(208g) Heat Transfer in a Recirculating Infusion Mash System

The Recirculating Infusion Mash System (RIMS) method for mash temperature control is commonly practiced by many homebrewers due to its ease of implementation, low cost and fast ramping rates. A drawback to RIMS is the potential to scorch the wort if the wall temperature eof the heating element exceeds 130C, the threshold for Maillard reactions. This can be avoided by ensuring sufficient wort flow. On the other hand, excessive wort flow rate can lead to grain bed compaction in the mash ton which is also an undesirable situation. Heat transfer in a typical homebrew RIMS system has not been characterized previously to the best of the authors’ knowledge.

In this work we experimentally measure the convective heat transfer coefficient in a RIMS tube setup that utilizes a commonly available hot water heater element. Constant heat flux is applied to the tube and the wall temperature, inlet and outlet temperatures are measured under various conditions. A Nusselt number correlation is developed using water and validated with actual beer wort. This new correlation will allow homebrewers to size their recirculation pumps and mash tuns with greater confidence.