Maurizio De Lucia

Benefits of Compressor Inlet Air Cooling for Gas Turbine Cogeneration Plants

Compressor inlet air cooling is an effective method for enhancing the performance of gas turbine plants. This paper presents a comparative analysis of different solutions for cooling the compressor inlet air for the LM6000 gas turbine in a cogeneration plant operated in base load. Absorption and evaporative cooling systems are considered and their performance and economic benefits compared for the dry low-NOx LM6000 version. Reference is made to two sites in Northern and Southern Italy, whose climatic data series for modeling the variations in ambient temperature during the single day were used, to account for the effects of climate in the simulation. The results confirmed the advantages of inlet air cooling systems. In particular, evaporative cooling proved to be cost-effective, though capable of supplying only moderate cooling, while absorption systems have a higher cost but are also more versatile and powerful in base load operation. An integration of the two systems proved to be able to give both maximum performance enhancement and net economic benefit.Copyright

Real-Time Detection of Cavitation for Hydraulic Turbomachines

Cavitation is an important problem in hydraulic machines that negatively affects their performance and may cause damages. Image processing techniques have been often used for visual analysis of cavitation conditions. Real-time detection of cavitation inception is more critical. This is usually performed by measuring related vibrations or electrical impedance, but coarse errors occur. Even if vision inspection is one of the first methods to analyse cavitation damages, this paper presents an innovative approach, i.e. a vision-based system for real-time detection of cavitation inception. Experimentation results in real conditions are reported, which were obtained by testing the system proposed. This technique can be applied to any hydraulic turbo-machine, provided that an optical access is available.

Performance Improvements of a Natural Gas Injection Station Using Gas Turbine Inlet Air Cooling

Gas Turbine (GT) performance seriously deteriorates at increased ambient temperature. This study analyses the possibility of improving GT power output and efficiency by installing a gas turbine inlet air cooling system.Different cooling systems were analyzed and preliminary cost evaluations for each system were carried out.The following three cooling systems were considered in detail:a) Traditional compression cooling system;b) Absorption single-acting cooling system using a solution of lithium bromide;c) Absorption double-acting cooling system using a solution of lithium bromide.Results clearly indicate that there is a great potential for GT performance enhancement by application of an Inlet Air Cooling (IAC). Technical and economical analyses lead to selection of a particular type of IAC for significant savings in capital outlay, operational and maintenance costs and other additional advantages.© 1997 ASME

A Comparison between Radial Rakes of Sensors and Axial Arrays of Microphones for the Experimental Investigation of Tone Noise in LPTs

The experimental investigation of turbomachinery noise requires to measure the acoustic field within annular test rigs. For this purpose, different in-duct measurement techniques are available. The most widely used are the arrays of flush-mounted microphones installed at the duct walls and the rakes of dynamic pressure sensors placed along the radial direction of the duct. Both methods have been implemented and used for several test campaigns performed at the Avio cold flow rig in Turin (Italy), in order to assess the acoustic performances, from the tonal noise point of view, of a model low-pressure-turbine representative of modern turbofan applications. This paper aims at performing a back-toback comparison between the results obtained by using these different experimental techniques. The results allowed to make assessments about the effectiveness of each experimental technique at analyzing tonal noise, highlighting the peculiar features of the two methods and their relative advantages and drawbacks.

Real-time defect detection on cloths

The detection and classification of defects is strongly useful for stopping in real time the cloth production when degenerative defects occur; for increasing the efficiency of production by limiting the decrement of price for cloth rolls. The paper describes the work performed for detecting defect of well-known manufacturers of cloths and machine builders for cloths (looms). The main goal has been to obtain a new and innovative production line endowed with a system for detecting defects in real-time. The system is based on image processing techniques with a special attention to the real-time constraints. An architecture separating an on-line defect detection and an off-line classification has been proposed. An intelligent optical head, assembled on the loom, has the duty to acquire images and to detect the defects in real-time. A server has the offline task to classify each defect detected by the head. In the paper, some new algorithms for defect detection have been proposed. These have been compared with a selection of the most interesting algorithms for the same purposed taken from the literature. The comparison has been conducted by on the basis of a large test set with several types of defects and by considering reliability, performance, and complexity.

Performance and Economic Enhancement of Cogeneration Gas Turbines Through Compressor Inlet Air Cooling

Gas turbine air cooling systems serve to raise performance to peak power levels during the hot months when high atmospheric temperatures cause reductions in net power output. This work describes the technical and economic advantages of providing a compressor inlet air cooling system to increase the gas turbine’s power rating and reduce its heat rate. The pros and cons of state-of-the-art cooling technologies, i.e., absorption and compression refrigeration, with and without thermal energy storage, were examined in order to select the most suitable cooling solution. Heavy-duty gas turbine cogeneration systems with and without absorption units were modeled, as well as various industrial sectors, i.e., paper and pulp, pharmaceuticals, food processing, textiles, tanning, and building materials. The ambient temperature variations were modeled so the effects of climate could be accounted for in the simulation. The results validated the advantages of gas turbine cogeneration with absorption air cooling as compared to other systems without air cooling.Copyright

Technique for Outdoor Test on Concentrating Photovoltaic Cells

Outdoor experimentation of solar cells is essential to maximize their performance and to assess utilization requirements and limits. More generally tests with direct exposure to the sun are useful to understand the behavior of components and new materials for solar applications in real working conditions. Insolation and ambient factors are uncontrollable but can be monitored to know the environmental situation of the solar exposure experiment. A parallel characterization of the photocells can be performed in laboratory under controllable and reproducible conditions. A methodology to execute solar exposure tests is proposed and practically applied on photovoltaic cells for a solar cogeneration system. The cells are measured with concentrated solar light obtained utilizing a large Fresnel lens mounted on a sun tracker. Outdoor measurements monitor the effects of the exposure of two multijunction photovoltaic cells to focused sunlight. The main result is the continuous acquisition of the - (voltage-current) curve for the cells in different conditions of solar concentration and temperature of exercise to assess their behavior. The research investigates electrical power extracted, efficiency, temperatures reached, and possible damages of the photovoltaic cell.

A new test cell for the evaluation of thermo-physical performance of facades building components

How do the new building façade components work under real climatic conditions? The question is especially related to the dynamic behaviour of new and complex components such as the ventilated walls, the Phase Change Material, or others that use nano-technologies and aerogels. One of the objectives of the undergoing research activity, named Abitare Mediterraneo, is the evaluation of their thermal behaviour through the use of an outdoor test cell, in order to reproduce under the real external conditions the performance of these components, and consequently define the main thermal parameters such as the attenuation factor and the thermal inertia, characterising the component; moreover, the results will be used to write new algorithms for dynamic simulation tools allowing an appropriate evaluation of the complex behaviour of the whole building at a real scale condition. The new test cell is realised in Florence, Italy. The design starts from the study of the experience of the existing PASSYS test cells, overtaking the main weakness of the building structure and of the heat-flux sensors.

Optical and Structural Characterization of Nickel Coatings for Solar Collector Receivers

The development of spectrally selective materials is gaining an increasing role in solar thermal technology. The ideal spectrally selective solar absorber requires high absorbance at the solar spectrum wavelengths and low emittance at the wavelengths of thermal spectrum. Selective coating represents a promising route to improve the receiver efficiency for parabolic trough collectors (PTCs). In this work, we describe an intermediate step in the fabrication of black-chrome based solar absorbers, namely, the fabrication and characterization of nickel coatings on stainless steel substrates. Microstructural characteristics of nickel surfaces are known to favorably affect further black chrome deposition. Moreover, the high reflectivity of nickel in the thermal infrared wavelength region can be advantageously exploited for reducing thermal emission losses. Thus, this report investigates structural features and optical properties of the nickel surfaces, correlating them to coating thickness and deposition process, in the perspective to assess optimal conditions for solar absorber applications.

Color prediction in textile application

Nowadays production systems of fancy yarns for knits allow the creation of extremely complex products in which many effects are obtained by means of color alteration. Current production technique consists in defining type and quantity of fibers by making preliminary samples. This samples are then compared with a reference one. This comparison is based on operator experience. Many samples are required in order to achieve a sample similar to the reference one. This work requires time and then additional costs for a textile manufacturer. In addition, the methodology is subjective. Nowadays, spectrophotometers are the only devices that seem to be able to provide objective indications. They are based on a spectral analysis of the light reflected by the knit material. In this paper the study of a new method for color evaluation of a mix of wool fibers with different colors is presented. First of all fiber characterization were carried out through scattering and absorption coefficients using the Kubelka-Munk theory. Then the estimated color was compared with a reference item, in order to define conformity by means of objective parameters. Finally, theoretical characterization was compared with the measured quantity. This allowed estimation of prediction quality.