Desiccant wheel regeneration heated by heat pumps
How a battery plant with a 500 m² dry room can heat its desiccant wheel regeneration air with heat pumps, and what it saves against electric regeneration heaters.
▶Video: Hot air from heat pump hot water
V05 · 2–2.5 minAir coils for spray dryers, stenters, kilns, paint booths and ovens
Video coming soon01Problem statement
- Regeneration heaters never stop. Desiccant wheels must be regenerated continuously, and electric heaters heating air to 100–120 °C run around the clock.
- Dew point depends on regeneration. If regeneration air temperature drops, the wheel is not fully dried and dry-room dew point rises.
- High energy per square metre. Dry rooms use far more energy per square metre than ordinary clean rooms, much of it for regeneration.
- Electric heating is expensive heat. Resistance heaters turn one kWh of electricity into one kWh of heat, at the full commercial tariff. A heat pump moves two to four kWh of heat for the same unit.
- Large connected load. Heater banks take a big share of the sanctioned load and push up maximum-demand charges.
02Use case
The reference plant assembles lithium-ion cells in a 500 m² dry room held at a dew point of about −40 °C, with a smaller low-humidity packing room. Desiccant dehumidifiers run 24 hours a day.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Dry-room wheel regeneration air | Air 35 → 110 °C | 2,500 m³/h × 1.1 kg/m³ × 1.005 kJ/kg·K × 75 K × 24 h | 1,382 |
| Packing-room wheel regeneration air | Air 35 → 100 °C | 800 m³/h × 1.1 kg/m³ × 1.005 kJ/kg·K × 65 K × 24 h | 383 |
| Storage and pipework standing losses | – | about 5% | 88 |
| Total useful heat | 1,853 | ||
Averaged over 20 running hours, the heat pumps need about 93 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- A SE-UHT air-source cascade, R245fa machine of about 95 kW, air-source cascade to 120 °C, sized per project.
- A 3,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric regeneration heaters stays connected behind a normally closed valve as standby.
- A hot-water coil is added to each regeneration air stream, upstream of the existing electric heater.
- The heat pumps supply pressurised water at up to 120 °C, lifting regeneration air to about 100–110 °C.
- The electric heater stays in series and trims to the final regeneration set point.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 95 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.6 (estimate) |
| Supply temperature | 120 °C |
| Storage | 3,000 L insulated tank |
Capacity is sized from the heat demand above. COP is an estimate until Sunniva engineering confirms the design.
Control philosophy
TT-101 at the tank top starts the heat pumps below 112 °C and stops them at 120 °C. TIC-201 and TIC-202 modulate the coil valves to hold air leaving each coil at set point. The electric heater controller trims to the regeneration temperature the dehumidifier needs. A dew-point alarm in the dry room overrides to full electric heat.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Lower round-the-clock load
Most of the continuous regeneration heat comes from the heat pumps instead of resistance heaters.
Dew point protected
The electric heater remains in series, so regeneration temperature is always guaranteed.
Works for pharma too
The same arrangement suits desiccant dehumidifiers in tablet, capsule and powder filling rooms.
Lower energy cost
Each kWh of electricity delivers about 1.6 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
Smaller electrical load
The heat pump draws roughly 1/1.6 of the power of the heaters it replaces, which frees sanctioned load and cuts demand charges.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Dehumidifier models and regeneration airflows
- Regeneration temperature set points
- Dry-room dew point and area
- Installed regeneration heater kW and hours
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Recover purge heat first. Many wheels have a purge section. Use it to preheat regeneration air before sizing heat pump duty.
- Pressurised loop. Water at 120 °C needs a loop rated for at least 4 bar with full safety valving and insulation.
- Ambient correction. Ratings are at 20 °C air. Ask Sunniva for the correction at your site's winter design temperature.
- Water quality. Scale forms quickly above 60 °C. Use softened make-up and keep the heat pump loop closed, with process fluids on the far side of an exchanger or coil.
- Performance figure. The COP on this page is an engineering estimate, not a data sheet value. Sunniva engineering will confirm it for the actual source and supply temperatures.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.
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Desiccant wheel regeneration heated by heat pumps
How a battery plant with a 500 m² dry room can heat its desiccant wheel regeneration air with heat pumps, and what it saves against electric regeneration heaters.
▶Video: Hot air from heat pump hot water
V05 · 2–2.5 minAir coils for spray dryers, stenters, kilns, paint booths and ovens
Video coming soon01Problem statement
- Regeneration heaters never stop. Desiccant wheels must be regenerated continuously, and electric heaters heating air to 100–120 °C run around the clock.
- Dew point depends on regeneration. If regeneration air temperature drops, the wheel is not fully dried and dry-room dew point rises.
- High energy per square metre. Dry rooms use far more energy per square metre than ordinary clean rooms, much of it for regeneration.
- Electric heating is expensive heat. Resistance heaters turn one kWh of electricity into one kWh of heat, at the full commercial tariff. A heat pump moves two to four kWh of heat for the same unit.
- Large connected load. Heater banks take a big share of the sanctioned load and push up maximum-demand charges.
02Use case
The reference plant assembles lithium-ion cells in a 500 m² dry room held at a dew point of about −40 °C, with a smaller low-humidity packing room. Desiccant dehumidifiers run 24 hours a day.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Dry-room wheel regeneration air | Air 35 → 110 °C | 2,500 m³/h × 1.1 kg/m³ × 1.005 kJ/kg·K × 75 K × 24 h | 1,382 |
| Packing-room wheel regeneration air | Air 35 → 100 °C | 800 m³/h × 1.1 kg/m³ × 1.005 kJ/kg·K × 65 K × 24 h | 383 |
| Storage and pipework standing losses | – | about 5% | 88 |
| Total useful heat | 1,853 | ||
Averaged over 20 running hours, the heat pumps need about 93 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- A SE-UHT air-source cascade, R245fa machine of about 95 kW, air-source cascade to 120 °C, sized per project.
- A 3,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric regeneration heaters stays connected behind a normally closed valve as standby.
- A hot-water coil is added to each regeneration air stream, upstream of the existing electric heater.
- The heat pumps supply pressurised water at up to 120 °C, lifting regeneration air to about 100–110 °C.
- The electric heater stays in series and trims to the final regeneration set point.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 95 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.6 (estimate) |
| Supply temperature | 120 °C |
| Storage | 3,000 L insulated tank |
Capacity is sized from the heat demand above. COP is an estimate until Sunniva engineering confirms the design.
Control philosophy
TT-101 at the tank top starts the heat pumps below 112 °C and stops them at 120 °C. TIC-201 and TIC-202 modulate the coil valves to hold air leaving each coil at set point. The electric heater controller trims to the regeneration temperature the dehumidifier needs. A dew-point alarm in the dry room overrides to full electric heat.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Lower round-the-clock load
Most of the continuous regeneration heat comes from the heat pumps instead of resistance heaters.
Dew point protected
The electric heater remains in series, so regeneration temperature is always guaranteed.
Works for pharma too
The same arrangement suits desiccant dehumidifiers in tablet, capsule and powder filling rooms.
Lower energy cost
Each kWh of electricity delivers about 1.6 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
Smaller electrical load
The heat pump draws roughly 1/1.6 of the power of the heaters it replaces, which frees sanctioned load and cuts demand charges.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Dehumidifier models and regeneration airflows
- Regeneration temperature set points
- Dry-room dew point and area
- Installed regeneration heater kW and hours
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Recover purge heat first. Many wheels have a purge section. Use it to preheat regeneration air before sizing heat pump duty.
- Pressurised loop. Water at 120 °C needs a loop rated for at least 4 bar with full safety valving and insulation.
- Ambient correction. Ratings are at 20 °C air. Ask Sunniva for the correction at your site's winter design temperature.
- Water quality. Scale forms quickly above 60 °C. Use softened make-up and keep the heat pump loop closed, with process fluids on the far side of an exchanger or coil.
- Performance figure. The COP on this page is an engineering estimate, not a data sheet value. Sunniva engineering will confirm it for the actual source and supply temperatures.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.