Heat transfer model for a micro-hydroponic greenhouse chamber

Surface cooling was investigated as an alternative to air conditioning for controlling the temperature inside prototype laboratory vessels used to acclimatize plants in a greenhouse in South Carolina. Conventional air conditioning circulates large volumes of air though a heat exchanger, but this is impractical for cooling the inside of sealed aseptic plant tissue culture vessels. The purpose of this research was to answer the question: Can a water jacket around a growth chamber cool sealed culture vessels adequately in a hot greenhouse under the summer sun? Influences on temperature control inside sealed polypropylene vessel prototypes were studied by extending vessel height and by varying vertical placement of solar collectors inside prototype vessels.; The general conclusion was that the surface cooling of chilled Acclimatron(TM) panels could limit heating in sealed tissue culture vessels by convection and radiation heat transfer, even in hot greenhouses. Natural convection compensated for extended air gaps over collectors in direct proportion to the difference in surface temperatures, but the effectiveness of thermal radiation increased exponentially with the difference between exchanging surface temperatures. As a result, radiation became the dominant heat transfer mechanism as greenhouse conditions approached maximum summer heat.