1,721,015 research outputs found
COMBUSTION CHARACTERIZATION OF HYBRID CATALYTIC BURNER FUELLED WITH METHANE – HYDROGEN MIXTURES
No full text
Hybrid catalytic combustion of methane/hydrogen mixtures
No full textHybrid catalytic combustion technology, which is a staged process comprising a preliminary catalytic partial oxidation (CPO) step followed by a homogeneous flame combustion with interstage heat removal, was tested for the first time with mixtures of methane and hydrogen. Short contact time CPO experiments were run to elucidate the effect of the progressive substitution of methane with H-2 in the fuel feed to the structured catalytic reactor, which was operated under self-sustained conditions at high temperature. Furthermore, a prototype radiant hybrid burner was realized and safely operated at atmospheric pressure with up to 80% vol. of H-2 in the fuel and a primary equivalence ratio in the range 2.4-4.0. Outstanding NOx emission levels were attained with pure methane feed, which were also confirmed with H-2-rich fuels, due to the effective reduction of both thermal and prompt NOx formation
Characterization of gas turbine burner instabilities by wavelet analysis of infrared images
No full textIn this paper, an optical approach characterizing the combustion fluctuations in a single burner atmospheric gas turbine test rig has decribed. The present investigation tests the optical technique during combustion trials campaign, in order to couple it to an acoustic one in a future activity to be developed on the same experimental setup. The analysis based on fast infrared imaging of flames, coupled with photomultiplier and microphones measurements, has been elaborated on a 3 MW gas turbine test rig equipped with full scale burner tested in atmospheric conditions. The rig has been purposely designed to be tuned on acoustic frequencies detected in the real gas turbine machine equipped with 24 burners and operating at 20 bars. The tests evidenced main oscillations at low frequencies around 82 Hz and 146 Hz. These frequencies have been recorded in real machine too. The IR technique allowed to identify these frequencies in the 2D dimensions under humming conditions. The results obtained by IR presented a good agreement with microphones and optical measurements. Moreover, further investigation based on wavelet analysis came out as an interesting tool to develop a methodology for fingerprinting different burners operating in different conditions from thermoacoustic point of view
Measurement of the Thermal Diffusivity of a Tire Compound by Mean of Infrared Optical Technique
No full textA new technique for the determination of the thermal diffusivity of a tyre compound is proposed. The diffusivity is defined as the ratio between the thermal conductivity and the product of the specific heat and density. This technique is based on infrared measurement and successive analysis of the tyre cooling. Tyre samples were heated up by a laser at constant power rate and the heating and the next cooling of the tyres were registered versus time by mean of thermocouples and infrared cameras. Determination of the thermal diffusivity was thus estimated by mean of home-made model.
The research activity was carried out in the laboratories of the department of Mechanics and Energetics of the University of Naples Federico II, in cooperation with the Combustion Institute of the CNR in Naples
A Glance at the World: Potential Benefits of Implementing Landfill Gas (LFG) Clean Development Mechanism (CDM) Projects at Waste Disposal Sites: Case Study for Implementation at Chunga Landfill Site in Lusaka, Zambia
No full textLandfilling has traditionally been the predominant waste management option in the developing world. Many of these landfill sites remain poorly managed which has led to serious negative impacts on human health and the local environment. Inadequate financing has been cited as one of the major barrier that makes it difficult for many landfill owners/operators to operate and manage their sites in an appropriate manner. The often low gate fees charged for the disposal of waste at such sites does not provide sufficient funds to incorporate adequate environmental mitigation processes. Consequently, many sites are operated as “open dumps” or semi-managed dumpsites which have associated environmental problems such as unabated emissions of landfill gas (LFG) and leachate discharge. Furthermore, once landfilling operations have ceased, no financial provisions are made for “after-care” of the site. This is in stark contrast to the situation in Europe and other developed regions of the world.
The Clean Development Mechanism (CDM) provides an opportunity for developing countries to substantially improve landfill site operation. The implementation of landfill gas capture projects not only decreases the environmental impact of methane gas but can lead to improved site management practices. It is also an opportunity to generate additional revenue through carbon credits and when possible, through energy generation. This paper explores how CDM projects offer economic benefits to overcome financial barriers to landfill site operation in developing countries. A case study has been used to illustrate the potential benefits of implementing a landfill gas CDM project at the Chunga landfill site in Lusaka, Zambia. Baseline greenhouse gases (GHGs) emissions were estimated for the site. It was found that implementing a landfill gas CDM project would generate revenue amounting to more than 18% of the gate fees over a 7-year crediting period. This additional revenue could supplement the operator’s budget required for site management and mitigate the environmental impacts currently associated with the site
GRAPHITE COMBUSTION IN HIGH ENTHALPY SUPERSONIC FLOW
No full textThe paper reports on the set up of an experimental protocol for the investigation of high temperature (1500K<T<2500K) graphite combustion in supersonic flow conditions. Cylindrical graphite specimens (3mm D, 100mm L) are exposed to supersonic flow of
nitrogen/oxygen mixtures in a small Planetary Entry Simulator, equipped with a plasma torch. The impact of the gas flow on the specimen determines a very sharp temperature rise. A fast IR camera allows to realize two-dimensional maps of the specimen temperature throughout the experiment. IR thermal images can also be of help to rebuild the consumption of the graphite rod. Results are checked against the sample weight loss and used to estimate the rate of carbon combustion and the oxygen concentration in the freestream
REALIZZAZIONE DI UN COMBUSTORE A METANO COME SORGENTE CALDA PER UNA GALLERIA IPERSONICA
No full textLa SPES (Small Planetary Entry Simulator) è una galleria ad arco in esercizio da lungo tempo presso il Laboratorio di Aerotermodinamica del DIAS di Napoli. I principali componenti di SPES sono un riscaldatore ad arco elettrico (torcia al plasma industriale, Sulzer-Metco tipo-9-M) operante con azoto puro, una camera di miscelazione in cui il plasma di azoto può essere miscelato con gas freddi per simulare atmosfere planetarie (ad es. ossigeno, anidride carbonica, metano) ; alcuni ugelli conici (rapporto di area 4, 20, 56, 100) per il funzionamento in regime supersonico/ipersonico; una camera cilindrica sottovuoto. Per le tipiche applicazioni di simulazione di condizioni di rientro atmosferico si hanno i seguenti valori dei parametri di impianto : Portata di massa: 1 g/s - Entalpia totale media : 15 MJ / kg - Pressione totale: 0,5 x 105 Pa. Recentemente abbiamo previsto la possibilità di modificare SPES per applicazioni energetiche e di qualifica di materiali ad alta temperatura di esercizio, che comportano portate massiche più alte ed entalpie totali più basse, in particolare:
Portata di massa : 10-100 g / s - entalpia totale media : 2 - 5 MJ / kg - Pressione totale: 0.1 - 1 MPa
La generazione di questi nuovi valori implica la sostituzione della torcia a plasma con un combustore. Inoltre, e’ necessario potenziare il sistema di vuoto, a causa delle portate massiche molto maggiori, e prevedere un sistema di abbattimento degli inquinanti. Il combustore progettato è equipaggiato con un bruciatore derivato da applicazioni per microturbine. Il combustibile utilizzato è il metano per le sue buone proprietà energetiche unite ad un utilizzo abbastanza sicuro e alla disponibilità a basso costo. L’aria per la combustione viene fornita da un serbatoio da 4,5 m3 caricato a 3 MPa. Le prove preliminari sono state eseguite a pressione totale di 0.4 MPa e temperatura totale di 1300 K, fornendo buoni risultati in termini di stabilità di funzionamento
- …
