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Contenuto archiviato il 2022-12-27

COMBINED INDUSTRIAL AND SOLAR HEAT RECOVERY PROCESS: USE OF BIOMASS

Obiettivo

The possibility of using waste heat for agricultural purposes, particularly the heating of plastic-walled greenhouses, was studied in a seven-year combined project run by the Bouches-dur-Rhone Chamber of Agriculture and the Atomic Energy Commissariat. They went into the possibility of using waste heat from nuclear or conventional power stations and that of the independent production of heat using three alternative sources of energy-groundwater, solar energy and energy obtained from rotting vegetation.
The solar system yielded best results when 15 l/m2h were dripped from the perforated tubes. (m2 of collecting surface). The solar system works best during spring and autumn. From February onwards the use of compost heat complets the autonomous heating of the greenhouse. The frost protection throughout the year is possible but demands a large volume of biomass. The growth during December - mid February is limited and the economical result would be poor. In order to keep for example 224 m2 greenhouse frost protected from February to March two heaps of compost would be necessary with a total mass of 42 t, and a total required additional surface of 35 m2.
The energy saving is approx. 7 l fuel per m2 greenhouse and year. The frost protection as a combination of solar and biomass-heat is only possible in sunny regions of southern Europe. It was found that garbage gave better results than pressed raisin residues.
The double walled greenhouse with the dripping equipment was tested by the 'commissariat d'Europe Atomique' de Cadarache France, already in a previous project. The actual work, supported by the European Commission, is orientated to the use of solar energy and biomass for heating the water. These thermal processes enable farmers to use the double walled greenhouses on sites where no inductrial cooling water or enough ground water is available. The compost was envestigated with pressed raisins (marc de raisin) and rural garbage.
The solar system is formed by black dripping pipes mounted in the inside of the double walls. When the solar irradiation is high enough the dripping water is heated during the passage in the black piping and during dripping down the internal transparent plastic wall. The solar heated water is stored during daytime and used during the night to heat the greenhouse with the same process. An overheating in spring can be thus avoided.
For the 224 m2 greenhouse the compost heap was 7 m long and had a volume of 21 m3. In order to compare the two fermentation processes two identical heaps were investigated simultaneously, one with raisin pipes the other with garbage. The heat exchangers were of polyethylene piping with an internal diameter of 13 mm and a total length of some 240 m in 36 loops.
In order to keep the areobic fermentation process going the heat extraction was done every 2nd day only.

Argomento(i)

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Meccanismo di finanziamento

DEM - Demonstration contracts

Coordinatore

Commissariat à l'Energie Atomique (CEA)
Contributo UE
Nessun dato
Indirizzo
Centre d'Études de Cadarache Sere-Ders
13113 SAINT-PAUL-LEZ-DURANCE
Francia

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