Pumpable ice technology
Encyclopedia
Pumpable ice technology is a technology to produce fluids or secondary refrigerants also called coolant
s with a viscosity of water or jelly and the cooling capacity of ice
. Pumpable ice is typically a slurry of ice crystals or particles ranging from 5 to 10,000 micrometers (1 cm) in brine
, seawater
or food liquid and gas bubbles, e.g., air, ozone
, carbon dioxide
.
In the most cases, a fresh water solid ice
, such as flake ice
, plate ice, tube ice
, shell ice or cubic ice, is crushed or ground, mixed with a sea water or salted water and pumped by conventional water pump
s.
Besides general terms such as pumpable, jelly or slurry ice
, there are many other trademark
s for this coolant such as “Beluga”, “optim”, “flow”, “fluid”, “jel”, “binary”, “liquid”, “maxim”, “whipped”, “Deepchill”, “bubble slurry” ice. These trademarks are authorized by industrial ice maker production companies in Australia, Canada, China,
Germany, Iceland, Israel, Russia, Spain, United Kingdom, USA.
The first is to manufacture commonly used forms of crystal solid ice such as plate, tube, shell or flake ice, by crushing and mixing it with water. This mixture of different ice concentration
s and dimensions (ice crystals can vary from 200 µm to 10 mm) is passed by pumps from storage tank
to the consumer. The constructions, specifications and applications of the current conventional ice makers are described in.
The idea of the second method is to create the crystallization
process inside of the volume of the cooled liquid.
Crystallization inside of the liquid’s volume can be accomplished by the vacuum
or cooling technologies. By vacuum technology, very low pressure forces a small part of the water to evaporate while the remaining water freezes forming water-ice mixture. Depending on the additives’ concentration, the final temperature of PI is between zero and –4 °C. The large volume of vapor and an operating pressure of about 6 mbar (600 Pa
) require the usage of a water vapor compressor with a large swept volume.
This PIT is economically reasonable and can be recommended for systems with cooling capacity of 300 TR (1 TR = 1 ton of refrigeration
= 12,000 BTU/h = 3.516 kW
) or larger.
Crystallization by cooling can be done using the direct or indirect systems.
is directly injected inside the liquid
The advantage of this method is the absence of any intermediate device between the refrigerant (R) and the liquid (L). However, the absence of heat loss between R and L in the process of thermal interaction (heat transfer
) may cause some insufficiencies that could keep this
method from its wide inoculation into the industry. The high level of safety
measures, the need for an additional step of a refrigerant separation and difficulties in producing crystals are disadvantages of this method.
(heat exchanger
-crystallizer) is assembled either horizontally or vertically. It have shell tubing assembled with one to a hundred inner tubes and containing a refrigerant that evaporates between the shell and the inner tubing. A liquid flows through the tubing of the small diameter. In the inside volume of the evaporator there are organized cooling
, supercooling
and freezing
of liquid due to the heat exchange with the crystallizer cooled wall.
The idea is to use a well-polished surface of the evaporator (dynamic scraped surface heat exchanger) and appropriate mechanisms to prevent tubing from the adhesion
of ice embryos, from a growth and a thickening of the ice on the inside cooling surface. A whip rod, a screw or a shaft with metallic or plastic wipers is usually used as mechanisms for removal.
Indirect PITs produce pumpable ice (PI) consisting of 5 to 50 micrometer crystals and having a number of advantages. By PIT it can be produced 1,000 kg of pure ice at the low energy expenditure of 60 to 75 kW·h instead of 90 to 130 kW·h required for the production of regular water ice (plate, flake, shell types). The further improvements will allow to reach a specific energy expenditure for ice production of 40 to 55 kW·h per 1,000 kg of pure ice and a high specific ice capacity per an area value of the evaporator cooling surface (up to 450 kg/(m2·h)).
Sometimes a gas can be added to the liquid flowing through the evaporator. It destroys a liquid laminar
layer on the cooled surface of the heat exchanger-crystallizer, increases flow turbulence
, and decreases the average viscosity
of PI.
Liquids, such as sea water, juice, brine
s, or glycol solutions of additives with more than 3–5% concentrations and a freezing point
less than −2 °C are used in the process.
Typically, the equipment for the production, accumulation and supplying of PI includes an ice maker(s),a storage tank
(s), a heat exchanger
, piping, pumps, electrical and electronic appliances and devices.
The PI with maximum ice concentration
of 40% can be pumped straight from the ice maker to the consumer. The final possible ice concentration of PI in the storage tank is 50%. The maximum value of cooling energy of PI, accumulated in the storage tank in a form of homogeneous phase, is about 700 kW·h which corresponds to 10–15 m3 volume of a storage tank. A mixer is used to prevent a separation of ice from the cooled liquid and keeps an ice concentration unchanged by time and the tank height. In this case the PI is transported from the storage tank to the place of consumption that could be hundreds meters apart. The practical ratio between the required electric power
of the submersible mixer
motor (kW) and the “kneaded” PI volume (m3) is 1:1.
In the tanks with volumes larger than 15 m3, PI is not mixed and the cold energy of stored ice is only used by a heat transfer
of liquid that circulates between a storage tank and the consumers of cold. There are the disadvantages of the existing ice storage reservoirs including the following:
The chaotic uncontrollable upsurge of ice ridges which arise due to the uneven splash of warm solution. This liquid comes from the heat exchanger and fed into a storage tank with ice for further cooling by the direct contact with the surface of the ice. As a result, because of uneven in space and time feed rate of the solution, the ice melts unevenly. Thus, the ice spikes rise above the ice surface, which leads to the destruction of spraying devices and the need to reduce the level of solution in the tank to avoid any breakage.
Accumulated in the tank ice turns into a large chunk. The warm liquid that comes from the air-conditioning system may generate channels through which the liquid could return to the system without being cooled. As a result of it, the accumulated ice will not be utilized in full.
An ineffective use of the volume of the accumulation tank leads to a decrease in an achievable maximum of ice concentration and inability to fill out the entire working volume of the accumulating tank.
The results of continuous research and design cause optimism and promise overcoming the above disadvantages in the nearest future that should initiate the transition to a mass production of cheap, reliable and energy efficient accumulating tanks. These tanks need to guarantee the decrease of quality (i.e., ice concentration) and to allow for a complete recovery of stored cold potential.
s of wastewaters. In this case, there is used a method including freezing
and melting
. It is based on two processes: proper freezing of sediments, the following melting and separation of liquid and solid phases. "Freezing and melting" leads to the variation of physical-chemical structure of sediments. This method is realized owing to redistribution of any form of the connection of moisture with solid particles of the sediment. It is better than chemical reagent coagulation. The sediment's freezing promotes the increasing of free water quantity into sediments and
improves an efficiency of sediment precipitating. The most of the moisture is capable to diffusion for any conditions. Therefore, if the velocity of crystal growing does not exceed 0.02 m/h, for moisture there is time to migrate from colloid cells to the crystal surface, and there it is frozen. After thawing, low frozen sediments return to the water well.
, vapor-compression, multi effect evaporation, reverse osmosis and electrodialysis
. Theoretically, freezing has some advantages over a lot of above mentioned methods. These advantages include a lower theoretical energy requirement, minimal potential for corrosion, and little scaling or precipitating. The disadvantage is that it involves a handling of ice and water mixtures that are mechanically complicated to move and process. A small number of desalination stations have been built over the last 50 years, but the process has not been a commercial success in the production of fresh water for municipal purposes. PIMs offer an affordable alternative because of the high
efficient of the crystallization process. Current models, however, do not have the necessary capacity for industrial desalination plants, but PIM smaller models suffice for small-scale desalination needs.
, vacuum-evaporation technology. In commercial operations, juice is normally concentrated by evaporation. Since 1962, the Thermally Accelerated Short Time Evaporator (TASTE) is widely used. TASTE evaporators are sufficient, sanitary, easy to clean, of high capacity, simple to operate, and at reasonably low cost. On the other hand, there is a heat damage to the product caused by the high temperature steam treatment. This treatment results in product quality and aroma loses. Because of a low value of the film coefficient between steam and treated juice, there is a very non-efficient heat transfer between mentioned mediums. It leads to cumbersome constructions of TASTE plants. The alternative way to concentrate juice and food liquid is by cooling and freezing process. In this case the crystals, containing pure water, are removed from juice
, wine
, or beer
by crystallization. The aroma, color
, and flavor
remain in the concentrated medium. The quality of freeze concentrated products cannot be
achieved by any other technology. The main advantages of PIT in comparison with other freezing techniques are lowest required energy expenditure and a possibility to tune a rate of the phase change boundary of liquid-solid ice. The last reason causes the increasing of the production of the pure water ice crystals and a simplifying of the separation between concentrated juice or food liquid and ice crystals.
- a liquid that is specially prepared for human consumption. In addition to the realization of basic human needs for drinking, drinks are a part of the culture of human society. In turn, the frozen carbonated beverage
(FCB) and frozen uncarbonated beverages (FUB) began to enjoy great popularity with the 1990 of the 20th century.
Pumpable ice technology is used in the manufacture of almost all, without exception, FCB and FUB.
, the owner of a small restaurant at the end of 1950 period.
For FCB manufacturing, there is used a mixture of flavored syrup, carbon dioxide gas (chemical formula CO2) and filtered water. Typically, the initial temperature of the mixture is (12-18)°C. Carbonated mixture is fed into the evaporator of FCB apparatus, freezes on the inner surface of the cylindrical evaporator and is scraped (peeled off) by the blades - mixers, rotating with an angular velocity of 60 to 200 revolutions per minute. In the internal volume of the crystallizer, a slight positive pressure (up to 3 bar) is supported to improve the dissolution of gas in the liquid. In modern FCB devices, there is realized a conventional refrigeration circuit with a capillary tube or thermostatic expansion valve and, usually, air condenser
. Refrigerant is fed either directly into the cavity of the two-wall evaporator or the spiral evaporator winded on the outer surface of the crystallizer. Material of the evaporator wall is the only stainless steel grade SS316L, allowed for a contact with food according to requirements of the U.S. Food and Drug Administration
(FDA). The evaporating temperature is -(32.0-20.0)°C. Manufacturers do not declare hourly capacity of FCB vehicles. However, the energy expenditure to produce 10.0 kg of FCB can be (1.5-2.0) kWh.
After mixing and freezing into the crystallizer - mixer, FCB pours through the nozzle in the cups. The end product is a thick mixture of suspended ice crystals with a relatively small amount of liquid. FCB quality depends on many factors, including the concentration and structure of ice crystals, as well as their size. The concentration of ice water mixture is determined accurately in accordance with the phase diagram
of the solution and can reach 50%. The maximum size of crystals is from 0.5 mm to 1.0 mm. The initial temperature of crystallization of the mixture depends on the initial concentration of ingredients into the water and lies between -2.0 °C to -0.5 °C. The final temperature of the product changes from -6.0 °C to -2.0 °C, depending on the brand of manufacturer.
There has been sudden interest in FCB seen in India. This is because India does not allow adding cubic ice produced from the city water to Coke-Cola because of the high probability of bacteriological contamination. FCB in the form of frozen Coke presents an alternative way to create an ice-chilled beverage.
FUB machines differ from FCB machines so that they do not require to maintain a small positive pressure in the working volume of the evaporator, the source of carbon dioxide gas and specially trained staff. Otherwise, the design of modern FUB machines is similar to FCB design vehicles. Actually, FUB is often much "wet" (lower concentration of ice in the mixture) than the produced FCB. On the other hand, FUB machines are not complicated and cheaper than FCB devices, and therefore, they are more common.
production market has risen steadily throughout the 1990s and its value is multibillion US dollars.
There are eight major ice cream markets in the world: United States, China, Japan, Germany, Italy, Russia, France, United Kingdom.
The key competitors in the industry are Unilever
and Nestle
, controlling more than one-third of the market. The top five ice-cream consuming countries are the United States, New Zealand, Denmark, Australia and Belgium.
The modern design of industrial ice cream freezers ensures a high level of machine/operator interface and top quality of the produced ice cream.
The manufacturing process of ice cream production includes pasteurization, homogenization and maturation of the ice cream mixture. The prepared mixture enters into the industrial double tube scraped crystallizer – heat exchanger, in which the processes of pre-freezing and churning of ice cream are realized. A refrigerant fluid evaporates and is circulating continually in a vessel jacket.
Usually, the initial temperature of an ice cream mixture equals (12-18)°C. After switching on of a freezer, an evaporating temperature of a refrigerant decreases up to minus (25-32)°C. The final temperature of the treated mixture into the scraped surface freezer is about minus 5 °C with an ice concentration of approximately (30-50)%, depending on the formula. During a freezing process ice crystals are formed at the inside surface of the crystallizer. The blades remove ice crystals formed on the inside cooled wall. The removed ice crystals are mixed with the bulk and continue to decrease the temperature and to improve the heat transfer within the product.
There are also rotating dashers that help to whip the mix and incorporate air bubbles into the mixture. Then the frozen product carries to the distributor.
The quality of ice cream and its smooth texture are depended on the structure of ice crystals, their dimensions and on the viscosity of the ice cream. Water freezes out of a liquid in its pure form as ice. The concentration of the remaining liquid of sugar is increased due to water removal and hence the freezing point
is further lowered. Thus the structure of ice cream can be described as a partly frozen foam with ice crystals and air bubbles occupying a majority of the space. The tiny fat globules flocculate and surround the air bubbles also in the form of a dispersed phase. Proteins and emulsifiers are in turn surround the fat globules. The continuous phase consists of a very concentrated, unfrozen liquid of sugars.
The final average diameter of ice crystals depends on the rate of freezing. As it is faster, the more nucleation
is promoted and the amount of smaller ice crystals is greater. Usually, after a cooling treatment into the freezer ice dimensions are about 35-80 micron.
and food industries. In comparison with a fresh water solid ice the main advantages of PI are the following: homogeneous, higher cooling rates of food and fish. PI flows like water and eliminates freeze burns and physical damage of cooled object, supports quality with longer shelf life
. PIT corresponds to Food
Safety & Public health
considerations (HACCP and ISO). Finally, PIT has lower specific energy expenditure in comparison with the existing technologies using a conventional fresh water solid ice.
s, like R-22
(Freon) and other hydro chlorofluorocarbon
s (HCFC’s).
Reasons to use PIT in this application are the following:
. Then a process of fermentation
s is realized to obtain this drink.
s, power plant energy consumption and pollution
, greenhouse gas emissions. The idea is to make and to accumulate PI during off-peak electricity hours with the lowest tariff of kW·h. The stored PI is used during middle or high tariff hours to cool the equipment or air supplied to buildings. The return on investment
s (ROI) is during 2–4 years. In comparison with Static and Dynamic ice storage systems, the overall heat transfer coefficient (OHTC) during the PI production is more than tens or hundreds times higher (efficient) than the same coefficient for the above mentioned TESS types. It explains by the presence of many different kinds of thermal resistances between the boiling refrigerant at the evaporator and water/ice in a storage tank of Static and Dynamic ice storage systems. The high value of OHTC of PIT-based TESS, causes a decrease of component volume, an increase of the maximum achievable concentration of ice in the volume of a storage tank, and it ultimately affects the price of equipment.TESSs based on PIT are installed in different countries: Japan, Korea, USA, UK and Saudi Arabia.
.
Benefits of PIT in medical applications are:
PI produced by Vacuum Ice Maker (VIM) Technology helps to professional skiers to increase the mode of training before and after winter season (during last Autumn months and in early spring time). For sports fans of skiing there is an opportunity to ski all year round.
The process of PI is organized as following. The salt solution is exposed to very low pressure inside the VIM. A small part of the salt solution evaporates in the form of water due to the vacuum forces, while the remaining liquid is frozen forming mixture. The water vapor is continuously evacuated from the VIM, is compressed and fed into a condenser due to the special construction centrifugal compressor. Standard water chiller
supplies cooling water at 5 °C in order to condense the water vapor. The liquid-ice mixture is pumped out from the freezing volume to the ice concentrator in which ice crystals separate from the liquid. The high concentration ice is extracted from the concentrator.
VIMs are already installed on the ski resort
s of Austria and Switzerland.
Coolant
A coolant is a fluid which flows through a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither causing nor...
s with a viscosity of water or jelly and the cooling capacity of ice
Ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...
. Pumpable ice is typically a slurry of ice crystals or particles ranging from 5 to 10,000 micrometers (1 cm) in brine
Brine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...
, seawater
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
or food liquid and gas bubbles, e.g., air, ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
, carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
.
History
The first time the possibility to mix water with ice, and to pump this PI, was realized by US Company North Star Ice Equipment Corporation, they called this mixture “liquid ice”.In the most cases, a fresh water solid ice
Ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...
, such as flake ice
Flake ice
Flake ice is a loose definition of a group of ice types with irregular particle sizes. These types can be roughly grouped into two main types, scale ice and granular ice'....
, plate ice, tube ice
Tube ice
Tube ice is a type of solid ice and water mixture in tube shape. It is made by a tube ice generator. It can be used in the cooling process, such as temperature controlling, fish fresh freezing, beverage bottle freezing, etc...
, shell ice or cubic ice, is crushed or ground, mixed with a sea water or salted water and pumped by conventional water pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...
s.
Besides general terms such as pumpable, jelly or slurry ice
Slurry ice
Slurry ice is a phase changing refrigerant made up of millions of ice “micro-crystals” 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, various alcohols and sugar...
, there are many other trademark
Trademark
A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...
s for this coolant such as “Beluga”, “optim”, “flow”, “fluid”, “jel”, “binary”, “liquid”, “maxim”, “whipped”, “Deepchill”, “bubble slurry” ice. These trademarks are authorized by industrial ice maker production companies in Australia, Canada, China,
Germany, Iceland, Israel, Russia, Spain, United Kingdom, USA.
Technological process
There are two relatively simple methods for the production of PI.The first is to manufacture commonly used forms of crystal solid ice such as plate, tube, shell or flake ice, by crushing and mixing it with water. This mixture of different ice concentration
Concentration
In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration...
s and dimensions (ice crystals can vary from 200 µm to 10 mm) is passed by pumps from storage tank
Storage tank
A storage tank is a container, usually for holding liquids, sometimes for compressed gases . The term can be used for reservoirs , and for manufactured containers. The usage of the word tank for reservoirs is common or universal in Indian English, American English and moderately common in British...
to the consumer. The constructions, specifications and applications of the current conventional ice makers are described in.
The idea of the second method is to create the crystallization
Crystallization
Crystallization is the process of formation of solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas. Crystallization is also a chemical solid–liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid...
process inside of the volume of the cooled liquid.
Crystallization inside of the liquid’s volume can be accomplished by the vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...
or cooling technologies. By vacuum technology, very low pressure forces a small part of the water to evaporate while the remaining water freezes forming water-ice mixture. Depending on the additives’ concentration, the final temperature of PI is between zero and –4 °C. The large volume of vapor and an operating pressure of about 6 mbar (600 Pa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
) require the usage of a water vapor compressor with a large swept volume.
This PIT is economically reasonable and can be recommended for systems with cooling capacity of 300 TR (1 TR = 1 ton of refrigeration
Ton of refrigeration
A ton of refrigeration or ton of refrigeration is a unit of power used in some countries to refer to the thermal load extraction capacity of refrigeration and air conditioning equipment.It is defined as the amount of latent heat absorbed by the fusion of a short ton of pure solid ice at 0 °C ...
= 12,000 BTU/h = 3.516 kW
Kw
kw or KW may refer to:* Kuwait, ISO 3166-1 country code** .kw, the country code top level domain for Kuwait* Kilowatt* Self-ionization of water Kw* Cornish language's ISO 639 code* Kitchener–Waterloo, Ontario, Canada...
) or larger.
Crystallization by cooling can be done using the direct or indirect systems.
Direct PITs
A refrigerantRefrigerant
A refrigerant is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase change from a liquid to a gas. Traditionally, fluorocarbons, especially chlorofluorocarbons, were used as refrigerants, but they are being phased out because of their ozone depletion...
is directly injected inside the liquid
The advantage of this method is the absence of any intermediate device between the refrigerant (R) and the liquid (L). However, the absence of heat loss between R and L in the process of thermal interaction (heat transfer
Heat transfer
Heat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...
) may cause some insufficiencies that could keep this
method from its wide inoculation into the industry. The high level of safety
Safety
Safety is the state of being "safe" , the condition of being protected against physical, social, spiritual, financial, political, emotional, occupational, psychological, educational or other types or consequences of failure, damage, error, accidents, harm or any other event which could be...
measures, the need for an additional step of a refrigerant separation and difficulties in producing crystals are disadvantages of this method.
Indirect PITs
In the indirect PITs the evaporatorEvaporator
An evaporator is a device used to turn the liquid form of some chemical into its gaseous form. For example, an evaporator is used in an air conditioning system to allow the compressed cooling chemical to evaporate from liquid to gas, absorbing heat in the process.-Uses:As stated above, an...
(heat exchanger
Heat exchanger
A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact...
-crystallizer) is assembled either horizontally or vertically. It have shell tubing assembled with one to a hundred inner tubes and containing a refrigerant that evaporates between the shell and the inner tubing. A liquid flows through the tubing of the small diameter. In the inside volume of the evaporator there are organized cooling
Cooling
Cooling is the transfer of thermal energy via thermal radiation, heat conduction or convection. It may also refer to:-Techniques:* Air conditioning* Air cooling* Computer cooling* Cryogenics* Conduction * Infrared solar cells* Laser cooling...
, supercooling
Supercooling
Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid....
and freezing
Freezing
Freezing or solidification is a phase change in which a liquid turns into a solid when its temperature is lowered below its freezing point. The reverse process is melting....
of liquid due to the heat exchange with the crystallizer cooled wall.
The idea is to use a well-polished surface of the evaporator (dynamic scraped surface heat exchanger) and appropriate mechanisms to prevent tubing from the adhesion
Adhesion
Adhesion is any attraction process between dissimilar molecular species that can potentially bring them in close contact. By contrast, cohesion takes place between similar molecules....
of ice embryos, from a growth and a thickening of the ice on the inside cooling surface. A whip rod, a screw or a shaft with metallic or plastic wipers is usually used as mechanisms for removal.
Indirect PITs produce pumpable ice (PI) consisting of 5 to 50 micrometer crystals and having a number of advantages. By PIT it can be produced 1,000 kg of pure ice at the low energy expenditure of 60 to 75 kW·h instead of 90 to 130 kW·h required for the production of regular water ice (plate, flake, shell types). The further improvements will allow to reach a specific energy expenditure for ice production of 40 to 55 kW·h per 1,000 kg of pure ice and a high specific ice capacity per an area value of the evaporator cooling surface (up to 450 kg/(m2·h)).
Sometimes a gas can be added to the liquid flowing through the evaporator. It destroys a liquid laminar
Laminar flow
Laminar flow, sometimes known as streamline flow, occurs when a fluid flows in parallel layers, with no disruption between the layers. At low velocities the fluid tends to flow without lateral mixing, and adjacent layers slide past one another like playing cards. There are no cross currents...
layer on the cooled surface of the heat exchanger-crystallizer, increases flow turbulence
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
, and decreases the average viscosity
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
of PI.
Liquids, such as sea water, juice, brine
Brine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...
s, or glycol solutions of additives with more than 3–5% concentrations and a freezing point
Freezing Point
Freezing Point is a news journal in the People's Republic of China which has been the subject of controversy over its criticism of Communist Party officials and the sympathetic ear it lent to a Chinese historian who had criticized official history textbooks...
less than −2 °C are used in the process.
Typically, the equipment for the production, accumulation and supplying of PI includes an ice maker(s),a storage tank
Storage tank
A storage tank is a container, usually for holding liquids, sometimes for compressed gases . The term can be used for reservoirs , and for manufactured containers. The usage of the word tank for reservoirs is common or universal in Indian English, American English and moderately common in British...
(s), a heat exchanger
Heat exchanger
A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact...
, piping, pumps, electrical and electronic appliances and devices.
The PI with maximum ice concentration
Concentration
In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration...
of 40% can be pumped straight from the ice maker to the consumer. The final possible ice concentration of PI in the storage tank is 50%. The maximum value of cooling energy of PI, accumulated in the storage tank in a form of homogeneous phase, is about 700 kW·h which corresponds to 10–15 m3 volume of a storage tank. A mixer is used to prevent a separation of ice from the cooled liquid and keeps an ice concentration unchanged by time and the tank height. In this case the PI is transported from the storage tank to the place of consumption that could be hundreds meters apart. The practical ratio between the required electric power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...
of the submersible mixer
Submersible mixer
A submersible mixer is a mechanical device that is used to mix sludge tanks and other liquid volumes. Submersible mixers are often used in sewage treatment plants to keep solids in suspension in the various process tanks and/or sludge holding tanks....
motor (kW) and the “kneaded” PI volume (m3) is 1:1.
In the tanks with volumes larger than 15 m3, PI is not mixed and the cold energy of stored ice is only used by a heat transfer
Heat transfer
Heat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...
of liquid that circulates between a storage tank and the consumers of cold. There are the disadvantages of the existing ice storage reservoirs including the following:
The chaotic uncontrollable upsurge of ice ridges which arise due to the uneven splash of warm solution. This liquid comes from the heat exchanger and fed into a storage tank with ice for further cooling by the direct contact with the surface of the ice. As a result, because of uneven in space and time feed rate of the solution, the ice melts unevenly. Thus, the ice spikes rise above the ice surface, which leads to the destruction of spraying devices and the need to reduce the level of solution in the tank to avoid any breakage.
Accumulated in the tank ice turns into a large chunk. The warm liquid that comes from the air-conditioning system may generate channels through which the liquid could return to the system without being cooled. As a result of it, the accumulated ice will not be utilized in full.
An ineffective use of the volume of the accumulation tank leads to a decrease in an achievable maximum of ice concentration and inability to fill out the entire working volume of the accumulating tank.
The results of continuous research and design cause optimism and promise overcoming the above disadvantages in the nearest future that should initiate the transition to a mass production of cheap, reliable and energy efficient accumulating tanks. These tanks need to guarantee the decrease of quality (i.e., ice concentration) and to allow for a complete recovery of stored cold potential.
Applications
Many research centers, ice maker producers, inventors stimulate progress in PIT. Due to the high energy efficiency, reduced size, low refrigerant charge, and to the fact that PIT is flexible to adapt it to different industrial segment requirements, there are many applications of this technology.Wastewater treatment
PIT can be recommended for cleaning (lightening) of sedimentSediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s of wastewaters. In this case, there is used a method including freezing
Freezing
Freezing or solidification is a phase change in which a liquid turns into a solid when its temperature is lowered below its freezing point. The reverse process is melting....
and melting
Melting
Melting, or fusion, is a physical process that results in the phase change of a substance from a solid to a liquid. The internal energy of a substance is increased, typically by the application of heat or pressure, resulting in a rise of its temperature to the melting point, at which the rigid...
. It is based on two processes: proper freezing of sediments, the following melting and separation of liquid and solid phases. "Freezing and melting" leads to the variation of physical-chemical structure of sediments. This method is realized owing to redistribution of any form of the connection of moisture with solid particles of the sediment. It is better than chemical reagent coagulation. The sediment's freezing promotes the increasing of free water quantity into sediments and
improves an efficiency of sediment precipitating. The most of the moisture is capable to diffusion for any conditions. Therefore, if the velocity of crystal growing does not exceed 0.02 m/h, for moisture there is time to migrate from colloid cells to the crystal surface, and there it is frozen. After thawing, low frozen sediments return to the water well.
Desalination of seawater
The existing commercialized desalination methods are multi-stage flash evaporationFlash evaporation
Flash evaporation is the partial vapor that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through a throttling valve or other throttling device. This process is one of the simplest unit operations...
, vapor-compression, multi effect evaporation, reverse osmosis and electrodialysis
Electrodialysis
Electrodialysis is used to transport salt ions from one solution through ion-exchange membranes to another solution under the influence of an applied electric potential difference. This is done in a configuration called an electrodialysis cell...
. Theoretically, freezing has some advantages over a lot of above mentioned methods. These advantages include a lower theoretical energy requirement, minimal potential for corrosion, and little scaling or precipitating. The disadvantage is that it involves a handling of ice and water mixtures that are mechanically complicated to move and process. A small number of desalination stations have been built over the last 50 years, but the process has not been a commercial success in the production of fresh water for municipal purposes. PIMs offer an affordable alternative because of the high
efficient of the crystallization process. Current models, however, do not have the necessary capacity for industrial desalination plants, but PIM smaller models suffice for small-scale desalination needs.
Processes of concentration of food liquid and juice
Currently a concentrating of juice, food liquids is made using reverse osmosisReverse osmosis
Reverse osmosis is a membrane technical filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and...
, vacuum-evaporation technology. In commercial operations, juice is normally concentrated by evaporation. Since 1962, the Thermally Accelerated Short Time Evaporator (TASTE) is widely used. TASTE evaporators are sufficient, sanitary, easy to clean, of high capacity, simple to operate, and at reasonably low cost. On the other hand, there is a heat damage to the product caused by the high temperature steam treatment. This treatment results in product quality and aroma loses. Because of a low value of the film coefficient between steam and treated juice, there is a very non-efficient heat transfer between mentioned mediums. It leads to cumbersome constructions of TASTE plants. The alternative way to concentrate juice and food liquid is by cooling and freezing process. In this case the crystals, containing pure water, are removed from juice
Juice
Juice is the liquid that is naturally contained in fruit or vegetable tissue.Juice is prepared by mechanically squeezing or macerating fruit or vegetable flesh without the application of heat or solvents. For example, orange juice is the liquid extract of the fruit of the orange tree...
, wine
Wine
Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...
, or beer
Beer
Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...
by crystallization. The aroma, color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...
, and flavor
Flavor
Flavor or flavour is the sensory impression of a food or other substance, and is determined mainly by the chemical senses of taste and smell. The "trigeminal senses", which detect chemical irritants in the mouth and throat as well as temperature and texture, are also very important to the overall...
remain in the concentrated medium. The quality of freeze concentrated products cannot be
achieved by any other technology. The main advantages of PIT in comparison with other freezing techniques are lowest required energy expenditure and a possibility to tune a rate of the phase change boundary of liquid-solid ice. The last reason causes the increasing of the production of the pure water ice crystals and a simplifying of the separation between concentrated juice or food liquid and ice crystals.
Production of frozen food liquids
"Food liquid" or drinkDrink
A drink, or beverage, is a liquid which is specifically prepared for human consumption. In addition to fulfilling a basic human need, beverages form part of the culture of human society.-Water:...
- a liquid that is specially prepared for human consumption. In addition to the realization of basic human needs for drinking, drinks are a part of the culture of human society. In turn, the frozen carbonated beverage
Frozen Carbonated Beverage
A frozen carbonated beverage is a mixture of flavored sugar syrup, carbon dioxide, and water that is frozen by a custom machine creating a drink comprising a fine slush of suspended ice crystals, with liquid. The final ice crystal concentration changes from 10% to 50%. It depenses on a type of...
(FCB) and frozen uncarbonated beverages (FUB) began to enjoy great popularity with the 1990 of the 20th century.
Pumpable ice technology is used in the manufacture of almost all, without exception, FCB and FUB.
Frozen carbonated beverages
FCB machine was invented by Omar KnedlikOmar Knedlik
Omar Knedlik , was the inventor of the ICEE frozen drink. He was born and raised a poor farm boy in Barnes, Kansas in 1916. Knedlik was a World War II veteran who bought his first ice cream shop after the war. He owned several hotels before moving to Coffeyville, Kansas, where he became the...
, the owner of a small restaurant at the end of 1950 period.
For FCB manufacturing, there is used a mixture of flavored syrup, carbon dioxide gas (chemical formula CO2) and filtered water. Typically, the initial temperature of the mixture is (12-18)°C. Carbonated mixture is fed into the evaporator of FCB apparatus, freezes on the inner surface of the cylindrical evaporator and is scraped (peeled off) by the blades - mixers, rotating with an angular velocity of 60 to 200 revolutions per minute. In the internal volume of the crystallizer, a slight positive pressure (up to 3 bar) is supported to improve the dissolution of gas in the liquid. In modern FCB devices, there is realized a conventional refrigeration circuit with a capillary tube or thermostatic expansion valve and, usually, air condenser
Condenser (heat transfer)
In systems involving heat transfer, a condenser is a device or unit used to condense a substance from its gaseous to its liquid state, typically by cooling it. In so doing, the latent heat is given up by the substance, and will transfer to the condenser coolant...
. Refrigerant is fed either directly into the cavity of the two-wall evaporator or the spiral evaporator winded on the outer surface of the crystallizer. Material of the evaporator wall is the only stainless steel grade SS316L, allowed for a contact with food according to requirements of the U.S. Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
(FDA). The evaporating temperature is -(32.0-20.0)°C. Manufacturers do not declare hourly capacity of FCB vehicles. However, the energy expenditure to produce 10.0 kg of FCB can be (1.5-2.0) kWh.
After mixing and freezing into the crystallizer - mixer, FCB pours through the nozzle in the cups. The end product is a thick mixture of suspended ice crystals with a relatively small amount of liquid. FCB quality depends on many factors, including the concentration and structure of ice crystals, as well as their size. The concentration of ice water mixture is determined accurately in accordance with the phase diagram
Phase diagram
A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions at which thermodynamically distinct phases can occur at equilibrium...
of the solution and can reach 50%. The maximum size of crystals is from 0.5 mm to 1.0 mm. The initial temperature of crystallization of the mixture depends on the initial concentration of ingredients into the water and lies between -2.0 °C to -0.5 °C. The final temperature of the product changes from -6.0 °C to -2.0 °C, depending on the brand of manufacturer.
There has been sudden interest in FCB seen in India. This is because India does not allow adding cubic ice produced from the city water to Coke-Cola because of the high probability of bacteriological contamination. FCB in the form of frozen Coke presents an alternative way to create an ice-chilled beverage.
Frozen uncarbonated beverages
The initial product for the FCB uses fruit and vegetable juices and drinks based on coffee and tea, yogurt. The research projects are conducted for the production of frozen wine and beer.FUB machines differ from FCB machines so that they do not require to maintain a small positive pressure in the working volume of the evaporator, the source of carbon dioxide gas and specially trained staff. Otherwise, the design of modern FUB machines is similar to FCB design vehicles. Actually, FUB is often much "wet" (lower concentration of ice in the mixture) than the produced FCB. On the other hand, FUB machines are not complicated and cheaper than FCB devices, and therefore, they are more common.
Ice cream
The ice creamIce cream
Ice cream is a frozen dessert usually made from dairy products, such as milk and cream, and often combined with fruits or other ingredients and flavours. Most varieties contain sugar, although some are made with other sweeteners...
production market has risen steadily throughout the 1990s and its value is multibillion US dollars.
There are eight major ice cream markets in the world: United States, China, Japan, Germany, Italy, Russia, France, United Kingdom.
The key competitors in the industry are Unilever
Unilever
Unilever is a British-Dutch multinational corporation that owns many of the world's consumer product brands in foods, beverages, cleaning agents and personal care products....
and Nestle
Nestlé
Nestlé S.A. is the world's largest food and nutrition company. Founded and headquartered in Vevey, Switzerland, Nestlé originated in a 1905 merger of the Anglo-Swiss Milk Company, established in 1867 by brothers George Page and Charles Page, and Farine Lactée Henri Nestlé, founded in 1866 by Henri...
, controlling more than one-third of the market. The top five ice-cream consuming countries are the United States, New Zealand, Denmark, Australia and Belgium.
The modern design of industrial ice cream freezers ensures a high level of machine/operator interface and top quality of the produced ice cream.
The manufacturing process of ice cream production includes pasteurization, homogenization and maturation of the ice cream mixture. The prepared mixture enters into the industrial double tube scraped crystallizer – heat exchanger, in which the processes of pre-freezing and churning of ice cream are realized. A refrigerant fluid evaporates and is circulating continually in a vessel jacket.
Usually, the initial temperature of an ice cream mixture equals (12-18)°C. After switching on of a freezer, an evaporating temperature of a refrigerant decreases up to minus (25-32)°C. The final temperature of the treated mixture into the scraped surface freezer is about minus 5 °C with an ice concentration of approximately (30-50)%, depending on the formula. During a freezing process ice crystals are formed at the inside surface of the crystallizer. The blades remove ice crystals formed on the inside cooled wall. The removed ice crystals are mixed with the bulk and continue to decrease the temperature and to improve the heat transfer within the product.
There are also rotating dashers that help to whip the mix and incorporate air bubbles into the mixture. Then the frozen product carries to the distributor.
The quality of ice cream and its smooth texture are depended on the structure of ice crystals, their dimensions and on the viscosity of the ice cream. Water freezes out of a liquid in its pure form as ice. The concentration of the remaining liquid of sugar is increased due to water removal and hence the freezing point
Freezing Point
Freezing Point is a news journal in the People's Republic of China which has been the subject of controversy over its criticism of Communist Party officials and the sympathetic ear it lent to a Chinese historian who had criticized official history textbooks...
is further lowered. Thus the structure of ice cream can be described as a partly frozen foam with ice crystals and air bubbles occupying a majority of the space. The tiny fat globules flocculate and surround the air bubbles also in the form of a dispersed phase. Proteins and emulsifiers are in turn surround the fat globules. The continuous phase consists of a very concentrated, unfrozen liquid of sugars.
The final average diameter of ice crystals depends on the rate of freezing. As it is faster, the more nucleation
Nucleation
Nucleation is the extremely localized budding of a distinct thermodynamic phase. Some examples of phases that may form by way of nucleation in liquids are gaseous bubbles, crystals or glassy regions. Creation of liquid droplets in saturated vapor is also characterized by nucleation...
is promoted and the amount of smaller ice crystals is greater. Usually, after a cooling treatment into the freezer ice dimensions are about 35-80 micron.
Fishery and food industry
PIT-based equipment can be used in the cooling processes in the fisheryFishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
and food industries. In comparison with a fresh water solid ice the main advantages of PI are the following: homogeneous, higher cooling rates of food and fish. PI flows like water and eliminates freeze burns and physical damage of cooled object, supports quality with longer shelf life
Shelf life
Shelf life is the length of time that food, drink, medicine, chemicals, and many other perishable items are given before they are considered unsuitable for sale, use, or consumption...
. PIT corresponds to Food
Safety & Public health
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...
considerations (HACCP and ISO). Finally, PIT has lower specific energy expenditure in comparison with the existing technologies using a conventional fresh water solid ice.
Supermarkets
TESSs based on PIT are attractive for air cooling in the supermarkets’ counters (showcases). At this application PI is circulated through the already available piping as a coolant. PI replaces environment unfriendly refrigerantRefrigerant
A refrigerant is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase change from a liquid to a gas. Traditionally, fluorocarbons, especially chlorofluorocarbons, were used as refrigerants, but they are being phased out because of their ozone depletion...
s, like R-22
Chlorodifluoromethane
Chlorodifluoromethane or difluoromonochloromethane is a hydrochlorofluorocarbon . This colorless gas is better known as HCFC-22, or R-22. It was once commonly used as a propellant and in air conditioning applications...
(Freon) and other hydro chlorofluorocarbon
Chlorofluorocarbon
A chlorofluorocarbon is an organic compound that contains carbon, chlorine, and fluorine, produced as a volatile derivative of methane and ethane. A common subclass are the hydrochlorofluorocarbons , which contain hydrogen, as well. They are also commonly known by the DuPont trade name Freon...
s (HCFC’s).
Reasons to use PIT in this application are the following:
- PI heat transfer rate results in compactness of the equipment. PIT equipment is smaller than that of other vendors of refrigeration equipment of the same capacity. It occupies less floor area, has lower volume and smaller weight;
- PI structure results in substantially better parameters of this cooling medium. The greater capacities can be calculated on any basis, including per one pass of the solution through the evaporator, per unit floor area occupied by the equipment, per unit weight of the equipment;
- With PIT it is easy to maintain a constant temperature inside the supermarket’s show cases or cabinets;
- PIT enables the cooling system to be more flexible and the cabinets can easily be rearranged according to increased or decreased requirements;
- PIT-based show cabinets need less refrigeration piping, less labor and cost to find leaks in comparison with direct expansion and refrigerantRefrigerantA refrigerant is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase change from a liquid to a gas. Traditionally, fluorocarbons, especially chlorofluorocarbons, were used as refrigerants, but they are being phased out because of their ozone depletion...
pump circulation systems; - Due to high efficiency of the PIT heat transfer process, it needs a very low refrigerant charge of cooling equipment;
- Unlike direct expansion systems, the PIT-based show cabinets and cases do not produce heat, since there is no need for air condenserCondenser (heat transfer)In systems involving heat transfer, a condenser is a device or unit used to condense a substance from its gaseous to its liquid state, typically by cooling it. In so doing, the latent heat is given up by the substance, and will transfer to the condenser coolant...
s under the cabinets. Therefore the air around the cabinets is not heated; - With PIT less energy is needed for defrosting of supermarket’s show cases and cabinets.
Production of Ice wine
Wide perspectives of PIT usage are opened for the production of special wines (reminiscent of similar "Richwine" or "Ice wine"). In comparison with the existing technology of Richwine production, PIT does not need for a few months on the freezing of grapes. Freshly squeezed grapes are harvested in a special container connected to the PI machine. The juice is pumped through PIM, from which comes as a mixture of ice (in the form of tiny, pure, free from the molecules juice, crystals), and a little more concentrated juice. Liquid ice returns to the accumulation tank, in which there is a natural (according to Archimedes law) separation between ice and juice. The cycle is repeated many times until the sugar concentration reaches (50 – 52)°BrixBrix
Degrees Brix is the sugar content of an aqueous solution.One degree Brix is 1 gram of sucrose in 100 grams of solution and represents the strength of the solution as percentage by weight . If the solution contains dissolved solids other than pure sucrose, then the °Bx is only approximate the...
. Then a process of fermentation
Fermentation (food)
Fermentation in food processing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. Fermentation in simple terms is the chemical conversion of sugars into ethanol...
s is realized to obtain this drink.
Thermal Energy Storage Systems
PIT-based Thermal Energy Storage System (TESS) can be used in the centralized water-cooled air conditioning systems in order to eliminate peak demand at the most critical time. It reduces the operating costs of the building, the need for new power plants and new transmission lineTransmission line
In communications and electronic engineering, a transmission line is a specialized cable designed to carry alternating current of radio frequency, that is, currents with a frequency high enough that its wave nature must be taken into account...
s, power plant energy consumption and pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
, greenhouse gas emissions. The idea is to make and to accumulate PI during off-peak electricity hours with the lowest tariff of kW·h. The stored PI is used during middle or high tariff hours to cool the equipment or air supplied to buildings. The return on investment
Return on investment
Return on investment is one way of considering profits in relation to capital invested. Return on assets , return on net assets , return on capital and return on invested capital are similar measures with variations on how “investment” is defined.Marketing not only influences net profits but also...
s (ROI) is during 2–4 years. In comparison with Static and Dynamic ice storage systems, the overall heat transfer coefficient (OHTC) during the PI production is more than tens or hundreds times higher (efficient) than the same coefficient for the above mentioned TESS types. It explains by the presence of many different kinds of thermal resistances between the boiling refrigerant at the evaporator and water/ice in a storage tank of Static and Dynamic ice storage systems. The high value of OHTC of PIT-based TESS, causes a decrease of component volume, an increase of the maximum achievable concentration of ice in the volume of a storage tank, and it ultimately affects the price of equipment.TESSs based on PIT are installed in different countries: Japan, Korea, USA, UK and Saudi Arabia.
Medicine
There have been developed a technological protective cooling process based on the implementation of a developed special ice slurry for medical applications. In this case PI can be injected intra-arterially, intravenously, along the external surfaces of organs by usage of laparoscopy, or even via the endotracheal tube. It is proving that PI selectively will cool organs to prevent or limit ischemic damage after a stroke or heart attack. Completed medical tests on animals simulated such as conditions as in-hospital kidney laparoscopic procedures. Results of French and US researchers must be approved by the U.S. Food and Drug AdministrationFood and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
.
Benefits of PIT in medical applications are:
- PI can be pumped easily through narrow catheters, providing high cooling capacity and rapid and targeted cooling of organs;
- PI may provide protective cooling and temperature management of target organs during surgery;
- PI helps victims of different medical emergencies including cardiac arrest and stroke.
Ski resorts
The Economic Impact of Global Warming causes a strong interest to produce snow for ski resorts at a warm weather even the ambient temperature is 20°C. The dimensions and power expenditure of the known snow-production equipment depend on humidity and wind. This snow-making equipment is based on the freezing of water droplets, sprayed into air, before reaching the surface of ground, and depends on the ambient temperature that needs to be lower than minus 4 °C.PI produced by Vacuum Ice Maker (VIM) Technology helps to professional skiers to increase the mode of training before and after winter season (during last Autumn months and in early spring time). For sports fans of skiing there is an opportunity to ski all year round.
The process of PI is organized as following. The salt solution is exposed to very low pressure inside the VIM. A small part of the salt solution evaporates in the form of water due to the vacuum forces, while the remaining liquid is frozen forming mixture. The water vapor is continuously evacuated from the VIM, is compressed and fed into a condenser due to the special construction centrifugal compressor. Standard water chiller
Water chiller
A water chiller is a mechanical device used to facilitate heat exchange from water to a refrigerant in a closed loop system. The refrigerant is then pumped to a location where the waste heat is transferred to the atmosphere....
supplies cooling water at 5 °C in order to condense the water vapor. The liquid-ice mixture is pumped out from the freezing volume to the ice concentrator in which ice crystals separate from the liquid. The high concentration ice is extracted from the concentrator.
VIMs are already installed on the ski resort
Ski resort
A ski resort is a resort developed for skiing and other winter sports. In Europe a ski resort is a town or village in a ski area - a mountainous area, where there are ski trails and supporting services such as hotels and other accommodation, restaurants, equipment rental and a ski lift system...
s of Austria and Switzerland.
See also
- Air conditioningAir conditioningAn air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...
- Crystallization (engineering aspects)
- Dynamic scraped surface heat exchanger
- Fish processingFish processingThe term fish processing refers to the processes associated with fish and fish products between the time fish are caught or harvested, and the time the final product is delivered to the customer...
- Fractional freezingFractional freezingFractional freezing is a process used in process engineering and chemistry to separate two liquids with different melting points. It can be done by partial melting of a solid, for example in zone refining of silicon or metals, or by partial crystallization of a liquid, for example "freeze...
- Frozen carbonated beverageFrozen Carbonated BeverageA frozen carbonated beverage is a mixture of flavored sugar syrup, carbon dioxide, and water that is frozen by a custom machine creating a drink comprising a fine slush of suspended ice crystals, with liquid. The final ice crystal concentration changes from 10% to 50%. It depenses on a type of...
- Frozen yogurtFrozen yogurtFrozen yogurt is a frozen dessert containing yogurt or other dairy products. It is slightly more tart than ice cream, as well as lower in fat...
- Ice creamIce creamIce cream is a frozen dessert usually made from dairy products, such as milk and cream, and often combined with fruits or other ingredients and flavours. Most varieties contain sugar, although some are made with other sweeteners...
- IcemakerIcemakerAn ice maker, ice generator,or ice machine may refer to either a consumer device for making ice, found inside a home freezer; a stand-alone appliance for making ice, or an industrial machine for making ice on a large scale...
- Ice wineIce wineIce wine is a type of dessert wine produced from grapes that have been frozen while still on the vine. The sugars and other dissolved solids do not freeze, but the water does, allowing a more concentrated grape must to be pressed from the frozen grapes, resulting in a smaller amount of more...
- Slush (beverage)Slush (beverage)A slush is a flavored frozen drink.There are a number of different kinds of slush drinks:* Frozen carbonated beverages, typified by the Slurpee or ICEE, are made by freezing a carbonated drink. These machines are complicated and expensive, and notably require a carbon dioxide supply...
- SupercoolingSupercoolingSupercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid....
- Therapeutic hypothermiaTherapeutic hypothermiaTherapeutic hypothermia, also known as protective hypothermia, is a medical treatment that lowers a patient's body temperature in order to help reduce the risk of the ischemic injury to tissue following a period of insufficient blood flow. Periods of insufficient blood flow may be due to cardiac...
- Thermal Energy StorageThermal energy storageThermal energy storage comprises a number of technologies that store thermal energy in energy storage reservoirs for later use. They can be employed to balance energy demand between day time and night time. The thermal reservoir may be maintained at a temperature above or below that of the...
- SnowmakingSnowmakingSnowmaking is the production of snow by forcing water and pressurized air through a "snow gun" or "snow cannon", on ski slopes. Snowmaking is mainly used at ski resorts to supplement natural snow. This allows ski resorts to improve the reliability of their snow cover and to extend their ski...
External links
- ASHRAE Technical Committee TC 3.1, Refrigerants and Secondary Coolants (ASHRAE T.C. 3.1)
- ASHRAE Technical Committee TC 6.9, Thermal Storage (ASHRAE T.C. 6.9)
- ASHRAE Technical Committee TC 10.2, Automatic Ice making Plants/Skating Rinks (ASHRAE T.C. 10.2)
- Cold chain management project Chill-On (EU's FP6)
- Desalination for water supply
- Industrial Crystallization
- Vacuum Freezing
- Thermal Energy Storage for Mine and Central Cooling Systems