Study On The Performance Of Gas Controlled Potassium Heat Pipe

Gas controlled Heat-Pipes(GCHPs)are special gas-loaded heat pipes,which can be used as a high-precision heat control technology.In the thermometry field,GCHPs can provide a uniform,stable and reproducible thermal environment too calibrate thermocouples,standard platinum resistance thermometers,and other temperature sensors to study the non-uniqueness of the temperature scale,and toimprove the capiability of the dissemination of temperature in China.Potassium Gas Controlled Heat-Pipes(GCPHP)are high-temperature heat pipes,usually operating over the temperature range from 400 ~oC to 900 ~oC.The main factors affecting the performance of the GCPHP are:working fluid purity,wick structure,pressure control in the heat pipe,and stability of the high-temperature standard platinum resistance thermometers.In order to develop a GCPHP with excellent performance,corresponding research on the above-mentioned factors was conducted,and effective technical solutions were proposed.In order to ensure the purity of the GCPHP working fluid,a vacuum degassing and vacuum filling system is designed to prevent that the high-purity potassium from being oxidized and contaminated.In addition,the the inert gas glove box with oxygen and water vapor concentration less than 0.05 ppm was used to complete the assembly of the GCHP.These effective measures are the key to the development of GCHP.In order to select a suitable wick and verify the rationality of the wick design,a sealed potassium heat pipe with a petal-shaped wick that can run horizontally was developed.The experimental results show that the temperature stability of the sealed potassium heat pipe is±5 mK.These technical parameters indicatethat that the wick has played an important role for the successful operation.At the same time,it was found that adjusting the temperature distribution of the heating furnace,the uniformity of the horizontal temperature field of the heat pipe can be effectively improved.Therefore,the GCPHP adopts the design of the wick.In order to improve the stability of the pressure control of the GCPHP,a high-precision pressure controller and pressure buffer tanks are used.The former improves the stability of dynamic pressure control,while the latter increases the volume,which can reduce the impact of pressure fluctuations.A high-precision pressure control system was built to achieve high-precision dynamic control of pressure to meet the pressure control requirements of GCPHP.The platinum wire of High-Temperature Standard Platinum Resistance Thermometer(HTSPRT)are affected by oxidation and deformation during use,which results in the resistance of the thermometer to change and affect the accuracy of the experimental data.In order to monitor the stability of the HTSPRT,a metal shell gallium melting point cell and an automatic reproduction device were developed.The drift of the HTSPRT at the gallium melting point realization value was monitored.In order to evaluate the performance of the gallium point cell,an international comparison was carried out between NIM and PTB.the comparison results show that the temperature differences were consistent within 0.01 mK.This is the best comparison result.An experimental performance study of GCPHP was carried out.The results show that when the pressures were dynamically controlled at 112773 Pa and 146769 Pa,the temperatures in the GCPHP are about 771?and 800?,and temperature stability fluctuates within±1 mK.In summary,many difficulties in the experiment of GCPHP were solved,the key technology of the development of GCPHP were mastered.The first GCPHP was successfully established in China.