Preliminary Study On A Two-Phase Thermocompressor Driven By Low-Grade Heat Sources

The two-phase heat-driven thermocompressor employs a displacer to shuttle the working fluid between the hot end and the cold end of the cylinder, where pressure fluctuates due to gas-liquid phase change. The thermocompressor using refrigerants with low boiling point, can generate large pressure ratio with small temperature difference. However, the operation mechanisms of the two-phase thermocompressor is not clear due to the insufficient research about the two-phase thermocompressor. The present work focuses on basic research and the performance of the two-phase thermocompressor. The following contents are included:1. Design of the two-phase thermocompressor driven by low-grade heat sources The first two-phase thermocompressor was designed and fabricated both by mechanics and thermodynamics in China.The methods and design process is described in detail.2. Preliminary experiments Preliminary experiments have been conducted on a self-made two-phase thermocompressor using n-hexane as working fluid. Pressure ratios as high as5or even higher is obtained with operating frequency of0.1Hz,0.2Hz and0.3Hz with heating power less than120W. The two-phase thermocompressor may be an efficient alternative in energy conversion of low-grade heat sources, such as waste heat, solar energy and so on. 3. Performance optimization experiments Some performance optimization experiments such as frequency experiments had been made based on the first self-developed two-phase thermocompressor, in order to obtain bigger pressure ratio. The results suggested that the whole performance is sensitive to the frequency of the piston and the cooling methods.