📋 Case Study
HVAC Coil Frost Detection and Defrost Optimization for Cold Storage Warehouse
Excessive defrost cycles wasting 18% compressor runtime; manual timers caused coil icing or incomplete melt
🏗️ Project Overview
−25°C frozen food distribution center in Minnesota
🎯 Challenge
Excessive defrost cycles wasting 18% compressor runtime; manual timers caused coil icing or incomplete melt
🔧 Design Approach
Model-based frost mass estimation using air-side ΔP, inlet dew point, and coil surface temp fusion + adaptive defrost initiation logic
📐 Design Diagram
AI-generated project design illustration
📐 Key Calculations
Frost Mass Accumulation Rate
ṁ_frost ≈ ṁ_air × (ω_in − ω_sat@T_coil)
Result: 1.7 g/s peak
Triggers defrost before airflow restriction
Defrost Energy Penalty
Q_defrost = m_frost × h_fg + Q_sensible
Result: 2.1 kWh/cycle
Benchmark for optimization target
📊 Results
Defrost frequency reduced by 41%, annual refrigeration energy down 11.6%, coil airflow maintained >95% nominal💡 Lessons Learned
- •Dew point sensor calibration is more critical than temperature accuracy
- •Frost density varies significantly with air velocity profile — requires multi-point sensing
✅ Key Takeaways
- 1Dew point sensor calibration is more critical than temperature accuracy
- 2Frost density varies significantly with air velocity profile — requires multi-point sensing