Rubber sheets dried cleanly in days
How a rubber processing unit drying 2,800 kg of wet sheet and crepe a day can replace a firewood smokehouse with closed-loop heat pump drying.
▶Video: Heat pump dryers for food and agri products
V08 · 2–2.5 minClosed-loop drying of spices, fruit, fish, grain and more
Video coming soon01Problem statement
- Slow and uneven smokehouse drying. Sheets near the firebox overheat and blister while sheets at the top stay damp, so a full charge takes 5 to 7 days and grading suffers.
- Smoke and soot on the product. Wood smoke darkens the sheet and leaves soot spots, which pushes rubber into a lower grade and a lower price.
- Wet season shortfalls. In the monsoon, firewood is damp and scarce and ambient air is saturated, so drying time stretches just when latex volumes are highest.
- Losses between fuel and process. Burning briquettes in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference unit collects field latex from smallholders and makes ribbed sheet and crepe rubber. It dries about 2,000 kg of wet sheet and 800 kg of wet crepe a day in batch chambers, with sheets hung on racks for several days.
| Product | Drying | Basis | Water removed, kg/day | Conventional heat, kWh/day |
|---|---|---|---|---|
| Ribbed sheet drying | Air 55–60 °C | 2,000 kg wet sheet/day, 35% → 1% moisture | 687 | 1,236 |
| Crepe rubber drying | Air 50–55 °C | 800 kg wet crepe/day, 30% → 1% moisture | 234 | 422 |
| Total | 921 | 1,658 | ||
Conventional hot-air dryers use about 1.8 kWh of heat per kg of water removed. That figure is the baseline the savings are measured against.
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
- 1 × SE-AA-DR-42 (42 kW) heat pump drying module, removing about 921 kg of water a day in roughly 19 running hours.
- The firewood and briquette smokehouse stays connected behind a normally closed valve as standby.
- The existing smokehouse chambers are sealed and fitted with racks, air ducts and a closed air loop through the heat pump dryer.
- Moisture is removed as condensate at the evaporator, so the chamber stays dry even when outside air is humid.
- Air temperature is held at 55–60 °C with a lower setting for crepe, which avoids tackiness and surface blisters.
Selected equipment
| Model | 1 × SE-AA-DR-42 |
|---|---|
| Heating capacity | 42 kW each, 42 kW total |
| Dehumidifying | about 49 L/h total (pro rata to the published 12–120 L/h range) |
| Drying air | rated 70 °C, 75 °C maximum |
| Refrigerant | R134a |
| Ambient | −5 to 43 °C |
| Water removed per kWh | about 2.4 kg |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TIC-201 holds chamber air at the set temperature and the dryer modulates its compressor to match. A humidity sensor in DC-201 lowers the fan speed as the sheet dries and ends the cycle when the moisture set-point is reached. The old smokehouse firebox is kept as standby for peak latex weeks.
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 tonne of dry rubber | – | – |
| CO₂ per year | – | – |
06Benefits
Cleaner, lighter sheet
No smoke or soot reaches the rubber, so colour stays even and grading improves.
Shorter drying cycle
Dehumidified air at a steady temperature typically cuts drying from about a week to 2 to 3 days.
Steady in the monsoon
The closed air loop does not depend on outside humidity or dry firewood.
Heat recovered from the moisture
The evaporator condenses water out of the air and the condenser puts that latent heat back into the drying air, so about 2.4 kg of water leaves per kWh of electricity.
Closed loop, clean product
Air recirculates inside the chamber. No dust, smoke or outside humidity reaches the product, whatever the weather.
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
- Wet sheet and crepe quantity per day in peak season
- Sheet thickness and present drying time
- Chamber dimensions and rack layout
- Present firewood or briquette use per week
- Target moisture and grade
- 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
- Mould prevention. Unsmoked sheet loses the preserving effect of smoke. Keep sheets well spaced, dry them without stopping, and ask the buyer whether an approved surface treatment is needed.
- Condensate handling. Condensate carries traces of serum and acid. Drain it to the effluent pit.
- Air distribution. Sheet racks block airflow. Design the ducting for even velocity across every rack so the top and bottom tiers dry together.
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
Rubber sheets dried cleanly in days
How a rubber processing unit drying 2,800 kg of wet sheet and crepe a day can replace a firewood smokehouse with closed-loop heat pump drying.
▶Video: Heat pump dryers for food and agri products
V08 · 2–2.5 minClosed-loop drying of spices, fruit, fish, grain and more
Video coming soon01Problem statement
- Slow and uneven smokehouse drying. Sheets near the firebox overheat and blister while sheets at the top stay damp, so a full charge takes 5 to 7 days and grading suffers.
- Smoke and soot on the product. Wood smoke darkens the sheet and leaves soot spots, which pushes rubber into a lower grade and a lower price.
- Wet season shortfalls. In the monsoon, firewood is damp and scarce and ambient air is saturated, so drying time stretches just when latex volumes are highest.
- Losses between fuel and process. Burning briquettes in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference unit collects field latex from smallholders and makes ribbed sheet and crepe rubber. It dries about 2,000 kg of wet sheet and 800 kg of wet crepe a day in batch chambers, with sheets hung on racks for several days.
| Product | Drying | Basis | Water removed, kg/day | Conventional heat, kWh/day |
|---|---|---|---|---|
| Ribbed sheet drying | Air 55–60 °C | 2,000 kg wet sheet/day, 35% → 1% moisture | 687 | 1,236 |
| Crepe rubber drying | Air 50–55 °C | 800 kg wet crepe/day, 30% → 1% moisture | 234 | 422 |
| Total | 921 | 1,658 | ||
Conventional hot-air dryers use about 1.8 kWh of heat per kg of water removed. That figure is the baseline the savings are measured against.
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
- 1 × SE-AA-DR-42 (42 kW) heat pump drying module, removing about 921 kg of water a day in roughly 19 running hours.
- The firewood and briquette smokehouse stays connected behind a normally closed valve as standby.
- The existing smokehouse chambers are sealed and fitted with racks, air ducts and a closed air loop through the heat pump dryer.
- Moisture is removed as condensate at the evaporator, so the chamber stays dry even when outside air is humid.
- Air temperature is held at 55–60 °C with a lower setting for crepe, which avoids tackiness and surface blisters.
Selected equipment
| Model | 1 × SE-AA-DR-42 |
|---|---|
| Heating capacity | 42 kW each, 42 kW total |
| Dehumidifying | about 49 L/h total (pro rata to the published 12–120 L/h range) |
| Drying air | rated 70 °C, 75 °C maximum |
| Refrigerant | R134a |
| Ambient | −5 to 43 °C |
| Water removed per kWh | about 2.4 kg |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TIC-201 holds chamber air at the set temperature and the dryer modulates its compressor to match. A humidity sensor in DC-201 lowers the fan speed as the sheet dries and ends the cycle when the moisture set-point is reached. The old smokehouse firebox is kept as standby for peak latex weeks.
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 tonne of dry rubber | – | – |
| CO₂ per year | – | – |
06Benefits
Cleaner, lighter sheet
No smoke or soot reaches the rubber, so colour stays even and grading improves.
Shorter drying cycle
Dehumidified air at a steady temperature typically cuts drying from about a week to 2 to 3 days.
Steady in the monsoon
The closed air loop does not depend on outside humidity or dry firewood.
Heat recovered from the moisture
The evaporator condenses water out of the air and the condenser puts that latent heat back into the drying air, so about 2.4 kg of water leaves per kWh of electricity.
Closed loop, clean product
Air recirculates inside the chamber. No dust, smoke or outside humidity reaches the product, whatever the weather.
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
- Wet sheet and crepe quantity per day in peak season
- Sheet thickness and present drying time
- Chamber dimensions and rack layout
- Present firewood or briquette use per week
- Target moisture and grade
- 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
- Mould prevention. Unsmoked sheet loses the preserving effect of smoke. Keep sheets well spaced, dry them without stopping, and ask the buyer whether an approved surface treatment is needed.
- Condensate handling. Condensate carries traces of serum and acid. Drain it to the effluent pit.
- Air distribution. Sheet racks block airflow. Design the ducting for even velocity across every rack so the top and bottom tiers dry together.
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.