Design Calculators - Mechanical

This calculator determines the Boiler Thermal Efficiency (%) using the direct method (input-output method). It also calculates Equivalent Evaporation, a key metric for comparing boiler performance. This tool is designed for practical industrial applications to assess boiler energy performance and optimize operations.

Key Inputs:

• Unit System: Select Metric (kg, kJ) or Imperial (lb, BTU) for consistency.
• Fuel Input Rate (M_fuel): The mass flow rate of fuel supplied to the boiler.
• Fuel Higher Heating Value (HHV): The energy content per unit mass of the fuel. It is crucial to use the HHV (Gross Calorific Value) for this method, which includes the latent heat of vaporization of water formed during combustion. Obtain this from reliable fuel analysis (e.g., ASTM D3176 for solids, ASTM D5291 for liquids).
• Steam Output Rate (M_steam): The mass flow rate of steam produced by the boiler.
• Enthalpy of Steam (h_steam): The specific enthalpy of the generated steam at its measured pressure and temperature (e.g., kJ/kg or BTU/lb). This value is critical and must be obtained accurately from recognized steam tables (e.g., ASME Steam Tables, IAPWS-IF97) or thermodynamic software.
• Enthalpy of Feedwater (h_feedwater): The specific enthalpy of the feedwater entering the boiler. This value must also be obtained accurately from steam tables based on feedwater temperature.

Calculated Outputs:

• Total Energy Input: The total thermal energy supplied by the fuel.
• Total Energy Output in Steam: The total thermal energy absorbed by the steam.
• Boiler Efficiency (\(\eta\)): The percentage of the energy input from the fuel that is successfully transferred to the steam.
• Equivalent Evaporation: The amount of steam generated "from and at" 100°C (212°F) per unit time, normalizing boiler output for performance comparison.

Important Note: For accurate results, ensure that all input data points (mass flow rates, HHV, and enthalpies) are derived from accurate field measurements under steady-state operating conditions and are consistent with the selected unit system. This calculator is a practical estimation tool and should be used in conjunction with detailed engineering analysis for critical applications.