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Based on the conjugate DarcyBrinkmanForchheymer hydrodynamic model and Schumann thermal model with boundary conditions of the second kind, a model with lumped parameters was proposed by means of geometric 2D averaging to identify the integral kinetics of the temperature elds of a porous matrix and a Newtonian coolant without phase transitions. The model was adapted for a heat-stressed surface by means of a porous compact heat exchanger with uniform porosity and permeability, obeying the modied KozenyCarman relation, in the form of a Cauchy problem, the solution of which was obtained in the nal analytical representation for the average volume temperatures of the coolant and the porous matrix. The possibility of harmonic damped oscillations of the temperature elds and the absence of coolant overheating in the starting condition of the cooling system were shown. For the dimensionless time of establishing the stationary functioning of the porous heat exchanger, an approximate estimate was obtained correlating with the known data of computational and full-scale experiments. Keywords: at porous heat exchanger; heat-stressed surface; boundary conditions of the second kind; time to settle a stationary warm regime.

In order to optimize the air environment temperature of the underground engineering equipment premises, it is necessary to conduct a comparative assessment of the operation of flow-through and counter-flow indirect-evaporative air coolers. Based on the previous mathematical models that describe the thermophysical processes in the channels of indirect evaporative coolers, an analysis of the structural and standard parameters of their operation is carried out. The most rational ratios of flows through the “wet” and “dry channels” are revealed and they ensure the maximum station cooling capacity. The transformer substation of the underground illustrates the effectiveness of their use. According to a result of the studies, it has been proved that the most rational ratio of air flows through wet and dry channels for flow-through indirect-evaporative coolers is 2.1-2.2, for counter-flow heat exchangers it is 3.0. The advantage of recuperation coolers is established by such indicators as: cooling capacity - 53.5%, air cooling range - 41%.

The paper presents the theoretical and experimental studies of the process of distribution of solid manure from the rolls by redesigned multi-bladed rotor type working bodies. With the developed model, the dependences of flight range of particles of fertilizer of blades radius of last row rotors at different angles of the installation of their radial position are got, which made it possible to determine the radius of the blades of the last row rotors to achieve the full width of sieving of fertilizer particles.