In this study, a one-dimensional heat transfer measurement device is developed based on the mathematical theory of the Angstrom method. To conform to the mathematical assumption, it is required that the device precisely controls the heat source to generate sinusoidal temperature signal. A thermo-electric module is used as the heat source for the measurement platform. This module is connected to a computer for program control, such that the temperature can be controlled quickly, precisely, and dynamically. In this study, five common heat-conducting materials are tested to verify the proposed one-dimensional heat transfer measurement device. By substituting the experimental results into the mathematical model of the Angstrom method, the thermal diffusion and thermal conductivity of the test material is calculated. The experimental results are compared with the physical properties of the materials, and the accuracy error is extremely low. This study confirmed that the Angstrom method theory applied thermal diffusivity and thermal conductivity measurement, which can be realized by thermo-electric temperature control technology.

This research designed a set of experimental instruments (TDMI) to measure the thermal diffusivity α of the material. TDMI is calibrated by pure substance such as copper, tin, lead, Aluminium 6061 etc., after done the calibration, the thermal conductivity of heat pipe 、 graphite sheet and vapour chamber also be measured. The repeatability error in this experiment, are within 5%. Compared with the thermal diffusivity data of those the pure substance from handbook while for the accurate relative error were within 10% as well.

Heat pipes are transport mechanisms that can carry heat fluxes ranging from 10 W/cm² to 20 KW/cm² at extremely fast speeds. Therefore, heat pipes are widely used in 1U servers, notebooks, PCs, etc. A heat pipe is a heat removal device comprising a vacuum pipe that charges a certain amount of working fluid and seals the tube. Hence, the heat pipe performance depends not only on the geometric parameters such as wall thickness, tube material, and wick material but also on the thermal properties of the working fluid such as latent heat, vapor pressure, viscosity, and vacuum pressure. Traditionally, the fluid inventory of heat pipes was measured by the lost weight method, that is measuring the weight of the heat pipe first, then, breaking the heat pipe, after drying in the oven, then weighting again, and the lost weight would be the weight of the working fluid. This paper presents a new methodological concept to measure the inventory by a basic energy mass balance equation. The Measurement theory not only calculates the fluid inventory but also the vacuum pressure data. The experimental results show that when the weight percentage of working fluid was larger than 10% of total pipe weight, the relative errors were within 4% when compared with the known inventory.

Subcooled heating/boiling process under pool condition is widely seen in present engineering applications such as nuclear spent fuel pool and reactor core under maintenances and/or accident scenarios. In order to understand the heat transfer characteristics and possible enhancement mechanism of using ultrasonic vibration to improve the heat removal performance and safety operating ranges, detail investigations are required. In this study, experimental tests are carried out to investigate the heat transfer performance under pool natural convection and subcooled boiling conditions, and ultrasonic vibration is introduced to evaluate the possible enhancement performance. The commercial stainless-steel circular-rod heaters and ultrasonic vibrators are utilized to generate the heat flux of 4 × 10^3 × 2 × 10^5 W/m^2 and ultrasonic vibration waves with a frequency of 40 kHz and a power of 150W. Experimental tests are divided into two groups: (1) pool natural convection and subcooled boiling tests without vibration (stationary), and (2) pool natural convection and subcooled boiling tests with ultrasonic vibration. These tests are carried out under atmosphere pressure (1atm) with three subcooled pool temperatures. Detailed experimental data such as surface temperature, fluid temperature and heater power are recorded during the tests, and the heat transfer coefficients are analyzed for different operating conditions. Through this study, an experimental database of pool-subcooled heat transfer from single phase natural convection to pool boiling is established, and the heat transfer enhancement performance is identified and determined under with and without ultrasonic vibration conditions. The results shows that the heat transfer enhancement is higher in single phase than in subcooled boiling. The heat transfer augmentation is better in high heat flux condition. This paper can provide clear experimental evidences and better understanding about the influences of ultrasonic waves on heat transfer performance in pool conditions, and the experimental database can be useful for future safety design of reactor core and fuel storage.