Andrew Strak (abstrak@accesswave.ca)
Mon, 14 Jun 1999 08:18:17 -0300
The only way to protect ice from 'heat loss' and actually 'heat gain' is to
insulate it from the environment. Any block type of ice is better
'insulated' that flake ice since its exchange area versus volume is much
smaller. The larger the blocks the relatively smaller the surface to volume
ratio and correspondingly melting rate and heat losses. I agree with you
that enthalpy of melting ice of different types should be asess differently
and probably those 67 kca/kg of wet flake ice are correct and for block and
cube melting ice they should be within the range 74-76 kcal/kg depending on
the particle size.
But Luis' question was related to microbiology and which type of ice would
ultimately support more bacteria growth over time. My answer is that this
one with a larger surface/volume ratio i.e. flake ice since bacteria growth
on solid or semi-solid objects is largely a surface phenomenum.
Best regards,
Andrew
>-----Original Message-----
>From: L. G. Limpus <lglimpus@coastnet.com>
>To: abstrak@accesswave.ca <abstrak@accesswave.ca>; luispasp@usp.br
><luispasp@usp.br>; seafood@ucdavis.edu <seafood@ucdavis.edu>
>Date: Friday, June 11, 1999 11:28 AM
>Subject: Re: ice on fish boats
>
>
>Dear Andrew,
>
>Technically I agree with you. I remember Gorden telling me that the data
>on commercial ice was taken when they first installed the ice pumping
>system in either Grimbsby or Hull in the late 50's or early 60's. I am
>sure there have been technological improvements since then to reduce ice
>heat loss. However, in many developing countries (and perhaps even
>developed ones) ice is shipped in blocks (and is not sub-cooled by the time
>it arrives) to a point
>where it is crushed (either mechanically or manually) where there is
>further heat loss. I wonder if in such circumstances, it may be better to
>use a lower figure than the technically correct 80 kcal/kg.
>
>L. G. Limpus
This archive was generated by hypermail 2.0b3 on Mon Jun 14 1999 - 07:25:57 PDT