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Greenhouse Chilled Water Cooling

Many greenhouses revert to ventilation and evaporative cooling to achieve the desired temperature. However, in warm and humid climates, it is not possible to cool down the greenhouse sufficiently with evaporative cooling. Other technology must be used, namely, active cooling. This cooling technology can be compared with air conditioning, but on a really big scale. It requires a chiller to provide the water and an air handling unit to cool and dehumidify the air.

Active cooling system in a greenhouse can be based on water cooling (this will provide chilled water with a minimal temperature of 4°C) or glycol solution (this solution can be cooled to temperatures far below 0°C!). The choice and the design will be based on the cooling demand and the energy costs.

Frank van Rooijen
Frank van Rooijen
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Advantages of Enerdes® Chilled Water Cooling Systems

In a closed-loop chilled water cooling system, the greenhouse air is continuously recirculated, and the cooling process is achieved through the circulation of chilled water within the system. The system typically consists of a chiller or cooling tower, a network of pipes or tubes to carry the chilled water, and heat exchange units placed within the greenhouse. Read more about the advantages below:

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Precise humidity and temperature control

Precise humidity control, along with temperature control offered by chilled water cooling, allows for a more comprehensive and precise greenhouse climate management. Greenhouse operators can fine-tune the conditions to meet the specific needs of different plant species or growth stages.

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Suitable for any outdoor climate

Greenhouses in regions with fluctuating weather patterns can benefit from the flexibility of chilled water cooling systems. The temperature of the chilled water can be adjusted based on the external climate, allowing for precise control over the greenhouse environment in response to changing weather conditions.

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Separate temperature and humidity zones

Different plants have varying temperature and humidity requirements for optimal growth. By dividing the greenhouse into separate zones, each with its own cooling system, greenhouse operators can create specific microclimates that cater to the needs of different crops. This ensures that each plant variety receives the ideal conditions to thrive, promoting better growth and yield.

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Minimal to no introduction of external air

By minimizing the introduction of external air, the system can avoid the need to heat or cool large volumes of fresh air from the outside. This reduces energy consumption, making the cooling process more efficient and cost-effective.

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How does a chiller work?

A chilled water cooling installation consists of a chiller and a piping network. Chilled water is transported throughout the greenhouse in a loop to provide cooling. The process during which water is used as the heat-transfer medium is called hydronics, in this case to provide cooling.

Using valves, the piping network can be divided into several groups, so the greenhouse can be segregated in several areas in which the temperature is controlled separately. Individual temperature zones are assigned in the greenhouse. The air handling units together with the chiller provide optimal greenhouse temperature and humidity conditions.

In the air handling unit, a fan draws warm and humid air past a heat exchanger with the chilled water, the cooling coils. The air is cooled and the moisture condenses. Cool and dry air is spread into the greenhouse. The temperature in the cooling coils is regulated with temperature sensors and valves and variable fan power influences the amount of air that is cooled. This allows precise climate control in the greenhouse.

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