Scotsman Self Contained Cuber CU2026 Spezifikationen PDF herunterladen (Seite 19)

Ice Systems

Wondering if you knew...

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Ice makes economic sense, …too!

As previously explained, using the right quantity of ice cubes (and in this case we mean its use in

beverages, as the base of a good drink) chills down and maintains the spirit at the correct temperatu-

re, enhancing the quality of the product, respecting the highest professional standards, and

bringing the overall Customer Experience to its peak.

We are left with the explanation of the impact that ice has on the proﬁtability of the enterprise. The

old saying: ”In the world there are two categories of people that are able to build their home with ice:

The Eskimos and the Bartenders!” is here to stay … let's see why…! Ice cubes, once in a glass, take up

space, volume. If we were to keep the size of the glass unchanged, as the quantity of ice increases, the

quantity of the liquid poured in the glass drops. Ice therefore replaces the liquid.

The quantity of liquid "displaced" will also depend on the shape of the ice used.

Let us analyse the displacement factor modiﬁcations according to the various types of ice used, in

decreasing increments.

In ﬁrst place we ﬁnd Nugget and Cublet Ice: these two types are those that by far (with the obvious

exception of a single ice cube, as tall and wide as the entire volume occupied by ice!) take up the

most volume in the glass.

In second place we ﬁnd ice cubes from small size to large. Medium to large size cubes will occupy less

volume than small size, nugget type, ice cubes. The volume of displaced liquid may have a diﬀerent

value according to the drink served. In any case, the displaced beverage will represent a lesser value

for the bar manager and therefore, leaving the selling price of the drink unchanged, a

higher proﬁt.

The best way to combine product quality, perceived value and proﬁt margin for the

bartender is the following:

• increase the size of the glass;

• pour generous quantities of ice;

• pour the correct quantity of spirit (same as previously served);

• if not a touch more;

• serve the drink in its best conditions, chilled, refreshing and able to maintain such temperature;

• continue to charge the same amount serving a better product, or, at this point, increase the selling

price without the doubt of upsetting any of the patrons!

Scientiﬁc Background about ice cubes

When an ice cube is poured into an ambient

temperature drink, the temperature of the

drink drops since the drink is supplying heat

to the ice cube. In turn, the cube warms-up.

When the temperature of the ice reaches the

melting point, 0ºC (32ºF), it changes its state

from solid to liquid.

So, in order to melt, the ice surface must

receive enough heat to bring its tempera-

ture up to 0ºC. In a glass ﬁlled with any liquid,

the ice cubes are in contact both with the liquid

and with the glass, and both these elements

have a higher temperature than the ice. Heat is

therefore transferred to the ice from both of

them.

As the process continues, ice receives additional

heat, the heat of fusion, so as to provide

suﬃcient energy to the water molecules to

separate from the ice structure and dissolve into

a liquid state. The temperature of the water

remains at 0ºC until all of the ice is melted.

Once all of the ice has melted, the tempera-

ture of the water (or drink) will begin to rise as

the ambient temperature, or body heat, transfer

additional heat to it. In terms of heat transfer,

some of the heat is applied by conduction:

if an ice cube is held in the palm of a hand, body

heat is transferred by conduction to the ice cube

until the ice cube has completely melted.

Resulting water will have the same temperature

as the hand, which in turn will send a signal of

coldness to our brain as heat is transferred to the

ice cube.

As the human body has much more heat energy

in it than is required to melt a small piece of ice,

the temperature of the body will only change

slightly. The temperature of the ice cube, on the

contrary, will change dramatically, leading to it

melting.

Heat may also transfer by convection. This

eﬀect takes place when heat is transferred within

a liquid that is ﬂowing freely.The liquid that is in

contact with the ice cube transfers its heat to the

ice (by conduction, due to the direct contact),

and the temperature of the liquid drops.

This causes the local density of the liquid to

increase, hence it sinks due to gravity.

The sinking liquid is replaced by warmer liquid,

which surfaces from other levels of the glass and

allows for more heat exchange to the take place

with the ice cube. The liquid circulation

originating from such change in density within

the ﬂuid or drink is called a convection

current.

By increasing the free circulation of your

drink near the ice cube (eg, by stirring), the

time it will take for the ice cube to melt and for

your drink to get cold will be reduced.

The diﬀerent conﬁgurations

and technologies in ice machines

An ice maker is an machine that uses the

refrigeration technology to freeze water

and turn it into ice, with diﬀerent sizes, shapes

and humidity percentages. The refrigeration

system of an ice machine is designed to absorb

heat from water and transfer it to the surroun-

ding environment, by means of a gas that is

initially compressed, then cooled-down until it

condensates into a liquid state (this heat

exchange process takes place in the condenser),

then allowed to boil, or evaporate, in a

controlled way, returning to its original state by

absorbing the needed heat from the water

that is brought in contact with it in the

“evaporator”.

The system consists of these main

components:

Compressor: pumps-in, compresses and

pushes- out the refrigerant gas, at a high

temperature and pressure, therefore rich in

energy, sending it into a closed circuit.

Condenser: the place where the refrigerant gas

condenses into a liquid state as heat is removed

and released to the surrounding environment.

An insuﬃcient heat exchange in the condenser

willresult into an incomplete gas condensation,

hence into a less eﬃcient ice making process.

Expansion valve: divides the ﬁrst,

high-pressure section of the circuit from the

second, low-pressure one, and regulates the

ﬂow of liquid refrigerant that enters the

evaporator to proceed and absorb heat from the

water.

Evaporator: here, the liquid refrigerant, due to

the pressure drop, can go back (evaporate) to its

original state of gas. In order to complete this

process, it needs heat - hence its subtraction

from the water, which in turn starts freezing and

forming ice. Once the ice is formed in whichever

way we need it (cubes, ﬂakes, etc) the freezing

cycle comes to a completion, and ice is detached

from the evaporator. This may be achieved in

diﬀerent ways: mechanically (forced iceharvest),

or by reversing the refrigerant ﬂow in the system

by sending it directly to the evaporator rather

than to the condenser. Hot gas will start melting

the ice, which will then fall-oﬀ by gravity.

A combination of the mechanical and thermal

actions may be adopted to speed up the

harvesting process.

Now, it should now be easier to under-

stand that:

• The refrigerant at high temperature can be

cooled down in the condenser by the means of

air circulation (forced air) or water circulation.

• The two main parameters that may aﬀect the

production capacity of an ice machine are:

• Room temperature (for units with air-cooled

condenser)

• Water Temperature (aﬀects both condensation

and ice production capacity)

As these parameters vary, so does the produc-

tion capacity of an ice machine vs the normal

conditions. Also, installing and commissioning

the ice machine correctly, and a regular machine

cleaning routine will ensure peak performance

rather than a sluggish one.

• The Air-Cooled Condenser (AS) looks like a

car radiator, cooled down by the action of a fan

which forces air through it. Both the griddle of

the condenser and/or the air-ﬁlter that protects

it, must be kept clean from the accumulation

of clogging agents, such as dust and grease to

maintain their function. Designed to work best

at a + 40° C ambient temperature, it will be

adversely aﬀected by an increase of the

ambient temperature and/or by a

decrease in the air ﬂow (which may also

occur in case of poor built-in installations), with

the consequent result of a decrease in the ice

machine production capacity. A water

condenser consists of a coil made of two pipes

welded together, where respectively water and

refrigerant gas ﬂow through. This system is less

demanding in terms of cleaning and mainte-

nance and it is recommended in temperature-

critical installations. Typically, water-cooled ice

machines are used where the heat exchange is

insuﬃcient, or where it may cause overheating,

and best where the inlet water-temperature is

consistently around 18°-20°C. Examples of such

situations, where water condensing is highly

recommended, are built-in installations with

reduced air ﬂow, or dusty environments, or

where the noise factor must be kept to a

minimum (the water cooled condenser is

virtually noiseless). The many advantages

oﬀered by the watercooled condensers

must be weighed against the increased

water consumption, with all the relevant

issues in terms of cost, availability and recycling

of this precious element. In areas where water

is rich in minerals, the use of a correctly sized

water-softening system is highly recommen-

ded. When speciﬁc local circumstances do not

allow for the use of a water condensed unit, we

may resort to variations on the standard

air-condensing system, such as:

• Remote Condenser (ASR): allows for a

remote installation of the condenser, away

from the location of ice maker. It means

removing all the heat-ejection and noise and

placing them (usually) outside. Large units

will also allow for SPLIT installations:

here, not only the compressor is remotely

installed, but also the refrigeration/condensing

system (the compressor and so on), typically

placed altogether outside of the ice produc-

tion site. Both these systems grant an

improved operation of ice machines that use

air condensers in high-ambient conditions.

General rule: a clean condenser will grant

better energy eﬃciency and a longer

working life of the refrigeration system

components. Smaller ice machines,

particularly aﬀected by the opposite condition,

are now equipped in the Scotsman 6 Series

with a “Clean Me!” light, positioned on the front

panel side to the On-Oﬀ switch, which alerts

the operator when the cleaning of the

condenser air ﬁlter is due.

1 - Evaporator

2 - Pump

3 - Compressor

4 - Condenser

Essentials of a freezing cycle in a Scotsman Gourmet Cuber

Make the best of your business

with Scotsman Ice!

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