Wen-Shing Lee

Latent Heat Storage in a Two-Phase Thermosyphon Solar Water Heater

This article experimentally studies the thermal performance of latent heat storage in a two-phase thermosyphon solar water heater, which utilizes the superior heat transfer characteristics of boiling and condensation, and eliminates drawbacks found in the conventional solar water heater. Experimental investigations are first conducted to study the thermal behavior of tricosane (paraffin wax 116), water, and sodium acetate NaCH3 COO·3H 2O used as energy storage materials. The results indicate that tricosane provides many advantages to be the energy storage material in the latent heat storage system. This study also examines the functions of charge and discharge thermal behaviors in a two-phase thermosyphon solar water heater. The results show that the system gives optimum charge and discharge performance under 40% alcohol fill ratio and with tricosane used as the energy storage material, and displays an optimum charge efficiency of 73% and optimum discharge efficiency of 81%. DOI: 10.1115/1.2147588

Performance and Bearing Load Analysis of a Twin Screw Air Compressor

To study the performance and estimate the oscillating bearing loads of a twin screw air compressor, a theoretical model is proposed in this paper. Based on the model, a computer simulation program is developed and effects of different design parameters such as rotor profile, geometric clearance, oil injected position, oil temperature, oil flow rate and other operational conditions are investigated. Output variables such as bearing loads, specific power, compression efficiency, volumetric efficiency, discharge temperature are obtained. Some of the results are then compared with experimentally measured data, and good agreements are found between the simulation results and the measured data.

Effect of Lubrication on the Performance and Dynamic Loads of Scroll Compressors

To study the effect of lubrication on the performance and dynamic loads of scroll compressors, a theoretical model is proposed in this paper. The model includes both thermal and dynamic analyses in which the lubrication theory is emphasized in particular. A computer simulation program is written accordingly, and the effects of different design parameters including oil flow rate, injection position, injection temperature and rotating speed are investigated. The output variables such as gas force, contact force, contact moment and thermal performance of the compressor are obtained. Some of the results are compared with experimentally measured data, and good agreements are found between the simulation results and the measured data. The applicability of the simulation program is thus verified.Analytical results from running this program can provide us valuable information on the design improvement of a scroll compressor.

Numerical Simulation and Performance Analysis of Twin Screw Air Compressors

A theoretical model is proposed in this paper in order to study the performance of oil-less and oil-injected twin screw air compressors. Based on this model, a computer simulation program is developed and the effects of different design parameters including rotor profile, geometric clearance, oil-injected angle, oil temperature, oil flow rate, built-in volume ratio and other operation conditions on the performance of twin screw air compressors are investigated. The simulation program gives us output variables such as specific power, compression ratio, compression efficiency, volumetric efficiency, and discharge temperature. Some of the above results are then compared with experimentally measured data and good agreement is found between the simulation results and the measured data.