Boiler Energy Flow Sankey Diagram

A Sankey diagram is an energy flow visualisation where the width of each band is proportional to the energy it carries. Fuel energy enters on the left and splits into multiple streams as it moves right. Green bands show useful heat reaching your process; red bands show losses. The wider a red band, the larger that loss. Use the sliders to adjust each loss and see how overall efficiency changes in real time.

While boiler combustion efficiency is often quoted at 85-88%, the delivered efficiency to the process is much lower. A coil heat exchanger system typically delivers 50-60% of input fuel energy as useful heat. Direct steam injection (sparging) systems are worse at 40-50%, primarily due to evaporative and splash losses from open tanks, plus steam trap failures.

Steam sparging injects live steam directly into a liquid bath. This creates violent turbulence that drives moisture and heat out of open tanks through evaporation and splashing. Steam traps in the distribution system leak and fail at rates of 4-10%. Combined with generation and distribution losses, sparging systems typically waste 50-60% of the fuel energy input. The evaporative losses alone can account for 15-20% of total input energy.

A heat pump uses electricity to move heat from a low-temperature source to a higher temperature, rather than generating heat by burning fuel. With a COP of 4.0, every 1 kWh of electricity moves 3 kWh of ambient heat plus the 1 kWh of electrical energy, delivering 4 kWh total. After a small 2-3% distribution loss, the net useful heat is approximately 390% of the electrical input. The Karnot iHEAT uses R290 (propane) refrigerant, which has a GWP of just 3, making it both energy-efficient and climate-friendly.