Design of an active subsurface system thermal energy supply to the bio-vegetation complex

Abstract

The efficiency of vegetable production in closed ground structures is directly dependent on the costs associated with creating artificial, controlled conditions for growing plants during the period when cultivation of them in open ground due to climatic conditions is impossible. One of the indicators of the economic efficiency of vegetable production in protected soil structures is labor costs and funds per 1 hundredweight, per 100 rubles of gross production, as well as energy costs, including thermal energy. Usually, solar, biological, electric and other types of heating are used to supply thermal energy to cultivation facilities, each of which has its own disadvantages. The bio-vegetation complexes structurally distinguished by the fact that cultivation beds are located on various foundations make it possible to create an active underground heating system. The paper presents the development of a design for an active subsurface system for thermal energy supply to the bio-vegetation complex and calculations of the main parameters of the system for autonomous operation of the object at negative outside air temperatures. The design of the active subsurface system for thermal energy supply to the bio-vegetation complex is proposed in the form of a heat-accumulating sand-gravel mass, inside of which there are heat supply circuits with a heat carrier closed with a concrete screed on top. The calculation of energy consumed by the active sub-ground thermal system providing optimal parameters of the growing medium corresponding to biological rhythms of plant development at low outside air temperatures is also presented. The study determines the area of the photovoltaic unit and the number of photovoltaic modules for generating electric energy in order to cover the spent thermal energy and the effective functioning of the active subsurface system for thermal energy supply to the bio-vegetation complex.