Methods of Freeze Protection for Fruit Trees by Means of Renewable Energy Sources

Abstract

As the Earth climate changes, the current horticulture gives rise to an acute issue - protecting fruit trees from spring frosts and their root system from freezing in severe winters with little snow. The authors substantiated the methods of how to protect fruit trees from frost and their root system from freezing, as well as a method of how to control their phenological phases based on the study of the heatmass- exchange intensification in a certain soil area occupied by the root system of a tree with various engineering aids to be designed. The aforesaid method is based on the operation of a heat and cold separator, which makes it possible to intensify heat transfer and expand the area of specific heat loads removed using a coolant - potassium salt brine (aqueous 30% KCL solution). The test results have shown that the coolant heated by the heat of the soil to a temperature of 12°С, gradually moving up at a depth of 0.9 m, heats the soil to 7°С at a depth of 0.5 m and up to 1°С on the surface of the earth at an ambient temperature of up to - 10°С. The heat of the lower soil layers comes up to the surface; in the soil area occupied by the root system, the temperature is redistributed, stabilized in a state that excludes freezing of the root system of the fruit tree. A rational value of the effective head has been determined to be equal to 2200 Н/m2 at the depth of the heated soil surface up to 1 m, with a specific heat flow of about 4•105 W/m2. In addition, a rational flow rate of the coolant is set equal to (1.5 ... 2.5) Gmin to produce more optimal heat transfer and additional body force of the heat and cold separator. The method of controlling the phenological phases of fruit trees by heating or cooling a certain soil area occupied by the root system is possible using an installation that generates power from the renewable resources (solar energy, wind or biogas plant), depending on climatic conditions and terrain.