Dr Perlata has a good idea (below) I will take it one more step
We can create a ice to fish ratio
mi/mf = (t1 - 0)/Lf = Tf/80
This says the Kg ice needed per Kg fish (or Lb per lb for that mater) is simply
80 divided by the fish temperature Thus
for cold water where Tf = 5 the ratio is 5/80 = 0.06
for moderate water temp Tf = 20 the ratio is ~ 0.25
for warm water eg in the Phillipines Tf = 35 ratio is ~ 0.44
using a cp of one also gives a 20% overcompensation which is in the right
direction.
The problem of couse is with a low ratio one may not get the ice throughly mixed
with the fish
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Responding to the message of <3971922A.9218B6BA@iloilo.net>
from jperalta@iloilo.net:
>
> Dear all:
>
> Here is an alternative.
>
> And may I use SI units?
>
> Assuming no heat losses, and ice temp is 0 C (normal ice temp); and that
> the final temp of fish sought is not lower than 0 C.
>
> Heat given off by the fish = Heat absorbed by melting ice
>
> mf cp (t1 - 0) = mi Lf
>
> where
> mf is the mass of fish in kg;
>
> cp is the specific heat of fish; I agree with parameters stated earlier
> but we could simplify further and make it 1(unity); kcal/kg-C
>
> t1 is the initial temp of the fish; C
>
> Lf is the latent heat of fusion of water; 80 kcal/kg; lastly
>
> m1 is the amount of ice; kg, (which is the one sought for), and could
> easily be calculated.
>
> This calculation is a fast estimate of the base ice requirements.. We
> normally use more than this value to compensate for transport heat
> losses and other losses/factors.
>
> ----------
>
> Another alternative is to use a "rule of thumb"; the ratio of 1 part
> ice to 2 parts fish. This seems to also satisfy the aforementioned
> calculations, and also compensating for the other heat lossess.
>
> Then of course, this assumes that the initial fish temp to be at normal
> water temp.; which is around 25 C.
>
> I hope this helps.
>
>
> Best regards,
>
> Jose
>
>
>
> --
> -----------------------
> Jose P. Peralta, Ph. D.
> Professor/Food Engineer
> Inst. of Fish Processing Technology
> College of Fisheries, Univ of the Phil Visayas
> 5023 Miag-ao, Iloilo, Philippines
> Tel (63 33) 315 8289
> FX (63 33) 315 8289, 315 8353
> Cell (0917) 302 1282
> EMail jperalta@loilo.net
> ------------------------
>
>
> .
Dr Ted Labuza tplabuza@tc.umn.edu
Prof. of Food Science Dept. of Food Science & Nutrition 136 ABLMS U of Minn St
Paul, MN 55108 Voice 612-624-9701 Fax 612-625-5272 home fax 651-483-3302
cellemail 6126697885@mobile.att.net
http://fscn.che.umn.edu/Ted_Labuza/tpl.html
"SURFING THE WAVES OF CYBERSPACE"
___
|กก|
| \|
|__| "The attitude of an engineer must be different than
| that of a mathematician. The engineer is concerned with
---|---- truth, not mere consistency." Biot
/ \
|___/__/\_____/
\ /\ /\ /\/\/\
\ /\ / \/ \ /\/
"Before I came here I was confused about this subject. Having listened to your
lecture I am still confused But on a higher level."- E. Fermi
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