{
  "node": {
    "id": "term:heat-transfer-modes",
    "type": "Term",
    "label": "Heat transfer modes",
    "properties": {
      "id": "heat-transfer-modes",
      "name": "Heat transfer modes",
      "aka": [
        "conduction",
        "convection",
        "thermal radiation"
      ],
      "section": "topic-thermal",
      "definition": "The three ways heat moves: conduction through solids and still fluids, convection carried by a moving fluid, and radiation emitted as infrared by every warm surface. In a pack, conduction takes heat from the cell into the cooling plate and convection carries it away in the coolant; radiation matters mainly at the high temperatures of thermal runaway.",
      "related": [
        "thermal-conductivity",
        "heat-transfer-coefficient",
        "thermography",
        "cooling-plate",
        "thermal-propagation"
      ],
      "url": "https://lemonergy.com/learn/glossary/heat-transfer-modes/",
      "mentions": [
        "thermal-runaway"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:4605",
      "source": "term:heat-transfer-modes",
      "target": "topic:topic-thermal",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:4606",
      "source": "term:heat-transfer-modes",
      "target": "term:thermal-conductivity",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4607",
      "source": "term:heat-transfer-modes",
      "target": "term:heat-transfer-coefficient",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4608",
      "source": "term:heat-transfer-modes",
      "target": "term:thermography",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4609",
      "source": "term:heat-transfer-modes",
      "target": "term:cooling-plate",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4610",
      "source": "term:heat-transfer-modes",
      "target": "term:thermal-propagation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/heat-transfer-modes/thermal-runaway",
      "source": "term:heat-transfer-modes",
      "target": "term:thermal-runaway",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:4612",
      "source": "term:heat-transfer-modes",
      "target": "reference:openstax-heat",
      "type": "cites",
      "properties": {
        "sourceFile": "wiki-references.json",
        "scope": "direct technical reference"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-thermal",
      "type": "Topic",
      "label": "Thermal management and heat transfer",
      "properties": {
        "id": "topic-thermal",
        "name": "Thermal management and heat transfer",
        "lede": "How heat is made, moved and removed in cells and packs, and the hardware that keeps a battery at the right temperature.",
        "context": "Select spatial detail for the question.",
        "example": "Equal total heat in different layouts can produce different gradients. Average temperature can miss a hot spot.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-aging/",
        "lesson_label": "Open temperature and aging"
      }
    },
    {
      "id": "term:thermal-conductivity",
      "type": "Term",
      "label": "Thermal conductivity",
      "properties": {
        "id": "thermal-conductivity",
        "name": "Thermal conductivity",
        "abbr": "k",
        "aka": [
          "λ",
          "through-plane conductivity",
          "in-plane conductivity"
        ],
        "section": "topic-thermal",
        "definition": "How readily a material conducts heat: the heat flux per unit temperature gradient. Cells are strongly anisotropic — around 25–45 W/(m·K) in-plane, along the metal foils, but below 1 W/(m·K) through-plane, across separators and coatings — so the side a cell is cooled from decides how hot its core runs.",
        "formula": "q″ = −k·dT/dx",
        "unit": "W/(m·K)",
        "related": [
          "thermal-resistance",
          "thermal-diffusivity",
          "thermal-characterisation",
          "thermal-interface-material",
          "biot-number",
          "thermal-model"
        ],
        "example": {
          "title": "Calculate a slab heat flow",
          "text": "An illustrative 2 mm layer with k = 1 W/(m·K), area 0.01 m² and a 10 K temperature difference transfers 50 W in steady one-dimensional conduction. Contact resistances and edge losses are omitted."
        },
        "url": "https://lemonergy.com/learn/glossary/thermal-conductivity/",
        "mentions": [
          "heat-flux",
          "thermal-gradient"
        ]
      }
    },
    {
      "id": "term:heat-transfer-coefficient",
      "type": "Term",
      "label": "Heat transfer coefficient",
      "properties": {
        "id": "heat-transfer-coefficient",
        "name": "Heat transfer coefficient",
        "abbr": "h",
        "aka": [
          "convection coefficient",
          "film coefficient"
        ],
        "section": "topic-thermal",
        "definition": "The heat carried away per unit area per kelvin of difference between a surface and the fluid passing it. Typical values are 5–25 W/(m²·K) for still air, 25–250 for forced air and hundreds to thousands for pumped liquid, which is why fast-charging packs are liquid-cooled. Thermal models use it as their cooling boundary.",
        "formula": "Q = h·A·ΔT",
        "unit": "W/(m²·K)",
        "related": [
          "heat-transfer-modes",
          "heat-flux",
          "biot-number",
          "thermal-model",
          "cooling-plate",
          "coolant"
        ],
        "example": {
          "title": "Estimate convective cooling",
          "text": "For an illustrative h = 20 W/(m²·K), area 0.1 m² and surface-to-fluid temperature difference 10 K, hAΔT gives 20 W of cooling. The coefficient depends on the actual flow and geometry."
        },
        "url": "https://lemonergy.com/learn/glossary/heat-transfer-coefficient/",
        "mentions": []
      }
    },
    {
      "id": "term:thermography",
      "type": "Term",
      "label": "Thermography",
      "properties": {
        "id": "thermography",
        "name": "Thermography",
        "aka": [
          "infrared thermography",
          "thermal imaging",
          "IR camera"
        ],
        "section": "topic-thermal",
        "definition": "Imaging surface temperature with an infrared camera, which converts the radiation a surface emits into a temperature map. It reveals hot welds, busbar joints and uneven cell heating at a glance, but bare metal reflects more than it emits, so shiny surfaces are usually coated matt black before measuring.",
        "related": [
          "hot-spot",
          "heat-transfer-modes",
          "temperature-sensor",
          "thermal-gradient",
          "laser-welding"
        ],
        "url": "https://lemonergy.com/learn/glossary/thermography/",
        "mentions": [
          "busbar"
        ]
      }
    },
    {
      "id": "term:cooling-plate",
      "type": "Term",
      "label": "Cooling plate",
      "properties": {
        "id": "cooling-plate",
        "name": "Cooling plate",
        "aka": [
          "cold plate"
        ],
        "section": "topic-thermal",
        "definition": "A flat aluminium channel assembly under or between the cells through which coolant, usually a water–glycol mix, is pumped. Heat crosses from cell to plate through a thermal interface material; the plate also sets the pack’s temperature uniformity.",
        "related": [
          "thermal-management",
          "thermal-interface-material",
          "immersion-cooling"
        ],
        "url": "https://lemonergy.com/learn/glossary/cooling-plate/",
        "mentions": [
          "thermal-gradient",
          "coolant"
        ]
      }
    },
    {
      "id": "term:thermal-propagation",
      "type": "Term",
      "label": "Thermal propagation",
      "properties": {
        "id": "thermal-propagation",
        "name": "Thermal propagation",
        "section": "topic-safety",
        "definition": "Thermal runaway spreading from one cell to its neighbours through conducted heat, hot gas and flame. Pack designs are judged by whether, and how slowly, a single failing cell takes the rest with it.",
        "related": [
          "thermal-runaway",
          "thermal-barrier",
          "venting",
          "module",
          "propagation-test"
        ],
        "url": "https://lemonergy.com/learn/glossary/thermal-propagation/",
        "mentions": []
      }
    },
    {
      "id": "term:thermal-runaway",
      "type": "Term",
      "label": "Thermal runaway",
      "properties": {
        "id": "thermal-runaway",
        "name": "Thermal runaway",
        "section": "topic-safety",
        "definition": "Self-accelerating heating in a cell: heat speeds up reactions that release more heat, until the cell vents, catches fire or ruptures. An internal short, overcharge or external heating can trigger it.",
        "related": [
          "onset-temperature",
          "thermal-propagation",
          "venting",
          "separator-shutdown",
          "thermal-runaway-energy",
          "exothermic"
        ],
        "lesson": "fundamentals/cell-anatomy/#short-circuit",
        "url": "https://lemonergy.com/learn/glossary/thermal-runaway/",
        "mentions": [
          "overcharge"
        ]
      }
    },
    {
      "id": "reference:openstax-heat",
      "type": "Reference",
      "label": "University Physics Volume 2, §1.6: Mechanisms of Heat Transfer",
      "properties": {
        "title": "University Physics Volume 2, §1.6: Mechanisms of Heat Transfer",
        "publisher": "OpenStax, Rice University",
        "url": "https://openstax.org/books/university-physics-volume-2/pages/1-6-mechanisms-of-heat-transfer",
        "type": "Textbook section",
        "scope": "Conduction, convection, radiation and thermal resistance.",
        "accessed": "2026-10-27"
      }
    }
  ]
}