ANALYSIS OF OPEN SUN DRYING EXPERIMENTS

Open sun drying has lost its previous importance due to the fact that different factors affect its reliability and the quality of the produc ts obtained. One of the set-backs for the analysis of solar drying exp eriments is their dependence on a non-controlled source of energy, i.e . solar radiation depends on climatic conditions and experiments are d ifficult to compare. It is thus necessary to investigate the advantage s of a particular set up as well as the climatic influences. open sun drying could constitute the natural reference, allowing the comparison of different drying strategies. A new way of standardizing drying tim es, based on solar radiation input, is proposed, to allow better evalu ation of the experiments. An equivalent time is defined, allowing comp arison of experiments carried out under different circumstances. Carro ts and potatoes were used in these experiments. The use of the average daily solar radiation 15.28 MJ m-2.d-1 in Palma de Mallorca (39.33-de grees-N, 2.37-degrees-E), is proposed for comparison purposes. An impr ovement of more than 12% in the explained variance was observed, the u nexplained variance being lower than 1%.