Change of Geometric Growth Parameters of Icicle Conglomerates on Horizontal Pipe Fittings at the Water Spray by Nuzzle
Background. Icicles can be used to produce and store ice using natural and artificial cold. It is possible to use the heat of the phase transition (water–ice) r0 = 334 kJ/kg in ventilation systems, and heat pump systems for heating and hot water supply during the ice accretion. It contributes to energy saving and allows avoiding the use of natural gas, expanding the application area of heat pumps to countries with frosty winters, and also reducing the installed capacity of heat generating equipment. For air crystallizer-heater pans, it is important to know the permissible distance between adjacent linear pipes, which ensures the passage of air without the fusion of adjacent rows and the distance between the tiers of linear pipes, which depends on the length of the icicles.
Objective. The aim of the paper is to investigate experimentally the processes of ice formation in icicle conglomerates on horizontal pipe fittings. Obtain mathematical dependencies for determining the rate of growth of icicle conglomerates in length and the rate of growth of ice shells around the pipes in the transverse direction at a constant surface irrigation density of the nozzle within ice accretion time.
Methods. Frosty air, with a temperature below 0 °C, is heated by the crystallization heat of water dispersed by the nozzle. Water, falling on the horizontal pipes, turns into ice, forming conglomerates of icicles. The economic and energy effect is bigger for lower environmental temperatures, when heating the air before the heat pump evaporators and the air-conditioning calorifiers. Accumulated ice can be used for cooling purposes in summer, increasing the economic effect.
Results. The icicle growth rate in length is the ratio of the average length of the icicles on the pipe to the period of their formation. From the experimental data obtained, the rate of icicle growth in length at a constant water spray be nuzzle is almost independent of the pipe diameter and the constituent material. At the same time, the outside air temperature has a significant effect on the growth rate of icicles in length. The process of length growth of icicle occurs with a decrease in its growth rate along its length with a constant water supply. The bigger the pipe diameter, the bigger the ice growth rate on the pipe fitting along the radius perpendicular to the axis of the pipe toward the nearby pipe fittings. This is due to better water subcooling, on a pipe of a larger diameter, which overcomes a larger path to the horizontal plane passing through the center of the pipe.Conclusions. The growth regularities of icicles on stands with different pipe fittings and methods of their irrigation are studied. The obtained results allow calculating the distance between the horizontal pipes to prevent the ice blocking of the air passage and the distance between the tiers of the pipes, ensuring a minimum distance between the icicle tiers before removing.
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