LMTD (Tofauti ya Wastani wa Halijoto kwa Logarithm) ni nguvu ya wastani ya ufanisi ya uhamishaji joto katika kiyeyusho cha joto. Inazingatia tofauti ya halijoto inayobadilika kati ya maji ya moto na baridi kando ya urefu wa kiyeyusho kwa kutumia wastani wa logarithm.

LMTD = (ΔT₁ − ΔT₂) / ln(ΔT₁/ΔT₂). For counter flow: ΔT₁ = T_h,in − T_c,out and ΔT₂ = T_h,out − T_c,in. For parallel flow: ΔT₁ = T_h,in − T_c,in and ΔT₂ = T_h,out − T_c,out.

Kwa nini mtiririko kinyume una ufanisi zaidi kuliko mtiririko sambamba?

Mtiririko wa kupinga hutoa LMTD ya juu zaidi kwa halijoto sawa za mlango/mwisho, kumaanisha eneo dogo zaidi la uhamishaji joto linahitajika. Maji baridi yanaweza pia kupashwa joto karibu na halijoto ya mlango wa maji moto, ambayo haiwezekani katika mtiririko sambamba.

LMTD haijafafanuliwa lini?

When ΔT₁ = ΔT₂ (equal temperature differences at both ends), the formula gives 0/0. In this special case, LMTD simply equals ΔT₁ = ΔT₂ (arithmetic mean equals log mean when both are equal).

What is Q = U × A × LMTD?

This is the basic heat exchanger design equation. Q is heat duty (W), U is overall heat transfer coefficient (W/m²K), A is heat transfer area (m²), and LMTD is the log mean temperature difference (K). Given any three, you can find the fourth.

Zana ya Uhandisi Isiyolipisha

Kikokotoo cha LMTD cha Kiyeyusho cha Joto

Calculate Log Mean Temperature Difference for parallel and counter flow heat exchangers. Optional Q=U·A·LMTD sizing.

LMTDKupinga & Sambamba#181

Results

LMTD ya Mtiririko wa Kupinga

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LMTD ya Mtiririko Sambamba

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Eneo la Mtiririko wa Kupinga (kama U & Q zimetolewa)

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Eneo la Mtiririko Sambamba (kama U & Q zimetolewa)

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Hot Side ΔT

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Cold Side ΔT

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Mchoro wa Halijoto (Mtiririko wa Kupinga)

LMTD Formula

Counter Flow

ΔT₁ = T_h,in − T_c,out | ΔT₂ = T_h,out − T_c,in

Parallel Flow

ΔT₁ = T_h,in − T_c,in | ΔT₂ = T_h,out − T_c,out

Mlingano wa Muundo

Mtiririko wa kupinga daima hutoa LMTD ya juu zaidi kuliko mtiririko sambamba kwa halijoto sawa, kumaanisha eneo dogo zaidi linahitajika.

Kikokotoo cha LMTD — Kibadilishaji Joto cha Mtiririko wa Kupinga & Sambamba

Published by Nikolai Shelkovenko on Febuari 15, 2026 Aprili 5, 2026

Results

LMTD Formula

Counter Flow

Parallel Flow

Mlingano wa Muundo

Duka

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