SolverOk SetCell:="$M$10", MaxMinVal:=2, ValueOf:=0, ByChange:="$B$5" SolverSolve UserFinish:=True Goal: Minimize diameter while keeping pressure drop < 40 mmH2O/m. If absorption is concentrated (CO₂ in MEA, SO₂ in caustic), the NTU equation becomes implicit. Use circular references with Enable Iterative Calculation (max iterations 1000, max change 0.0001). 4. Error Trapping In every formula, add IFERROR . For example:
=EXP( -2.5 * LN(X) - 1.2 ) [Approximate; use published tables for accuracy] Then back-calculate area: A = Gas_flow_rate / G_flood . Diameter = SQRT(4*A/π) . Using the Leva correlation (simplest for Excel): scrubber design calculation excel best
Calculate (m³/m²·h):