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This paper investigates the possibility to individually balance the specific shaking forces and shaking moment of the slider-crank mechanism. The most common mean of balancing the slider crank mechanism is to use a counter mass. This solution is applied for almost every slider-crank mechanism used in commercial mechanical devices. However the nature of the mechanism does not allow a perfect balancing in such a way. The different nature of motions that govern the piston displacement and crank rotation imply that a counter mass can only statically balance the mechanism. An ideal dynamic balancing cannot be achieved this way. Therefore in this paper the excitations that act on the mechanism are split by the nature of motion that generates them and balanced accordingly. Two motions are defined, respectively the motion of the piston and the motion of the crank. The inertia force associated with the crank motion is balanced by building a dynamically equivalent system around the axis of the crankshaft while the excitation associated with the motion of the piston is balanced with a progressive spring with two rates.

This study aims to validate the use of R744 for a resonant twin piston compressor for domestic applications. The vapor-compression refrigeration is the most commonly approached method for cooling household appliances such as refrigerators and air conditioning systems. The R134a refrigerant is one of the most suitable refrigerants from an energetic point of view. R744 (CO2) compressors are less efficient, but the fact that the R134a raises serious environmental issues pushes commercial trend towards the usage of R744 [1]-[3]. Use of R744 in household appliances is currently an open topic and no company has switched yet to the environmental-friendly alternative. In this paper the fill efficiency will be simulated in order to validate if a conventional compressor such as the opposite twin piston compressor is capable of filling with refrigerant when operating at a 50Hz frequency. Such a validation can enable further investigations regarding the replacement of R134a with R744.

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