Math & Numbers

Heat Exchanger LMTD Calculator (Log Mean Temperature Difference)

Compute the Log Mean Temperature Difference (LMTD) of a heat exchanger for parallel or counter flow. Parallel flow: ΔT₁ = T_h,in - T_c,in and ΔT₂ = T_h,out - T_c,out; counter flow: ΔT₁ = T_h,in - T_c,out and ΔT₂ = T_h,out - T_c,in. LMTD = (ΔT₁ - ΔT₂)/ln(ΔT₁/ΔT₂), or ΔT₁ when ΔT₁ = ΔT₂. A non-positive terminal difference (temperature cross) is physically impossible and is rejected. Optionally, with the overall heat transfer coefficient U (W/(m²·K)) and the heat transfer area A (m²), the heat transfer rate Q = U·A·LMTD (W) is returned. Temperatures are used only as differences: Δ°C = ΔK and Δ°F ×5/9 = ΔK; the LMTD is reported in K.

json· JSON resultOpen tool

Quick start

Call this tool from your code in three languages.

cURL

curl -X POST 'https://api.elysiatools.com/en/api/tools/heat-exchanger-lmtd' \
  -H 'Content-Type: application/json' \
  -d '{"flowType":"counter","hotInletTemp":100,"hotOutletTemp":60,"coldInletTemp":20,"coldOutletTemp":50,"tempUnit":"°C","heatTransferCoeff":0,"area":0,"decimalPlaces":4}'

API reference

Send a POST request with your inputs as JSON. File parameters require a separate upload first.

Endpoint

HTTP

POST https://api.elysiatools.com/en/api/tools/heat-exchanger-lmtd

Parameters

Name	Type	Required	Description
flowType	select	No	Flow arrangement: Parallel Flow (both streams in the same direction) or Counter Flow (opposite directions).
hotInletTemp	number	Yes	Hot-stream inlet temperature T_h,in, in the selected Temperature Unit.
hotOutletTemp	number	Yes	Hot-stream outlet temperature T_h,out, in the selected Temperature Unit.
coldInletTemp	number	Yes	Cold-stream inlet temperature T_c,in, in the selected Temperature Unit.
coldOutletTemp

MCP integration

Add this tool to your Model Context Protocol server so AI agents can list and call it.

Server configuration

Add this block to your MCP client configuration:

mcp.json

{
  "mcpServers": {
    "elysiatools-heat-exchanger-lmtd": {
      "name": "heat-exchanger-lmtd",
      "description": "Compute the Log Mean Temperature Difference (LMTD) of a heat exchanger for parallel or counter flow. Parallel flow: ΔT₁ = T_h,in - T_c,in and ΔT₂ = T_h,out - T_c,out; counter flow: ΔT₁ = T_h,in - T_c,out and ΔT₂ = T_h,out - T_c,in. LMTD = (ΔT₁ - ΔT₂)/ln(ΔT₁/ΔT₂), or ΔT₁ when ΔT₁ = ΔT₂. A non-positive terminal difference (temperature cross) is physically impossible and is rejected. Optionally, with the overall heat transfer coefficient U (W/(m²·K)) and the heat transfer area A (m²), the heat transfer rate Q = U·A·LMTD (W) is returned. Temperatures are used only as differences: Δ°C = ΔK and Δ°F ×5/9 = ΔK; the LMTD is reported in K.",
      "baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=heat-exchanger-lmtd",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

List available tools

After connecting to the SSE endpoint, list the exposed tools:

tools/list

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list"
}

Call this tool

Invoke the tool by its id, passing arguments built from its parameters:

tools/call

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "heat-exchanger-lmtd",
    "arguments": {
  "flowType": "counter",
  "hotInletTemp": 100,
  "hotOutletTemp": 60,
  "coldInletTemp": 20,
  "coldOutletTemp": 50,
  "tempUnit": "°C",
  "heatTransferCoeff": 0,
  "area": 0,
  "decimalPlaces": 4
}
  }
}

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