Conversion of Thermal Energy to Gas Flow Kinetic Energy in the Bionic Leaf Stomata

Abstract

In the technical field, the potential energy of gas under pressure is converted into mechanical kinetic energy by means of special complex channels. Leaf stomata perform a similar function in plant leaves. The shape of leaf stomata channels is much more sophisticated compared to gas flow transformation channels in energy production facilities. There is a biological prototype of a heat engine in the leaf, where leaf stomata convert thermal energy into mechanical kinetic energy of the flow with a change in leaf temperature. The paper presents experimental research on thermal energy conversion into mechanical kinetic energy of the flow in plant leaf stomata. The values of biological heat engine in a plant leaf and the associated processes are minute. The operation of the biological heat engine in a plant leaf was proven by indirect experimental measurements. After applying a light source flux to a plant leaf and inducing a temperature change in the tissues of the plant leaf, the rotational movements of a freely hanging plant leaf about the suspension axis were studied. When studying the dependence of plant leaf rotation movements on the area of the plant leaf, it was found that at a 150 W light source, the angle of rotation increased as the area of the plant leaf increased. For a plant leaf with an area of 52.5 ± 1.9 cm2, the angle of rotation reached 165°; 29.1 ± 1.1 cm2—143°; 16.0 ± 0.8 cm2—92°; and 9.2 ± 0.6 cm2—44°. The angular speed of plant leaf rotation was from 0.070–0.262 rad/s. The influence of light sources on the rotation angle of the plant leaf was studied; when illuminating the active leaf area of 25.0 ± 1.0 cm2 of the plant with a 40 W power light source, after 11 s, the rotation angle reached 31°, 60 W—97°, 100 W—131° and 150 W—134°. The effect of light sources (from 40 to 150 W) on the angular rotation speed of the plant leaf varies at 0.049–0.213 rad/s, respectively.