Banana ripening airflow, and cooling requirements, are a little-understood “art”.
But there is a science to it…we will try to explain.
Most fruit have a specific heat of 9/10th’s of a BTU per pound. We use 1 BTU/pound as the cooling requirement (sometimes, like with avocados, for the heating too,) to be safe.
So, if you want to be able to cool your fruit by 1-degree (F) per hour, and you have 40,000 pounds of it, you need 40,000 BTU’s/hr of cooling capacity, plus extra loads for fan motors and other heat contributions, so we use a factor of 2-times, and say that we need 80,000 BTUs/hr for the task.
Airflow at static pressure is a little more tricky. It is almost impossible to predict how a commodity and packaging and palletization will react to airflow pressures, but there are some guidelines we can suggest.
For pressurized ripening, there are both tarp and tarpless systems. As a general rule of thumb, tarp systems need less airflow at higher static pressure (because the tops of the pallets are sealed off), and tarpless designs need more airflow at lower static pressure (because more air leaks out the tops of the pallets).
For tarp systems, we like 1,000 cfm per pallet, at 0.6″ water column static pressure.
For tarpless designs, we like 1,500 cfm per pallet, at 0.4″ static pressure.
In most cases, larger diameter fans can produce more cfm at higher static pressure, than can smaller diameter fans.