In order to calculate the temperature and time duration needed to lower the moisture content of barley during the drying stage, the amount of water in the barley seed must first be calculated. Standard barley seed is purchased with a 14.5% moisture content and weighs 48 lbs. per bushel. Multiplying 48 lbs. by .145 gives 6.96 lbs. of water per bushel of barley. Subtracting 6.96 lbs. from 48 lbs. gives 41.04 lbs. of dry mass barley per bushel.

During steeping and germination, the moisture content of barley must be raised to 40%-50%. The calculation shown below shows how many lbs. of water must be in a bushel of barley to raise its moisture content to 40%:

Because there are already 6.96 lbs. of water in the bushel of barley, 20.41 lbs. of water must be added to the barley to raise its moisture content to 40%. Doing the same calculation, but with the desired moisture content of 50%, 34.06 lbs. of water must be added per bushel of barley. Since our malting system will only be dealing with 10 lbs. of barley at a time, only 4.25 lbs. of water will need to be added to achieve 40% moisture content and 7.1 lbs. of water will need to be added to achieve 50% moisture content.

After germination, the barley will need to be dried from 40-50% moisture content to 3-8% moisture content to stop the enzymatic processes of sprouting. If the barley is at 40% moisture content, 32-37% of water will need to be removed from the seeds. If the barley is at 50% moisture content, 42-47% of water will need to be removed. Our seeds already contained 1.45 lbs. of water before we added water. If our seeds are at 40% moisture content, they contain 5.7 lbs. of water. We will need to remove 1.82 lbs. of water to achieve 8% moisture content and 2.11 lbs. of water to achieve 3% moisture content. If our barley is at 50% moisture content, it contains 8.55 lbs. of water. We will need to remove 3.59 lbs. of water to achieve 8% moisture content and 4.02lbs. of water to achieve 3% moisture content.

During the drying process, seeds are dried by running the seeds through air. It is common for the air during the drying process to have a temperature between 130 and 200°F. This hotter air is used to help create different flavors that can be pulled out during the brewing process. Knowing the psychometric properties of the air and the lbs. of water present in the seeds, the flow-rate of air and the amount of BTU/min. can be calculated to achieve the desired moisture content. Assuming ambient air is 70°F with 50% relative humidity, the humidity ratio, enthalpy, and specific volume can be found to be 0.00778 , 25.3 , and 13.514 ,respectively. Air at 200°F with 50% relative humidity has properties of 0.40194 , 510.145 , and 27.31 . Air at 131°F with 50% relative humidity has properties of 0.05245 , 90.1415 , and 16.1298 .Using air at 200°F and the ambient air at 70°F, the can be calculated to be 0.394 . Dividing the lbs. of water needed to be taken out of the barley by the lbs. of dry air needed to dry the barley can be calculated to be...

For example, barley at starting 40% moisture content and wanting to be dried to 8% moisture content using air at 200°F, has 1.82 lbs. of water that needs to be removed. We calculated that our air can remove 0.394 (lb. of water/lb.of dry air) . So…

Multiplying this number by the specific volume or the air at 200F gives:

If we wanted the drying process to take two days, we can divide this number by 2 days (2,880 minutes):

Using the lbs. of dry air (4.62 lbs.), the BTU/min can also be calculated by multiply the lbs. of dry air by the enthalpy and then dividing by the total time:

A chart has been provided below to show the different ranges.