Unit definitions
Brewing Vessel Calibration Constants
A brewing vessel is calibrated by adding heated strike water to it and measuring the temperature decay of the water over time. This provides two calibration constants; the vessel's heat capacity, cv [J/K], and its heat loss coefficient, hlc [W/K].
The assumptions here are:
The heat loss during the initial 5 minutes can be included into the vessel's heat capacity calculations
The heat loss from 5 minutes on can be attributed to exponential heat loss through the vessel walls
The specific heat of ingredients and the vessel's heat capacity are constant
Note that Mathcad uses implicit unit conversions, you may need to do this explicitly in your code.
Ambient
Water temperature at specific times (minutes)
Water volume
Convert water volume to mass
Specific heat of water
Find Heat Capacity of Vessel
Initial Temperature of vessel
Strike water temperature
Equilibrium temperature
Heat capacity of strike water
Conservation of energy gives...
Solving for vessel's heat capacity
Sanity check for equilibrium temperature
Check
Characterize Temperature Decay
Time constant of temperature decay
Temperature vs. time function
... in deg F
Plot exponential temperature decay
(prevent solver from substituting values)
Find time derivative of temperature decay at the following time:
Find Heat Loss Coefficient of Vessel
Power loss at T = T5
Example on how to use the calibration constants
The calibration constants are used to select a strike water temperature to hit a target mash temperature. The example will also show what the temperature is at the end of the mash.
Mass of grist
Mash thickness
Mash water volume
Mass of mash water
Heat capacity of water
Specific heat of grist
Heat capacity of grist
Grist temperature
Target mash temperature
Strike water temperature
Mash temp time constant
Mash time
Temperature at mash end
Back to Jansson's mash physics page