Clear Ice industrial generation issues

[ddice]

TL;DR

Problems generating industrial clear Ice tube. The ice is cracking and we don't know why.

Summary: Problems generating industrial clear Ice tube. The ice is cracking and we don't know why.

Summary: Problems generating industrial clear Ice tube. The ice is cracking and we don't know why.

Hi all!

I'm an engineer from Spain and I'm working in a new project (factory ice).

We have developed a new ice generator but we need our knowledge to solve one problem we have.

Our ice is cracked and we are looking for "perfect Cristal ice" so we have to make ice without cracking.

We are thinking about the cracking could be taking place in two different processes:
1- During ice generation process (freezing water process)
2- During defrost process (when we defrost the tube to unmold the ice, before cut it)

We generate the ice at -10 Celsius and we unmold the ice about 4, 10 Celsius.

One of our theories is that the temperature stress is too high and the ice crack.

Any expert here could help us?

Thanks in advance.

I attach some pictures when you can see it.

 

[trurle]

This is definitely a stress problem.
The problem is what you are trying to freeze the ice symmetrically from sides. This method results in highly compressed core of ice tube (visible on last photos) which tends to produce cracks when ice weaken after release. Therefore both (1) and (2) is correct. The ice making machines i seen in Japan usually release stresses by forming ice between set of metal plates, odd ones are kept at 0C and even ones are strongly cooled.
To fix to the problem, you should likely reduce thickness of cooling die, which will introduce enough asymmetry to prevent stressed core formation. It will also reduce ice output rate though.