Calculator Inputs
Use volume flow or direct mass flow.
Example Data Table
| Case | Basis | Flow | Density | Cp | Exhaust °C | Reference °C | Efficiency | Recoverable Heat |
|---|---|---|---|---|---|---|---|---|
| Paint Oven Exhaust | Volume | 2400 m³/h | 1.18 kg/m³ | 1.02 | 180 | 30 | 65% | 78.23 kW |
| Dryer Stack | Volume | 5200 m³/h | 1.10 kg/m³ | 1.03 | 240 | 35 | 70% | 234.81 kW |
| Thermal Process Vent | Mass | 0.95 kg/s | 1.15 kg/m³ | 1.08 | 165 | 35 | 60% | 80.03 kW |
Formula Used
ṁ = (Volumetric Flow ÷ 3600) × Density
ΔT = Exhaust Temperature − Reference Temperature
Q = ṁ × Cp × ΔT
Qrecovered = Q × Recovery Efficiency
Daily kWh = Recoverable kW × Hours per Day
Annual Savings = Annual kWh × Energy Price
This model treats cp and density as constant values. It estimates sensible heat only. It does not directly include latent heat, fouling losses, control cycling, pressure drop penalties, or moisture condensation effects.
How to Use This Calculator
- Select the calculation basis.
- Enter volumetric flow or direct mass flow.
- Provide gas density and specific heat.
- Enter exhaust and reference temperatures.
- Add recovery efficiency and operating schedule.
- Enter energy price and emission factor.
- Click calculate to view results and chart.
- Use CSV or PDF export for reporting.
Frequently Asked Questions
1. What does this calculator estimate?
It estimates sensible exhaust heat, recoverable heat, annual recovered energy, annual value, and carbon reduction using steady operating assumptions.
2. When should I use volumetric flow?
Use volumetric flow when stack measurements are in m³/h. The calculator converts it to mass flow using the entered gas density.
3. When should I use direct mass flow?
Use direct mass flow when process data already provides kg/s. This avoids extra conversion and reduces uncertainty from density assumptions.
4. Why is specific heat important?
Specific heat links mass flow and temperature change to thermal power. A poor cp estimate can noticeably change heat recovery results.
5. Does this include latent heat?
No. The calculator focuses on sensible heat. Wet exhaust streams may contain extra latent energy not captured by this simplified method.
6. What recovery efficiency should I enter?
Enter the expected performance of your heat recovery device or system. Many practical systems fall below ideal values due to fouling and controls.
7. Can I use this for economic screening?
Yes. It is useful for early feasibility checks, budgeting, and comparing opportunities before detailed thermal design work begins.
8. What improves result accuracy?
Use measured temperatures, representative flow data, realistic cp and density values, and practical efficiency estimates from actual equipment or vendor data.