SU1366850A1 - Channel for moving heat-transfer agent - Google Patents

Abstract

Invention Mob. Used in heat exchangers with intensifying inserts in channels made of a porous permeable structure. The purpose of the invention is to reduce the hydraulic resistance of the channel. The porous insert, installed in the canape with overlapping section, is made with porosity (P) variable along the channel length. At the same time, the specific surface of the insert along the channel length increases with decreasing P. And decreases with increasing P. The change in P and specific surface compensate for changes viscosities of bone and gas, which can, in the case of constant P and specific surface, lead to an increase in the flow resistance of the channel. 4 hp f-ly, 2 ill. with

Description

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The invention relates to power, chemical and transport engineering and can be used in heat exchange devices with intensifying inserts in channels that are made of a porous permeable structure.

The purpose of the invention is to reduce the hydraulic resistance of the channel.

Figure 1 shows the gas-liquid heat exchanger, longitudinal section; 2 shows a channel for the evaporation of a liquid.

The tube-in-tube heat exchanger contains inner 1 and outer

2 pipes with central 3 and ring 4 channels. The annular channel 4 is closed from the ends of the krppki 5, B-to analov

3 and 4 are installed with overlapping sections of porous inserts with a variable porosity along the channel. The insert in the central channel 3 is formed in the form of a pack of plates 6-11, and in the annular channel 4 - in the form of a pack of plates 12-17. In order to reduce the flow resistance of the channel, the porosity of the plates 6-11 either increases monotonically, and the specific surface decreases, or vice versa: the porosity of the plates 6-11 monotonously decreases, and the specific surface increases. Similarly, the porosity and the specific surface of the plates 12-17 vary.

in channel 4.

Channel 18 for the heat carrier changing the aggregate state (vapor condensation) during the transfer process consists of a pipe 19 in which a porous permeable insert is installed with a variable porosity along the channel. The insert is made in the form of a plate pack 20-25. In order to reduce the flow resistance of the channel, the porosity of the plates at the length of the channel first kills (for example, plates 20,21 and 22), and the specific surface increases (for example, plates 23- 25), and the specific surface decreases. Thus, porosity porosity in channel 18 has a minimum value in the cross section located between the inlet section 26 and outlet section 27.

The heat exchanger operates as follows.

Mass flow velocity gas (pv) moves through the channel.

4. Liquid at mass velocity (pv), j moves through channel 3 Heat is transferred from the liquid to plates 6-11, then through the wall to plates 12-17, and from them to the gas flow (pv) j. The hydraulic resistance of the insert in channel 3 is equal to

4Рз + f (1 (pv) 2R ЪТ / р, (1)

where o /, f, - constant dp given

material size; B is the thickness of the insert; R is gas constant; - temperature and pressure;

 - gas viscosity. The fact that the viscosity of a gas increases with increasing T increases, and as can be seen from formula (1). On the other hand, the coefficient oi is proportional, and the coefficient, k |, n, n, is a value not less than unity G. The change in porosity and specific surface of the plates 12-17 is compensated by this increase, i.e. the total hydraulic resistance of channel 3 is reduced.

For liquids, viscosity increases with decreasing temperature. Therefore, the hydraulic resistance of the insert in the channel- 4 increases with a drop in temperature, as can be seen from the following modification of formula (1):

35

P (p) xJ

Changes in porosity and specific surface compensate for the growth of ip.

The proposed heat exchanger can also be used to dampen the gas flow (fv) 2 and to heat the liquid flow (v), for which it is necessary to change

the direction of movement of these coolants.

Channel 18 for evaporation of the liquid operates as follows. Heat flow from the side of the wall

q. The fluid supplied to the channel 18 from the side of the section 26 at a mass velocity (pv) is heated in the plates 20-25, evaporated in the plate 22, then the steam is heated in the plates 23-25.

Changes in the porosity and specific surface compensate for changes in the viscosity of the liquid and gas, which, according to formulas (1) and (2), can be at constant porosity and specific.

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Claims (5)

Claim 1. The channel for moving the coolant, comprising a porous insert with a porosity variable in length along the channel and having a porosity varying in length, characterized in that, in order to reduce hydraulic resistance, the insert is made with a specific surface increasing along the length of the channel with decreasing porosity and with a specific surface area decreasing along the channel length ~ with increasing porosity. 2. The channel according to claim 1, with the fact that when moving 25 of the heated gas, the insert is made with porosity increasing in the direction of gas movement. I 3. Channel pop. 1, characterized in that when moving the heated fluid, the insert is made with porosity, decreasing in the direction of fluid movement. I 4. Channel pop. 1, characterized in that when moving the cooled fluid, the insert is made of '8 porosity, increasing in the direction of fluid movement. I • 5. The channel according to claim 1, characterized in that for the coolant that changes the aggregate state during the movement, the insert is made with porosity having a maximum value in the cross section located in the area between the input and output sections ”fie.1 fie.2