23-09-2014, 09:45 AM
ADVANCES IN FOOD REFRIGERATION
[attachment=68313]
Food refrigeration is BIG
Annual investment in refrigerating equipment: US$170
Annual refrigerated foodstuffs: US$1200 billion
(3.5 times USA military budget)
700-1000 million household refrigerators
300 000 000 m3 of cold-storage facilities
and causes big problems!
Ozone-depleting effects - Montreal protocol
Global-warming effects - Kyoto agreement
Immersion and Spray Chillers/Freezers
faster than air chilling, especially for small products
absorption of liquid or solutes by the product, leading to undesirable appearance or other quality losses
cross-contamination between products
leaching of food components such as fat
effluent disposal problem
Selection and Operation of Refrigeration Components
Freezers and chillers:
Extract heat within a certain time from product and other sources
Cool product uniformly
Avoid surface drying, contamination, microbial growth and other quality problems
Avoid condensation
CFD Models
Can simulate the flow field outside the product (air, water, cryogen...) as well as inside
Computationally expensive (fast computers, lots of memory, days of runtime)
Software expensive (especially for non-U)
Need lots of expertise to use properly
Need lots of time for data preparation
Accuracy NOT guaranteed even when all the above are satisfied!
CONCLUSIONS
Attention to details needed in design and operation of refrigeration facilities.
Growing computer power allows more precise simulation of processes and prediction of product quality.
CFD is not yet the answer to the maiden’s prayers.
In near, computer control and optimisation of refrigeration processes will become more widespread.
[attachment=68313]
Food refrigeration is BIG
Annual investment in refrigerating equipment: US$170
Annual refrigerated foodstuffs: US$1200 billion
(3.5 times USA military budget)
700-1000 million household refrigerators
300 000 000 m3 of cold-storage facilities
and causes big problems!
Ozone-depleting effects - Montreal protocol
Global-warming effects - Kyoto agreement
Immersion and Spray Chillers/Freezers
faster than air chilling, especially for small products
absorption of liquid or solutes by the product, leading to undesirable appearance or other quality losses
cross-contamination between products
leaching of food components such as fat
effluent disposal problem
Selection and Operation of Refrigeration Components
Freezers and chillers:
Extract heat within a certain time from product and other sources
Cool product uniformly
Avoid surface drying, contamination, microbial growth and other quality problems
Avoid condensation
CFD Models
Can simulate the flow field outside the product (air, water, cryogen...) as well as inside
Computationally expensive (fast computers, lots of memory, days of runtime)
Software expensive (especially for non-U)
Need lots of expertise to use properly
Need lots of time for data preparation
Accuracy NOT guaranteed even when all the above are satisfied!
CONCLUSIONS
Attention to details needed in design and operation of refrigeration facilities.
Growing computer power allows more precise simulation of processes and prediction of product quality.
CFD is not yet the answer to the maiden’s prayers.
In near, computer control and optimisation of refrigeration processes will become more widespread.