Cold-store condenser heat turned into process hot water
How a frozen foods plant with a 3,000 tonne cold store can make its 60–75 °C process hot water from refrigeration condenser heat, and what it saves against a diesel boiler.
▶Video: Heating and cooling from one machine
V11 · 2–2.5 minWater-source heat pumps that chill and heat at the same time
Video coming soon01Problem statement
- Two utilities working against each other. The ammonia plant rejects hundreds of kilowatts to the cooling tower day and night, while a diesel generator heats water for the same site.
- Cooling tower water and chemical use. All condenser heat leaves through the cooling tower, which costs make-up water, blowdown and treatment chemicals.
- Peaky hot-water demand. CIP and blancher start-up draw large volumes in short bursts, so the hot-water generator is sized for the peak and runs at poor part load.
- Losses between fuel and process. Burning diesel 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 plant blanches and freezes vegetables and makes ice cream, about 25 tonnes of product a day over two shifts. It runs a 3,000 tonne frozen store with an ammonia plant of about 600 kW that operates around the clock. Hot water is used for CIP, crate washing and blancher make-up.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Blancher make-up water preheat | 70 °C | 10,000 L/day, 28 → 70 °C | 488 |
| CIP for ice-cream mix plant | 75 °C | 2 cycles × 3,000 L, 30 → 75 °C | 314 |
| Crate and tray washing | 60 °C | 8,000 L/day, 30 → 60 °C | 279 |
| Storage and pipework standing losses | – | about 5% | 54 |
| Total useful heat | 1,134 | ||
Averaged over 20 running hours, the heat pumps need about 57 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 Customized water-source cascade machine of about 60 kW, two-stage water-source machine built to duty, lifting 32 °C to 80 °C.
- A 2,000 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: cold-store condenser cooling water at about 32 °C. Lowering the condenser water temperature reduces the ammonia compressors' head pressure and the cooling tower load.
- The diesel-fired hot-water generator stays connected behind a normally closed valve as standby.
- The heat pumps take heat from the ammonia condenser water return at about 32 °C before it reaches the cooling tower.
- Hot water at 80 °C is stored in an insulated tank sized to cover a full CIP cycle and blancher start-up.
- Because the cold store runs 24 hours, the source is always available and the heat pumps can run long, steady hours.
Selected equipment
| Machine | Customized water-source cascade |
|---|---|
| Capacity | about 60 kW, built to duty |
| Concept | two-stage water-source machine built to duty, lifting 32 °C to 80 °C |
| COP used | 2.7 (estimate) |
| Supply temperature | 80 °C |
| Storage | 2,000 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 calls the heat pumps on below 75 °C and off at 80 °C. TT-102 at the bottom gives an early start before CIP. TIC-201, TIC-202 and TIC-203 hold each user at its own temperature. The diesel generator stays as standby if the tank top falls below 70 °C.
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 product | – | – |
| CO₂ per year | – | – |
06Benefits
Heat that is already paid for
The refrigeration plant already rejects this heat. The heat pumps only add the lift from 32 °C to 80 °C.
Lower condensing pressure
Taking heat out of the condenser water helps the ammonia plant run at lower head pressure in summer.
Less cooling tower water
Every kilowatt recovered is a kilowatt the cooling tower no longer evaporates.
Lower energy cost
Each kWh of electricity delivers about 2.7 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
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
- Refrigeration capacity and condenser water flow and temperatures
- Running hours of the ammonia plant across seasons
- CIP schedule and tank volumes
- Blancher make-up and crate wash volumes
- 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
- Ammonia safety. The heat pumps connect only to the condenser cooling water, never to the ammonia circuit, so no change to the refrigeration plant's safety case is needed.
- Cooling tower water. Condenser water is often hard and dosed. Use a plate exchanger between the tower loop and the heat pumps, with a strainer and a cleaning connection.
- 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.
- 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.
Talk to us
Cold-store condenser heat turned into process hot water
How a frozen foods plant with a 3,000 tonne cold store can make its 60–75 °C process hot water from refrigeration condenser heat, and what it saves against a diesel boiler.
▶Video: Heating and cooling from one machine
V11 · 2–2.5 minWater-source heat pumps that chill and heat at the same time
Video coming soon01Problem statement
- Two utilities working against each other. The ammonia plant rejects hundreds of kilowatts to the cooling tower day and night, while a diesel generator heats water for the same site.
- Cooling tower water and chemical use. All condenser heat leaves through the cooling tower, which costs make-up water, blowdown and treatment chemicals.
- Peaky hot-water demand. CIP and blancher start-up draw large volumes in short bursts, so the hot-water generator is sized for the peak and runs at poor part load.
- Losses between fuel and process. Burning diesel 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 plant blanches and freezes vegetables and makes ice cream, about 25 tonnes of product a day over two shifts. It runs a 3,000 tonne frozen store with an ammonia plant of about 600 kW that operates around the clock. Hot water is used for CIP, crate washing and blancher make-up.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Blancher make-up water preheat | 70 °C | 10,000 L/day, 28 → 70 °C | 488 |
| CIP for ice-cream mix plant | 75 °C | 2 cycles × 3,000 L, 30 → 75 °C | 314 |
| Crate and tray washing | 60 °C | 8,000 L/day, 30 → 60 °C | 279 |
| Storage and pipework standing losses | – | about 5% | 54 |
| Total useful heat | 1,134 | ||
Averaged over 20 running hours, the heat pumps need about 57 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 Customized water-source cascade machine of about 60 kW, two-stage water-source machine built to duty, lifting 32 °C to 80 °C.
- A 2,000 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: cold-store condenser cooling water at about 32 °C. Lowering the condenser water temperature reduces the ammonia compressors' head pressure and the cooling tower load.
- The diesel-fired hot-water generator stays connected behind a normally closed valve as standby.
- The heat pumps take heat from the ammonia condenser water return at about 32 °C before it reaches the cooling tower.
- Hot water at 80 °C is stored in an insulated tank sized to cover a full CIP cycle and blancher start-up.
- Because the cold store runs 24 hours, the source is always available and the heat pumps can run long, steady hours.
Selected equipment
| Machine | Customized water-source cascade |
|---|---|
| Capacity | about 60 kW, built to duty |
| Concept | two-stage water-source machine built to duty, lifting 32 °C to 80 °C |
| COP used | 2.7 (estimate) |
| Supply temperature | 80 °C |
| Storage | 2,000 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 calls the heat pumps on below 75 °C and off at 80 °C. TT-102 at the bottom gives an early start before CIP. TIC-201, TIC-202 and TIC-203 hold each user at its own temperature. The diesel generator stays as standby if the tank top falls below 70 °C.
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 product | – | – |
| CO₂ per year | – | – |
06Benefits
Heat that is already paid for
The refrigeration plant already rejects this heat. The heat pumps only add the lift from 32 °C to 80 °C.
Lower condensing pressure
Taking heat out of the condenser water helps the ammonia plant run at lower head pressure in summer.
Less cooling tower water
Every kilowatt recovered is a kilowatt the cooling tower no longer evaporates.
Lower energy cost
Each kWh of electricity delivers about 2.7 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
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
- Refrigeration capacity and condenser water flow and temperatures
- Running hours of the ammonia plant across seasons
- CIP schedule and tank volumes
- Blancher make-up and crate wash volumes
- 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
- Ammonia safety. The heat pumps connect only to the condenser cooling water, never to the ammonia circuit, so no change to the refrigeration plant's safety case is needed.
- Cooling tower water. Condenser water is often hard and dosed. Use a plate exchanger between the tower loop and the heat pumps, with a strainer and a cleaning connection.
- 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.
- 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.