Download or read book Heat Transfer and Fluid Transport of Supercritical CO2 in Enhanced Geothermal System with Local Thermal Non equilibrium Model written by and published by . This book was released on 2014 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The heat transfer and fluid transport of supercritical CO2 in enhanced geothermal system (EGS) is studied numerically with local thermal non-equilibrium model, which accounts for the temperature difference between solid matrix and fluid components in porous media and uses two energy equations to describe heat transfer in the solid matrix and in the fluid, respectively. As compared with the previous results of our research group, the effect of local thermal non-equilibrium mainly depends on the volumetric heat transfer coefficient ah, which has a significant effect on the production temperature at reservoir outlet and thermal breakthrough time. The uniformity of volumetric heat transfer coefficient ah has little influence on the thermal breakthrough time, but the temperature difference become more obvious with time after thermal breakthrough with this simulation model. The thermal breakthrough time reduces and the effect of local thermal non-equilibrium becomes significant with decreasing ah.

Download or read book Enhanced Geothermal Systems EGS with CO2 as Heat Transmission Fluid A Scheme for Combining Recovery of Renewable Energy with Geologic Storage of CO2 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: It has been suggested that enhanced geothermal systems (EGS) may be operated with supercritical CO2 instead of water as heat transmission fluid (D.W. Brown, 2000). Such a scheme could combine recovery of geothermal energy with simultaneous geologic storage of CO2, a greenhouse gas. At geothermal temperature and pressure conditions of interest, the flow and heat transfer behavior of CO2 would be considerably different from water, and chemical interactions between CO2 and reservoir rocks would also be quite different from aqueous fluids. This paper summarizes our research to date into fluid flow and heat transfer aspects of operating EGS with CO2. (Chemical aspects of EGS with CO2 are discussed in a companion paper; Xu and Pruess, 2010.) Our modeling studies indicate that CO2 would achieve heat extraction at larger rates than aqueous fluids. The development of an EGS-CO2 reservoir would require replacement of the pore water by CO2 through persistent injection. We find that in a fractured reservoir, CO2 breakthrough at production wells would occur rapidly, within a few weeks of starting CO2 injection. Subsequently a two-phase water-CO2 mixture would be produced for a few years, followed by production of a single phase of supercritical CO2. Even after single-phase production conditions are reached, significant dissolved water concentrations will persist in the CO2 stream for many years. The presence of dissolved water in the production stream has negligible impact on mass flow and heat transfer rates.

Download or read book Low Temperature Enhanced Geothermal System Using Carbon Dioxide as the Heat Transfer Fluid written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes work toward a supercritical CO2-based EGS system at the St. Johns Dome in Eastern Arizona, including a comprehensive literature search on CO2-based geothermal technologies, background seismic study, geological information, and a study of the possible use of metal oxide heat carriers to enhance the heat capacity of sCO2. It also includes cost estimates for the project, and the reasons why the project would probably not be cost effective at the proposed location.

Download or read book Transcritical CO2 Heat Pump written by Xin-rong Zhang and published by John Wiley & Sons. This book was released on 2021-02-17 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: A timely and comprehensive introduction to CO2 heat pump theory and usage A comprehensive introduction of CO2 application in heat pump, authored by leading scientists in the field CO2 is a hot topic due to concerns over global warming and the 'greenhouse effect'. Its disposal and application has attracted considerable research and governmental interest Explores the basic theories, devices, systems and cycles and real application designs for varying applications, ensuring comprehensive coverage of a current topic CO2 heat transfer has everyday applications including water heaters, air-conditioning systems, residential and commercial heating systems, and cooling systems

Download or read book Flow and Heat Transfer in Geothermal Systems written by Aniko Toth and published by Elsevier. This book was released on 2016-10-11 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow and Heat Transfer in Geothermal Systems: Basic Equations for Description and Modeling Geothermal Phenomena and Technologies is the ideal reference for research in geothermal systems and alternative energy sources. Written for a wide variety of users, including geologists, geophysicists, hydro-geologists, and engineers, it offers a practical framework for the application of heat and flow transport theory. Authored by two of the world's foremost geothermal systems experts, whose combined careers span more than 50 years, this text is a one-stop resource for geothermal system theory and application. It will help geoscientists and engineers navigate the wealth of new research that has emerged on the topic in recent years. - Presents a practical and immediately implementable framework for understanding and applying heat and flow transport theory - Features equations for modelling geothermal phenomena and technologies in full detail - Provides an ideal text for applications in both geophysics and engineering

Download or read book Technical Feasibility of Utilization of Carbon Dioxide as a Heat Transfer Medium for Geothermal Energy Extraction in Indonesia Based on Simulation Studies written by Fabiola Pardede and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a need to generate clean, sustainable power to meet the current demand in Indonesia. The current capacity only meets 86.4% of population demand even though Indonesia is ranked 10th in global coal reserves and 4th in geothermal potential. According to Indonesias 35,000 MW power plan, the government is making an effort to increase energy consumption from coal and renewable energy by 2025. Coal and biomass power plants play an important role in the generation of electricity in Indonesia. Approximately 25% of Indonesias energy consumption is from coal, and power generation is continually moving towards cleaner methods, such as gasification and utilization of renewable energy. Due to high volcanic and tectonic activities, it is predicted that more than 27,000 MW of potential untapped geothermal energy is available in Indonesia. Combining several of the most advanced clean technologies could change the foreseeable focus of power generation methods. Coal-based, gasification combined cycle power plants integrated with supercritical carbon dioxide (CO2)-based geothermal systems could potentially generate electricity with high efficiency and low carbon emissions, without the intermittency associated with solar and wind power.There is an increased need for carbon dioxide sequestration from fossil fuel plants, due to rapid increase in atmospheric CO2 levels. Ready-to-sequester carbon dioxide is available from a coal based, Integrated Gasification Combined Cycle (IGCC) power plant with high efficiency. This CO2, while being sequestered, can also be used as a heat transfer medium in a geothermal power generation system in Indonesia. This thesis examines the novel concept of utilizing CO2 from a coal-based IGCC power plant as a heat transfer medium to extract renewable geothermal energy in order to offset the energy required for compression in the CO2 sequestration process. The Darajat geothermal field in Indonesia has a high reservoir temperature that is available at relatively shallow depths. Based on earlier work, it is assumed that 10% of the carbon dioxide is sequestered within the reservoir while drawing thermal energy from a 2.6 km depth, to generate power using a direct CO2 turbine and a binary power plant. All 680 kg/s of supercritical CO2 are distributed evenly among 10 injection wells in the reservoir to be used as a heat transfer medium, and for partial sequestration. The carbon dioxide stream from the 10 production wells and the compressed supercritical CO2 from the IGCC plant are recirculated back to the injection wells. Heat rejection from the CO2 produced is accepted by the Organic Rankine Cycle to generate power. The IGCC plant CO2 output from the pre-combustion and post-combustion processes is matched with the amount of CO2 sequestered to maintain constant circulation for the geothermal plant. ASPEN Plus software was used to simulate the geothermal power plant, circulation system, carbon dioxide heat extraction from the reservoir, and each fluid necessary to drive a closed loop Organic Rankine Cycle.Among the working fluids examined, isobutane, n-butane, R134a, and R245fa, the most suitable for the Darajat system, which has a 200C reservoir temperature, was isobutane. This study also discusses the energy generated from a carbon dioxide turbine and a recuperated Organic Rankine Cycle by varying the temperatures and pressures of carbon dioxide injection based on an existing Darajat geothermal reservoir located in Indonesia. Power generated by a direct CO2 turbine and a binary power plant is compared with the 17.4 MW of power required to compress the CO2 for sequestration. CO2 utilization in the supercritical phase is found to be more advantageous than subcritical CO2 for power generation when using a direct CO2 turbine. A deeper, 3.6 km injection point for the Darajat-Enhanced Geothermal System yields 18.3 MW with approximately 15 years of lifetime, while a natural Darajat geothermal system with the existing wells can potentially improve the technical feasibility with a larger CO2 flow rate for additional power generation.

Download or read book Recent Advancement of Thermal Fluid Engineering in the Supercritical CO2 Power Cycle written by Jeong Ik Lee Ik Lee and published by . This book was released on 2020-10 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Special Issue is a compilation of the recent advances in thermal fluid engineering related to supercritical CO2 power cycle development. The supercritical CO2 power cycle is considered to be one of the most promising power cycles for distributed power generation, waste heat recovery, and a topping cycle of coal, nuclear, and solar thermal heat sources. While the cycle benefits from dramatic changes in CO2 thermodynamic properties near the critical point, design, and analysis of the power cycle and its major components also face certain challenges due to the strong real gas effect and extreme operating conditions. This Special Issue will present a series of recent research results in heat transfer and fluid flow analyses and experimentation so that the accumulated knowledge can accelerate the development of this exciting future power cycle technology.

Download or read book Geoenergy Modeling I written by Norbert Böttcher and published by Springer. This book was released on 2016-06-27 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: This introduction to geothermal modeling deals with flow and heat transport processes in porous and fractured media related to geothermal energy applications. Following background coverage of geothermal resources and utilization in several countries, the basics of continuum mechanics for heat transport processes, as well as numerical methods for solving underlying governing equations are discussed. This examination forms the theoretical basis for five included step-by-step OpenGeoSys exercises, highlighting the most important computational areas within geothermal resource utilization, including heat diffusion, heat advection in porous and fractured media, and heat convection. The book concludes with an outlook on practical follow-up contributions investigating the numerical simulation of shallow and deep geothermal systems.

Download or read book Mathematical modeling of fluid flow and heat transfer in geothermal systems an introduction in five lectures written by Karsten Pruess and published by . This book was released on 2002 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Enhanced Geothermal Systems EGS Using CO2 as Working Fluid Anovelapproach for Generating Renewable Energy with Simultaneoussequestration of Carbon written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Responding to the need to reduce atmospheric emissions of carbon dioxide, Donald Brown (2000) proposed a novel enhanced geothermal systems (EGS) concept that would use CO2 instead of water as heat transmission fluid, and would achieve geologic sequestration of CO2 as an ancillary benefit. Following up on his suggestion, we have evaluated thermophysical properties and performed numerical simulations to explore the fluid dynamics and heat transfer issues in an engineered geothermal reservoir that would be operated with CO2. We find that CO2 is superior to water in its ability to mine heat from hot fractured rock. CO2 also has certain advantages with respect to wellbore hydraulics, where larger compressibility and expansivity as compared to water would increase buoyancy forces and would reduce the parasitic power consumption of the fluid circulation system. While the thermal and hydraulic aspects of a CO2-EGS system look promising, major uncertainties remain with regard to chemical interactions between fluids and rocks. An EGS system running on CO2 has sufficiently attractive features to warrant further investigation.

Download or read book Coabsorbent and Thermal Recovery Compression Heat Pumping Technologies written by Mihail-Dan Staicovici and published by Springer Science & Business. This book was released on 2014-04-18 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces two of the most exciting heat pumping technologies, the coabsorbent and the thermal recovery (mechanical vapor) compression, characterized by a high potential in primary energy savings and environmental protection. New cycles with potential applications of nontruncated, truncated, hybrid truncated, and multi-effect coabsorbent types are introduced in this work. Thermal-to-work recovery compression (TWRC) is the first of two particular methods explored here, including how superheat is converted into work, which diminishes the compressor work input. In the second method, thermal-to-thermal recovery compression (TTRC), the superheat is converted into useful cooling and/or heating, and added to the cycle output effect via the coabsorbent technology. These and other methods of discharge gas superheat recovery are analyzed for single-, two-, three-, and multi-stage compression cooling and heating, ammonia and ammonia-water cycles, and the effectiveness results are given. The author presents absorption-related topics, including the divided-device method for mass and heat transfer analysis, and truncation as a unique method for a better source-task match. Along with advanced gax recovery, the first and second principles of COP and exergy calculation, the ideal point approaching (i.p.a.) effect and the two-point theory of mass and heat transfer, the book also addresses the new wording of the Laplace equation, the Marangoni effect true explanation, and the new mass and heat exchangers based on this effect. The work goes on to explore coabsorbent separate and combined cooling, heating, and power (CHP) production and advanced water-lithium bromide cycle air-conditioning, as well as analyzing high-efficiency ammonia-water heat-driven heating and industrial low-temperature cooling, in detail. Readers will learn how coabsorbent technology is based on classic absorption, but is more general. It is capable of offering effective solutions for all cooling and heating applications (industry, agriculture, district, household, etc.), provided that two supplying heat-sink sources with temperatures outdistanced by a minimum of 12-15oC are available. This book has clear and concise presentation and illustrates the theory and applications with diagrams, tables, and flowcharts.

Download or read book Supercritical CO2 Heat Transfer Study Near Critical Point in a Heated Circular Tube written by Akshay Khadse and published by . This book was released on 2020 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supercritical CO2 (sCO2) power cycle is an up-and-coming technology to produce electricity from various heat sources. Apart from power cycles, sCO2 can also be used as coolant in centralized cooling system and stand-alone cooling device. However, lack of accurate predication tools such as heat transfer coefficient correlations and insufficient knowledge behind fundamental heat transfer processes can hinder its practical realization in key energy and cooling systems. The overall objective of the study is to extend fundamental knowledge about heat transfer and fluid flow processes in conduits pertinent to sCO2 power cycle. The emphasis here is investigation of heat transfer effects of three testing parameters: heat flux, inlet mass flux and inlet temperature. Experimental setup for this heat transfer study is designed considering limitations due to high pressure rating requirements and thus follows unconventional approach to calculate heat transfer coefficient. Test section chosen is a horizontal stainless steel tubing of inner diameter of 9.4 mm and heated length of 1.23 m with uniform volumetric heat generation within tubing walls. The designed test apparatus and data reduction process are validated with high pressure air experiments. Nusselt numbers are calculated at top, bottom and sidewall locations to demonstrate effects of buoyancy. Enhancement of heat transfer at bottom wall surfaces and deterioration at top wall surfaces is observed as the main effect of buoyancy. It was observed that effects of buoyancy increase with heat flux and decrease with mass flux. Buoyancy effects are also decreased for fluid temperatures higher than pseudocritical temperature. Nusselt numbers calculated from experimental results are compared with Nusselt number from available correlations in literature. It is hinted that near critical region where property variations are significant, one correlation alone may not accurately predict heat transfer for different regimes of geometry, mass flux and heat flux.

Download or read book On the Production Behavior of Enhanced Geothermal Systems with CO2as Working Fluid written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical simulation is used to evaluate mass flow and heatextraction rates from enhanced geothermal injection-production systemsthat are operated using either CO2 or water as heat transmission fluid. For a model system patterned after the European hot dry rock experimentat Soultz, we find significantly greater heat extraction rates for CO2 ascompared to water. The strong dependence of CO2 mobility (=density/viscosity) upon temperature and pressure may lead to unusualproduction behavior, where heat extraction rates can actually increasefor a time, even as the reservoir is subject to thermal depletion. Wepresent the first-ever three-dimensional simulations of CO2injection-production systems. These show strong effects of gravity onmass flow and heat extraction, due to the large contrast of CO2 densitybetween cold injection and hot production conditions. The tendency forpreferential flow of cold, dense CO2 along the reservoir bottom can leadto premature thermal breakthrough. The problem can be avoided byproducing from only a limited depth interval at the top of thereservoir.

Download or read book Development and Validation of Multidimensional Models of Supercritical CO2 Energy Conversion Systems for Nuclear Power Reactors written by and published by . This book was released on 2015 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: A general objective of this project was to develop, verify and validate mechanistic multidimensional models of local flow and heat transfer in supercritical carbon dioxide (S-CO2) devices and systems, and to demonstrate the application of the new models to selected components of S-CO2 nuclear energy transport systems. Both steady-state and time-dependent operating conditions have been investigated. The overall workscope consisted of the following three major parts: Development, testing and validation of a mechanistic model of forced-convection heat transfer in heated channels cooled using S-CO2 at slightly supercritical pressures; Development, testing and verification/validation of a new model of the dynamics of closed- loop S-CO2 heat transport systems; and, Formulation, testing and verification of a mechanistic model for the analysis of flow and pressure distribution in S-CO2 compressors. The results of the work performed for the project have been documented in several publications.

Download or read book Experimental Investigation of Supercritical Heat Transfer of Carbon Dioxide in Parallel Square Microchannels with a Single Wall Constant Heat Flux Boundary Condition written by Kyle R. Zada and published by . This book was released on 2017 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the vicinity of the pseudocritical point, supercritical carbon dioxide (sCO2) undergoes a steep change in properties from “liquid-like” to “gas-like” as it is heated at a constant pressure. At the same time, there is a large spike in specific heat which can yield high heat transfer coefficients and heat capacity rates. These unique properties have made sCO2 an attractive working fluid in next generation power and HVAC&R technologies. Microchannel heat exchangers are being used to safely and efficiently utilize the high pressure fluid in these applications. However, prior investigation of heating of supercritical CO2 has primarily focused on circular, uniformly heated channels at relatively low heat flux for nuclear power applications. Thus, it is unclear if models and correlations developed from large circular tube data can be scaled down to the smaller, non-circular channels, with non-uniform heating. In the present work, a methodology is developed to experimentally characterize heat transfer for multiple parallel microchannels with a hydraulic diameter of 0.75 mm and aspect ratio of 1. Experiments are conducted over a range of heat fluxes (20 ≤ q” ≤ 40 W cm−2), mass fluxes (500 ≤ G ≤ 1000 kg m−2 s−1), reduced pressure (1.03 ≤ P[subscript R] ≤ 1.1), and inlet temperatures (20 ≤ T[subscript in] ≤ 100°C) in a parallel square microchannel test article with a single-wall constant heat flux boundary condition. Local and average heat transfer coefficients are experimentally measured and the results are compared to previously developed correlations. The predictive capabilities for the supercritical models were poor, with the lowest mean absolute percent error (MAPE) of 55.3% for the range of bulk fluid temperatures, heat fluxes, and mass fluxes. Interestingly, subcritical correlations were also investigated and yielded much lower MAPE than 80% of the supercritical correlations even though the effects of variable fluid properties were not taken into account. The subcritical correlations did not incorporate property ratios to account for the variability in fluid properties; in some supercritical correlations it was found to add additional uncertainty for the case of the present study. The effects of buoyancy and flow acceleration were also evaluated. Based on dimensionless criteria, buoyancy was expected to play a role in heat transfer, especially when the bulk fluid temperature is below the pseudocritical temperature. However, the relative importance of flow acceleration was inconclusive. Despite the apparent importance of buoyancy effects, heat transfer was not degraded, as would be expected in larger, circular, uniformly heated tubes. The mixed convection could be inducing a density driven swirling with the stratification of low-density fluid near the top (unheated). This would ultimately improve the heat transfer at the bottom portion of the test section channels. Therefore, the flow geometry and the non-conventional heated boundary could be improving the heat transfer even with buoyancy driven effects under supercritical conditions.

Download or read book Numerical Simulation and Optimization of Carbon Dioxide Utilization and Storage in Enhanced Gas Recovery and Enhanced Geothermal Systems written by James H. Biagi and published by . This book was released on 2014 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: With rising concerns surrounding CO2 emissions from fossil fuel power plants, there has been a strong emphasis on the development of safe and economical Carbon Capture Utilization and Storage (CCUS) technology. Two methods that show the most promise are Enhanced Gas Recovery (EGR) and Enhanced Geothermal Systems (EGS). In Enhanced Gas Recovery a depleted or depleting natural gas reservoir is re-energized with high pressure CO2 to increase the recovery factor of the gas. As an additional benefit following the extraction of natural gas, the reservoir would serve as a long-term storage vessel for the captured carbon. CO2 based Enhanced Geothermal Systems seek to increase the heat extracted from a given geothermal reservoir by using CO2 as a working fluid. Carbon sequestration is accomplished as a result of fluid losses throughout the life of the geothermal system. Although these technologies are encouraging approaches to help in the mitigation of anthropogenic CO2 emissions, the detailed mechanisms involved are not fully understood. There remain uncertainties in the efficiency of the systems over time, and the safety of the sequestered CO2 due to leakage. In addition, the efficiency of both natural gas extraction in EGR and heat extraction in EGS are highly dependent on the injection rate and injection pressure. Before large scale deployment of these technologies, it is important to maximize the extraction efficiency and sequestration capacity by optimizing the injection parameters. In this thesis, numerical simulations of subsurface flow in EGR and EGS are conducted using the DOE multiphase flow solver TOUGH2 (Transport of Unsaturated Groundwater and Heat). A previously developed multi-objective optimization code based on a genetic algorithm is modified for applications to EGR and EGS. For EGR study, a model problem based on a benchmark-study that compares various mathematical and numerical models for CO2 storage is considered. For EGS study a model problem based on previous studies (with parameters corresponding to the European EGS site at Soultz) is considered. The simulation results compare well with the computations of other investigators and give insight into the parameters that can influence the simulation accuracy. Optimizations for EGR and EGS problems are carried out with a genetic algorithm (GA) based optimizer combined with TOUGH2, designated as GA-TOUGH2. Validation of the optimizer was achieved by comparison of GA based optimization studies with the brute-force run of large number of simulations. Using GA-TOUGH2, optimal time-independent and time-dependent injection profiles were determined for both EGR and EGS. Optimization of EGR problem resulted in a larger natural gas production rate, a shorter total operation time, and an injection pressure well below the fracture pressure. Optimization of EGS problem resulted in a precise management of the production temperature profile, heat extraction for the entire well life, and more efficient utilization of CO2. The results of these studies will hopefully pave the way for future GA-TOUGH2 based optimization studies to improve the modeling of CCUS projects.

Download or read book Thermoeconomic Analysis of a New Geothermal Utilization CHP Plant in Tsetserleg Mongolia written by Purevsuren Dorj and published by . This book was released on 2005 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: