Fish and prawns dried hygienically in a closed loop
How a seafood drying unit handling 1.9 tonnes of fresh fish and prawn a day can dry it in a closed-loop heat pump dryer, and what it saves against electric heater dryers.
▶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
- Sun drying is unhygienic. Open-yard drying exposes fish to flies, dust and birds, and fails export and modern retail hygiene checks.
- Hot air hardens the surface. Drying above 55 °C forms a hard outer skin that traps moisture inside and leads to spoilage in storage.
- Monsoon stops production. Humid weather makes sun drying impossible just when catch prices are low.
- 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 unit is near a fishing harbour and dries anchovy, ribbonfish and Bombay duck, plus small prawns for dried shrimp, about 1.9 tonnes of fresh catch a day. Product is salted, washed and loaded onto racks in a single morning shift.
| Product | Drying | Basis | Water removed, kg/day | Conventional heat, kWh/day |
|---|---|---|---|---|
| Fish (anchovy, ribbonfish, Bombay duck) | Air 40–50 °C | 1,500 kg/day salted fish, 78% → 16% | 1,107 | 1,993 |
| Prawns for dried shrimp | Air 45–50 °C | 400 kg/day boiled prawn, 80% → 18% | 302 | 544 |
| Total | 1,410 | 2,537 | ||
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
- 3 × SE-AA-DR-21 (63 kW total) heat pump drying modules, removing about 1,410 kg of water a day in roughly 19 running hours.
- The electric heater cabinet dryer stays connected behind a normally closed valve as standby.
- A closed-loop heat pump dryer holds air at 40–50 °C and low humidity, drying fish evenly from the inside out.
- The chamber is sealed, so odour stays inside and the product is protected from flies and dust.
- Racks from the existing yard or cabinet dryers can be reused.
Selected equipment
| Model | 3 × SE-AA-DR-21 |
|---|---|
| Heating capacity | 21 kW each, 63 kW total |
| Dehumidifying | about 74 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 drying air at 40 °C at the start to avoid case hardening, then raises it towards 50 °C as moisture falls. A return-air humidity sensor sets the dehumidifying duty. The batch ends on a target return-air humidity or set time.
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 fresh fish | – | – |
| CO₂ per year | – | – |
06Benefits
Hygienic product
Sealed drying keeps flies, dust and birds off the fish, which opens up better markets.
No case hardening
Low, stepped air temperatures dry fish evenly and improve shelf life.
Year-round drying
Production continues in the monsoon when fish are cheapest.
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.
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
- Species dried and daily quantities
- Salting practice and moisture in
- Target moisture out and market
- Present drying method and time
- 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
- Salt corrosion. Salted fish gives off salty, moist air. Use epoxy-coated coils, stainless racks and a corrosion-resistant chamber lining.
- Odour and condensate. Condensate carries fish odour and salt. Drain it to the effluent system, not to open ground.
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
Fish and prawns dried hygienically in a closed loop
How a seafood drying unit handling 1.9 tonnes of fresh fish and prawn a day can dry it in a closed-loop heat pump dryer, and what it saves against electric heater dryers.
▶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
- Sun drying is unhygienic. Open-yard drying exposes fish to flies, dust and birds, and fails export and modern retail hygiene checks.
- Hot air hardens the surface. Drying above 55 °C forms a hard outer skin that traps moisture inside and leads to spoilage in storage.
- Monsoon stops production. Humid weather makes sun drying impossible just when catch prices are low.
- 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 unit is near a fishing harbour and dries anchovy, ribbonfish and Bombay duck, plus small prawns for dried shrimp, about 1.9 tonnes of fresh catch a day. Product is salted, washed and loaded onto racks in a single morning shift.
| Product | Drying | Basis | Water removed, kg/day | Conventional heat, kWh/day |
|---|---|---|---|---|
| Fish (anchovy, ribbonfish, Bombay duck) | Air 40–50 °C | 1,500 kg/day salted fish, 78% → 16% | 1,107 | 1,993 |
| Prawns for dried shrimp | Air 45–50 °C | 400 kg/day boiled prawn, 80% → 18% | 302 | 544 |
| Total | 1,410 | 2,537 | ||
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
- 3 × SE-AA-DR-21 (63 kW total) heat pump drying modules, removing about 1,410 kg of water a day in roughly 19 running hours.
- The electric heater cabinet dryer stays connected behind a normally closed valve as standby.
- A closed-loop heat pump dryer holds air at 40–50 °C and low humidity, drying fish evenly from the inside out.
- The chamber is sealed, so odour stays inside and the product is protected from flies and dust.
- Racks from the existing yard or cabinet dryers can be reused.
Selected equipment
| Model | 3 × SE-AA-DR-21 |
|---|---|
| Heating capacity | 21 kW each, 63 kW total |
| Dehumidifying | about 74 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 drying air at 40 °C at the start to avoid case hardening, then raises it towards 50 °C as moisture falls. A return-air humidity sensor sets the dehumidifying duty. The batch ends on a target return-air humidity or set time.
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 fresh fish | – | – |
| CO₂ per year | – | – |
06Benefits
Hygienic product
Sealed drying keeps flies, dust and birds off the fish, which opens up better markets.
No case hardening
Low, stepped air temperatures dry fish evenly and improve shelf life.
Year-round drying
Production continues in the monsoon when fish are cheapest.
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.
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
- Species dried and daily quantities
- Salting practice and moisture in
- Target moisture out and market
- Present drying method and time
- 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
- Salt corrosion. Salted fish gives off salty, moist air. Use epoxy-coated coils, stainless racks and a corrosion-resistant chamber lining.
- Odour and condensate. Condensate carries fish odour and salt. Drain it to the effluent system, not to open ground.
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.