Nowadays, the Organic Rankine Cycle (ORC) system, which operates with organic fluids, is one of the leading technologies for "waste energy recovery". It works as a conventional Rankine Cycle but, as mentioned, instead of steam/water, an organic fluid is used. This change allows it to convert low temperature heat into electric energy where required. Large numbers of studies have been carried out to identify the most suitable fluids, system parameters and the various configurations. In the present market, most ORC systems are designed and manufactured for the recovery of thermal energy from various sources operating at "large power rating" (exhaust gas turbines, internal combustion engines, geothermal sources, large melting furnaces, biomass, solar, etc.); from which it is possible to produce a large amount of electric energy (30 kW ÷ 300 kW). Such applications for small nominal power sources, as well as the exhaust gases of internal combustion engines (car sedan or town, ships, etc.) or small heat exchangers, are very limited. The few systems that have been designed and built for small scale applications, have, on the other hand, different types of expander (screw, scroll, etc.). These devices are not adapted for placement in small and restricted places like the interior of a conventional car. The aim of this work is to perform the preliminary design of a turbo-expander that meets diverse system requirements such as low pressure, small size and low mass flow rates. The expander must be adaptable to a small ORC system utilizing gas of a diesel engine or small gas turbine as thermal source to produce 2-10 kW of electricity. The temperature and OPEN ACCESSEnergies 2014, 7 7068 pressure of the exhaust gases, in this case study (400-600 °C and a pressure of 2 bar), imposes a limit on the use of an organic fluid and on the net power that can be produced. In addition to water, fluids such as CO2, R134a and R245fa have been considered. Once the operating fluids has been chosen, the turbine characteristics (dimensions, input and output temperature, pressure ratio, etc.) have been calculated and an attempt to find the "nearly-optimal" combination has been carried out. The detailed design of a radial expander is presented and discussed. A thermo-mechanical performance study was carry out to verify structural tension and possible displacement. On the other hand, preliminary CFD analyses have been performed to verify the effectiveness of the design procedure.

Fabricating entire systems with both electrical and mechanical content through on-demand 3D printing is the future for high value manufacturing. In this new paradigm, conformal and complex shapes with a diversity of materials in spatial gradients can be built layer-by-layer using hybrid Additive Manufacturing (AM). A design can be conceived in Computer Aided Design (CAD) and printed on-demand. This new integrated approach enables the fabrication of sophisticated electronics in mechanical structures by avoiding the restrictions of traditional fabrication techniques, which result in stiff, two dimensional printed circuit boards (PCB) fabricated using many disparate and wasteful processes. The integration of Additive Manufacturing (AM) combined with Direct Print (DP) micro-dispensing and robotic pick-and-place for component placement can 1) provide the capability to print-on-demand fabrication, 2) enable the use of micron-resolution cavities for press fitting electronic components and 3) integrate conductive traces for electrical interconnect between components. The fabrication freedom introduced by AM techniques such as stereolithography (SL), ultrasonic consolidation (UC), and fused deposition modeling (FDM) have only recently been explored in the context of electronics integration and 3D packaging. This paper describes a process that provides a novel approach for the fabrication of stiff conformal structures with integrated electronics and describes a prototype demonstration: a volumetrically-efficient sensor and microcontroller subsystem scheduled to launch in a CubeSat designed with the CubeFlow methodology.

Currently, one of the leading technologies for the “energy recovery” adopting a Rankine cycle (ORC) with organic fluids. ORC system operates like a conventional Rankine cycle, but instead of steam/water, uses an organic fluid. This change allows to convert low temperature heat and generate, where required, electricity. A large amount of studies were carried out to identify the most suitable fluids, system parameters and the various configurations. In reality, most ORC systems are designed and manufactured for recovery of thermal energy from various sources but at “large power rating” (exhaust gas turbines, internal combustion engines, geothermal sources, large melting furnaces, biomass, solar, etc.) from where it is possible to produce electric energy (30kW ÷ 300kW), but for the application of this system for small nominal power, as well as the exhaust gases of internal combustion engines (car sedan or town, ships, etc.) or smaller heat exchangers, there are very few applications. The aim of this work is to design a turbo-expander that meets system requirements: low pressure, small size, low mass flow rates. The Expander must be adaptable to a small ORC system utilizing gas of a diesel engine or small gas turbine to produce 2–10 kW of electricity. The temperature and pressure of the exhaust gases, in this case study (400–600° C and at a pressure of 2 bar), imposes a limit on the use of an organic fluid and on the net power that can be produced. In addition to water, organic fluids such as CO2, R134a and R245fa have been considered. Once the fluid has been chosen operating, the turbine characteristics (dimensions, temperature, input and output pressure ratio, etc.) have been calculated and an attempt to find the “nearly-optimal” has been carried out. The detailed design of radial Expander is presented and discussed. An initial thermo-mechanical performance study is carried out to verify structural tension and possible displacement. Next step of the research here proposed will be the CFD simulation to improve or modify the chosen blade profile.

Apoteósico homenaje a un monumento, símbolo del auge y el empuje comercial que caracterizó a Barranquilla a finales del siglo XIX y principios del XX, se levantó imponente el edificio de la vieja aduana, que representa la huella de un pasado esplendoroso de una ciudad que adquirió un protagonismo en el escenario regional, nacional e internacional dejando atrás ciudades como Santa Marta y Cartagena, las cuales resaltaran como puertos de embarqué y desembarque, tan sólo en los siglos anteriores.

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