Tuesday, August 7, 2012

Greenhouse Temperature Control Using Phase Change Materials

Passive heating and cooling in greenhouse using PCM 22P.

The green color represents the inside temperatures of the Sycamore greenhouse at AB-Tech.  The red color represents the temperatures outside of the greenhouse.  The left side of the graph exhibits temperatures inside and out of the greenhouse before the PCM installation. From the end of January to mid-April, 2012, when its hot outside, its even hotter inside the greenhouse.  There is little visible red.

PCM 22P was installed at the end of April.  The graph on the right illustrates how phase change materials passively control temperature inside the greenhouse.   Pretty impressive results considering that temperatures from January to April are cooler than in mid-summer.  Without the PCM installation, greenhouse temperatures would've been much hotter during the summer months.  The fact that temperatures inside the greenhouse are consistently 15-20 degrees lower with the PCM than without it, is significant and exciting.

The phase change material in the greenhouse eliminates temperature extremes that would normally occur with our changing seasons, not to mention it retains optimal temperatures for plant growth.