Hi Peter
At present we are quoting a belt freezing tunnel, about 108kW for freezing product. We have been working with a company Star Frost. In our case they gave us the tunnel refrigeration capacity needed, checked it and found it to be about 25% too high, must be a safety factor
What about blowing dehum air accross the chips before they enter the tunnel to dry them, a dehumed air lock would surface dry the chips and keep out moist air.

Nitro tunnels will eat energy, pay back for a refrigerated tunnel is less than 5 years, tipically 2.5 years.

Kind Regards. Andy