The effects of compressor speed variation on the heat transfer inside a speed controlled compressor were investigated in this study. Based on the lumped capacitance ntethod, the temperatures of the compressor components, the oil, and the refrigerant gas within the shell were modeled and simulated on a relative scale. A diffenmt heat transfer coefficient correlation was developed to evaluate the...

A rotary vane expander has been developed to replace the throttling valve for improving the COP of transcritical CO2 refrigeration system. Due to the serious internal leakage, the expander efficiency is not satisfactory. This paper presents the theoretical and experimental investigation on the internal leakage in a rotary vane expander prototype. Firstly, the leakage flow rate through the inter...

The objective of this theoretical investigation was to find a capable and economical way of controlling high speed refrigeration compressors with a low number of cylinders. Compressors with 4 cylinders or more allow control by cutting-off one or two cylinder blocks because the remaining blocks maintain a sufficient smoothness of low speed fluctuation. The type of regulation to be found in this ...

A new kind of pneumatic climbing robot is presented to meet the requirements of glass-wall cleaning for high-rise buildings, which is totally actuated by pneumatic cylinders and attached to the glass wall with vacuum suckers. Using the pneumatic actuators the climbing robot can be made lightweight and dexterous. At the same time the movement driven by pneumatic actuators has the characteristic ...

The flow over a pair of counter-rotating cylinders is investigated numerically and experimentally. It is demonstrated that it is possible to suppress unsteady vortex shedding for gap sizes from one to five cylinder diameters, at Reynolds numbers from 100 to 200, expanding on the more limited work by Chan & Jameson (Intl J. Numer. Meth. Fluids, vol. 63, 2010, p. 22). The degree of unsteady wake ...

The flow of dilute suspensions in a rotating filter separator consisting of a rigid, porous, polyethylene cylindrical filter rotating within an outer cylindrical shell was studied using laser-based velocity measurement techniques. The centrifugal instability of the Taylor–Couette flow results in toroidal vortices stacked in the annulus. The velocity field of the particles is very similar to tha...