LMTD_NTU_HeatExchanger_Calculator.xlsx

	A	B	C	D	F	G
1	LMTD Heat-Exchanger Sizing Calculator
2	chemenggcalc.com — enter values in the yellow cells; results update automatically

3
4	INPUTS — Stream Temperatures & Arrangement				Typical U values (W/m²·K)
5	Parameter	Value	Unit	Notes	Service	U range
6	Hot inlet, Tₕ,in	90.0	°C		Water – water	800–1500
7	Hot outlet, Tₕ,out	50.0	°C		Steam – water	1500–4000
8	Cold inlet, Tᴄ,in	20.0	°C		Water – light organics	350–900
9	Cold outlet, Tᴄ,out	40.0	°C		Water – heavy organics	60–300
10	Flow arrangement	Counter-current	–	Choose from dropdown	Gas – water	20–300
11					Gas – gas	10–50
12	INPUTS — Duty & Heat Transfer				Condenser (steam)	1500–4000
13	Parameter	Value	Unit	Notes	Condenser (organics)	300–1200
14	Hot stream mass flow, ṁ	5.00	kg/s	Used if direct duty = 0	Reboiler (steam heated)	900–1700
15	Hot stream Cp	4.180	kJ/kg·K	Water ≈ 4.18	Air cooler (water)	300–450
16	Direct duty, Q (optional)	0.0	kW	Enter to override stream duty
17	Overall coefficient, U	850	W/m²·K	See reference table →
18	LMTD correction factor, F	1.00	–	1.0 pure counter-current; <1 multi-pass
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20	RESULTS
21	Parameter	Value	Unit	Formula
22	ΔT₁ (hot end)	50.00	K	counter: Tₕ,in−Tᴄ,out \| co: Tₕ,in−Tᴄ,in
23	ΔT₂ (cold end)	30.00	K	counter: Tₕ,out−Tᴄ,in \| co: Tₕ,out−Tᴄ,out
24	Input check	OK	–	ΔT must be positive at both ends
25	LMTD	39.15	K	(ΔT₁−ΔT₂)/ln(ΔT₁/ΔT₂)
26	Heat duty, Q	836.0	kW	direct entry, else ṁ Cp ΔTₕ
27	Corrected mean ΔT, F×LMTD	39.15	K	F × LMTD
28	Required area, A	25.12	m²	Q / (U · F · LMTD)
29	Cold stream duty check, ṁCp	41.80	kW/K	implied ṁCp of cold stream
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31	Notes & Assumptions
32	• Steady state, constant Cp, negligible heat losses. If either stream changes phase, enter the duty directly (latent heat) instead of ṁCpΔT.
33	• F = 1 for pure counter-current or when one stream is isothermal (condensing/boiling). For 1-2 shell-and-tube, read F from TEMA charts using P and R; keep F ≥ 0.75.
34	• If the sheet shows TEMPERATURE CROSS, the outlet temperatures are thermodynamically impossible for the chosen arrangement — co-current cannot cross; counter-current crossing needs multi-pass F correction or a different configuration.
35	• The cold-stream ṁCp check lets you verify the cold-side flow implied by the energy balance is realistic.
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