Prototype device for fluid flow management in coaxial pipes of root zone heating systems
Burchi, G.; Cacini, S.; Fedrizzi, M.
International Symposium on Advanced technologies and management towards sustainable greenhouse ecosystems “GreenSys 2011” 05-10 June 2011, Halkidiki, (Greece)
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The soil or the soil-less substrates for horticultural greenhouse cultivations need to be heated during the winter. Usually the ground is heated by means of an hydraulic system associated with a boiler.
A prototype of an innovative hydraulic system, consisting of coaxial pipes, was designed and tested in 2008 and 2009 with the aim to reduce energy consumption and to obtain a higher temperature uniformity along the baseline in the substrate, compared with a traditional root zone heating system. The innovative system showed very interesting results during the winter season, but during the early spring and autumn tests, when the greenhouse was heated only during the night, the system resulted slow in reaching the set temperatures and consumed more energy.
This suggested the design and test of a prototype for the management of hydraulic fluid flows in the coaxial pipes of the innovative root zone heating baseline. The preliminary trials were carried out in march-april 2010 under the Italian Research Project “F.LO.R.ENER.”
In relation to the external environmental conditions and to the requirements of the new heating system, the device allowed the management of the flow of fluid streams in the coaxial tubes from a countercurrent flow system to a concurrent flow. This feature allowed better operating conditions for the innovative heating system, i.e. higher heating uniformity and energy saving, also in spring.
The tests showed the positive features of the prototype that, in comparison to the conventional root zone heating baseline, led to a better temperature homogeneity in the crop substrate and showed a mean 28% reduction of energy consumption.
Further trials will be conducted for longer periods during the next autumn and spring 2010-2011.