Developing Efficient Temperature Control for HERMS: A Study on P, P-Logic, PI, and PID Controllers

Abstract

The Heat Exchange Recirculating Mash System (HERMS) is widely used in craft brewing to maintain precise temperature control during the mashing process, which is crucial for achieving optimal sugar extraction and mash efficiency. This study investigates the performance of four different temperature control strategies-P, P-logic, PI, and PID-in maintaining the desired mash temperature profile. The system was modeled using both First-Order Plus Delay (FOPD) and Second-Order Plus Delay (SOPD) models to optimize controller gains through Skogestad's method. Validation of the control strategies was conducted through simulations in MATLAB Simulink. The results showed that while P-logic control maintained stable temperature with 0% overshoot, PI and PID controllers achieved the same with only 30% input energy, compared to 100% used by P-logic. A real-world mashing is conducted with P-logic control. Wort quality was also assessed, with specific gravity, pH, and mash efficiency analyzed. This study highlights the trade-offs between control precision and energy consumption, providing valuable insights for improving HERMS system efficiency in both homebrewing and commercial applications.