Analysis of heat transfer during glass forming

Α thermal model is described which is intended to simulate internal heat transfer in glass being cooled by the mold and plunger after pressing. The heat transfer analysis in glass accounts for the spectral nature of radiation, the dependence of the thermophysical properties of glass on temperature and the contact heat transfer between mold and glass as well as plunger and glass during and after pressing. Heat exchange between glass and mold as well as plunger across a very small gap by contact conduction and thermal radiation are also accounted for. To assess the utility of the Rosseland diffusion approximation for radiative transfer, the results are compared with those based on rigorous formulation of radiative transfer. Numerical solutions have been obtained for typical condidons simulating symmetric and asymmetric cooling as well as cyclic operation, and the results are presented and discussed. During the dwell time thermal contact conduction between the glass and the mold as well as plunger is the dominant heat extraction mechanism from the glass. Results show that radiation from the surface of the glass plays a relatively small part in the heat extraction process, but radiation from the interior of the glass is much more significant but less important than thermal contact conduction

Flame Radiation, Structure, and Scalar Properties in Microgravity Laminar Fires

Results from microgravity combustion experiments conducted in the Zero Gravity Research Facility (ZGF) 5.18 second drop facility are reported. The results quantify flame radiation, structure, and scalar properties during the early phase of a microgravity fire. Emission mid-infrared spectroscopy measurements have been completed to quantitatively determine the flame temperature, water and carbon dioxide vapor concentrations, radiative emissive power, and soot concentrations in microgravity laminar methane/air, ethylene/nitrogen/air and ethylene/air jet flames. The measured peak mole fractions for water vapor and carbon dioxide are found to be in agreement with state relationship predictions for hydrocarbon/air combustion. The ethylene/air laminar flame conditions are similar to previously reported results including those from the flight project, Laminar Soot Processes (LSP). Soot concentrations and gas temperatures are in reasonable agreement with similar results available in the literature. However, soot concentrations and flame structure dramatically change in long-duration microgravity laminar diffusion flames as demonstrated in this report

A Cost Effective Multi-Spectral Scanner for Natural Gas Detection

The objective of this project is to design, fabricate and demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first year of the project, a laboratory version of the multi-spectral scanner was designed, fabricated, and tested at EnUrga Inc. The multi-spectral scanner was also evaluated using a blind Department of Energy study at the Rocky Mountain Oilfield Testing Center. The performance of the scanner was inconsistent during the blind study. However, most of the leaks were outside the view of the multi-spectral scanner that was developed during the first year of the project. Therefore, a definite evaluation of the capability of the scanner was not obtained. Despite the results, sufficient number of plumes was detected fully confirming the feasibility of the multi-spectral scanner. During the second year, the optical design of the scanner was changed to improve the sensitivity of the system. Laboratory tests show that the system can reliably detect small leaks (20 SCFH) at 30 to 50 feet. A prototype scanner was built and evaluated during the second year of the project. Only laboratory evaluations were completed during the second year. The laboratory evaluations show the feasibility of using the scanner to determine natural gas pipeline leaks. Further field evaluations and optimization of the scanner are required before commercialization of the scanner can be initiated

A study of the effects of preheat and steam addition on the flame structure and NO formation in laminar counterflow flames

An experimental and numerical study has been conducted to examine the effects of air-preheat and steam addition on flame structure and NO formation in laminar counterflow flames. The measurements for NO and major species were performed using a sampling technique and theoretical predictions were carried out using the OPPDIF code with GRI MECH 2.11. The major species predictions for diffusion and partially premixed laminar flames show good agreement with the measurements. For C2 species, the predictions showed significant over-estimate for all experimental conditions. The predictions for NO in the diffusion flames show good agreement with the measurements of the peak mole fraction. However, significant over-predictions were found on the fuel-rich side of the diffusion flames. The agreement improves with increasing levels of partial premixing and excellent match is obtained for the highest levels of partial premixing. Detailed effects of air-preheat and steam addition on the flames were studied using numerical simulations. Preheat of air increases CO concentration and decreases CO2 concentration by enhancing dissociation of CO 2. The NO formation increased by two-fold with an increase of air-preheat from 300 K to 560 K. This increase of NO is the result of the increase in the rate of prompt initiation reaction. Steam addition into diffusion and partially premixed flames causes an increase in OH radical concentrations and a decrease in H atom concentrations. The increased OH and decreased H atom concentration enhance CO oxidation. Steam addition significantly reduces NO formation by reducing CH concentrations in diffusion and partially premixed flames. The CH concentration decreases via direct combination with the abundant H2O with steam addition. State relationships independent of scalar dissipation rates were established from the measurements with air-preheat. The air-preheat increases scatter in the CO and H2 mole fraction profiles. Independent of the level of steam addition and scalar dissipation rates, the state relationships were obtained for CH4, O2 and N2. However, the state relationships for CO, CO2 and H2 must be obtained for each level of steam addition, but are still independent of the scalar dissipation rates

A COST EFFECTIVE MULTI-SPECTRAL SCANNER FOR NATURAL GAS DETECTION

The objective of this project is to design, fabricate and field demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first six months of the project, the design for a laboratory version of the multispectral scanner was completed. The optical, mechanical, and electronic design for the scanner was completed. The optical design was analyzed using Zeemax Optical Design software and found to provide sufficiently resolved performance for the scanner. The electronic design was evaluated using a bread board and very high signal to noise ratios were obtained. Fabrication of a laboratory version of the multi-spectral scanner is currently in progress. A technology status report and a research management plan was also completed during the same period

Fan Beam Emission Tomography for Estimating Scalar Properties in Laminar Flames

A new method of estimating temperatures and gas species concentrations (CO2 and H2O) in a laminar flame is reported. The path-integrated, spectral radiation intensities emitted from a laminar flame at multiple wavelengths and view angles are calculated using a narrow band radiation model. Synthetic data, in the form of radial profiles of temperature and gas concentrations, are used in these calculations. The calculations mimic measurements that would theoretically be obtained using a mid-infrared spectrometer with a scanner. The path integrated spectral radiation intensities are deconvoluted using a maximum likelihood estimation method in conjunction with an iterative scheme. The deconvolution algorithm accounts for the self-absorption of radiation by the intervening gases, and provides the local temperature and gas species concentrations. The deconvoluted temperatures and gas concentrations are compared with the synthetic data used for calculating the spectral radiation intensities. The deconvoluted temperatures and gas species concentrations are within 0.5 % of the synthetic data. The deconvolution algorithm is expected to provide combustion researchers with an easy method of obtaining the radial profiles of major gas species concentrations and temperatures in laminar flames non-intrusively using a mid-infrared spectrometer with a scanner

Fan Beam Emission Tomography for Laminar Fires

Obtaining information on the instantaneous structure of turbulent and transient flames is important in a wide variety of applications such as fire safety, pollution reduction, flame spread studies, and model validation. Durao et al. has reviewed the different methods of obtaining structure information in reacting flows. These include Tunable Laser Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy, and Emission Spectroscopy to mention a few. Most flames emit significant radiation signatures that are used in various applications such as fire detection, light-off detection, flame diagnostics, etc. Radiation signatures can be utilized to maximum advantage for determining structural information in turbulent flows. Emission spectroscopy is most advantageous in the infrared regions of the spectra, principally because these emission lines arise from transitions in the fundamental bands of stable species such as CO2 and H2O. Based on the above, the objective of this work was to develop a fan beam emission tomography system to obtain the local scalar properties such as temperature and mole fractions of major gas species from path integrated multi-wavelength infrared radiation measurements