SU1728690A2 - Method of control of leak-proofness of thermal siphons - Google Patents

Abstract

The invention relates to the monitoring of leaktightness and the determination of the impedance of thermitrons and heat pipes and allows the information content to be expanded by determining, together with their integrity, the magnitude of the impedance. The element of high thermal conductivity is heated to the boiling point of the coolant and is installed on the free surface of the evaporator of the thermosyphon. Keeping the power of heat generation constant, two different thermal disturbances of the heat transfer medium are successively set. The corresponding thermal perturbation powers and the temperature of the contact surface of the high thermal conductivity element are measured and the differential thermal resistance of the thermosyphon is determined. According to the magnitude of the latter, taking into account one of the temperatures of the contact surface and the thermal perturbation power corresponding to it, judge the magnitude of the impedance. 1 il. (Ls

Description

The invention relates to leakage tests, as well as to determining the thermal resistance (impedance) and quality characteristics of thermosyphons and heat pipes used to cool power semiconductor devices in converters of electrical traction and power supply.

There is a known method for monitoring the tightness of thermosyphons nos. 920419. that thermal perturbation of the heat carrier of thermosyphons is created, and its tightness is judged by the temperature change on the surface of the latter, and to control thermosyphons assembled with semiconductor devices, an element with high thermal conductivity is used; the evaporator of the thermosyphon and measure the temperature on the contact surface of the element, which is judged on the temperature change on the surface of the thermosyphon,

In the known device, operational control of the tightness of thermosyphons assembled in modules with semiconductor devices of power converters is achieved due to differences in the thermal conductivity of thermosyphons and heat pipes, depending on their tightness.

The aim of the invention is to expand the information content of the method by determining, along with the tightness of the thermosyphons, their thermal resistance.

X |

to

00 O Yu O

Yu

This goal is achieved by simultaneously measuring the temperature on the contact surface of a high thermal conductivity element, measuring the power of its thermal perturbation, changing this power and repeating all previous operations, determining the differential thermal resistance value from the difference in temperatures and powers measured in both cases thermosyphon, and the magnitude of the latter, taking into account one of the established temperatures of the contact surface of the element of high thermal conductivity and the corresponding power and thermal disturbance judged thermal resistance of thermosyphon.

The drawing shows an example of the implementation of the device that implements the sequence of operations of this method.

The device comprises a heater 1 with a high thermal conductivity element 2 mounted on the free surface of the evaporator of thermosyphon 3 assembled with power semiconductors 4. A temperature sensor, such as a thermocouple 5, is mounted on the contact surface of the element 2 with thermosyphon 3.

As heating elements 2, semiconductor devices 4 themselves can be used. Then element 2 of high thermal conductivity with thermocouples 5 is installed between devices 4 and evaporators of thermosyphons 3 and pressed with special device 9 to the thermosyphon. The heater is connected to a source of controlled voltage 6, which specifies the amount of power of the heater, to which a fan is also connected with a heater of air supplied for cooling the thermosyphon. The device 7 controls the monitoring process in accordance with the embedded algorithm and performs the processing as well as the indication of the output information signals.

The method is carried out as follows.

Element 2 is heated to a temperature that boils the coolant, and with heater 1 is installed on the free surface of the evaporator of the thermosyphon. Then, keeping the heat generation power of the heater 1 constant, two different thermal disturbances of the heat transfer medium are successively set, the duration of which ensures the steady-state value of the temperature of the element 2, which is fixed by the thermocouple 5. Judging by the temperature variation on the contact surface of the element 2, the hermetic character of the thermosyphon is differential

thermal resistance and temperature threshold of the beginning of the conduction of the heat pipe, Device 7, acting on voltage regulator 6, provides preheating element 2 to a temperature corresponding to the boiling of the coolant, the required flow of the fan 8, the calculated temperature of the air supplied by the fan 8, the installation of the heater 1 on

the free surface of the thermosyphon 3, creates successively two different thermal perturbations of the thermosyphon, measures and controls the power of the thermal perturbations of the thermosyphon element temperature

high thermal conductivity in the place of its contact with the thermosiphon evaporator, controls the process of stabilizing the power of thermal perturbations and the duration of the process in terms of reaching the set temperature, and provides for the programmed calculation and indication of the output information signals. The method provides operational control of the tightness of thermosyphons assembled in modules with power semiconductor devices. In addition, it provides an extension of the information content of the method by

along with the hermetic character of thermosyphon thermal resistance, the sequence of operations for determining thermal resistance makes it possible to determine

the values of its components: the differential thermal resistance and the temperature of its thermal conductivity threshold, which characterize the quality of the thermosyphon (heat pipe).

Thermal resistance of thermosyphon

is defined by the expression

R Ii + Rg

where Rg. -r p is the value of the differential thermal resistance, is equal to the ratio of the difference of the established temperatures of the contact surface of the high thermal conductivity element and

thermosyphon to the corresponding power difference of thermal perturbations of thermosyphon, ° С / W;

Ta T2 - Rg P2 is the temperature threshold of the beginning of the conduction of the heat pipe, determined by the value of the differential thermal resistance and one of the values of the steady-state temperature of the high thermal conductivity element and the corresponding thermal power

thermosyphon perturbations, ° С.

Formula from the method of monitoring the tightness of thermosyphons auth.St. No. 920419, that is, in order to expand the information content by determining, along with the tightness of thermosyphons, their thermal resistance, while measuring the temperature on the contact surface of a high thermal conductivity element, they measure its thermal perturbation power. , change this power and 0

all previous operations are repeated, the differential thermal resistance of the thermosyphon is measured by the difference in the temperatures and powers measured in both cases, and the thermal resistance is measured by one of the established temperatures of the contact surface of the high thermal conductivity element and the corresponding thermal perturbation power. thermosyphon.

Claims (1)

Claim A method for monitoring the tightness of thermosiphons according to ed. No. 920419, which is related to the fact that, in order to expand the information content by determining, along with the tightness of the thermosyphons their thermal resistance, simultaneously with measuring the temperature on the contact surface of the element of high thermal conductivity, the power of its thermal disturbance is measured, this power is changed and 10 all previous operations are repeated, by the difference in temperature and power measured in both cases, the differential thermal resistance of the thermosiphon is determined, and by the value of the latter, taking into account one of were becoming the contact surface temperature high thermal conductivity member and the corresponding thermal power disturbance judged thermosyphon heat resistance.