freezer efficiency

[altoid3000]

I am thinking of a new ambitious project with our freezers. We have a spiral freezer to freeze meat patties. I want to increase the throughput through this freezer. What have is ammonia refrigeration system. I have space limitations and the total size of the freezer can not be increased. I was thinking of designing baffles to direct air flow in all the freezing zones well. I am also thinking of increasing the cooling coil size. Apart of ingenious design of baffles, what other ways can I focus on?

 

[25362]

Thinking aloud: assuming the refrigeration system "as is" can handle more load and must not be upgraded, minimize oil carry over into the vaporizing coil, use lowest possible temperatures of vaporization, adopt finned coils...

 

[pennpoint]

altoid3000
Minimize frosting of the coil. Maintain air velocities, Possibly add GN2 purge.

Regards
pennpoint

 

[RACandH]

Subcooling, Subcooling, Subcooling

 

[altoid3000]

Thanks a lot for all your suggestions. Has any one tried putting baffles in the freezer to increase air velocity in the critical freezing zones? I was thinking that it might an effective option. What are you thoughts on that?

Has anyone tried putting baffles in the freezer to enhance the overall efficiency? I came across a paper in food engineering journal which talks about putting baffles in the freezer to increase air velocity in freezing zones. They mention dramatic decrease in freezing times. I was wondering if anyone has tried this kind of technique.

 

[sailoday28]

Have you figured in the cost of electricty for the added power required of the fans?

 

[sterl]

Impingerment freezers focus air flow and use a lot of fan horsepower to get an inline air-based freezer up to the capacity of a cryo freezer of the same lenght and width...But getting a spiral to the same heat transfer as an impingement freezer is not going to be easy, and may very well play hell with your enclosure.

Whether or not there is much to be gained is pretty easily identified...but compare Spirals to Spirals.

How much you can achieve with sheeting and baffles and more fans can be "modelled" by comparison with the most efficient models of such freezers...If you've got one made by somebody other than Frigoscandia, compare its real heat transfer per square foot of exposed and product-covered belt with that of a current Frigoscandia; then compare your fan horsepower with that of a current "high end" Frigoscandia. It will set your target for you in a hurry.
By the way: Too dense a belt loading will make your freezer go through the top of its efficiency cureve, and the higher the freezer performance is, the greater the downhill slope of that curve...
Of course the easiest way to get more out of it is to make it operate colder, and that has the added benefit of reducing shrink and distortion. That approach means more compressor horsepower, which means condensers and vessels and pumps and so on.

By the way, for the clarification of RACandH: please indicate whether this system is Recirculated or Gravity flooded...neither arrangement will benefit from subcooling but depending on the coil performance, it may very well benefit from liquid inductors.