import type { BoilerEfficiencyInput, BoilerEfficiencyResult } from './types.js';
/**
 * Calculate boiler thermal efficiency using the direct (input-output) method.
 *
 * η = (steamOutput × (steamEnthalpy − feedwaterEnthalpy)) / (fuelRate × fuelHeatValue) × 100
 *
 * Heat values are converted from kJ to kW by dividing by 3600 (kJ/h → kW).
 *
 * @param input - Boiler operating parameters
 * @returns Boiler efficiency result with heat balance and optional annual metrics
 */
export declare function boilerEfficiency(input: BoilerEfficiencyInput): BoilerEfficiencyResult;
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