Forced convective, nonequilibrium post-CHF heat transfer data (766 points) have been obtained at ... more Forced convective, nonequilibrium post-CHF heat transfer data (766 points) have been obtained at high pressure and low mass flux ranges not previously tested. The data are unique in that the superheated vapor temperature was measured at multiple elevations allowing the direct calculation of vapor generation rates. The data are useful for verification or development of nonequilibrium heat and mass transfer models. Current film boiling heat transfer correlations do not predict the data well. The Dougall-Rohsenow equilibrium correlation is the only one investigated that reasonably predicts the measured wall heat fluxes. Current vapor generation rate models do not adequately predict the measured vapor generation rates.
Geothermal energy piles are an environmentally friendly energy source and an innovative approach ... more Geothermal energy piles are an environmentally friendly energy source and an innovative approach to melt snow on the bridge surface and minimize or eliminate the use of deicing salt. However, the application potential of energy piles for bridge deicing or snow melting has not been fully explored for different climates. In this study, the feasibility of using energy piles for bridge deicing in eight cities of the United States was investigated. Temperature response function (G function) method was validated and used to estimate the extracted heat from energy piles installed in the soils with different thermal properties, which was used to heat the bridge deck during snowing. The results of numerical simulation and statistical analysis confirm that the performance of the geothermal deicing system depends on the weather conditions during snowing and thermal properties of soils. The coverage rate of the geothermal system (percentage of snowing time that the geothermal deicing system can keep the bridge surface above 0°C) increases with the increasing air temperature and thermal diffusivities of soils, and decreases with the increasing precipitation rate and wind speed. This deicing method is promising in cities with higher average air temperature and low precipitation rate during snowing.
A supplemental main steam condenser cooling system is under development, which utilizes a phase c... more A supplemental main steam condenser cooling system is under development, which utilizes a phase change material (PCM). This PCM rejects heat to the cool atmosphere at night until it is fully frozen. The frozen PCM is available for condenser cooling during peak daytime electric demand. Three calcium chloride hexahydrate (CaCl2·6H2O)-based PCMs were selected for development after being characterized using differential scanning calorimetry (DSC). Additives to minimize supercooling and phase separation have demonstrated good performance after long and short-term thermal cycling. Corrosion testing under both isothermal and cycling conditions was conducted to determine long-term compatibility between several common metals and the selected PCMs. Several metals were demonstrated to have acceptably low corrosion rates for long-term operation, despite continual immersion in the selected hydrated salts. A system optimization model was developed, which utilizes a 3D modeling approach called the Layered Thermal Resistance (LTR) model. This model efficiently models the nonlinear, transient solidification process by applying analytic equations to layers of PCM. Good agreement was found between this model and more traditional computational fluid dynamics (CFD) modeling. Next phases of the work includes prototype testing and a techno-economic analysis of the technology.
Forced convective, postcritical heat flux heat transfer experiments with water flowing upward in ... more Forced convective, postcritical heat flux heat transfer experiments with water flowing upward in a vertical tube have been conducted at the Idaho National Engineering Laboratory. Thermodynamic nonequilibrium in the form of superheated vapor temperatures was measured at a maximum of three different axial levels. Steady state experiments were conducted at pressures of 0.2 to 0.7 MPa, mass fluxes of 12
Forced-convective postcritical heat flux (CHF) heat transfer data have been obtained at low flow ... more Forced-convective postcritical heat flux (CHF) heat transfer data have been obtained at low flow rates and low pressures (0.2 to 0.7 MPa) for water flowing in a vertical tube. Significant magnitudes of superheat (up to 510 K) were found. The steady state data are in agreement with other reported low-flow and low-pressure nonequilibrium data. Nonequilibrium vapor temperatures were measured at
Two optical techniques for use in detecting liquid contacts in film and transition boiling regime... more Two optical techniques for use in detecting liquid contacts in film and transition boiling regimes were developed. The first optical method involves the measurements of liquid contacts on a high-temperature glass boiling surface in a transient experiment. The second technique utilizes a small fiber-optic probe mounted flush on a copper surface. Experiments have indicated the probe is sufficiently fast responding to provide accurate local measurements of liquid to solid contact in film and transition boiling regimes. The relationship between surface superheat and liquid contact time fraction was determined for both methods.
Forced convective, nonequilibrium post-CHF heat transfer data (766 points) have been obtained at ... more Forced convective, nonequilibrium post-CHF heat transfer data (766 points) have been obtained at high pressure and low mass flux ranges not previously tested. The data are unique in that the superheated vapor temperature was measured at multiple elevations allowing the direct calculation of vapor generation rates. The data are useful for verification or development of nonequilibrium heat and mass transfer models. Current film boiling heat transfer correlations do not predict the data well. The Dougall-Rohsenow equilibrium correlation is the only one investigated that reasonably predicts the measured wall heat fluxes. Current vapor generation rate models do not adequately predict the measured vapor generation rates.
Geothermal energy piles are an environmentally friendly energy source and an innovative approach ... more Geothermal energy piles are an environmentally friendly energy source and an innovative approach to melt snow on the bridge surface and minimize or eliminate the use of deicing salt. However, the application potential of energy piles for bridge deicing or snow melting has not been fully explored for different climates. In this study, the feasibility of using energy piles for bridge deicing in eight cities of the United States was investigated. Temperature response function (G function) method was validated and used to estimate the extracted heat from energy piles installed in the soils with different thermal properties, which was used to heat the bridge deck during snowing. The results of numerical simulation and statistical analysis confirm that the performance of the geothermal deicing system depends on the weather conditions during snowing and thermal properties of soils. The coverage rate of the geothermal system (percentage of snowing time that the geothermal deicing system can keep the bridge surface above 0°C) increases with the increasing air temperature and thermal diffusivities of soils, and decreases with the increasing precipitation rate and wind speed. This deicing method is promising in cities with higher average air temperature and low precipitation rate during snowing.
A supplemental main steam condenser cooling system is under development, which utilizes a phase c... more A supplemental main steam condenser cooling system is under development, which utilizes a phase change material (PCM). This PCM rejects heat to the cool atmosphere at night until it is fully frozen. The frozen PCM is available for condenser cooling during peak daytime electric demand. Three calcium chloride hexahydrate (CaCl2·6H2O)-based PCMs were selected for development after being characterized using differential scanning calorimetry (DSC). Additives to minimize supercooling and phase separation have demonstrated good performance after long and short-term thermal cycling. Corrosion testing under both isothermal and cycling conditions was conducted to determine long-term compatibility between several common metals and the selected PCMs. Several metals were demonstrated to have acceptably low corrosion rates for long-term operation, despite continual immersion in the selected hydrated salts. A system optimization model was developed, which utilizes a 3D modeling approach called the Layered Thermal Resistance (LTR) model. This model efficiently models the nonlinear, transient solidification process by applying analytic equations to layers of PCM. Good agreement was found between this model and more traditional computational fluid dynamics (CFD) modeling. Next phases of the work includes prototype testing and a techno-economic analysis of the technology.
Forced convective, postcritical heat flux heat transfer experiments with water flowing upward in ... more Forced convective, postcritical heat flux heat transfer experiments with water flowing upward in a vertical tube have been conducted at the Idaho National Engineering Laboratory. Thermodynamic nonequilibrium in the form of superheated vapor temperatures was measured at a maximum of three different axial levels. Steady state experiments were conducted at pressures of 0.2 to 0.7 MPa, mass fluxes of 12
Forced-convective postcritical heat flux (CHF) heat transfer data have been obtained at low flow ... more Forced-convective postcritical heat flux (CHF) heat transfer data have been obtained at low flow rates and low pressures (0.2 to 0.7 MPa) for water flowing in a vertical tube. Significant magnitudes of superheat (up to 510 K) were found. The steady state data are in agreement with other reported low-flow and low-pressure nonequilibrium data. Nonequilibrium vapor temperatures were measured at
Two optical techniques for use in detecting liquid contacts in film and transition boiling regime... more Two optical techniques for use in detecting liquid contacts in film and transition boiling regimes were developed. The first optical method involves the measurements of liquid contacts on a high-temperature glass boiling surface in a transient experiment. The second technique utilizes a small fiber-optic probe mounted flush on a copper surface. Experiments have indicated the probe is sufficiently fast responding to provide accurate local measurements of liquid to solid contact in film and transition boiling regimes. The relationship between surface superheat and liquid contact time fraction was determined for both methods.
Uploads
Papers by S Neti