Perform advanced heat exchanger calculations using LMTD, NTU-Effectiveness, and U-Value methods
Perform calculations using LMTD, NTU-Effectiveness, or U-Value Estimation methods
Calculate heat transfer using Log Mean Temperature Difference
The Log Mean Temperature Difference (LMTD) method is used when the inlet and outlet temperatures of both fluids are known or can be determined. The heat transfer rate is calculated as: Q = U × A × F × ΔTlm, where U is the overall heat transfer coefficient, A is the heat transfer area, F is the correction factor, and ΔTlm is the log mean temperature difference.
The Number of Transfer Units (NTU) method is useful when the outlet temperatures are unknown. Effectiveness (ε) is defined as the ratio of actual heat transfer to maximum possible heat transfer. The NTU is calculated as NTU = UA/Cmin, where Cmin is the minimum heat capacity rate between the two fluids.
The overall heat transfer coefficient (U) depends on the heat exchanger type, fluid properties, flow rates, and fouling factors. Typical values range from 10-100 W/m²·K for gas-gas exchangers to 300-1,200 W/m²·K for water-water plate exchangers. The overall resistance is the sum of individual resistances: 1/U = 1/hhot + Rfoul + δ/k + 1/hcold.
