Organic Rankine Cycle (ORC) systems are increasingly gaining relevance in the renewable and sustainable energy scenario. Recently our research group published a manuscript identifying a new type of thermodynamic cycle entitled Buoyancy Organic Rankine Cycle (BORC) [1]. In this work we present two main contributions. First, we propose a refined thermodynamic model for BORC systems accounting for the specific heat of the working fluid. Considering the refined model, the efficiencies for Pentane and Dichloromethane at temperatures up to 100°C were estimated to be 17.2%. Second, we show a proof of concept BORC system using a 3 m tall, 0,062 m diameter polycarbonate tube as a column-fluid reservoir. We used water as a column fluid. The thermal stability and uniformity throughout the tube has been carefully simulated and verified experimentally. After the thermal parameters of the water column have been fully characterized, we developed a test body to allow an adequate assessment of the BORC-system’s efficiency. We obtained 0,84% efficiency for 43,8ºC working temperature. This corresponds to 35% of the Carnot efficiency calculated for the same temperature difference. Limitations of the model and the apparatus are put into perspective, pointing directions for further developments of BORC systems.

Recently, the Gauss rifle has gained attention as an interesting problem for physics and engineering education. In this manuscript we propose and analyze a novel problem that, while being related to the Gauss rifle, is rather simpler: the Gauss pendulum, which yields more consistent results and allows further agreement between model, simulation and experimental data. The Gauss pendulum, unlike the rifle, does not involve rotational movement of balls and the difference between the initial and final energy state of the system can be easily accessed by measuring the final height of the swinging projected ball. An extensive assessment of a Gauss pendulum has been developed using free software and accessible laboratory equipment. Focusing on the validation of the magnetic potential well model to understand the gain in kinetic energy, it was possible to obtain a remarkable agreement between the experimental and theoretically simulated data.