Iiraustralia99005.pdf

IIR 20th INTERNATIONAL CONFERENCE
REFRIGERATION INTO THE THIRD MILLENIUM
19-24 September 1999, Sydney, AUSTRALIA
SLURRY ICE BASED FOOD CHILLING APPLICATIONS
Zafer URE C.Eng, M.Sc., MCIBSE, MASHRAE, M.Inst.R , MIIR
EPS Limited, Unit 18, The Business Village, Wexham Road, Berkshire, SL2 5HF, UK Telephone: (+44) 1753 - 692212, Facsimile: (+44) 1753 - 692457, E-Mail: URE @ COMPUSERVE.COM
Synopsis

Environmental concerns over the ozone depletion potential of some CFCs used today have
prompted a search for alternative cooling technologies. A number of Dynamic and Static ice
production methods have been developed for various applications.
Slurry ice technology is the latest addition to other existing ice production techniques and it
has the potential to achieve considerable environmental as well as economic benefits for
both central cooling systems and direct ice production for ever expanding ice applications.
Any conventional primary refrigerants can be used for slurry ice production.
The cooling capacity of slurry ice can be four to six times higher than that of conventional
chilled water, depending on the ice fraction. The nature of the Binary (Crystal) ice formation
allows end users to pump the ice and there are many slurry ice-based cooling systems
operating around the world. Most air conditioning installations are based on ice storage,
where the warm return water is used to melt the ice when required. Slurry ice is also
circulated in close loop distribution systems directly for process and product chilling
applications.
This paper investigates the advantages and disadvantages of using slurry ice food chilling
applications. The most important physical properties and characteristics for Food Grade
pumpable ice solution are presented in a form that will help food engineers and consultants
to develop effective and efficient Slurry-Ice based Food Chilling system designs.

Keywords;

CFC - Chloro Fluoro Carbon, (TES) Thermal Energy Storage, Slurry-ICE, iiraustralia99005
1.0 - INTRODUCTION
Society’s reliance on food cooling technology ranges from domestic refrigerators, to full
production of all types of fresh and frozen food production. As a result, modern
refrigeration technologies together with a wide range in food processing and preservation
infrastructures have evolved around wide spread usage of refrigeration.
Direct or indirect ice usage has also expanded over the years to reduce operational costs
and improve food quality and therefore many type of Dynamic and Static ice production
methods have been developed for various food chilling applications.
It is vital to establish a balance between "energy consumption" and "environment
protection" and therefore any change in refrigeration technology by means of introducing
new refrigerants or by adopting new techniques must be carefully balanced to reduce the
overall environmental impact.
Environmental concerns over the ozone depletion potential of some CFCs used today have
prompted a search for alternative cooling technologies. Slurry ice technology is the latest
addition to other existing ice production techniques and it has the potential to achieve
considerable environmental as well as economic benefits for direct ice production forever
expanding ice applications.
Any conventional primary including natural refrigerants can be used for slurry ice production.
The cooling capacity of slurry ice can be four to six times higher than that of conventional
chilled water, depending on the ice fraction.
There are many slurry ice-based cooling systems operating around the world and most air
conditioning installations are based on ice storage, where the warm return water is used to
melt the ice. Slurry ice is also circulated in close loop distribution systems directly for
process, district and product cooling applications.

2.0 CURRENT ICE PRODUCTION TECHNOLOGIES
Ice production techniques can be divided into two main groups (1) namely Dynamic and
Static systems, Table 2.1, and the produced ice can be used either directly to chill the
product such as fish, vegetables, meat, poultry etc. or indirectly as secondary coolant for the
latent heat cooling effect such as ice storage TES systems for air conditioning and process
cooling as a secondary cooling medium.
STATIC ICE PRODUCTION
DYNAMIC ICE PRODUCTION
1 - Ice Builders
1 - Plate Harvester
2 - Ice Banks
2 - Tube Harvester
3 - Encapsulated Ice Modules
3 - Flake Ice Machines
4 - Binary Ice Machines
b) Flat Containers
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Table 2. 1 - Current Ice Production Technology
3 - SLURRY ICE TECHNOLOGY

Slurry-ICE is a suspension of a crystallised water-based ice solution and the icy slurry can
be pumped, hence, it is also called “Binary-ICE”, “ Liquid-ICE” or “Pumpable-ICE”
(2). The handling characteristics, as well as the cooling capacities can be matched to suit any
application by means of simply adjusting the percentage of ice concentration.
Slurry-Ice comprises microscopic ice crystals giving a total surface area for heat exchanging
that is very large in comparison with the conventional ice chilling concept and therefore ice
instantly melts to meet the varying product cooling load. This ensures steady and accurate
product final temperature control (3).
3.2 SLURRY ICE APPLICATIONS FOR FOOD PROCESSING
The important benefit of slurry ice is the “ rapid cooling capacity” compared with air blast
and conventional ice / chilled water cooling systems. Hence, it offers significantly reduced
cooling times (4). Slurry-ICE systems not only offer superior cooling performance and a
significant installation cost reduction but the food chilling operating costs can also be reduced
due to increased production rates for a given food processing application.
Sea water or alternatively brine solutions are the most commonly used SlurryICE production
techniques within the sea food industry (5) but they can not be applied for other food chilling
applications due to undesirable taste and visual impacts. Hence, the majority of Binary ice
applications remain in sea food application with the exception of the poultry and meat
industry which is utilised by means of relatively expensive harvester tank arrangements to
reduce the salt concentration.
The main criteria for a pumpable food ice application are taste and visual impact of the final
product. Hence, the solution MUST not affect taste or appearance. Even a low salt
concentration may spoil the food product and when the product is dried some salt based
solution leave an undesirable white residue.
Further to extensive research of the commonly used food additives, author has identified a
number of potential freeze depressants for pumpable ice production which can be used on
food products and a general list of these additives can be found in Table 1. However, further
research had to be carried out to establish ideal combinations of these chemicals to form a
physically and thermodynamically acceptable SlurryICE solution from the available ice slurry
production machinery and their officially acceptable limits as a food additive for the food
production point of views.
The main criteria for NO TASTE and NO VISUAL IMPACT remained the main target for
this search and following various combination of these fluids, author managed to test and
produce satisfactory freeze depressant combination out of the enclosed list to satisfy all the
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NUMBER CHEMICAL NAME
CHEMICAL NAME
Copper complexes of chlorophyll and chlorophyllins Ethyl ester of beta-apo-8'-carotenic acid Table 1 – Food Additives for SlurryICE Applications
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However, freeze depressants can be considered as the first hurdle towards the conquest of
a satisfactory pumpable ice solution for food application. Majority of these chemicals causes
excessive corrosion problems and the low concentration levels for food application expose
the solution to bacterial growth. Hence, it is vital to provide satisfactory Corrosion Inhibitor
and Biocide combinations to pass strict food hygiene regulations. Some of the commonly
used corrosion inhibitors and biocides are not acceptable for food production or they may
cause operational problems for the ice production machine as well as the quality of the
pumpable ice solution.
Following extensive tests, an acceptable combination of FREEZE DEPRESSENT,
CORROSION INHIBITOR and BIOCIDE mixture has been established to satisfy all
the criteria set above. For simplicity, this solution is referred to as FoodICE solution as part
of this paper and the thermodynamic and physical properties are included in Table 2.
Table 2 – FoodICE Physical Properties
Majority of the food chilling applications remains above –2 °C, which is considered to be the limit before frost damage. The above solution is used for food chilling testing for various types of food chilling applications and the relevant cooling curves can be seen in Figure 3.2.1, Figure 3.2.2 and Figure 3.2.3 for meat, vegetable and fruit cooling applications respectively. Fish (Bream)
Chicken Leg
Chicken Breast
Pork Leg Core
Pork Leg Middle
Temperature (C)
Time ( x minutes )
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Figure 3.2.1 – Meat Cooling Test using FoodICE solution. Temperature (C) 2
Time ( x minutes)
Figure 3.2.2 – Vegetable Cooling Test using FoodICE solution. Temperature (C)
Time ( x minutes)
Figure 3.2.3 – Fruit Cooling Test using FoodICE solution. iiraustralia99005
Test results indicate significantly reduced cooling times and superior product quality in comparison with conventional techniques. The shelf life of these products is also significantly increased due to the rapid cooling effect. iiraustralia99005
4- CONCLUSION
There are many type of slurry ice production machinery operating around the world and a
slurry ice rapid food cooling system can provide all the benefits offered by conventional ice
/chilled water cooling technologies with additional benefits;
• Hygienic Systems
• Quick Response
• Reduced Equipment Size
• Capital Cost Saving
• Energy Cost Saving
• Energy Saving
• Improved System Operation
• Flexibility for the Future Capacities

Moreover, the pumpable characteristic over any other type of ice production system offers
efficient compact equipment design, flexibility of location of storage tank(s) and the most
economical capacity and duty balancing for any given food chilling application (6).
Storage tank(s) can be placed: under, beside, inside, or on top of a building and can be any
shape or size to match building and architectural requirements.
FoodICE is a very versatile cooling medium. The handling characteristics, along with the
cooling capacities can be matched to suit any application by means of simply adjusting the
percentage of ice concentration.
As they are microscopic the ice crystals melt quickly to meet varying cooling loads instantly.
FoodICE not only offers higher efficiency and cost effective ice production but also its
unique pumping and easy handling characteristics provide totally sealed “Hygienic Systems”,
increased production, flexibility of operating temperature and consistency of application, for
optimum results.

Direct contact pumpable ice chills faster, providing instant protection, maintaining freshness
and preserving colour. The tightly packed pumpable ice inhibits air entraintment, which is the
main cause for causes premature ice melting as in the case of solid ice for transport and
storage applications. Hence, FoodICE lasts longer in comparison with solid ice.
The challenge for designers and food manufacturers is to explore the possibility of every
alternative design solutions, which can minimise the use of energy for the refrigeration
system. A FoodICE based cooling systems may be the answer for many food chilling
applications for an Environmentally Friendly and Economical alternative.
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REFERENCES
Ure Z., “Slurry Ice Based Cooling Systems”, International Conference on Energy Research and Development, 9-11 November 1998, Safat, KUWAIT Gladis P. S. et al, EPRI International Conference on Sustainable Thermal Energy Storage, 7-9 August 1997, Minneapolis, Minnesota, USA Snoek W. C., “First North American Conference & Exhibition on Emerging Clean Air Technologies and Business Opportunities”, Toronto, 26-30 September Malter L., “ Binary Ice-Generation and Applications of Pumpable Ice Slurries for Indirect Cooling”, “Application for Natural Refrigerants Proceedings”, Page 527, Aarhus, 3-6 September 1996, Denmark 5- Paul J. / Jahn E. “Ice - Application of Liquid, Pumpable Ice-Slurries and Status of the Technology”, , 6 February 1997, The Institute of Refrigeration Proceeding Ure Z., “ Ice Production in the next Millennium”, Page 12-14, October 1996 iiraustralia99005

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