RU2482404C1 - Low-temperature thermostat - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: proposed low-temperature thermostat comprises temperature control unit, working bath filled with heat carrier, grate to support specimens and temperature gage. Preset temperature and temperature field homogeneity are maintained by dispensing liquid nitrogen from vacuum flask into working bath filled with heat carrier via electrically driven valve controlled by control unit. Then, liquid nitrogen gets onto spreader shield and flows down into heat carrier. Then, substances are mixed by spraying nozzle by feeding compressed gas therein. Thus extra circulation of heat carrier is ensured.

EFFECT: homogeneous temperature field.

1 dwg

Description

The invention relates to mechanical engineering and can be used to test the strength of metal samples.

Known low-temperature thermostat containing a temperature control unit, immersed in the bath and fixed with screws with inlet and outlet pipes, a refrigeration machine, thermostat cover, coolant, a grill for placing samples, a temperature sensor, a cable connecting the control unit and the refrigeration machine, overflow pipe, drain hose (advertising brochure of LLC "Termeks", prototype).

The disadvantages of this design are large dimensions, design complexity and high cost.

The technical result to which this invention is directed is the simplicity and reliability of the low-temperature thermostat, designed to maintain temperature and ensure a uniform temperature field.

This technical result is achieved using the design of a low-temperature thermostat. The low-temperature thermostat contains a temperature control unit, a working thermos bath filled with coolant, a grate for placing samples, and a temperature sensor. Maintaining a predetermined temperature and uniformity of the temperature field is carried out using a dosed liquid nitrogen from a thermos tank into a working thermos bath filled with coolant through an electrovalve controlled by a temperature control unit. Then, liquid nitrogen enters the divider screen and flows into the coolant. Everything is uniformly mixed by the nozzle circuit by supplying a compressed gaseous substance. Thus provide additional circulation of the coolant.

The drawing shows a device and a functional diagram of a low-temperature thermostat.

The design of the low-temperature thermostat consists of a temperature control unit 1, a liquid nitrogen thermos tank 2, a tank cover 3, an output tube 4, an upper removable panel 5, a splitter screen 6, a thermos bath 7, compensation wires 8, a temperature sensor 9, and a block power supply 10, connecting wires 11, a valve for supplying compressed gaseous substances (for example, compressed air) 12, a pressure gauge 13, a connecting hose 14, an electrovalve for supplying liquid nitrogen 15, a hatch for the upper panel 16, handles for removing the upper panel 17, the input th nozzle for injecting compressed gas species (e.g., compressed air) 18, injector loop with holes 19 to accommodate the lattice patterns 20, 21 the coolant.

The operation of the low-temperature thermostat consists in maintaining the temperature from -80 ° C to -10 ° C of the circulating heat carrier 21 (for example, ethyl alcohol) and ensuring a uniform temperature field in the working thermos bath 7. The heat carrier 21 is circulated with compressed gaseous material (for example, compressed air) ) coming from the air line through the valve 12, under pressure P = 0.2-0.3 cm ² , controlled by a pressure gauge 13. Then through the connecting hose 14, inlet pipe 18 and the nozzle circuit 19 with holes ⌀ 1.5 mm all around labor working bath-thermos 7.

Maintaining in the temperature range from -80 ° C to -10 ° C of the coolant 21 by cooling with liquid nitrogen is carried out by the temperature control unit 1. The temperature of the coolant 21 in the working bath thermos 7 is measured by a sensor 9, which is a platinum resistance thermometer. Depending on the set task (temperature setpoint value and its rate of change) and the actual coolant temperature, the electronic circuit of the control unit generates control commands to the liquid nitrogen supply solenoid valve 15 through the power supply unit 10. Liquid nitrogen enters the solenoid valve 15 from the thermos tank at atmospheric pressure 2 and further through the screen-divider 6 flows into the coolant 21 of the working bath-thermos 7, where they are additionally mixed by the nozzle circuit. Technological insulating lattice 20 is designed to accommodate samples for testing. The hatch of the upper panel 16 is provided with a slot for attaching self-centering forceps (not shown). Handles 17 on the sides of the upper panel 5 are used to separate it from the body of the working bath thermos 7.

For two years, this low-temperature thermostat has been used in combination with a pendulum driver type 2130 KM-0.3 for testing the strength of metal samples with NIST notch according to the Charpy method for low LL and high LV types of energy. Compliance status has been confirmed twice by the American National Institute of Standards and Technology for Material Reliability (Boulder, Colorado 80305-3328).

Claims (1)

A low-temperature thermostat containing a temperature control unit, a working bathtub filled with coolant, a grate for placing samples, a temperature sensor, characterized in that maintaining the set temperature and uniformity of the temperature field is carried out using dosed liquid nitrogen from the thermos tank to the working thermos bath, filled with coolant through an electrovalve controlled by a temperature control unit, onto a liquid nitrogen screen-divider and then into the coolant, uniformly transfer eshivaemy loop-injector, which provides additional coolant circulates through the compressed gaseous substance.