Lesson 4 - Wort Boiling Technology and Process Control

Point of reflection – reconvene: Welcome back. So, what did you calculate? What effect will this have?

First, we need to rearrange our heat transfer equation:

Q=UAΔT

Internal calandria:

External calandria:

This shows that a higher surface area (external calandria) reduces the required temperature difference to supply the same amount of heat. A lower ΔT is believed to be beneficial for foam stability, flavour quality and flavour stability so the wort from the external calandria in this example should be superior. A lower ΔT also reduces the rate of fouling, meaning the frequency of CIP is lower and more brews per day should be possible. It also reduces the steam pressure required. If the wort boiling temperature is 100°C, then the steam temperature of the external calandria is 114.7°C. This translates into a steam pressure of 0.6 bar (using steam tables). With the internal calandria, the steam temperature would be 136.9°C, translating into a steam pressure of 2.2 bar. A lower steam pressure that achieves the same results means that steam supply equipment will be lower cost and the risks associated with higher pressure steam will be reduced.