Wort Knockout Plate Heat Exchanger Sizing Calculator
Size brewhouse sanitary plate heat exchangers (PHE), calculate Log Mean Temperature Difference (LMTD), cooling water flow rates, and hot liquor heat recovery.
Brewhouse Knockout Parameters
Coolant Stream & Thermal Coefficients
Heat Exchanger Sizing
Thermal Performance Breakdown
Recommended Tools & Equipment
Tested hardware and components for high reliability
Engineering Fundamentals: Brewhouse Plate Heat Exchanger Sizing
Wort cooling must occur rapidly (within 30 to 45 minutes) to minimize Dimethyl Sulfide (DMS) precursor formation, prevent bacterial contamination from airborne wild microbes, and produce cold trub break before yeast pitching.
1. Log Mean Temperature Difference (LMTD)
For counter-current flow through sanitary chevron plates:
ΔT_1 = T_wort_in - T_water_outΔT_2 = T_wort_out - T_water_inLMTD = (ΔT_1 - ΔT_2) / ln(ΔT_1 / ΔT_2)
A minimum temperature approach (ΔT_2) of 5°F to 8°F is required for single-stage water cooling; if city water exceeds 60°F in summer, a two-stage heat exchanger using chilled glycol in the second stage is necessary.
2. Heat Transfer Area Formulation
The total heat transfer area (A) is governed by Newton's law of cooling:
Q = m_wort × c_p,wort × (T_wort_in - T_wort_out)A = Q / (U × LMTD)
Where U is the overall heat transfer coefficient (typically 700–850 BTU/h·ft²·°F for corrugated 316 stainless plates with turbulent liquid flow).
3. Hot Liquor Tank (HLT) Heat Recovery
The cooling water stream absorbs the rejected wort heat and exits the heat exchanger at 165°F to 180°F. Pumping this hot discharge directly into the Hot Liquor Tank (HLT) captures over 85% of brewhouse thermal energy for the subsequent mash-in and CIP cleaning.
Frequently Asked Questions
Why must wort knockout cooling be completed within 45 minutes?
Leaving hot wort in the whirlpool or kettle above 140°F (60°C) causes continuous non-enzymatic synthesis of Dimethyl Sulfide (DMS), producing cooked-corn off-flavors. Rapid cooling also accelerates trub precipitation and minimizes bacterial contamination risk.
When is a two-stage plate heat exchanger required instead of a single-stage?
A single-stage heat exchanger relies entirely on incoming cold tap water. If tap water temperatures exceed 60°F during summer months, single-stage units cannot chill wort down to ale pitching temperatures (65°F) or lager temperatures (48°F). A two-stage unit uses city water in the first stage and 28°F glycol in the second stage.
What is the standard water-to-wort flow ratio for brewhouse knockouts?
Commercial breweries typically operate at a water-to-wort ratio of 1.1:1 to 1.3:1. This balances rapid cooling kinetics while producing the exact volume of 165°F to 180°F hot water needed to fill the Hot Liquor Tank for the next brew day.
What causes fouling and pressure drops in brewery plate heat exchangers?
Proteinaceous hot trub, hop debris, and calcium oxalate (beer stone) coat the chevron corrugations over time. This reduces the heat transfer coefficient U and increases pump backpressure, requiring routine caustic and acid Clean-In-Place (CIP) recirculation.