Creating a Discrete Model of Sap Processing Thermodynamics

Abstract

Running a successful maple syrup operation requires attention to detail, specifically with regards to production efficiency. Despite new technology and the innovation of new production methods, the amount of energy it takes to bring sap to the sugar concentration (measured as degrees Brix or °Bx) for maple syrup remains constant. The rule of thumb used to help sugar makers estimate their fuel costs was that it takes 400,000 BTU to bring 2 °Bx sap into maple syrup.1 This rule of thumb is a close estimate, but it neglects the change in boiling point as the solution becomes more concentrated. Additionally, the amount of energy required to boil changes depending on the final concentration of syrup.2 The thermodynamic model of the sap boiling process presented here accounts for changes in the composition of the solution as it undergoes boiling, resulting in a difference in energy of +5%, +3%, and +1% for 68, 67, and 66 °Bx syrup respectively. These differences are important for all sugar makers, as they also directly affect the cost of fuel per gallon of syrup for all fuel types. This model can be used by sugarmakers when calculating how much fuel they would need at different levels of concentration and with different fuel types to assess costs associated with producing maple syrup.