Electrode coater ovens heated with recovered heat
How a 0.5 GWh lithium-ion electrode line can heat its coater oven air with a water-source heat pump running on recovered exhaust heat, and what it saves against electric air heaters.
▶Video: Waste-heat recovery heat pumps
V10 · 2–2.5 minLifting warm water from condensers, effluent and process cooling to useful heat
Video coming soon01Problem statement
- Ovens are a large electrical load. Coater ovens heat large volumes of fresh air to 100–120 °C with electric heaters, often the biggest single load in electrode making.
- Exhaust heat is cooled away. Hot, solvent-laden exhaust has to be cooled before NMP can condense, and that heat goes to chillers and cooling towers.
- Temperature uniformity matters. Uneven drying causes binder migration, cracking and poor adhesion, so oven zones must hold set point tightly.
- 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 coats cathode and anode foils for lithium-ion cells, about 0.5 GWh a year. Two roll-to-roll coaters with multi-zone ovens run round the clock, and NMP is recovered from the cathode oven exhaust by condensation.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Oven fresh-air heating | Air 35 → 100 °C | 4,000 m³/h × 1.1 kg/m³ × 1.005 kJ/kg·K × 65 K × 20 h | 1,597 |
| NMP evaporation from cathode coating | 100–110 °C | 1,500 kg NMP/day × 510 kJ/kg | 213 |
| Oven shell losses | 100–120 °C | 200 m² oven shell × 0.1 kW/m² × 20 h | 400 |
| Storage and pipework standing losses | – | about 5% | 110 |
| Total useful heat | 2,320 | ||
Averaged over 20 running hours, the heat pumps need about 116 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
- 5 × SE-WWUHT-27 (135 kW total) (SE-WWUHT water-source, R245fa) delivering 120 °C, covering the day's 2,320 kWh in about 17.2 running hours.
- A 4,500 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: oven exhaust heat-recovery loop at about 55 °C. Pre-cooling the exhaust before the NMP condenser cuts chiller load and improves solvent recovery.
- The electric air heaters in coater ovens stays connected behind a normally closed valve as standby.
- A water coil in the oven exhaust, ahead of the NMP condenser, recovers heat into a 55 °C loop that feeds the heat pump evaporator.
- The heat pump supplies pressurised water at up to 120 °C to fresh-air coils on both coater ovens.
- The existing electric heaters stay in each zone and trim the last few degrees and the hottest zones.
Selected equipment
| Model | SE-WWUHT-27 × 5 |
|---|---|
| Heating capacity | 27 kW each, 135 kW total |
| COP | 2.93 at the data sheet's rated condition (60/55 °C source water) |
| Power input | about 46.0 kW total at rated conditions |
| Rating | water or steam to 120 °C, R245fa |
| Supply temperature | 120 °C |
| Storage | 4,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the tank top starts the heat pump below 112 °C and stops it at 120 °C. TIC-201 and TIC-202 hold the fresh-air coil outlets at 100 °C. Zone controllers on the electric heaters trim each zone to its recipe temperature. The exhaust recovery coil has a bypass so NMP condenser conditions are never upset.
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 | – | – |
| Cost per MWh of cell capacity | – | – |
| CO₂ per year | – | – |
06Benefits
Lower oven power
Most of the fresh-air heating moves from resistance heaters to the heat pump.
Better NMP recovery
Pre-cooling the exhaust before the condenser reduces chiller load and helps solvent capture.
Stable drying
Preheated air at a steady temperature makes zone control easier and more uniform.
Lower energy cost
Each kWh of electricity delivers about 2.9 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 1/2.9 of the power of the heaters it replaces, which frees sanctioned load and cuts demand charges.
Built-in redundancy
Several machines share the load. If one is serviced, the others and the storage carry most of the day, with the existing heater in reserve.
07Engineering pointers
Site data to collect
- Coater speed, web width and coating weight
- Oven fresh-air and exhaust flows and temperatures
- NMP use and recovery rate
- Installed heater kW per zone
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
Design notes
- Solvent and LEL safety. The exhaust recovery coil sits in a solvent stream. Use stainless steel, keep it within the oven's LEL monitoring and avoid any ignition source.
- Pressurised water at 120 °C. Size pipework, expansion and safety valves for at least 4 bar and insulate all hot lines.
- Dry-room interface. Keep heat pump plant and water lines outside the dry room to avoid any moisture risk.
- Electrical. About 46 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Source stream. The source must give up roughly two-thirds of the heat delivered. Confirm its flow and temperature over a full production day, and filter it before the evaporator.
- 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.
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.
Talk to us
Electrode coater ovens heated with recovered heat
How a 0.5 GWh lithium-ion electrode line can heat its coater oven air with a water-source heat pump running on recovered exhaust heat, and what it saves against electric air heaters.
▶Video: Waste-heat recovery heat pumps
V10 · 2–2.5 minLifting warm water from condensers, effluent and process cooling to useful heat
Video coming soon01Problem statement
- Ovens are a large electrical load. Coater ovens heat large volumes of fresh air to 100–120 °C with electric heaters, often the biggest single load in electrode making.
- Exhaust heat is cooled away. Hot, solvent-laden exhaust has to be cooled before NMP can condense, and that heat goes to chillers and cooling towers.
- Temperature uniformity matters. Uneven drying causes binder migration, cracking and poor adhesion, so oven zones must hold set point tightly.
- 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 coats cathode and anode foils for lithium-ion cells, about 0.5 GWh a year. Two roll-to-roll coaters with multi-zone ovens run round the clock, and NMP is recovered from the cathode oven exhaust by condensation.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Oven fresh-air heating | Air 35 → 100 °C | 4,000 m³/h × 1.1 kg/m³ × 1.005 kJ/kg·K × 65 K × 20 h | 1,597 |
| NMP evaporation from cathode coating | 100–110 °C | 1,500 kg NMP/day × 510 kJ/kg | 213 |
| Oven shell losses | 100–120 °C | 200 m² oven shell × 0.1 kW/m² × 20 h | 400 |
| Storage and pipework standing losses | – | about 5% | 110 |
| Total useful heat | 2,320 | ||
Averaged over 20 running hours, the heat pumps need about 116 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
- 5 × SE-WWUHT-27 (135 kW total) (SE-WWUHT water-source, R245fa) delivering 120 °C, covering the day's 2,320 kWh in about 17.2 running hours.
- A 4,500 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: oven exhaust heat-recovery loop at about 55 °C. Pre-cooling the exhaust before the NMP condenser cuts chiller load and improves solvent recovery.
- The electric air heaters in coater ovens stays connected behind a normally closed valve as standby.
- A water coil in the oven exhaust, ahead of the NMP condenser, recovers heat into a 55 °C loop that feeds the heat pump evaporator.
- The heat pump supplies pressurised water at up to 120 °C to fresh-air coils on both coater ovens.
- The existing electric heaters stay in each zone and trim the last few degrees and the hottest zones.
Selected equipment
| Model | SE-WWUHT-27 × 5 |
|---|---|
| Heating capacity | 27 kW each, 135 kW total |
| COP | 2.93 at the data sheet's rated condition (60/55 °C source water) |
| Power input | about 46.0 kW total at rated conditions |
| Rating | water or steam to 120 °C, R245fa |
| Supply temperature | 120 °C |
| Storage | 4,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the tank top starts the heat pump below 112 °C and stops it at 120 °C. TIC-201 and TIC-202 hold the fresh-air coil outlets at 100 °C. Zone controllers on the electric heaters trim each zone to its recipe temperature. The exhaust recovery coil has a bypass so NMP condenser conditions are never upset.
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 | – | – |
| Cost per MWh of cell capacity | – | – |
| CO₂ per year | – | – |
06Benefits
Lower oven power
Most of the fresh-air heating moves from resistance heaters to the heat pump.
Better NMP recovery
Pre-cooling the exhaust before the condenser reduces chiller load and helps solvent capture.
Stable drying
Preheated air at a steady temperature makes zone control easier and more uniform.
Lower energy cost
Each kWh of electricity delivers about 2.9 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 1/2.9 of the power of the heaters it replaces, which frees sanctioned load and cuts demand charges.
Built-in redundancy
Several machines share the load. If one is serviced, the others and the storage carry most of the day, with the existing heater in reserve.
07Engineering pointers
Site data to collect
- Coater speed, web width and coating weight
- Oven fresh-air and exhaust flows and temperatures
- NMP use and recovery rate
- Installed heater kW per zone
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
Design notes
- Solvent and LEL safety. The exhaust recovery coil sits in a solvent stream. Use stainless steel, keep it within the oven's LEL monitoring and avoid any ignition source.
- Pressurised water at 120 °C. Size pipework, expansion and safety valves for at least 4 bar and insulate all hot lines.
- Dry-room interface. Keep heat pump plant and water lines outside the dry room to avoid any moisture risk.
- Electrical. About 46 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Source stream. The source must give up roughly two-thirds of the heat delivered. Confirm its flow and temperature over a full production day, and filter it before the evaporator.
- 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.
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.