Energy and exergy analysis of microchannel central solar receivers for pressurised fluids

Within the new generation of advanced central solar receivers, microchannel pressurised gas receivers are emerging as reliable and efficient alternatives to operate at high temperatures and pressures. This paper presents an optimisation and comparative analysis of different compact plate-fin type structures, constituting the receiver’s absorber panels, classified according to the type of fin arrangement inside: plain rectangular, plain triangular, wavy, offset strip, perforated, and louvred fin. A versatile thermo-fluid receiver model is implemented, allowing simple variation of characteristic geometric parameters of each structure. Exergy efficiency is chosen as the optimisation function, as it considers both heat and pressure losses. The framework of the analysis is set by the receiver’s boundary conditions, operating at the design point conditions of a solar thermal power plant. For each compact structure, the optimal configuration is determined, providing interesting findings that have not been reported in the state-of-the-art to date. Although all geometries show good thermal performance, the perforated and plain rectangular configurations demonstrate the best exergy efficiencies of 59.21% and 58.80%, respectively, favouring taller and narrower channels. This analysis methodology could be seamlessly extrapolated to other gases and working conditions, owing to the thermo-fluid model’s versatility, to reveal the optimal configuration for each case.This work has been developed within the framework of the ACES2030-CM project, funded by the Regional Research and Development in Technology Programme 2018 (ref. P2018/EMT-4319). The authors would like to thank the support of the Spanish Ministry of Economy and Competitiveness through the PID2019-110283RB-C31 project

Quantitative body movement and gesture assessment in ergonomics

We present a technique for the ergonomic assessment of motor tasks and postures. It is based on movement analysis and it integrates the perceived discomfort scores for joints motion and the time involvement of the different body districts. It was tested on eight subjects performing reaching movements. The experimental protocol was designed to have an a priori expected comfort ranking, namely, higher values in presence of more uncomfortable tasks. The preliminary assessment of the Method for Movement and Gesture Assessment (MMGA) in the ergonomic evaluation of reaching tasks gave promising results and showed the effectiveness of the index. Moreover, the proposed method was applied for the comparison between a real refrigerator and a new concept: MMGA manifested its applicability and resolution in the quantitative ergonomic assessment of accessibility and usability tasks. Next improvements of MMGA concern the integration of movement dynamics and the design of absolute-assessment studies with respect to working time. Future applications of the method might be the integration into CAD tools and human motion simulation to provide an early comparative evaluation of the ergonomics of the prototyping process and workplace redesign in industry

Chapter1: A multifactorial approach and method for assessing ergonomic characteristics in biomedical technologies

The ergonomic assessment of healthcare products is becoming regulatory, but current state of art relies on checklist of end-users interview about general or limited aspects. Ergonomics deals with the human as a whole and as a part of a more complex system; instead the assessment of objects and products is often treated separating the different components of the interaction: physical, sensory, cognitive. This research aims to develop an integrated method and a protocol for qualitative and quantitative evaluation of ergonomic features in healthcare products. The integration of methods for a global and more comprehensive ergonomic assessment can be used in a proactive way in the early stages of development. Basic methodological approaches refer to biomechanics and product usability assessment techniques. The first one is based on the measurement of angular excursions of the joints associated with the implementation of the human motion detectable in dedicated laboratory; the second method rely on direct observations and on site experiments supported by questionnaires/interviews to quantify ease of use and user satisfaction by means of special scales of assessments. The methodological approach here proposed is aimed to integrate ethnographic analysis, biomechanical analysis, and cognitive usability assessment within a multifactorial approach for the evaluation of ergonomic characteristics