Use Chilled Water for Precise Greenhouse Cooling & Control
Many researchers and institutions are turning to chilled water cooling systems in greenhouses because they offer more precision in cooling and control. With research considerations in mind and where efficiency and precision are paramount, the ultimate goal is to tightly control the environment. Given their efficiency advantages, chilled water systems are more commonly found in large, institutional installations than in commercial greenhouses.
How Greenhouse Cooling Works
Hydronics is the use of water as the heat-transfer medium in heating and cooling systems. Historically, in large-scale commercial and institutional buildings, a hydronic system may include both a chilled and a heated water loop, to provide for both heating and air conditioning. Chillers and cooling towers may be used separately or together as means to provide water cooling, while boilers heat water.
Chilled water cooling is a hydronic process by which chilled water is circulated through a loop piping system. Circulator pumps force the water through a heat exchanger, where a fan draws warm air out and cools it as it passes over cold coils. A system may be broken up into individual temperature zones using either multiple circulator pumps or a single pump and electrically operated zone valves.
Like a radiant heating system, chilled water cooling is controlled and regulated by the operation‘s environmental controls, allowing scientists to precisely control the temperature of their plants and the greenhouse climate. Direct digital controls not only provide precise environmental control, but also allow for energy and cost savings.
Precise Greenhouse Cooling Alternative
Most commercial greenhouses use evaporative cooling, which can cool air to about 10 to 20 degrees below the outside temperature. Evaporative cooling systems lower air temperature using mists, sprays, or wetted pads. Introducing water into ventilation air increases relative humidity while lowering the air temperature. The typical evaporative pad cooling system draws outside air into the building through wet vertical pads. As air flows past the moist pad surfaces, some of the moisture evaporates into the air stream. Heat is withdrawn from the air during this process and the air leaves the pad at a lower temperature with higher moisture content.
Chilled water cooling systems are equally efficient. One type of chilled water cooling system consists of the passage of warm air across cold coils. The air is then dehumidified for office or residential applications.
The difference between this type of system and the system Delta T Solutions offers is that our process does not dehumidify the air as it is cooled. In the institutional greenhouse setting, the air is cooled to a temperature at or around dew point to avoid condensation of the air.
Customized Greenhouse Cooling Solutions
Chilled water cooling provides precise control to research institutions at an expense that is not easily justified for commercial grower. The system was not designed economically for commercial growers, but may appear in some commercial settings where very tightly controlled temperature ranges are a high priority.
Chilled Water System Considerations for Greenhouses
Consider these factors when selecting chilled water cooling systems:
- Installed cost
- Energy consumption
- Space requirements
- Freeze prevention
- Building height, size, shape
- System cooling and heating capacity
- Centralized maintenance
- Stability of control
To date, Delta T Solutions has installed several chilled water cooling systems, and we currently have more projects on the drawing board. To learn more, contact us at 800-552-5058, or email: firstname.lastname@example.org