RU218772U1 - Normal curing chamber - Google Patents

Abstract

The utility model relates to test equipment. A chamber of normal hardening, containing a cabinet in the form of a cabinet with a zone for accommodating material samples to be tested, in which a machine and hardware compartment is located in the upper part of the cabinet, separated from the zone for accommodating material samples to be tested by a partition. This section contains a device for humidifying and mixing the internal air volume of the cabinet with a fan driven by an electric motor, the impeller of which is brought inside the chamber and placed above the water tank, a heating device, a control unit for humidity and temperature parameters inside the cabinet volume, which includes dry and wet sensors placed inside the chamber, and a refrigeration unit with a condenser. The impeller of a separate fan for blowing dry and wet sensors is located inside the chamber, and the electric motor for driving the impeller of this fan is located in the machine room, and the electric motor for driving the fan of the humidification and mixing device for the internal air volume of the cabinet is located in the machine room, while on the shaft of this motor on the side opposite to the placement of the impeller of the fan of the device for humidifying and mixing the internal air volume of the cabinet, located inside the chamber, an additional impeller is fixed, located inside the machine-hardware compartment for supplying air flow towards the condenser of the refrigeration unit. 5 ill.

Description

The utility model relates to testing equipment and concerns the design of a normal hardening test chamber (NST) designed for hardening (storage) of samples of concrete, mortar, cement, dry building mixtures on a cement binder under normal conditions (temperature 20±2°C; relative humidity 95 ±5%) according to GOST 10180-2012 (chamber with normal curing conditions), GOST 5802-86 (normal storage chamber), GOST 310.1-76, GOST 30744-2001 (wet storage chamber (cabinet), GOST R 58277-2018 (sample holding chamber), as well as for any other testing of the technical characteristics of various materials. The design of the CNT is considered, designed for operation in enclosed spaces in a non-explosive environment that does not contain salt fogs, conductive dust, corrosive gases or vapors that destroy metal and insulation.

Preset temperatures and/or predetermined air humidity for a specific desired climatic regime are created in the space of the samples, that is, inside such CSTs. Chambers for normal hardening and wet storage of samples (CST) are designed for hardening and wet storage of concrete samples under normal conditions in accordance with GOST 10180-2012 and GOST 18105-2018, cement samples in accordance with GOST 30744-2001 and mortar samples in accordance with GOST 5802-86. At the same time, chambers for normal hardening and wet storage of samples can be used as chambers for thawing samples of autoclaved cellular concrete at a temperature of (18±2)°C and relative humidity (95±2)°C according to GOST 31359-2007.

It is essential for such test chambers to create devices that provide fast in time and guaranteed accuracy in obtaining the temperature and relative humidity of the air within the limits of temperature and humidity specified by regulatory documents.

So known is CST, which contains a case in the form of a cabinet with a zone for placing concrete samples to be studied, in which in the upper part of the cabinet there is a humidification device in the isothermal mode of the internal air volume of the cabinet, a fan, as well as a heating device and a control unit for humidity and temperature parameters inside the volume cabinet, made on the basis of a programmable microprocessor with the function of manually setting the humidity and temperature parameters and automatically maintaining the set parameters when they are reached, while the CNT is equipped with a refrigeration unit, the evaporator (cooler) of which is combined with the heating element of the heating device and placed in the outgoing air stream next to blade fan of the air humidification and mixing device, which includes the specified blade fan, configured to form an air flow at a speed of 3.0 m/s to 4.0 m/s to direct the air flow towards the evaporator (cooler) combined with a heating element of a heating device, for evaporating water directly from the surface filled with tap water and installed under the specified fan tray without picking up the water itself, while the walls of the chamber are insulated to limit the influence of the temperature outside the case on the temperature inside it (RU 142475, F24F 3/14 , publ. June 27, 2014).

This solution is taken as a prototype.

The disadvantage of this solution lies in the insufficiently reliable system for measuring relative air humidity in a psychrometric-type chamber, since the blower motor for dry and wet sensors is located inside the chamber. In the presence of an electric motor for blowing dry and wet sensors located inside the chamber, parasitic heat is generated in the chamber from the operation of this engine, which increases the number of starts of the chamber refrigeration machine and affects the accuracy of readings of humidity and temperature sensors.

The second significant drawback of the technical solution of the prototype is the placement inside the chamber of the electric motor of the fan drive of the device for humidifying and mixing the internal air volume of the chamber, which is also a source of parasitic heat in the chamber from the operation of this engine and excessively increases the number of inclusions of the chamber refrigeration machine.

This utility model is aimed at achieving a technical result, which consists in increasing the accuracy of measurements and the reliability of the measuring equipment when the camera is in operation for continuous and unlimited in time for a long time.

The specified technical result is achieved by the fact that in a normal hardening chamber containing a cabinet in the form of a cabinet with a zone for placing material samples to be studied, in which a machine and hardware compartment is located in the upper part of the cabinet, separated from the zone for accommodating material samples to be studied by a partition. In the machine room there is a refrigeration unit with a condenser, a device for humidifying and mixing the internal air volume of the cabinet with a fan driven by an electric motor, the impeller of which is brought inside the chamber and placed above the water tank. A heating device, a control unit for humidity and air temperature parameters inside the cabinet volume, including dry and wet sensors blown by a separate fan, and an impeller of a separate fan blowing dry and wet sensors are located inside the chamber. The electric motor for driving the impeller of a separate fan for blowing dry and wet sensors is located in the machine room, and the motor drive for the fan of the device for humidifying and mixing the internal air volume of the cabinet is also located in the machine room, while on the shaft of this motor on the side opposite to the location located inside chamber of the impeller of the fan of the device for humidifying and mixing the internal air volume of the cabinet, an additional impeller located inside the machine room is fixed to supply the air flow towards the condenser of the refrigeration unit.

These features are essential and are interconnected with the formation of a stable set of essential features sufficient to obtain the desired technical result.

This utility model is illustrated by a specific example of execution, which, however, is not the only possible one, but clearly demonstrates the possibility of achieving the required technical result.

In FIG. 1 - general view of the CST with open doors;

fig. 2 - general view of the machine-hardware department of the CST, without the front panel;

fig. 3 - layout of fans and electric motors;

fig. 4 - unit for blowing dry and wet sensors;

fig. 5 - the layout of the elements of the refrigerating machine set.

According to this utility model, the design of a normal hardening chamber is considered, used for hardening (storing) samples of concrete, mortar, cement, dry building mixes on a cement binder under normal conditions at a temperature of 20 ± 2 ° C, relative humidity 95 ± 5% according to GOST 10180- 2012.

In the general case, CST (Fig. 1) contains a body insulated along the walls 1, which is made with doors 2 for access to the rack area 3 placed inside, used to place the test samples of concrete, mortar, cement. Above this shelving area there is a machine-hardware compartment 4, separated from the area of placement of material samples to be investigated by a partition 5, which is the bottom of this compartment. The front instrument panel 6 of this compartment is simultaneously a panel for placing controls for 7 modes of operation of the camera and displaying the current values of temperature and humidity and operating time. The operation of the chamber is controlled (measuring temperature and humidity, turning on and off the humidifier fan 9, turning on and off the refrigeration machine or heater, indicating the operation of actuators, indicating emergency modes) by a microprocessor controller according to a specially set program in automatic mode. The control panel can be made in a display version.

The use of an evaporative-type humidification system in isothermal mode, which provides for the evaporation of water directly from the surface of the evaporation tank in the form of a tray 8 using a high-speed humidifier fan with an air flow rate of 3.0 m/s to 4.0 m/s, allows achieving high relative humidity air from 95 to 100%. At the same time, when filling the tray with water, there are no special requirements for water, ordinary tap water is used, and the tray itself is equipped with breakwaters to prevent water from being picked up by the blades of the humidifier fan impeller.

In the machine room (Fig. 2) there is a device for humidifying and mixing the internal air volume of the cabinet with a humidifier fan driven by an electric motor 9, the impeller 10 of which is brought inside the chamber and placed above the water tank (above the water-filled tray 8) and a refrigeration unit with a condenser 13. A heating device, a cooling device, a control unit for humidity and temperature parameters inside the cabinet volume, including dry and wet sensors 11 and 12, blown by a separate fan, respectively, are located inside the chamber.

The impeller 14 of a separate fan blowing dry and wet sensors 11 and 12 is located inside the chamber (Fig. 3), and the electric motor 15 of the drive of the impeller 14 of this fan is located in the machine room 4.

The electric motor 9 of the fan drive of the device for humidifying and mixing the internal air volume of the cabinet is located in the machine room 4. At the same time, an additional impeller 16 is fixed on the shaft of this electric motor on the side opposite to the placement of the impeller 10 located inside the chamber of the fan of the device for humidifying and mixing the internal air volume of the cabinet. , located inside the machine room 4 for supplying air flow towards the condenser 13 of the refrigeration unit, next to which the compressor 17 is located. used in modifications that do not require forced cooling during operation.

The task that this utility model solves is to create a reliable system for measuring relative humidity in a psychrometric-type chamber, which is solved by placing the electric motor 15 for blowing dry and wet sensors 11 and 12 not inside the chamber, but in the machine room 4 of the chamber.

To measure the relative humidity of the air in the chamber, an extremely simple and trouble-free classical system for measuring humidity by the psychrometric method was used, which has high accuracy, the minimum possible inertia and good reliability when the chamber is operated for continuous and unlimited long-term operation under conditions of maximum relative humidity.

The majority of manufacturers of normal curing chambers use sorption-capacitive type humidity sensors, which are not able to function for a long time in conditions of 95÷100% relative air humidity due to their natural drift in these temperature and humidity conditions and distortion of humidity readings. The use of capacitive humidity sensors cannot provide the required humidity measurement accuracy.

The sorption-capacitive sensor was created in the 70s of the last century and practically replaced all other types of sensors. Due to the high accuracy, reliability, and long-term stability of capacitive sensors, devices based on them are widely used to measure humidity in all branches of human activity. However, there are a number of tasks in which the use of capacitive sensors is limited due to their significant drawback, which manufacturers rarely mention - drift during prolonged exposure to an environment with humidity above 90%. The drift value increases with increasing humidity, temperature, and duration of stay at high humidity and can reach 10%.

This feature of capacitive sensors does not allow the use of "conventional" hygrometers for continuous monitoring of humidity in long-term processes with a relative humidity of more than 90%. And this is a very wide class of tasks, including humidity control in climatic thermal chambers, where, when testing products for exposure to high humidity, according to, for example, GOST 5802-86 (clause 10.6.2. The main samples must be tested for frost resistance at 28 days of age after 10.6.3 Control samples intended for compression testing should be stored in a normal hardening chamber at a temperature of (20 ± 2) ° C and a relative humidity of at least 90%).

At the same time, there are special models of hygrometers on the market designed for long-term operation in high humidity conditions. In these devices, the sensor overheats relative to the environment, as a result of which the relative humidity at the measurement point does not exceed 70-85%. The transmitter calculates the partial pressure of the water vapor from the sensor temperature and the measured relative humidity. A separate measuring transducer monitors the air temperature. Then, based on the known values of partial pressure and temperature, the relative humidity of the air is calculated. But such devices are expensive and not all of them are certified in Russia, there are problems with maintenance and verification.

By removing from the internal space of the chamber to the machine-hardware compartment of the electric motor of the humidifier fan and the fan for blowing dry and wet sensors of the humidity measurement system, the elimination of parasitic heat from the operating electric motors in the chamber is achieved and, accordingly, the number of starts of the chamber refrigerating machine is reduced.

And due to the use of a two-shaft type humidifier fan electric motor, an additional fan blowing the condenser of the refrigerating machine is excluded from the composition of the refrigerating machine set.

In this regard, and due to these design innovations, the installed electric power of the chamber is 750 W even for a chamber with a volume of 1500 liters, which is 2 times less than that of the prototype, which leads to a significant reduction in power consumption during long-term operation of the chamber.

Claims (1)

A normal hardening chamber containing a cabinet in the form of a cabinet with a zone for placing material samples to be studied, in which in the upper part of the cabinet there is a machine and hardware compartment, separated from the zone for accommodating material samples to be investigated by a partition, this compartment houses a refrigeration unit with a condenser, a humidification device and mixing the internal air volume of the cabinet with a fan driven by an electric motor, the impeller of which is brought inside the chamber and placed above the water tank, a heating device, a control unit for humidity and temperature parameters inside the cabinet volume, which includes dry and wet sensors blown by a separate fan, placed inside chamber, characterized in that the impeller of a separate fan for blowing dry and wet sensors is located inside the chamber, and the electric motor for driving the impeller of this fan is located in the machine room, the impeller for the fan of the humidifier and mixing the internal air volume of the cabinet is located inside the chamber, and the electric motor for driving the impeller of this fan located in the machine room, while on the shaft of this electric motor on the side opposite to the placement of the fan impeller located inside the chamber of the device for humidifying and mixing the internal air volume of the cabinet, an additional impeller is fixed, located inside the machine room for supplying air flow towards the refrigeration condenser installation.

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