Question 1

How much cooling does a blast freezer need?

Accepted Answer

Freezing 1,000 kg of meat from +4C down to a -18C core takes roughly 90 kWh of heat removal. Divide by the freezing window (say 8 hours) and add about 15% for fans and door losses, and you need around 13 kW of refrigeration at the freezing temperature. The load scales directly with daily throughput and with how warm the product arrives.

Question 2

What is air-cycle refrigeration?

Accepted Answer

Air-cycle machines use plain air as the refrigerant. A turbo-compressor squeezes air (it gets hot), the heat is rejected, and the air then expands through a turbine and drops far below -100C in one step. No synthetic refrigerant, no oil, no defrost cycles, and one machine covers -40C to -110C — a range that would otherwise need a two-stage cascade plant or liquid nitrogen.

Question 3

Is air-cycle cheaper to run than a cascade freezer?

Accepted Answer

It depends on the temperature. Down to about -40C air temperature, a good CO2 or two-stage system uses less electricity per kWh of cooling. Below about -50C the picture flips: cascade efficiency collapses while air-cycle barely changes, and at -60C to -80C — sashimi-grade tuna territory — air-cycle or LN2 are the only practical options, and air-cycle avoids the LN2 delivery bill entirely.

Question 4

Why freeze at -60C instead of -35C?

Accepted Answer

Colder air freezes food roughly twice as fast, so the same tunnel handles more product per day. Faster freezing forms smaller ice crystals, which means less drip loss when the product thaws — typically 1 to 3% more sellable weight. For tuna, -60C storage also locks the red colour, which is the difference between sashimi price and cannery price.

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