Performance and Economic Comparison of Solar Cooling Configurations

In this paper a performance and economic comparison of solar cooling configurations using a new integrated approach combining the hourly thermal-optical performance assessment of the solar systems with the economic aspects has been conducted. Evacuated tube solar collectors with single effect LiBr absorption chiller and compact solar linear concentrating Fresnel collectors with single effect or medium temperature double effect LiBr absorption chiller have been taken into account. Considering that all the produced cold thermal energy could be delivered to a final user, the latter solar cooling configuration shows the possibility to have the Levelized Cost Of Cooling (LCOC) comparable with standard electric compression cooling. However, technology improvements and economy of scale are necessary in order to reduce solar field cost in the range 150-250 €/m2

Evaluation of friction enhancement through soft polymer micro-patterns in active capsule endoscopy

Capsule endoscopy is an emerging field in medical technology. Despite very promising innovations, some critical issues are yet to be addressed, such as the management and possible exploitation of the friction in the gastrointestinal environment in order to control capsule locomotion more actively. This paper presents the fabrication and testing of bio-inspired polymeric micro-patterns, which are arrays of cylindrical pillars fabricated via soft lithography. The aim of the work is to develop structures that enhance the grip between an artificial device and the intestinal tissue, without injuring the mucosa. In fact, the patterns are intended to be mounted on microfabricated legs of a capsule robot that is able to move actively in the gastrointestinal tract, thus improving the robot’s traction ability. The effect of micro-patterned surfaces on the leg-slipping behaviour on colon walls was investigated by considering both different pillar dimensions and the influence of tissue morphology. Several in vitro tests on biological samples demonstrated that micro-patterns of pillars made from a soft polymer with an aspect ratio close to 1 enhanced friction by 41.7% with regard to flat surfaces. This work presents preliminary modelling of the friction and adhesion forces in the gastrointestinal environment and some design guidelines for endoscopic devices

Levelized Cost of Heat for Linear Fresnel Concentrated Solar Systems

In this paper, a deep investigation upon levelized cost of heat (LCOH) produced by small-scale solar linear concentrating Fresnel collectors (CSLFC) is proposed. Solar industrial process heat applications have temperature requirements from about 60 °C to 260 °C. CSLFCs can effectively integrate conventional fossil fuel thermal systems. The study is addressed to assess technology cost projection needed to achieve competitive LCOH. So, on the basis of a framework specifically developed for these economic assessments, the best investment scenarios, in terms of industrial application, geographical location and technical design solutions, where to effectively apply the technology of CSLFC, are highlighted. The analysis has been focused on specific cost of several existing CSLFCs associated with declared performances at different operating temperatures. Two main classes of CSLFC with different total efficiency (optical and thermal) corresponding to various design solutions and specific cost were selected. The expected performances in the whole application temperature range have been evaluated through Glayx Tech proprietary simulation code, including optical and thermal unsteady analysis. A huge database coming from full CSLFC simulation varying latitude, yearly DNI, operating fluid, outlet temperature, thermal storage options, has been collected. CLSFC design and performance requirements are the key-choice to achieve competitive LCOH: the use of high efficiency – high cost components is not always rewarding in terms of final LCOH and must be attentively decided basing on site, irradiation, heat quality and LCOH target. In this perspective, CLSFCs are the most promising for industrial small scale heat applications since they show the greatest potential to reduce manufacturing costs

Fabrication of layered polydimethylsiloxane/perfluoropolyether microfluidic devices with solvent compatibility and valve functionality

The development of multilayer soft lithography methodology has seen polydimethysiloxane (PDMS) as the preferred material for the fabrication of microfluidic devices. However, the functionality of these PDMS microfluidic chips is often limited by the poor chemical resistance of PDMS to certain solvents. Here, we propose the use of a photocurable perfluoropolyether (PFPE), specifically FOMBLIN® MD40 PFPE, as a candidate material to provide a solvent-resistant buffer layer to make the device substantially impervious to chemically induced swelling. We first carried out a systematic study of the solvent resistance properties of FOMBLIN® MD40 PFPE as compared with PDMS. The comparison presented here demonstrates the superiority of FOMBLIN® MD40 PFPE over PDMS in this regard; moreover, the results permitted to categorize solvents in four different groups depending on their swelling ratio. We then present a step-by-step recipe for a novel fabrication process that uses multilayer lithography to construct a comprehensive solvent-resistant device with fluid and control channels integrated with a valve structure and also permitting easy establishment of outside connections. © Springer-Verlag Berlin Heidelberg 2013

Levelized cost of heat for linear Fresnel concentrated solar systems

In this paper, a deep investigation upon levelized cost of heat (LCOH) produced by small-scale solar linear concentrating Fresnel collectors (CSLFC) is proposed. Solar industrial process heat applications have temperature requirements from about 60°C to 260°C. CSLFCs can effectively integrate conventional fossil fuel thermal systems. The study is addressed to assess technology cost projection needed to achieve competitive LCOH. So, on the basis of a framework specifically developed for these economic assessments, the best investment scenarios, in terms of industrial application, geographical location and technical design solutions, where to effectively apply the technology of CSLFC, are highlighted. The analysis has been focused on specific cost of several existing CSLFCs associated with declared performances at different operating temperatures. Two main classes of CSLFC with different total efficiency (optical and thermal) corresponding to various design solutions and specific cost were selected. The expected performances in the whole application temperature range have been evaluated through Glayx Tech proprietary simulation code, including optical and thermal unsteady analysis. A huge database coming from full CSLFC simulation varying latitude, yearly DNI, operating fluid, outlet temperature, thermal storage options, has been collected. CLSFC design and performance requirements are the key-choice to achieve competitive LCOH: the use of high efficiency - high cost components is not always rewarding in terms of final LCOH and must be attentively decided basing on site, irradiation, heat quality and LCOH target. In this perspective, CLSFCs are the most promising for industrial small scale heat applications since they show the greatest potential to reduce manufacturing costs. © 2013 The Authors

DEVELOPMENT OF A PDMS PERISTALTIC MICROPUMP FOR MICRO ANALYSIS SYSTEMS IN PROTEIN ASSAYS

Microfluidics is a field that provides tools and concepts for elaborating complex lab-on-a-chip devices. The integration of actuators on the chip is a crucial issue, since it is difficult to control many independent fluid channels by a few external devices. From this standpoint, polydimethylsiloxane (PDMS) is an advantageous material, because active elements, such as valves and pumps, can be easily integrated thanks to its elastomeric properties. Active components can be fabricated using multilayer soft lithography technique. Valves are formed at the intersection between a fluidic channel and a control channel located in two separate layers. When pressure is increased in the control channel (e.g. injecting air) the membrane separating the two channels deflects and closes the fluidic channel, blocking the flow inside. Assembling three valves in series, one can fabricate peristaltic pumps. This micropump was designed to be integrated in a micro analysis system for protein assays. The designed actuator, in combination with two one-shot micropumps and a set of microvalves, will provide the entire fluidic control for biological tests

Microfluidic chip with temporal and spatial concentration generation capabilities for biological applications

This paper details the control and operation of a new microfluidic chip whose architecture of three sets of five fluidic channels is capable of generating both spatially and temporally varying concentration gradients. It is housed in a Petri dish where the cells are first seeded and preconditioned and then exposed to the biochemical gradients produced by the chip. The flow in the fluidic channels is regulated by crisscrossing control channels with the contact interfaces acting as valves. The pneumatic control and operation of the chip have been automated with LABVIEW and thoroughly tested. The results for the single channel case have also been validated by a comprehensive computational model whose formulation is described