T4 18650 thermal hybrid grammar#

Tier-4 thermo-topological battery grammar benchmark with analytic, explicit-circuit, and hybrid-thermal evaluator modes.

See Grammar Problem Catalog for the grammar family index.

Quick Facts#

Field

Value

Problem ID

battery_18650_t4_thermal_hybrid_grammar

Problem Family

grammar

Implementation

design_research_problems.problems.grammar._battery_tiers:Battery18650T4ThermalHybridGrammarProblem

Capabilities

discrete-actions, external-adapter, serializable-state, statement-markdown

Study Suitability

none

Tags

grammar, battery, tiered, tier-4, thermal-topology, hybrid

Taxonomy#

Formulation

discrete_grammar

Convexity

not_applicable

Design Variable Type

mixed

Is Dynamic

no

Orientation

engineering_practical

Feasibility Ratio Hint

0.02

Objective Mode

multi

Constraint Nature

hard

Bounds Summary

tier-3 topology/pose controls plus thermal-parameter tuning actions

Tags

grammar, battery, tiered, tier-4, thermal-topology, hybrid

Benchmark Contract#

Benchmark Question

How well do grammar methods co-design topology, geometry, and thermal controls when evaluator fidelity can be stepped up without changing representation?

Physically Modeled

Tier-3 topology allocation and pose geometry; Thermal control variables for convection, passive cooling, and ambient conditions; PyBaMM-derived thermal priors and steady-state thermal-network evaluation in hybrid mode

Deliberate Surrogates

Electrical scoring can remain surrogate or projected explicit depending on evaluation_mode; Hybrid thermal scoring still projects topology-allocation states to a canonical explicit netlist

Representation Mode

thermal_topology

Default Evaluation Mode

hybrid_thermal

Supported Evaluation Modes

analytic_surrogate, explicit_circuit, hybrid_thermal

Validation Scope

Qualitative thermal trend validation; Mode-consistency checks across analytic, explicit, and hybrid evaluators

Solver Role

grammar benchmark; no packaged optimizer

Statement#

Tier 4 unlocks thermal-system design variables in addition to Tier-3 topology and geometry decisions. The grammar supports topology edits, pose edits, and cooling-condition tuning actions with a PyBaMM-backed thermal evaluator.

This is the highest-freedom battery rung in the tiered ladder.

Tier-4 extends tier-3 actions with thermal-parameter tuning. In addition to topology and geometry edits, actions can adjust:

  • h (convective cooling coefficient)

  • G_passive (passive thermal conductance)

  • T_ambient (ambient condition)

  • thermal model selector (lumped or multi_node_2node)

Thermal heating term (from PyBaMM-derived resistance prior):

  • I_cell = I_load / P_eq

  • q_i = I_cell^2 * R_eff(SOC_ref)

Multi-node mode (default) solves steady-state balances over nodes [core_i, surface_i, coolant], with inter-cell conductance edges G_ij derived from geometric proximity, local cooling terms G_sc,i, and coolant-to-ambient conductance.

Reported T_max is max_i(T_core_i), not an averaged pack temperature.

BattMo/PyBattMo integration is intentionally deferred in this release to keep the core benchmark path Python-only and CI-stable.

Problem Shape#

Field

Value

State Type

tuple

Initial Transition Count

16

Initial Rule Names

adjust_cell_count, adjust_series_count, move_cell_x, move_cell_y, move_cell_z, tune_ambient, tune_cooling_coefficient, tune_passive_cooling

Manifest Parameters#

Key

Value

ambient_temperature_bounds

{“lower”: 5.0, “upper”: 45.0}

cooling_coefficient_bounds

{“lower”: 5.0, “upper”: 50.0}

evaluation_mode

hybrid_thermal

imbalance_model

min_stage

load_current_a

60

max_cell_count

24

max_depth_mm

500

max_height_mm

250

max_width_mm

500

maximum_temperature_c

60

minimum_capacity_ah

10

minimum_current_a

60

minimum_spacing_mm

2

objective_weights

{“cost”: 0.25, “temperature”: 0.4, “volume”: 0.35}

passive_cooling_bounds

{“lower”: 0.1, “upper”: 10.0}

target_voltage_v

14.8

thermal_airflow_axis

x

thermal_contact_decay_mm

2

thermal_contact_resistance_k_per_w

2.5

thermal_flow_shadowing_factor

0.25

thermal_model

multi_node_2node

thermal_neighbor_clearance_mm

8

thermal_reference_soc

0.5

voltage_tolerance_v

0.1

Initial Transition Summary#

Rule Name

Transition Count

adjust_cell_count

2

adjust_series_count

2

move_cell_x

2

move_cell_y

2

move_cell_z

2

tune_ambient

2

tune_cooling_coefficient

2

tune_passive_cooling

2

Library Interface#

  • initial_state()

  • enumerate_transitions(state)

  • enumerate_next_states(state)

  • evaluate(state)