A recuperator is a type of heat exchanger that recovers waste heat from exhaust gases to preheat incoming air or gas, improving energy efficiency in combustion systems. It is commonly used in biogas systems, industrial furnaces, gas turbines, and HVAC applications
How a Recuperator Works
- Hot exhaust gas passes through one side of the recuperator.
- Cold incoming air/gas flows in the opposite direction (counter-flow design).
- Heat transfer occurs through conductive walls (metal or ceramic), warming the incoming stream.
- Preheated air enters the combustion chamber, reducing fuel consumption.
Types of Recuperators
- Metallic Recuperators
- Made of stainless steel or heat-resistant alloys.
- Used in moderate-temperature applications (<1,000°C).
- Common in biogas boilers, industrial heaters.
- Ceramic Recuperators
- Handle very high temperatures (>1,000°C).
- Resistant to corrosion (e.g., from H₂S in biogas).
- Used in kilns, high-efficiency furnaces.
- Plate Recuperators
- Compact, with stacked metal plates for heat exchange.
- Common in biogas CHP (combined heat and power) systems.
- Shell-and-Tube Recuperators
- Robust design for high-pressure applications.
- Used in large-scale biogas plants.
Benefits in Biogas Systems
✔ Energy Efficiency – Reduces fuel needs by preheating combustion air.
✔ Lower Emissions – More complete combustion = fewer pollutants.
✔ Cost Savings – Decreases operational fuel expenses.
✔ Improved Combustion Stability – Preheated air ensures consistent biogas burning.
Applications
- Biogas Combustion Engines (CHP) – Recovers exhaust heat for better efficiency.
- Biogas Boilers & Furnaces – Preheats air for cleaner burning.
- Industrial Drying Processes – Reuses waste heat from flue gases.
- Gas Turbines – Enhances thermal efficiency.
Comparison with Regenerators
| Feature | Recuperator | Regenerator |
| Heat Transfer | Continuous (direct) | Alternating (storage-based) |
| Efficiency | Moderate (~70%) | Very High (~90%) |
| Maintenance | Low | Higher (moving parts) |
| Cost | Lower | Higher |
Considerations When Choosing a Recuperator
- Temperature range (exhaust gas vs. material limits).
- Corrosion resistance (important for biogas with H₂S).
- Pressure drop (should not restrict gas flow).
- Cleaning requirements (soot or condensate build-up).