Surface tension and solution evaporation of aqueous solutions of sodium lauryl sulfate (SLS), ECOSURF™ EH-14, and ECOSURF™ SA-9 under natural convection is examined through experimental methods. SLS is an anionic surfactant while EH-14 and SA-9 are environmentally-friendly nonionic surfactants. Surfactants are known to affect evaporation performance of solutions and are studied in relation to water loss prevention and heat dissipation. Surfactants could be useful under drought conditions which present challenges to water management on a yearly basis in arid areas of the world. Recent water scarcity in the greater Los Angeles area, south eastern Africa nations, eastern Australia and eastern Mediterranean countries has high cost of water loss by evaporation. Surfactants are studied as a potential method of suppressing evaporation in water reservoirs. Surfactants are also studied as performance enhancers for the working fluid of heat dissipation devices, such as pulsating heat pipes used for electronics cooling. Some surfactants have been shown to lower thermal resistances and friction pressure in such devices and thereby increase their efficiency. The static surface tensions of the aqueous-surfactant solutions are measured with surface tensiometer using Wilhelmy plate method. The surfactants are shown to lower surface tension significantly from pure water. The surface tension values found at the Critical Micelle Concentration are 33.8 mN/m for SLS, 30.3 mN/m for EH-14, and 30.0 mN/m for SA-9. All three surfactants reduced natural convection water loss over 5 days with SLS showing the greatest effect on evaporation rates. The maximum evaporation reduction by each surfactant from distilled water with no surfactants after 5 days is 26.1% for SLS, 20.8% for EH-14, and 18.4% for SA-9.

A steady state model of a supercritical organic Rankine cycle (SORC) was created in MATLAB and validated. Fluid properties were obtained using NIST REFPROP. Various working fluids were tested, including pentane (R601), isopentane (R601a), butane (R600), isobutane (R600a), butene, and cis-butene. Pentane and isopentane have not been of focus for SORCS at these temperatures. Varying turbine inlet temperatures ranging from 170 to 240°C were tested with the heat source provided by a medium temperature geothermal reservoir. A parametric analysis was performed on varying inlet pressure and turbine inlet temperature in comparison to first law efficiency, second law efficiency, effectiveness, and net work produced to analyze the overall and exergetic performance of each fluid. Optimum first law efficiency ranged from 17 to 22%. Cis-butene and pentane performed the best in all performance factors analyzed. Pentane and isopentane performed the best at pressures near or below their critical point. It was also found that near the critical temperature, a subcritical ORC has better performance than an SORC. This study is beneficial for not only geothermal energy but for applications that can provide operating temperatures between 170 to 240°C.

Evaporation process is a crucial part of many fundamental industrials and medicals process. This paper numerically model a novel method of steam generation and enhanced evaporation using solar thermal energy. In this model, a capillary-raised fluid flows through a porous medium under localized heating condition, and the phase change from liquid to vapor at the liquid-vapor interface occurs. The hydrophilic porous material facilitates the capillary forces for better transportation of the bulk water through the porous media to the surface of porous media where the absorbed solar energy deliver to the amount of water inside the pores. The high capillary force due to the micro size inter connected pores inside the medium will rise the fluid from the cold bulk reservoir and the highly concentrated solar radiation focused inside the medium will evaporates the liquid very effectively. Based on this approach, the absorbed solar energy is delivered into the specific small pores of porous media that initiate the localized evaporation process. The steam generated from this economical technique could be used greatly for thermal solar desalinations process, sterilization process, etc. A CAD model of such porous media was developed using SolidWorks package. The mesh will be generated on the CAD file and the model was imported into the ANSYS Fluent for solving the governing equations. The mass transfer along with the fluid flow and heat transfer then solved. The simulations were done under different conditions including the hour distribution of irradiation in an average summer day and winter day to estimate steam generation rate. Produced vapor were from 13.96 kg/m 2 to 18.95 kg/m 2 in typical summer and winter days, respectively. The results show a temperature changes between 26.9°C and 54.4 °C. Development of the 3D numerical model and its implementation in existing data facilitates better understanding of the transport phenomena through the porous media.

Many power plants in the Electric Reliability Council of Texas (ERCOT) region require a large amount of water for system cooling. To improve the understanding of potential risks of electricity generation curtailment due to drought, an assessment of water availability and its potential impacts on generation during drought was performed. For this impact analysis, we identified three drought scenarios based on historical drought records and projected climate data from the Geophysical Fluid Dynamics Laboratory global climate model, for greenhouse gas emission scenario A2 defined by the Intergovernmental Panel on Climate Change. The three drought scenarios are (1) 2011 drought conditions (the worst drought in history), with the current level of water use; (2) a single-year drought (2022) projected for the period of 2020–2030, with the assumed projected water use level for 2030; and (3) a multiple-year drought constructed with climate data for 1950–1957 and water demand projected for 2030. The projected drought scenario in 2022 and the historical droughts in 2011 and 1950–1957 represent two different precipitation patterns in the Texas-Gulf river basin. The hydrologic model constructed for the Texas-Gulf river basin covers most of the ERCOT region. The model incorporates climate and water use data that correspond to three drought scenarios, respectively, to estimate evapotranspiration, water yield from watersheds, stream flow and water storage in reservoirs. Using criteria based on observed (< 50% storage) and predicted (< 55% storage) reservoir data, we identified 15 low-storage reservoirs in 2011, 10 in 2022, and 20 in 1956 (the last year of the multiple-year drought). The power plants that are supported by these reservoirs would be potentially at risk of being derated for thermoelectric cooling because of a lack of water supply. These power plants are located mainly in watersheds near and between Houston and Austin, as well as surrounding Dallas.

Presently, the typical gas turbine based power generator relies on a large, expensive skid system to provide lubrication to the bearings. These skids consist of a large number of expensive components, many of which require maintenance that drives operating cost and creates environmental hazards. A smart lube system based on recently developed technology enables dramatic simplification and cost reduction of the skid system and significantly reduces oil consumption along with the frequency and cost of maintenance. Such a system would take advantage of the availability of advanced pump system controls and fluid nozzle technology to drastically reduce the quantity of oil required, and the resultant heat rejection. As a result, the sizes of reservoir, cooler, filter and piping are greatly reduced. The cost of components, support equipment and maintenance activities will also be reduced to a fraction of their present values.

Methane hydrate dissociation is studied using numerical and experimental approaches for a low carbon dioxide (CO 2 ) emission power generation system utilizing methane hydrate. A novel power generation system has been proposed by authors, in which methane gas produced from oceanic methane hydrate reservoir by thermal stimulation method is used as fuels. The performance of the power generation system and the heat loss during the injection of hot seawater to the methane hydrate layer were investigated in previous study. However, the estimation of the methane gas production rate from the methane hydrate reservoir is necessary to evaluate the performance of whole system. In this study, we conducted the numerical simulation of methane hydrate reservoir. In order to evaluate the reaction rate of methane hydrate dissociation, the methane hydrate formation and dissociation experiment was conducted. The result of numerical simulation indicates the necessity of improvement of the production process to supply the heat of hot water effectively. From the experimental result, it comes to see that consideration of the scale effect of the methane hydrate construction is necessary to describe the dissociation rate.

A series of laboratory experiments on self-circulating thermosyphon (SCT) was carried out. The thermosyphon system consists of heating section, condenser, reservoir, and heat exchanging section. The basic performance was elucidated. The present thermosyphon system works by itself under certain conditions of tilting angle of the condenser, the water filling rate, and the input power. The startup time of the present system is remarkably improved. The effect of the buoyancy on the driving force is indicated through the tilting angle of the condenser.

A simulation model of the hydraulic system of a hydroelectric power plant is developed and implemented in a real time simulator. The main purpose of the simulator is to test the performance of actual governor control systems using hardware-in-the-loop techniques, in which the actual governor control system is connected to a real time simulator instead of being connected to real equipment. This paper focuses on the modeling of the hydraulic system to be implemented in the simulator. The model consists of an unrestricted reservoir, conduits to transport water, and a turbine to convert the potential energy of the fluid into mechanical power. A nonlinear mathematical model for a non-elastic water column is implemented. Effects due to a surge tank and to various turbines connected to a common tunnel are included in the model by considering head and flow variations at the junction of the common tunnel and the individual penstocks. The model is evaluated by comparing results from simulations with field tests from a four-unit hydroelectric power plant (55 MW per unit). Comparisons show that the model reproduces the general behavior of the field tests. However some deviations are observed during the transient response, in particular the simulation results appear to respond faster than field data.

A model of a Hybrid Power Plant (HPP) consisting of Compressed Air Energy Storage (CAES) coupled with a wind farm is presented. This kind of plant aims at overcoming some of the major limitations of wind-generated power plants, including low power density and an intermittent nature owing to variable weather conditions. In CAES, energy is stored in the form of compressed air in a reservoir during off-peak periods and used on demand during peak periods to generate power with a turbo-generator system. Such plants can offer significant benefits in terms of flexibility in matching a fluctuating power demand, particularly when coupled with wind turbines. For the hybrid power plant considered in this study, results show that advantages in terms of economics, energy savings and CO 2 mitigation can be achieved.