Articles
SOME RESULTS FROM THE HEATING OF GREENHOUSE WITH POWER STATION CONDENSER COOLING WATER
A brief description is given of the preliminary work prior to construction, the layout of the scheme, the types of heating systems employed and the main design features.
To date, three crop trials have been conducted; late planted tomatoes followed by over-winter lettuce and finally, early planted tomatoes.
The latter trial is still in progress.
During the first partial season’s trial, the two greenhouses with direct contact (evaporative) heat exchangers suffered reductions in the market return from the tomato crop due to the depressed yield and quality of the fruit compared with the other greenhouse which was heated by relatively conventional fan assisted fin-tube convector units Further disadvantages of heat exchange by direct contact were apparent when the greenhouse heating systems were tested.
In comparison to the greenhouse with the fan assisted fin-tube units, a considerable increase in the value of the surface heat loss coefficient was identified.
For the second (1977) tomato crop trial, heating by direct contact exchange was retained in only one of the three greenhouses.
Its incompatibility with the production of early crops in a protected environment under U.K. conditions was confirmed at an early stage.
The yield from the other (dry) greenhouses, although not as high as that expected from the best commercially heated crops grown over a similar period is sufficiently encouraging for the trials to be continued for at least a further year.