ISHS Acta Horticulturae 456: II Modelling Plant Growth, Environmental Control and Farm Management in Protected Cultivation
ESTABLISHMENT AND VALIDATION OF A MODEL TO ESTIMATE ENERGY CONSUMPTION OF LOCALIZED HEATING OF GREENHOUSE SUBSTRATES |
| Authors: | R.M. Benavente, S. De la Plaza, L.M. Navas, J.L. García, E. Hernández, L. Luna |
| Keywords: | Heating wire, soil temperature, modelling, energy saving, gerbera |
| Abstract:
One of the variables with more influence in crop physiology is soil temperature. One interesting system for localized heating of greenhouses substrates is the use of electric wire. For the best economic benefit, it is possible to optimize these installations by predicting the quantitative effect of such heating systems on soil temperatures, using soil temperature modelling as a tool. In this work, localized heating of substrate with buried electric wire was studied and energy consumption with different energy savings and economic cost with different operating strategies were analized. A based-computer model was developed for estimating changes in substrate temperatures, as a function of time and depth, and energy consumption with different configurations (energy savings) of substrate heating by using electric wire. The model predicted the energy consumption of localized heating in the experimental configurations with a good accuracy, showing an average error of under 7 %. It is concluded the model is an useful tool to assess and predict energy consumption joint to this localized heating system and to evaluate energy savings efficiency, in each case estimating the energy consumed by the localized substrate heating by using electric wire. As for the energy evaluation of the localized heating, the configuration with thermal insulation, a layer of sand of 0.07 m width under the substrate as a heat accumulator and heating wire buried in the substrate between 0.20 and 0.25 m depth is the best configuration for electric systems of localized substrate heating. As for the economic analysis, results showed that the best strategy was the use of heating in night tariff hours in combination with accumulator materials. In this experiment, substrate heating at 18 °C, monitored at 0.1 m depth, caused a 14% increase in the production of the flowers cut from the gerbera. | |
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