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Kelvion Heat Exchange Solutions

RETHINK
THERMAL EFFICIENCY

Solutions

RETHINK SOLUTIONS

Varying extreme conditions require different solutions, from cold to very hot climates, all over the world. Factors such as the maximum temperature required for the given process, and the availability of water will influence which free cooling system to choose. Typical heat rejection systems include dry coolers, adiabatic coolers, hybrid coolers and cooling towers.

Effective ambient temperature

The performance of a heat exchanger is proportional to the temperature difference between the process medium and the heat transfer medium flowing through it.

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OPTIMIZING FREE COOLING POTENTIAL AND IMPROVING EFFICIENCY BY REUSING WASTE HEAT

There is no one fits all solution. In this paper we’ll have a closer look on the different technologies, climate trends and heat recovery cases to encourage you to rethink thermal efficiency 

READ MORE and DOWNLOAD OUR TECH-PAPER

DRY COOLER

The performance of this technology is highly dependent on the difference in temperature between the process water mixture and the ambient air flowing through the exchanger.

Dry coolers transfer energy by heating the ambient air and thus they require a large air flow volume.
This means that a dry cooler’s 
performance is directly governed by the dry bulb temperature of the atmosphere.

Ambient Temperature

Water Availability

Energy Consumption

Water Consumption

ADIABATIC SYSTEM

One way of optimising a dry cooler is to use an adiabatic cooler with a spray or pad system. The adiabatic system reduces the temperature of the air within the exchanger by evaporating water into the ambient air to increase its humidity.

This is effective due to the fact that, as you increase the humidity, you also reduce its dry bulb temperature.

Adiabatic dry coolers are able to offset high ambient temperatures throughout the year, increasing the free cooling potential of a site.

ADIABATIC
SPRAY SYSTEM

Ambient Temperature

Water Availability

Energy Consumption

Water Consumption

ADIABATIC
PAD SYSTEM

Ambient Temperature

Water Availability

Energy Consumption

Water Consumption

HYBRID COOLER

Another solution to enhance your free cooling potential in very hot regions is a hybrid system.

The hybrid cooler offers 2 different cooling modes. A dry mode where heat is exchanged with ambient air via its sensible enthalpy. In wet mode the system is watering the coil and uses the water sensible enthalpy as well as its latent enthalpy, via an adiabatic effect where air is evaporating the water.

This allows the system to work with ambient dry bulb temperature well above process fluid outlet temperature.

Ambient Temperature

Water Availability

Energy Consumption

Water Consumption

CLIMATE IS KEY

Ambient temperature is not the only metric to be considered. The effficiency of heat exchanger is also highly influenced by the difference between process temperature out and ambient temperature.

Assuming the below temperatures and a process temperature of 35°C we can see the following:

COLD CLIMATE

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You will have a difference of 35°-25° = 10K

As the temperature difference between process temperature and ambient temperature is high enough, a dry cooler could be the right choice here. In case of  extreme low ambient conditions measures like shutters could maintain uptime operation 

HOT CLIMATE

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You will have a difference of 35°-33° = 2K

This difference is too low to allow efficient heat rejection. Adiabatic systems can reduce the air inlet temperature up to 8-10 K 

VERY HOT CLIMATE

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You will have a difference of 35°-38° = -3K

The difference is negative and needs to be increased with an appropriate system like an hybrid cooler. 

You could achieve the requested capacity even with an ambient temperature higher then you process out temperature because you are using wet cooling.

This can reduce the air inlet temperature up to 12 K 

This is something that Dry Coolers could never achieve in any case, and that adiabatic would struggle to do and could even be impossible to achieve (because no wet cooling, and no 100% humidification of air).

A Cooling Tower could manage these high ambient temperatures as well but at the expense of higher water consumption and higher normative requirements.

EXPLORE SOME CLIMATE CASES

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Climate Cases

FRANKFURT

To achieve a capacity of 2000 kW:
[based on water in: 40°C / water out: 35°]

 

  • In this region, a Dry Cooler will need assistance only 5% of the time.
     

  • A Hybrid Cooler could meet the required capacity the whole year long while taking 50% less footprint than an Adiabatic Pad system and significantly less water than a cooling tower.

Annual Temperature Distribution

4-15°C

39°C

-9°C

Mean Temperature

Relative
Humidity

Majority

Hours

Maximum Temperature

Minimum Temperature

Temperature [°C]

Hours per year

Free Cooling

Footprint

Electric Consumption

Water Consumption

DRY COOLER

100%

95%

-

ADIABATIC

112%

100%

HYBRID

72%

100%

COOLING TOWER

49%

100%

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Initial Unit Cost

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Frankfurt

BEIJING

To achieve a capacity of 2000 kW:
[based on water in: 40°C / water out: 35°]

  • In this region, a Dry Cooler is not appropriated, and only adiabatic or wet cooling solutions are suitable.
     

  • A Hybrid Cooler take less footprint than the 2 other Adiabatic solutions while being effective 100% time of the year. 

Annual Temperature Distribution

-2-28°C

40°C

-14°C

Mean Temperature

Relative
Humidity

Majority

Hours

Maximum Temperature

Minimum Temperature

Temperature [°C]

Hours per year

Free Cooling

Footprint

Electric Consumption

Water Consumption

DRY COOLER

100%

97%

-

ADIABATIC

112%

99%

HYBRID

39%

100%

COOLING TOWER

18%

100%

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Initial Unit Cost

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Beijing

HOUSTON

To achieve a capacity of 2000 kW:

[based on water in: 40°C / water out: 35°]

 

  • Due to high ambient, Dry Coolers could only meet the demand w/o assistance 61% of the year.
     

  • While a Hybrid Cooler could achieve the capacity the whole year long while consuming less electrical power and footprint compared to an Adiabatic Pad system and significantly less water than a Cooling Tower.

Annual Temperature Distribution

19-29°C

41°C

-2°C

Mean Temperature

Relative
Humidity

Majority

Hours

Maximum Temperature

Minimum Temperature

Temperature [°C]

Hours per year

Free Cooling

Footprint

Electric Consumption

Water Consumption

DRY COOLER

100%

61%

-

ADIABATIC

112%

91%

HYBRID

72%

100%

COOLING TOWER

37%

100%

DryCooler_Product.png

Initial Unit Cost

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CoolingTower_Product.png
Houston

DUBAI

To achieve a capacity of 2000 kW:

[based on water in: 40°C / water out: 35°]

 

  • In this region, a Dry Cooler is not appropriated, and only adiabatic or wet cooling solutions are suitable.
     

  • 2 Adiabatic Pad systems are required whereas only 1 Hybrid Cooler is needed with less water consumption than a cooling tower, which is also crucial in this area. 

Annual Temperature Distribution

21-33°C

46°C

11°C

Mean Temperature

Relative
Humidity

Majority

Hours

Maximum Temperature

Temperature [°C]

Hours per year

Minimum Temperature

Free Cooling

Footprint

Electric Consumption

Water Consumption

DRY COOLER

-

-

-

-

ADIABATIC

100%

97%

HYBRID

48%

100%