SU754195A1 - Method of preventing deposits on heat exchange duct walls - Google Patents

Description

(54) METHOD OF PREVENTION OF SEDIMENTS ON THE WALLS OF HEAT EXCHANGE CHANNELS

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The invention relates to methods for preventing deposits on the walls of heat exchange channels and can be used in heating and ventilation systems of industrial, public and agricultural buildings.

Methods are known for preventing deposits on the walls of heat exchange channels by filling the latter with particles of fine-grained material that are fluidized by means of heat-exchangeing media 1 circulating through the channels.

A disadvantage of the known methods is the impossibility of disposing of heat exchange media.

Utilization devices are used to increase the efficiency of heating and ventilation systems. As the last, recuperative air-air heat exchangers became widespread. The warm, polluted air that is removed from the room is fed into the exhaust channels of the heat exchanger, and the fresh, cold air enters the room through the flow channels of the heat exchanger. When air moves through the heat exchanger channels as a result of heat and

mass transfer occurs cooling of the exhaust air and heating of the supplied air. Steam, passage in the exhaust air, during cooling, changes its state of aggregation and is released on the heat exchange surface either in liquid form or, if the heat exchange surface has a negative temperature, in the form of ice. The presence of ice B channels of the heat exchanger significantly reduces the heat transfer and aerodynamic characteristics of the latter, and with a significant amount of ice layer, makes the entire structure inoperable.

The purpose of the invention is to eliminate the above disadvantage.

This goal is achieved by circulating exhaust air at a rate 1.25-1.4 times faster than the rate of circulation of the incoming air.

The described method for preventing deposits is carried out as follows.

Claims (1)

20 Channels for supply and exhaust air are arranged vertically and gas distribution grids are placed at their inlet and outlet. Particles of fine-grained material are introduced into the space of the channels between the grids. Exhaust and supply air is supplied from bottom to top. When air circulates through the heat exchanger in the channels, the bed of particles of fine-grained material fluidizes. The circulation of exhaust air in the channels is carried out at a rate greater than the rate of circulation of the supply air. In the case of fluidization of particles, an increase in the heat transfer coefficient is observed both from the side of the exhaust air and from the side of the supply air. Since the air circulation rate in the channels is different, the heat transfer coefficients will also vary; on the side of exhaust air, its value will exceed the value of the heat transfer coefficient on the side of supply air. With this ratio of coefficients, the boundary of the transition of positive temperatures to negative (0 ° С) is penetrated inside the intake air channel, and the heat exchange surface itself will have higher temperatures. In the layer of pneumatic particles, vapor condensation from exhaust air occurs not on the heat exchange surface, but on the surface of the particles themselves. Particles with moisture settled on them are lowered to the lower gas distribution grid. When the forces of gravity exceed the forces of adhesion of moisture to particles, the separation of moisture from particles occurs. Moisture flows through the gas distribution valve into the duct, from which it is then removed. Due to the fact that steam condensation from exhaust air occurs on the surface of the fine-grained material of the particles, moisture is restricted to the heat exchange surface. Phenomena accompanying the fluidization process (increase in the temperature of the heat exchange surface, restriction of moisture access to the heat exchange surface, which is the initial material of ice crystals), can prevent icing. The use of particles of fine-grained material in the heat exchanger-heat exchanger channels allows supplying air with a temperature of –25 ° C without danger of frosting on the surfaces of walls of heat exchange channels. Claims The prevention of deposits on the walls of the heat exchange channels by filling the latter with particles of fine-grained material that is fluidized by circulating through the channels of heat-exchanging media, characterized in that, in order to prevent the walls of the channels from icing up when using heat-exchanging and exhaust air, the circulating air to exhaust the walls. exhaust air is carried out at a rate of 1.25-1.4 times the circulating air flow rate. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 282354, cl. F 28 D 13/00, 1968.