Techno-economic projections for advanced small solar thermal electric power plants to years 1990-2000

Advanced technologies applicable to solar thermal electric power systems in the 1990-200 time-frame are delineated for power applications that fulfill a wide spectrum of small power needs with primary emphasis on power ratings less than 10MWe. Projections of power system characteristics (energy and capital costs as a function of capacity factor) are made based on development of identified promising technologies and are used as the basis for comparing technology development options and combinations of these options to determine developmental directions offering potential for significant improvements. Stirling engines, Brayton/Rankine combined cycles and storage/transport concepts encompassing liquid metals, and reversible-reaction chemical systems are considered for two-axis tracking systems such as the central receiver or power tower concept and distributed parabolic dish receivers which can provide efficient low-cost solar energy collection while achieving high temperatures for efficient energy conversion. Pursuit of advanced technology across a broad front can result in post-1985 solar thermal systems having the potential of approaching the goal of competitiveness with conventional power systems

Conception of the cognitive engineering design problem

Cognitive design, as the design of cognitive work and cognitive tools, is predominantly a craft practice that currently depends on the experience and insight of the designer. However, the emergence of a discipline of cognitive engineering promises a more effective alternative practice, one that turns on the prescription of solutions to cognitive design problems. In this paper, the authors first examine the requirements for advancing cognitive engineering as a discipline. In particular, they identify the need for a conception for explicitly formulating cognitive design problems. A proposal for such a conception is then presented

Microturbopompe avec isolation thermique pour cycle Rankine sur puce

Les micromoteurs thermiques (Power-MEMS) pourraient offrir une alternative aux batteries pour répondre aux besoins d’énergie compacte et distribuée pour des applications telles que l'électronique portable, les robots, les drones et les systèmes embarqués, les capteurs et les actionneurs. La microturbine à vapeur de cycle thermodynamique de Rankine fait partie de ce domaine de micromoteurs. Ce dispositif est destiné à la génération d’électricité à petite échelle à partir de la récupération de la chaleur perdue. Dans ce contexte, l’objectif de ce travail est la fabrication et la démonstration expérimentale d’une microturbopompe à haute température pour implémenter le cycle de Rankine. Une configuration originale qui intègre l’isolation thermique est, tout d’abord, proposée. Cette configuration est constituée d’un empilement de cinq tranches (silicium et verre) pour enfermer un rotor hybride (silicium et verre) supporté par des paliers hydrostatiques. Le rotor est un disque de 4 mm de diamètre et de 400 µm d’épaisseur avec des pales de turbine sur le dessus et une pompe visqueuse à rainures en spirale sur le dessous. Une technique de micromoulage de verre a été développée dans ce travail pour intégrer du verre dans le rotor comme un matériau isolant thermiquement. La microturbopompe est fabriquée avec succès en utilisant les méthodes de microfabrication des MEMS. Tout d'abord, les paliers hydrostatiques, la turbine et le fonctionnement de la pompe sont caractérisés, jusqu'à une vitesse de rotation de 100 kRPM. La turbine a fourni 0,16 W de puissance mécanique et le débit de la pompe était supérieur à 2.55 mg/s. Ensuite, la première démonstration d'une turbopompe MEMS fonctionnant à des températures élevées a été réalisée. Une comparaison a été faite avec un rotor non isolé pour prouver l'efficacité des stratégies d'isolation thermique. La turbopompe MEMS isolée a été démontrée à 160°C du côté de la turbine. Par extrapolation, la microturbopompe devrait fonctionner jusqu'à une température de 400°C avant que la température dans la pompe n'atteigne 100°C. Pour la première fois, une microturbopompe pour un fonctionnement à haute température est fabriquée et caractérisée

Waste Heat Recovery From a Compression Ignition Engine using a Combined Diesel Particulate Filter Heat Exchanger

Compression ignition (CI) engines have been a figurehead in the transportation industry for decades. However, as environmental regulations dictate increasingly strict emissions guidelines for engines, technologies must accordingly advance. To this end, this thesis describes the work of validating a combined diesel particulate filter heat exchanger (DPFHX) for CI engine exhaust waste heat recovery (WHR) in a Rankine Cycle (RC), a concept introduced in the first chapter of this thesis. The second chapter includes a comprehensive literature review, indicating the increasing prevalence of WHR in the literature. Additionally, with RC as the principal system for WHR and engine exhaust as the primary heat source, this research is exceptionally relevant. Furthermore, the primary aspects of an RC WHR system requiring individual optimization are the heat exchangers and expanders along with working fluid selection. As such, the third chapter discusses experiments to analyze and compare the DPFHX with various working fluids; thus, incorporating the literature trends of working fluid comparison and component specificity in the methodology. Consequently, in the DPFHX, water achieved a higher heat transfer rate by over 60% than the 50% by volume mixture of water and ethylene glycol, the two optimal working fluids in the apparatus without DPF cores. However, alterations made to the DPF cores’ outer diameters and lengths when installing them in the heat exchanger tubes prevented them from achieving the expected outcome (i.e., improving apparatus performance). Finally, the fourth chapter links the conclusions from this work to recommendations for future efforts to investigate DPFHXs

Applications of aerospace technology in the electric power industry

An overview of the electric power industry, selected NASA contributions to progress in the industry, linkages affecting the transfer and diffusion of technology, and, finally, a perspective on technology transfer issues are presented

Methods for heat transfer and temperature field analysis of the insulated diesel phase 2 progress report

This report describes work done during Phase 2 of a 3 year program aimed at developing a comprehensive heat transfer and thermal analysis methodology for design analysis of insulated diesel engines. The overall program addresses all the key heat transfer issues: (1) spatially and time-resolved convective and radiative in-cylinder heat transfer, (2) steady-state conduction in the overall structure, and (3) cyclical and load/speed temperature transients in the engine structure. During Phase 2, radiation heat transfer model was developed, which accounts for soot formation and burn up. A methodology was developed for carrying out the multi-dimensional finite-element heat conduction calculations within the framework of thermodynamic cycle codes. Studies were carried out using the integrated methodology to address key issues in low heat rejection engines. A wide ranging design analysis matrix was covered, including a variety of insulation strategies, recovery devices and base engine configurations. A single cylinder Cummins engine was installed at Purdue University, and it was brought to a full operational status. The development of instrumentation was continued, concentrating on radiation heat flux detector, total heat flux probe, and accurate pressure-crank angle data acquisition

Microfabricated rankine cycle steam turbine for power generation and methods of making the same

In accordance with the present invention, an integrated micro steam turbine power plant on-a-chip has been provided. The integrated micro steam turbine power plant on-a-chip of the present invention comprises a miniature electric power generation system fabricated using silicon microfabrication technology and lithographic patterning. The present invention converts heat to electricity by implementing a thermodynamic power cycle on a chip. The steam turbine power plant on-a-chip generally comprises a turbine, a pump, an electric generator, an evaporator, and a condenser. The turbine is formed by a rotatable, disk-shaped rotor having a plurality of rotor blades disposed thereon and a plurality of stator blades. The plurality of stator blades are interdigitated with the plurality of rotor blades to form the turbine. The generator is driven by the turbine and converts mechanical energy into electrical energy

Combined Diesel Particulate Filter/Heat Exchanger for Engine Exhaust Waste Heat Recovery with Organic Rankine Cycle

Diesel Particulate Filters (DPFs) are currently being used to remove Particulate Matter (PM) from compression ignition engine exhaust streams with collection efficiencies approaching 100%. These devices capture soot by forcing the exhaust gases through porous walls, where entrapment of the particulates initially occurs. Eventually, a cake layer begins forming on the inlet channel walls, causing an increased pressure drop through the device and necessitating a soot combustion event to unload the filter. The exothermic nature of these regeneration events serve to enhance the thermal energy content of the exhaust, which already contains approximately one-third of the fuel energy being consumed by the engine. Typically, the energy from both sources is expelled to the atmosphere, destroying the ability to produce useful work from the exhaust heat. However, a novel device described here as a Diesel Particulate Filter/Heat Exchanger (DPFHX) may be coupled to an Organic Rankine Cycle (ORC) to simultaneously provide particulate matter filtration and waste heat recovery. The DPFHX concept is based on the shell-and-tube heat exchanger geometry and features enlarged tubes to contain DPF cores, allowing energy capture from the engine exhaust while preserving the standard technique of PM abatement. Since the working fluid circulating on the shell side collects heat from the exhaust, the DPFHX serves as the organic Rankine cycle’s evaporator. Along with the cycle’s pump, expander, and condenser, the DPFHX forms an ORC capable of transforming exhaust waste heat into supplementary power for the engine. Reducing exergy destruction in this manner meets the two main objectives of engine research; the reduction of fuel consumption and emissions. The degree to which the proposed DPFHX-ORC system achieves these goals is a focus of this dissertation, where the advancement of this technology occurs primarily through theoretical efforts. As precursors to the eventual DPFHX-ORC computer model, individual ORC and DPF models are created. With respect to simulating an ORC, a historical study of the ORC WHR literature informs the design choices associated with building an ORC model. Authors in this research area note that the two dominant factors influencing cycle performance are the working fluid and expander selections. Based on these findings, eight dry fluids (butane, pentane, hexane, cyclopentane, benzene, toluene, R245fa, and R123) compatible with reciprocating expanders are identified for use in an ORC model. By simulating WHR from a Yanmar L100V diesel engine, the component-based ORC constructed illustrates an approximate 10% improvement to the engine’s efficiency across all operating conditions and favors the use of pentane or cyclopentane as the cycle’s working fluid. These results are consistent with reported ORC outputs in the literature and demonstrate the ORC model’s value as a component of the DPFHX-ORC model. The second foundational component is a DPF model, which is developed using the DPF governing equations in area-conserved format. A series of model validation efforts show that the DPF model is capable of generating accurate thermodynamic parameter profiles in the inlet and outlet channels, along with tracking the monolith temperatures and soot combustion. However, extension of the model to include external heat transfer to the ORC working fluid requires the creation of a novel multi-dimensional DPFHX computer model due to the small DPF core size and enhanced heat transfer in a DPFHX. This model does not follow traditional multi-dimensional modeling schemes by allowing heat transfer with and without the DPF cores as intermediaries. Also, the model does not couple inlet and outlet channels, or force all walls bordering an individual channel to have uniform conditions. The DPFHX model provides heat recovery predictions for coupling with the ORC model, allowing power output predictions from the entire system based on the single cylinder Yanmar test cell at the University of Kansas as the waste heat source. By matching the energy leaving the engine exhaust to the heat entering the ORCs working fluid, a DPFHX-ORC model is constructed in MATLAB. At very low engine load (227.3 W), the ORC system generates 156.8 W of power, corresponding to a 69.0% efficiency improvement over the engine alone. At typical engine loads (1726.7 W to 6205.5 W), the DPFHX-ORC system provides an efficiency increase between 9.5-13.7%. Along with the illustrated fuel consumption reduction is a reduction of all emissions by the same amount, following a short warm up period. The reduction of hydrocarbons and carbon monoxide are unaffected by installation of the DPFHX, and conversion efficiencies of nitrogen oxides are maintained by placing the selective catalytic reduction hardware before the DPFHX, alleviating concerns of low-temperature conversion. Due to the energy removal taking place in the DPFHX, PM collection occurs at reduced temperature levels; however, the efficiency of this process remains high due to the mechanical nature of filtration