jedheatexchanger1

JED / THERMAL TOOLS

Heat Exchanger Calculators

Quick calculations for heat duty, temperature difference and cooling-water flow, plus common engineering unit conversions.

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Calculator

Heat Duty Calculator

Estimate the heat that must be removed or added from liquid flow, fluid properties and inlet/outlet temperatures. Use the result to prepare your cooling requirements.

01 / Liquid heat balanceExample values loaded · edit to suit your duty

Water reference: cₚ = 4.18 kJ/kg·K; density = 998 kg/m³ (approximately 20°C). Use supplied properties for other liquids or operating conditions.

Volume flow is converted to mass flow using the displayed density.

HEAT OUTINLETOUTLETSINGLE-PHASE LIQUID
Simplified flow diagram · not to scale
Heat Duty
—kW

Calculate to see the result.

Discuss your cooling requirements →
Formula, assumptions & sources

Q̇ = ṁ × cₚ × |Tin − Tout|   ·   ṁ = ρ × V̇

Internally: Q̇ in W, ṁ in kg/s, cₚ in J/(kg·K), temperature change in K. A temperature change of 1 K equals a change of 1°C.

  • Steady flow, one liquid phase, approximately constant properties over the entered range.
  • No boiling, condensation, tank cooling time or heat loss to the surroundings is calculated.
  • The water preset is a rounded reference near 20°C, not a temperature-dependent property model. Use supplier data at the mean fluid temperature for oil and other liquids.
  • The result is a heat load; it does not confirm that a particular exchanger can achieve it.

Formula reference: DOE Heat Transfer Handbook. Units: NIST SI conversion factors. BTU and kcal use International Table (IT) definitions. GPM means US gallons per minute.

A preliminary heat-load calculation for steady, single-phase liquids. Final exchanger selection also depends on pressure drop, materials and operating conditions.

LMTD Calculator

Calculate the log mean temperature difference from the hot- and cold-side inlet and outlet temperatures. Compare ideal counterflow and parallel-flow arrangements.

02 / Temperature driving forceExample values loaded · edit to suit your duty

Enter the four stream temperatures. The diagram shows where each inlet and outlet is located.

HOT STREAMCOLD STREAM
Simplified flow diagram · not to scale
LMTD
—K

Calculate to see the result.

Discuss your cooling requirements →
Formula, assumptions & sources

LMTD = (ΔT₁ − ΔT₂) / ln(ΔT₁ / ΔT₂)

Counterflow: ΔT₁ = Thot,in − Tcold,out; ΔT₂ = Thot,out − Tcold,in.

Parallel flow: ΔT₁ = Thot,in − Tcold,in; ΔT₂ = Thot,out − Tcold,out.

  • When the two end differences are equal, LMTD equals that common difference.
  • Both end differences must be positive. A counterflow cold outlet may be warmer than the hot outlet if the end differences remain positive.
  • Assumes steady single-phase streams and approximately constant heat capacities and overall heat transfer coefficient.
  • This is the ideal LMTD. Actual multipass shell-and-tube and crossflow arrangements require an appropriate correction or a different analysis.
  • LMTD is a temperature difference, not a fluid temperature or an efficiency percentage. This tool does not check the heat balance between the streams.

Reference: DOE Heat Transfer Handbook.

For ideal counterflow or parallel flow. A result does not verify a complete exchanger design or its heat balance.

Cooling Water Flow Calculator

Estimate the cooling-water flow needed for a known heat load and an allowable water temperature rise. View the result in L/min, m³/h and US GPM.

03 / Water flow requirementExample values loaded · edit to suit your duty

Default water properties are rounded values near 20°C. For greater accuracy, enter water properties at the mean operating temperature.

HEAT OUTINLETOUTLETSINGLE-PHASE LIQUID
Simplified flow diagram · not to scale
Cooling Water Flow
—L/min

Calculate to see the result.

Discuss your cooling requirements →
Formula, assumptions & sources

ṁ = Q̇ / (cₚ × ΔT)   ·   V̇ = ṁ / ρ

ΔT is water outlet temperature minus water inlet temperature. The same heat load needs more water when the allowed temperature rise is smaller.

  • Steady single-phase liquid water, no evaporation or heat loss to the surroundings.
  • Assumes the water receives all of the entered heat load. Actual exchanger performance, velocity limits and fouling may require different operating flow.
  • This calculates thermal flow only. Pump head, pipe size, pressure drop and available site flow must be checked separately.
  • Default cₚ = 4.18 kJ/(kg·K), ρ = 998 kg/m³: rounded water reference near 20°C. Use supplied values when operating conditions differ.

Formula: DOE Heat Transfer Handbook. Unit definitions: NIST SI conversion factors. BTU and kcal use IT definitions; 1 US refrigeration ton = 12,000 BTU/h (IT).

Thermal flow estimate only. Actual exchanger performance, water velocity and system pressure drop require separate checks.

Heat Exchanger Unit Converter

Convert common heat-transfer and drawing units, including thermal power, flow, temperature, pressure, length and area. Choose the quantity and units before converting.

04 / Engineering unitsExample values loaded · edit to suit your duty

Choose the physical quantity before selecting units.

kWBTU/hSAME QUANTITY · DIFFERENT UNITS
Unit comparison
Heat Exchanger Unit Converter
—BTU/h (IT)

Calculate to see the result.

Formula, assumptions & sources

Conversions use a common base unit for each physical quantity. Temperature conversion includes an offset; temperature-difference conversion does not.

  • 1 BTU (IT) = 1,055.05585262 J; 1 kcal (IT) = 4,186.8 J.
  • 1 US gallon = 3.785411784 L; 1 Imperial gallon = 4.54609 L.
  • 1 inch = 25.4 mm; 1 lb = 0.45359237 kg.
  • 1 US refrigeration ton = 12,000 BTU/h (IT).
  • Volume flow cannot be converted to mass flow without fluid density. These are separate categories.
  • Displayed values are rounded; the calculation retains additional precision.

Reference: NIST SI conversion factors.

Check the quantity and unit definition before comparing drawing data or quotations.