A hybrid power generation system: solar-driven Rankine engine–hydrogen storage

This paper reports on the feasibility of a hybrid power generation system consisting of a solar energy-driven Rankine engine and a hydrogen storage unit. Solar energy, the power for the hybrid system, is converted into electrical power through a combination of a solar collector, a tracking device to maintain proper orientation with the sun and a Rankine cycle engine driving an electrical power generator. Excess electricity is utilized to produce hydrogen for storage through electrolysis of water. At the solar down time, the stored hydrogen can be used to produce high-quality steam in an aphodid burner to operate a turbine and with a field modulated generator to supplement electric power. Case studies are carried out on the optimum configuration of the hybrid system satisfying the energy demand. A numerical example based on the actual measured solar input is also included to demonstrate the design potential. Copyright © 2001 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34879/1/744_ftp.pd

Thermoeconomic optimization for a finned-tube evaporator configuration of a roof-top bus air-conditioning system

This paper presents a methodology of a design optimization technique that can be useful in assessing the best configuration of a finned-tube evaporator, using a thermoeconomic approach. The assessment has been carried out on a direct expansion finned-tube evaporator of a vapor compression cycle for a roof-top bus air-conditioning (AC) system at a specified cooling capacity. The methodology has been conducted by studying the effect of some operational and geometrical design parameters for the evaporator on the entire cycle exergy destruction or irreversibility, AC system coefficient of performance (COP), and total annual cost. The heat exchangers for the bus AC system are featured by a very compact frontal area due to the stringent space limitations and structure standard for the system installation. Therefore, the current study also takes in its account the effect of the variation of the design parameters on the evaporator frontal area. The irreversibility due to heat transfer across the stream-to-stream temperature difference and due to frictional pressure drops is calculated as a function of the design parameters. A cost function is introduced, defined as the sum of two contributions, the investment expense of the evaporator material and the system compressor, and the operational expense of AC system that is usually driven by an auxiliary engine or coupled with the main bus engine. The optimal trade-off between investment and operating cost is, therefore, investigated. A numerical example is discussed, in which a comparison between the commercial evaporator design and optimal design configuration has been presented in terms of the system COP and evaporator material cost. The results show that a significant improvement can be obtained for the optimal evaporator design compared with that of the commercial finned-tube evaporator that is designed based on the conventional values of the design parameter

A Study of the relation of combustion to the emission of atmospheric contaminants

http://deepblue.lib.umich.edu/bitstream/2027.42/6651/5/bac9341.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/6651/4/bac9341.0001.001.tx

Hematoma extradural do vértex: relato de caso Epidural hematoma at the vertex: case report

Relatamos caso incomum de um paciente de 37 anos com hematoma extradural traumático do vértex com sintomas de hipertensão intracraniana. O diagnóstico foi feito através da tomografia do crânio em cortes coronais e o paciente foi submetido a craniotomia com drenagem do hematoma.<br>We report the unusual case of a 37 years old man with an epidural traumatic hematoma at the vertex with intracranial hypertension symptoms. The diagnostic was achieved with coronal cranial tomographic scans and a craniotomy was performed for hematoma removal