Papers by Author: C.H. Liu

Abstract: A new optical encoder system is presented for displacement measurement by the curve fitting method. In this paper, another pondering model is based on the previous development. That is the new measurement method using a homemade periodical gray level code, which can be used to replace the traditional doublet grating. A high precision is achieved by a fitting method with one single-frequency harmonic function. The experiment result shows that the concept is feasible.

Abstract: This study presents an analysis of surfactant added by CuO and Al2O3 nano-sized particles of different percentages. After adding suspending nanocrystalline particles into lubricant of machines, the nano-sized particles will augment the heat transfer characteristics of fluids. Some former studies showed that such liquids pose a great potential for heat transfer enhancement. By applying nanofluids to heat transfer of machine lubricant, this paper attempts to explore dominating factors of heat transfer performance from various weight concentrations of nano-sized particles, the correlation among wall temperature, heat flux, rotational Reynolds number, Nusselt number, Grashof number and rotational Grashof number of four different concentrations. The results show that nano-sized particle lubricant offer a better heat transfer performance than typical lubricants. Since random movement and diffusing effect of nano-sized particles are one crucial factor for an increased heat transfer coefficient, adding 3.5% weight concentration nano-sized particle lubricant will produce an optimum heat transfer performance among Case I~IV.