The main purpose of the present study is to clarify some mechanisms about fluid flowing through rectangle microchannels. The experimental study of single phase flow in rectangle microchannels are performed in this work with emphasis on the influence of hydraulic diameters and aspect ratios in different rectangle microchannels. In the present paper, distilled water, ethanol and R113 are used as the working fluids and flow through rectangular cooper microchannels with different hydraulic diameters, aspects ratios and relative roughness. The hydraulic diameters of rectangle cooper microchannels with the relative roughness of 1.5%-6% and the Reynolds ranges from 20-9500. Pressure drop data are used to characterize the friction factor in laminar region, the transition region and the turbulent region.
The transient short hot wire method for measuring fluid thermal conductivity requires an unsteady two-dimensional solution for heat conduction from a fine wire into the surrounding sample fluid. The efficiency of the method depends on the speed and accuracy of the calculation of the wire temperature. We compare two analytical solutions, two numerical solutions and the solution from a commercial code in terms of accuracy, total calculation time, grid convergence and ease of implementation. It is shown that all solution methods tested can obtain the same transient wire temperature to within about 20 mK.