Energy Balance Calculator

• •Use the Energy Balance Calculator when solving homework or exam problems that require quick numerical verification of your hand calculations — instant feedback helps identify arithmetic errors before they propagate.
• •Use it during the early design phase to rapidly iterate on parameters and narrow down feasible configurations before committing time to detailed finite element simulations or full design packages.
• •Use it when reviewing a colleague's calculation or checking a vendor's data sheet for plausibility — a quick sanity check can prevent costly downstream errors.
• •Use it to generate reference data for a technical report or presentation without manual computation, ensuring consistent, reproducible numbers throughout the document.
• •Use it in the field when a quick estimate is needed and a full engineering software package is not available.

The Energy Balance Calculator is a precision engineering calculation tool designed for students, engineers, and technical professionals. Open system steady-state energy balance (SFEE): Q − Ws = ΔH + ΔKE + ΔPE with built-in steam table enthalpy data All calculations are performed using established engineering formulas from the relevant scientific literature and standards. Inputs support both metric (SI) and imperial unit systems, with unit conversion handled automatically — simply select your preferred unit from the dropdown next to each field. Results are computed instantly in the browser without sending data to a server, ensuring both speed and privacy. This calculator is intended as a supplementary tool for learning and design exploration; always verify results against authoritative references for safety-critical applications.

The steady-flow energy equation (SFEE) for an open system is Q − W_s = Δh + ΔKE + ΔPE, where Q is heat added per unit mass, W_s is shaft work per unit mass, Δh is enthalpy change from inlet to outlet, ΔKE is kinetic energy change, and ΔPE is potential energy change. For most process equipment (pumps, compressors, heat exchangers, reactors), kinetic and potential energy changes are negligible compared to enthalpy changes, simplifying to Q − W_s = Δh. For a heat exchanger with no shaft work: Q = Δh × ṁ, where ṁ is the mass flow rate. For a turbine or compressor with no heat transfer: W_s = −Δh × ṁ. For reactors with both heat transfer and chemical reaction: Q = ṁ_out · h_out − ṁ_in · h_in + reaction heat, where reaction heat = −ΔH_rxn × ξ (negative for exothermic, positive for endothermic). Enthalpies are referenced to a common state (usually 25°C reference); enthalpy of reaction at 25°C plus sensible heat to the actual temperature gives the correct value. The first law is applied to each unit operation in a process, and the results are combined to close the plant-wide energy balance. The calculator handles steady-state energy balances on 2-stream and 3-stream systems with built-in component property tables for common species.

• •Reactor cooling or heating requirements: compute the Q removed or added to maintain target temperature given reaction heat and flow conditions.
• •Heat exchanger duty: Q = ṁ·cp·ΔT for each side, used to size heat exchangers and specify cooling water or steam requirements.
• •Turbine and compressor sizing: compute shaft work from enthalpy change and mass flow rate; size drive motor or generator accordingly.
• •Plant-wide steam balance: track steam generation in boilers, use in process heating, condensation, and return as condensate; identify net steam demand.
• •Furnace and combustor design: compute fuel required to achieve target outlet temperature given feed conditions and heat loss.