster heat transfer. Better product protection – the smooth, round crystals do not damage product, unlike other forms of sharp, jagged ice (flake, block, shell, etc.). Even cooling – unlike other irregular shaped ice which mostly conducts heat through the air, the round shape of the slurry crystals enables them to flow freely around the entire product, filling all air pockets to uniformly maintain direct contact and the desired low temperature.

Slurry ice generators Slurry ice is generated using a unique type of ice-making technology. Conventional ice generators produce sharp edged, dry ice fragments, not the small, spherical crystals found in slurry ice. In traditional brine chiller systems, crystals forming inside the solution would block or damage the system.

Scraped surface generators The world’s first patent for a slurry ice generator was filed by Sunwell Technologies Inc. of Canada in 1976. Sunwell Technologies Inc. introduced slurry ice under the trade name deepchill ice, in the late 1970s. Slurry ice is created through a process of forming spherical ice crystals within a liquid. The slurry ice generator is a scraped-surface vertical shell and tube heat exchanger. It consists of concentric tubes with refrigerant flowing between them and the water/freezing point depressant solution in the inner tube. The inner surface of the inner tube is wiped using a mechanism which in the original Sunwell design consists of a central shaft, spring-loaded plastic blades, bearings, and seals. The small ice crystals formed in the solution near the tube surface are wiped away from the surface and mixed with unfrozen water, forming the slurry. Other slurry ice generators adapted the first idea of wiping the surface using an auger originally designed to create flake ice. Wipers also can be brushes or fluidized bed heat exchangers for ice crystallization. In these heat exchangers, steel particles circulate with the fluid, mechanically removing the crystals from the surface. At the outlet, steel particles and slurry ice are separated.

Direct contact generators An immiscible primary refrigerant evaporates to supersaturate the water and form small, smooth crystals. With direct contact chilling, there is no physical boundary between the brine and the refrigerant, increasing the rate of heat transfer. However, the major disadvantage of this system is that a small amount of refrigerant stays in the brine, trapped in the crystals. This refrigerant is pumped with the slurry out of the generator and into the environment.

Supercooling generators Pure water is supercooled in a chiller to −2°C and released through a nozzle into a storage tank. Upon release, it undergoes a phase transition, forming small ice particles with 2.5% ice fraction. In the storage tank, it is separated by the difference in density between ice and water. The cold water is supercooled and released again, increasing the ice fraction in the storage tank. However, a small crystal in the supercooled water or a nucleation cell on the surface will act as a seed for ice crystals and block the generator.

Illustrations

Worked examples

Example 1 — a first encounter with Slurry ice

Start with the simplest possible case. Write down what Slurry ice claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Slurry ice before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Slurry ice ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Slurry ice

In research: Slurry ice appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Slurry ice in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Slurry ice is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fish processing, Food preservation, Refrigerants, so understanding it makes those chapters shorter.
In everyday life: Look for Slurry ice outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Slurry ice in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Slurry ice means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Slurry ice out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Slurry ice in simple terms?

Why does Slurry ice matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Slurry ice?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Slurry ice.