Smart Greenhouse Uses Liquid Crystal
Liquid crystal technology is being used in a greenhouse project launched jointly by Cleveland Botanical Garden and by Kent State University’s Liquid Crystal Institute in Ohio. The idea is to use the liquid crystal panels to manage the amount of sunlight that enters the greenhouse. Two greenhouses were recently unveiled — a control with plain glass and another with liquid crystal panels.
The panels have liquid crystals dispersed as droplets in a polymer resin sandwiched between two pieces of glass. Each panel is wired to allow an extremely low current to pass through the liquid crystal matrix. When powered off, the particles are randomly oriented. When light passes through, a fog is created because the light is randomly reflected and scattered. When the panel is powered on, the liquid crystal molecules line up in parallel, allowing light to pass through a transparent window. Varying the voltage varies the transparency of the panels.
An experimental greenhouse at the Cleveland Botanical Garden has liquid crystal panels to control heat and light.
Researchers are installing monitoring equipment inside both greenhouses to measure the light and the heat coming through, along with the total energy consumption. According to lead researcher John West of Kent State, they hope to see significant reductions in the heating and cooling costs.
The next step is to develop liquid crystal greenhouse glazing that can control the wavelength of light as well as the intensity. For example, wavelengths that fuel photosynthesis would be allowed, while IR wavelengths could be shaded to prevent heat buildup. In the summer, this could be used to keep heat from entering; in the winter, shading could prevent heat from escaping.
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