Lithium-Battery Dry-Room HVAC, Silica-Gel Desiccant Wheels & Psychrometric Mass Balance
Rotary Desiccant Wheel Moisture Removal & Regen Formula
Calculate AHRI 940 Moisture Removal Capacity MRC (kg/h), Process Latent Heat of Sorption Released (kW), Reactivation Heater Thermal Input (kW), and Specific Regeneration Energy (kWh/kg).
Cooling coils freeze solid near 0 °C dew point—sub-zero dry rooms rely on desiccant wheels that trade latent vapor into sensible heat!
Chilled-water or DX cooling coils cannot dehumidify air below `~4 °C` dew point (`~5.0` g/kg) without icing the fins; pharmaceutical tablet rooms, ice rinks, and EV lithium-battery dry rooms use a slowly rotating (`8–12` rev/h) honeycomb **Silica-Gel / Molecular-Sieve Desiccant Wheel**! Across the `270°` Process Sector (`Q_proc` m³/h at dry-air density `rho`), water vapor adsorbs from Inlet Humidity Ratio `w_in` (g/kg) down to `w_out` (g/kg), delivering **Moisture Removal Capacity `MRC = (Q_proc * rho * (w_in - w_out)) / 1,000`** (`kg/h`) while releasing Latent Heat of Condensation + Wetting (`~2,450` kJ/kg -> `Q_lat = (MRC * 2,450) / 3,600` kW) as warm dry process air! Across the `90°` Reactivation Sector (`Q_reg` m³/h heated through `Delta_T_reg = 90–140 °C`), Regeneration Thermal Power `Q_reg,kW = ((Q_reg * rho) / 3,600) * 1.006 * Delta_T_reg` desorbs the trapped moisture at Specific Thermal Intensity `Q_reg,kW / MRC` (`kWh/kg` water removed)!
Verify on a Pharmaceutical Tablet-Press Desiccant Dehumidifier—Process_Airflow `Q_p` = 3,200.0 m³/h (B2), Air_Density `rho` = 1.20 kg/m³ (B3), Process_Inlet_Humidity `w_in` = 13.80 g/kg (B4), Dry_Discharge_Humidity `w_out` = 4.20 g/kg (`1.4 °C` dew point, B5 -> `MRC = 36.86` kg/h in E2 & Latent Release = `25.09` kW in E3), Reactivation_Airflow `Q_r` = 1,050.0 m³/h (B6), and Reactivation_Heater_Rise `Delta_T_r` = 95.0 °C (B7): Reactivation Heater Input equals `33.45` kW (E4), or `0.91` kWh per kg of moisture removed (E5)!
| AHRI 940 Desiccant Wheel KPI (Qp=3,200 m³/h, 13.8 -> 4.2 g/kg, Qr=1,050 m³/h @ +95°C) | Formula | Verified Output |
|---|---|---|
| Moisture Removal Capacity MRC (kg/h) | (Qproc * rho * (w_in_g_kg - w_out)) / 1000 | 36.86 kg/h (47.23 kg/h @ 1.5 g/kg deep dry) |
| Latent Sorption Heat Released (kW) | (MRC_kg_hr * 2450) / 3600 | 25.09 kW (32.14 kW @ 1.5 g/kg) |
| Reactivation Heater Power (kW) | ((Qreg * rho) / 3600) * 1.006 * dT_reg_C | 33.45 kW (44.01 kW @ +125 °C regen) |
| Specific Regen Energy (kWh / kg) | Reactivation_Power_kW / MRC_kg_hr | 0.91 kWh/kg (0.93 kWh/kg @ +125 °C) |
AHRI 940 Desiccant Moisture Removal Capacity & Specific Regeneration Formula
Validate `Process_Air > 0` m³/h, `Density` in `[0.8, 1.5]` kg/m³, `0 <= w_out < w_in <= 40` g/kg, `Regen_Air > 0` m³/h, and `Regen_DeltaT` in `[40, 180]` °C!
=LET(qp_h, B2, rh_a, B3, wi_g, B4, wo_g, B5, qr_h, B6, dt_r, B7, mr_k, (qp_h * rh_a * (wi_g - wo_g)) / 1000, pw_r, ((qr_h * rh_a) / 3600) * 1.006 * dt_r, IF(OR(qp_h <= 0, rh_a < 0.8, rh_a > 1.5, wo_g < 0, wi_g <= wo_g, wi_g > 40, qr_h <= 0, dt_r < 40, dt_r > 180), "Invalid Desiccant Input", ROUND(pw_r / mr_k, 2)))Sub-Zero Dew-Point 1.50 g/kg Deep-Drying Upgrade Check (Set w_out = 1.50 g/kg & Regen Rise = 125.0 °C)
Boost reactivation burner rise to `B7 = 125.0 °C` to drive Process Discharge Humidity down to `B5 = 1.50` g/kg (`-11 °C` frost point!): `MRC` E2 climbs to `47.23` kg/h (`32.14` kW sorption heat in E3), Reactivation Power E4 rises to `44.01` kW, and Specific Regeneration Intensity E5 edges from `0.91` to `0.93` kWh/kg!
=IF(ISTEXT(E5), E5, ROUND(((B6 * B3) / 3600) * 1.006 * B7, 2))Try the example
Use the original values or change them to test your understanding.