SU785831A1 - Salt-type moisten air generator - Google Patents

Description

The invention relates to a measurement technique and is intended to test and calibrate various types of hygrometers. Hygrostats are known in which the reduction of the temperature difference between the salt solution and the air is carried out by applying a shielding partition in the cartridge that separates the bulk of the salt solution from the useful volume of the working chamber fil. In this case, only an insignificant part of the solution is involved in establishing the hygrothermal equilibrium. Therefore, under the conditions of monotonically varying air temperature in the working chamber of the hygrostat, the temperature of the solution is practically equalized with the temperature of the air inside the hygrostat and, depending on the type of salt solution being used, is in the range of 0.03-0.4 C. The temperature difference also contributes to lowering the rate of air temperature rise to 0.4Nuz / hour, achieved through the use of thermal insulation of the working chamber (passive thermostatting). In such hygrostats, saturated salt solutions are prepared at ambient temperature, and then placed in a working hygrostat, which may have a higher RF temperature. Since in this case the solubility of the salt increases, it is in the hygrostat. psygoryagosti occurs, caused by the solution in a venous step condition. Salt hygrostats with remote cassettes are known in which the preservation of the saturated state of the solution is ensured by an out & l of its intensive mixing 2). Obviously, in such hygrostats, it is necessary to measure with high accuracy the temperature difference of the vapor-air mixture at the outlet of the cassette and in the working chamber.

In this case, the error in measuring the temperature difference will be determined by the class (accuracy) of the temperature measuring means used. Salt-type hygrostats with remote cassettes are complex devices.

The closest to the claimed invention in its technical nature is a salt generator containing a thermostatically controlled working chamber with an air duct, means for mixing air and a removable cartridge with a salt solution.

A known generator (hygrostat) has a number of significant drawbacks:

the cassette is made of thermally insulating material, which, in combination with a significant solution mass, has

high heat capacity, is the reason for the high inertia of hygrothermal processes occurring in the hygrostat, and, consequently, the occurrence of the temperature difference between the salt solution and air;

a cartridge with a saturated salt solution is installed directly on the bottom of the working chamber, which, if there is a constant temperature difference between the walls (bottom) of the working chamber and air, also causes an unacceptable difference in temperature between the salt solution and the air circulating in the working chamber of the hygrostat;

reversing circulating in

the hygrostat jacket air flow used to eliminate the temperature gradient along its movement, as well as mixing the air in the useful volume of the working chamber by crossing the air flow moving near it. side walls, significantly complicates the design of the hygrostat and does not provide the necessary uniformity of the temperature field in the working chamber due to the thermal inertia of the walls of the chamber and the insufficient sensitivity of the primary temperature transducers of the regulator.

The aim of the invention is to exclude. Differences in temperature of the salt and air solution and ensuring high uniformity of the temperature in the floor in the useful volume of the hygrostat chamber

In order to eliminate the temperature difference between the air and the salt solution, the cash register is installed in the duct on its side walls, it is insulated

from 1ShH and from the lower side of the piece with longitudinal metal ribs.

To exclude the error caused by the transition of the salt solution to a non-palatable state when its temperature rises, in the proposed hygrostat the solution is used as a thin layer of moistened salt crystals. In this case, with an increase in the salt solubility, only the ratio of salt crystals and solution changes, and the salt solution, due to molecular diffusion, restores its state.

In the proposed hygrostat cassette installed in the duct inside the usable volume, having a high uniformity of temperature and air flow rate. In this position, the cassettes retain the same heat exchange conditions at all points on its surface, which ensures a high uniformity of the temperature of the active surface of the salt solution.

The use of ribs made it possible to develop the surface of the cassette and intensify its heat exchange with the air circulating in the working chamber. Due to the fact that the cassette is made of a thin metal sheet, it is thermally insulated from the duct and, together with the salt solution, has a low heat capacity, its temperature, and hence the temperature of the solution, almost coincides with the temperature of the air blowing the cassette. Therefore, in the proposed hygrostat, the value of the temperature difference between the air and the salt solution is mainly determined by the magnitude of the non-uniformity of the air temperature field in the useful volume of the work- ing; whose camera.

The high uniformity of the floor temperature of the air circulating in the useful volume of the working chamber in the proposed hygrostat is achieved by using a plate with an electric heater installed on it. The plate is located between the back wall of the working chamber and the cold junction thermopile and is made of metal of high thermal conductivity. The use of a plate with an electric heater that has thermal contact with a cold junction thermopile allowed cyKfMHpoaan. heat fluxes (released by the electric heater and absorbed by the thermopile) and get a uniform temperature field with a temperature almost equal to the specified thermosaturation temperature in the place of its contact with st5, the working chamber chamber. Equality of plate temperatures and temperature of the bridge eliminates the occurrence of temperature gradients along the walls of the working and thus, under steady thermal conditions, eliminates the source of unevenness of the air temperature field in its useful volume. These significant differences make it possible to bring the temperature difference between the salt solution and the air to a negligible value, as well as to ensure a uniform field of temperature in the useful volume of the working chamber of the hygrostat. The drawing shows a General view of the proposed hygrostat (Fig. T) and the section aa (Fig.2). The hygrostat is a thermostatically controlled working chamber 1, in the useful volume of which cassette 2 is placed. The cassette is made of a thin metal sheet, on the underside of which are the length of the rib 3, and the inner side is covered with a thin layer of moistened salt crystals 4. The increase in the surface of the cassette due to use of ribs allowed to intensify heat transfer. cassettes with air and thereby ensure that its temperature is equalized with the temperature of the circulating air. The cassette is mounted on guides 5 made of heat insulating material and located inside the useful volume & on the walls of the air duct 6. The air duct provides directional movement (which is completely acted upon) in the air flow hygrostat. A fan driven by an electric motor 8 is used to mix the air in the hygrostat's working chamber. A metal plate 9 with an electric heater Y installed on it is attached to the rear wall of the working chamber. The electric heater is connected to an automatic temperature regulator 11. The temperature control in the hygrostat is controlled by electric power at constant cooling capacity of the cold generator. A thermopile 12 is used as a cold generator, mounted on the outside of the plate. With such an arrangement of the electric heater AND thermopile, the plate temperature is almost equal to the temperature of the hygrostat, which eliminates temperature gradients along the walls of the working chamber. Forced removal of heat from the hot junctions of the thermopile is carried out by the radiator 13 blown by the fan 14. The working chamber of the hygrostat is equipped with a removable door 15. The hygrostat's working volume is sealed with a rubber gasket and screws 16. The screws provide reliable thermal contact to the inside wall of the hygrostat. The walls of the working chamber, flnv connection of the flush hygrometers on the door of the working chamber are equipped with a terminal. we are 17. Primary converters hygro meters 18 are located on shelf 19, fixed on the inside of the door. At the bottom of the door is a window that is sealed by a cover 20 through which the cartridge is replaced without removing the door. Due to this, the change of tapes has virtually no effect on the steady-state temperature of the hygrostat. Temperature measurement in the working chamber is made with a thermometer 21. The proposed hygrostat works as follows. The primary transducers of the hygrometers 18 with the door 15 open are mounted on shelf 19, and their switching wires are connected to terminals 17. Then the cartridge 2 with saturated salt solution, the type of which is determined by the required value of relative humidity or dew point, is inserted into the useful volume of the working chamber. . Next, the working volume is sealed with a door, after which the thermostatic circuit and the air mixing device are turned on. The stability of the air flow is required and maintained by means of automatic temperature controllers II. After the riirporef Mii4ecKoro equilibrium is reached, the temperature meter 21 determines the temperature of the air circulating in the working volume of the hygrostat. The value of humidity, established in hygrotate, is determined by the measured temperature and dependency graphs

Claims (2)

Claim 1. Salt generator of moist air containing a thermostatic working chamber with an air duct, means for mixing air and a removable cassette with salt solution, characterized in that, in order to improve the accuracy of the humidity obtained, the cassette is installed in the air duct on its side walls and is insulated from them and from the bottom side L-4 FIG. 2 is equipped with longitudinal metal ribs. 2. Salt moist air generator pop. 1, characterized in that a plate of high thermal conductivity metal is installed on the inner wall of the working chamber, on one side of which an electric heater is fixed, and on the other, a thermobarrier.