Download or read book Challenges for Designing Closed loop Geothermal Systems written by Sai Liu and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Closed-loop geothermal systems (CLGS) are a novel heat extraction technique not requiring continuous fluid supply. The mechanism controlling the efficiency of closed-loop systems has not been well analyzed, so it lacks theory basis to design them. Working fluid is circulated only inside the wellbore, so heat extraction efficiency can be limited, which brings challenges to extensive application of closed-loop systems. At high temperatures in geothermal reservoirs, polymer seals may experience thermal deformation and degradation, which could cause leaks of circulating fluid in the wellbore. To address these challenges, a systematic numerical study was first conducted to explore factors affecting heat extraction efficiency of closed-loop systems and approaches to improving the efficiency. Then, experimental work was conducted to develop high-temperature resistant polymer composites for sealing geothermal wells. With the finite element methods, a coupled three-dimensional model was established for a basic closed-loop geothermal system (CLGS) and an enhanced closed-loop geothermal system (ECLGS). Effects of critical design factors on heat extraction of CLGS were investigated quantitatively. Increasing the cement thermal conductivity enhances both produced fluid temperature and thermal power. The effect of cement thickness is correlated with the value of its thermal conductivity. As the circulation rate increases, the temperature of produced fluid decreases while thermal power increases asymptotically. Using a circulating fluid with high heat capacity would result in higher thermal power. A dimensionless analysis was conducted, through which two dimensionless numbers were derived to integrate the effects of different factors. With the dimensionless numbers, effects of different individual factors can be evaluated comprehensively, which brings convenience to parameter design. Heat extraction through the ECLGS was also simulated. The objective of the ECLGS is to increase the heat transfer rate from rock to working fluid by thermally-conductive fractures connected to the wellbore. Simulation results suggest that fractures could improve heat extraction performance of the system noticeably. There exists a critical fluid circulation rate beyond which net power starts to decrease. To further improve heat extraction, a conductive plug along fractures was defined and incorporated in the system. The conductive plug could further improve heat extraction performance significantly. Effects of plug thermal conductivity, plug size, and plug shape were ascertained. Finally, a dimensionless analysis was also performed for ECLGS, through which three dimensionless numbers were derived to integrate different affecting factors. Then, polymer composites for sealing geothermal were developed by compounding treated graphite with ethylene propylene diene monomer (EPDM) rubber. First, the performances of two types of graphite, small-size lamellar graphite (SFG15) and graphite nanoplatelets (GNP), were studied. Second, the performance of high concentrations of treated SFG15 was examined. Experimental results show that treated SFG15 and GNP both enhance the temperature resistance of EPDM by over 80°C. High concentrations (9 wt.%) of treated graphite remarkably enhances the storage modulus of and reduces the loss factor (tan [delta]) of EPDM at high temperatures. Adding treated graphite significantly enhances the specific heat capacity of EPDM and remarkably increases heat energy required to melt it. The onset degradation temperature of EPDM-SFG15 nanocomposites is up to 30 °C higher than that of plain EPDM. In this dissertation, the mechanism controlling performance of closed-loop systems and approaches to improving the performance were explored. The developed polymer nanocomposites, with enhanced mechanical and thermal properties, are a promising candidate for the material used to seal closed-loop geothermal wells. The results and conclusions achieved in this dissertation may provide a reference for optimally designing closed-loop systems.

Download or read book Geothermal Heating and Cooling written by Stephen P. Kavanaugh and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geothermal Heating and Cooling is a complete revision of Ground-Source Heat Pumps: Design of Geothermal Systems for Commercial and Institutional Buildings, which is recognized as the primary reference for nonresidential ground-source heat pump (GSHP) installations. This new work takes advantage of the many lessons learned since the time of the original publication, when GSHPs were primarily residential applications. Many improvements have evolved, and performance data, both positive and negative, is now available to guide the development of best practices. This essential guide for HVAC design engineers, design-build contractors, GSHP subcontractors, and energy/construction managers also provides building owners and architects with insights into characteristics of quality engineering firms and the information that should be provided by design firms competing for GSHP projects.This revision draws on new ASHRAE and industry research in critical areas, as well as measured data from long-term installations and optimized installation practices used by high-production GSHP contractors. Nearly all chapters and appendices were completely rewritten, and they include coverage of closed-loop ground (ground-coupled), groundwater, and surface-water systems plus GSHP equipment and piping. Additional information on site characterization has been added, including a new hydrogeological chapter. Another new chapter contains results of recent field studies, energy and demand characteristics, and updated information to optimize GSHP system cost. While other publications deal primarily with ground-coupled heat pumps, this text includes detailed coverage of groundwater, surface-water, and GSHP costs.Tables, graphs, and equations are provided in both Inch-Pound (I-P) and International System (SI) units. As a bonus, supplemental Microsoft® Excel® macro-enabled spreadsheets for a variety of GSHP calculations accompany the text.

Download or read book Thermal Performance Evaluations of Fractured and Closed loop Geothermal Reservoirs written by Nicolás Rangel Jurado and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Earth's interior contains an enormous amount of heat that can be exploited for carbon-free direct-use or electricity generation. Even though numerous studies have predicted that geothermal power will become an important contributor to the world's energy mix, the use of these resources is still growing at a notably slow speed compared to other renewable energy alternatives. This thesis uses computational models to explore the technical challenges that two kinds of geothermal resources face to reach full commercialization. In particular, the temporal evolution of heat production of several fractured and closed-loop geothermal reservoirs is investigated. Thermal-hydraulic simulations are conducted for a fractured meso-scale geothermal reservoir in northern New York, USA. The modeling parameters considered here are constrained by empirical data related to lithology, hydrogeology, and thermal behavior measurements collected on site. This work shows how the addition of realistic complexities, that are well-constrained by field data and often disregarded, can significantly improve the thermal performance predictions compared to overly simplified models. Additionally, the results presented here highlight the importance of characterizing subsurface permeability distributions in order to optimize thermal efficiency and devise appropriate reservoir management strategies that extend the lifespan of geothermal reservoirs. To evaluate how closed-loop or advanced geothermal systems (AGS) compare to alternative ways of extracting geothermal energy, several AGS designs displaying varying reservoir and operating conditions are evaluated to estimate their heat and temperature generating potential. Our findings indicate that the thermal efficiency of AGS is characterized by a considerable exergy loss. Sensitivity analyses show that varying different parameters have slight and moderate improvements on thermal performance, however, AGS designs appear to present multiple technical challenges making them less cost-competitive than both conventional hydrothermal systems and enhanced geothermal systems (EGS). The following key findings summarize the results of these two studies: 1) if well-constrained, computational models are a good tool to assess, manage and intervene geothermal reservoirs to ensure their long-term sustainability, 2) non-uniform permeability can drastically modify fluid flow and heat transport processes in geothermal reservoirs compared to theoretical models that consider homogenous reservoir properties, 3) prospecting adequate subsurface properties is of critical importance to develop geothermal reservoirs, and 4) despite their recent popularity, closed-loop systems are expected to be considerably less productive than other types of geothermal resources at a similar scale.

Download or read book Geothermal Heat Pump and Heat Engine Systems written by Andrew D. Chiasson and published by John Wiley & Sons. This book was released on 2016-09-19 with total page 491 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unique approach to the study of geothermal energy systems This book takes a unique, holistic approach to the interdisciplinary study of geothermal energy systems, combining low, medium, and high temperature applications into a logical order. The emphasis is on the concept that all geothermal projects contain common elements of a "thermal energy reservoir" that must be properly designed and managed. The book is organized into four sections that examine geothermal systems: energy utilization from resource and site characterization; energy harnessing; energy conversion (heat pumps, direct uses, and heat engines); and energy distribution and uses. Examples are provided to highlight fundamental concepts, in addition to more complex system design and simulation. Key features: Companion website containing software tools for application of fundamental principles and solutions to real-world problems. Balance of theory, fundamental principles, and practical application. Interdisciplinary treatment of the subject matter. Geothermal Heat Pump & Heat Engine Systems: Theory and Practice is a unique textbook for Energy Engineering and Mechanical Engineering students as well as practicing engineers who are involved with low-enthalpy geothermal energy systems.

Download or read book Analysis and Design of Energy Geostructures written by Lyesse Laloui and published by Academic Press. This book was released on 2019-10-19 with total page 1098 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis and Design of Energy Geostructures gathers in a unified framework the theoretical and experimental competence available on energy geostructures: innovative multifunctional earth-contact structures that can provide renewable energy supply and structural support to any built environment. The book covers the broad, interdisciplinary and integrated knowledge required to address the analysis and design of energy geostructures from energy, geotechnical and structural perspectives. This knowledge includes (Part A) an introduction to the technology; (Part B) the fundamentals of heat and mass transfers as well as of the mechanics of geomaterials and structures required to address the unprecedented behavior of energy geostructures; (Part C) the experimental evidence characterizing the considered geostructures; (Part D) various analytical and numerical modeling approaches to analyze the response of energy geostructures; and (Part E) the performance-based design and detailing essentials of energy geostructures. - Proposes the theoretical and practical application essentials required to address the analysis and design of energy geostructures from energy, geotechnical and structural perspectives - Presents a substantial amount of resolved exercises on key aspects governing the behavior and performance of energy geostructures to be considered in analysis and design - Summarizes and discusses the most recent scientific and technical knowledge about energy geostructures, including energy piles, energy tunnels and energy walls

Download or read book Geothermal HVAC written by Jay Egg and published by McGraw Hill Professional. This book was released on 2010-11-05 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: In-depth, practical details on geothermal HVAC systems This definitive guide covers commercial and residential geothermal heating, ventilation, and air conditioning technologies and explains how to take advantage of their money- and energy-saving features. Geothermal HVAC: Green Heating and Cooling reviews the array of choices currently available, offers market values for systems based on varying options and conditions, and describes how to pair the best systems for each application and budget. Whether you're a contractor or a consumer, you'll find out what you need to know to implement a geothermal HVAC system in a retrofit or new construction project, and start benefiting from this sustainable, affordable technology. Find out how to: Learn the basic types of heat transfer--convection, conduction, and radiation Understand how geothermal earth-coupled heat pumps work Determine which ground loops to use for earth coupling to best meet the demands of the site Use load sharing to channel the heat differential of one device into useful energy for another Calculate system efficiencies and heat gain and loss Understand geothermal project proposals and system pricing Benefit from incentives, tax credits, and rebates for geothermal HVAC systems Calculate your long-term return on investment Verify that your installed system is working as intended Troubleshoot your system and avoid common problems

Download or read book Commercial Program Development for a Ground Loop Geothermal System written by Paul A. Gross (II) and published by . This book was released on 2011 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of the earth's thermal energy to heat and cool building space is nothing new; however, the heat transfer approximations used in modeling geothermal systems, leave uncertainty and lead to over sizing. The present work is part of a Wright State effort to improve the computer modeling tools used to simulate ground loop geothermal heating and cooling systems. The modern computer processor has equipped us with the computation speed to use a finite volume technique to solve the unsteady heat equation with hourly time steps for multi-year analyses in multiple spatial dimensions. Thus we feel there is more need to use approximate heat transfer solution techniques to model geothermal heating and cooling systems. As part of a DOE funded project Wright State has been developing a ground loop geothermal computer modeling tool that uses a detailed heat transfer model based on the governing differential energy equation. This tool is meant to be more physically detailed and accurate than current commercial ground loop geothermal computer codes. The Wright State code allows the geothermal designer to optimize the system using a number of outputs including temperature field outputs, existing fluid temperature plots, heat exchange plots, and even a histogram of the COP data. Careful attention to the algorithm speed allows for multi-year simulations with minimal computation cost. Once the thermal and heat transfer computations are complete, a payback period calculator can compare any conventional heating and cooling system to the designed geothermal system and payback periods are displayed. The work being presented as part of this thesis deals with five issues that were required to make the Wright State geothermal computer code a reality. The five aspects of this modeling tool addressed by this thesis work are: energy load calculations, GUI (graphical user interface) development, turbulence model development, heat pump model development, and two-dimensional numerical grid development. The energy load, or heating and cooling load, calculations are handled using the sophisticated DOE program called EnergyPlus. This thesis work developed a technique for coupling EnergyPlus to the Wright State geothermal code and devising a way for novice users to obtain energy loads quickly and easily, while still allowing expert users to utilize the full strength of EnergyPlus. The GUI for the Wright State computer program was developed with the novice and expert users in mind. The GUI offers ease of use while maintaining the ability for the expert users to setup unique designs for simulation. A unique way of modeling the effects of turbulent flow in the ground tube has allowed the Wright State code to maintain low computation times, while having small errors for a wide range of Reynolds numbers. To make the Wright State ground loop computer model more complete, a heat pump was developed as part of this work. The heat pump model uses the performance characteristics of commercial heat pumps to determine the performance of the geothermal system. The energy transport in the fluid is determined and used to select one of eighteen water-to-air heat pumps that calculate hourly COP's for all system conditions. The calculated heat pump efficiencies are used in an energy balance with hourly building loads to calculate the next iteration's bulk temperature entering the ground loop. Additional details are provided in this thesis on each of these five, important, computer modeling issues.

Download or read book Geothermal Energy Systems written by Ibrahim Dincer and published by Elsevier. This book was released on 2021-03-25 with total page 527 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geothermal Energy Systems provides design and analysis methodologies by using exergy and enhanced exergy tools (covering exergoenvironmental, exergoeconomic, exergetic life cycle assessment, etc.), environmental impact assessment models, and sustainability models and approaches. In addition to presenting newly developed advanced and integrated systems for multigenerational purposes, the book discusses newly developed environmental impact assessment and sustainability evaluation methods and methodologies. With case studies for integrated geothermal energy sources for multigenerational aims, engineers can design and develop new geothermal integrated systems for various applications and discover the main advantages of design choices, system analysis, assessment and development of advanced geothermal power systems. - Explains the ability of geothermal energy power systems to decrease global warming - Discusses sustainable development strategies for using geothermal energy sources - Provides new design conditions for geothermal energy sources-based district energy systems

Download or read book Geoenergy Modeling II written by Haibing Shao and published by Springer. This book was released on 2016-10-06 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is dedicated to the numerical modeling of shallow geothermal systems. The utilization of shallow geothermal energy involves the integration of multiple Borehole Heat Exchangers (BHE) with Ground Source Heat Pump (GSHP) systems to provide heating and cooling. The modeling practices explained in this book can improve the efficiency of these increasingly common systems. The book begins by explaining the basic theory of heat transport processes in man-made as well as natural media. . These techniques are then applied to the simulation of borehole heat exchangers and their interaction with the surrounding soil. The numerical and analytical models are verified against analytical solutions and measured data from a Thermal Response Test, and finally, a real test site is analyzed through the model and discussed with regard to BHE and GSHP system design and optimization.

Download or read book ERDA Energy Research Abstracts written by and published by . This book was released on 1983 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1992 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Ground Source Heat Pump Systems written by Simon Rees and published by Woodhead Publishing. This book was released on 2016-05-13 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Ground-Source Heat Pump Systems relates the latest information on source heat pumps (GSHPs), the types of heating and/or cooling systems that transfer heat from, or to, the ground, or, less commonly, a body of water. As one of the fastest growing renewable energy technologies, they are amongst the most energy efficient systems for space heating, cooling, and hot water production, with significant potential for a reduction in building carbon emissions. The book provides an authoritative overview of developments in closed loop GSHP systems, surface water, open loop systems, and related thermal energy storage systems, addressing the different technologies and component methods of analysis and optimization, among other subjects. Chapters on building integration and hybrid systems complete the volume. - Provides the geological aspects and building integration covered together in one convenient volume - Includes chapters on hybrid systems - Presents carefully selected chapters that cover areas in which there is significant ongoing research - Addresses geothermal heat pumps in both heating and cooling modes

Download or read book Tabulated Database of Closed Loop Geothermal Systems Performance for Cloud Based Technical and Economic Modeling of Heat Production and Electricity Generation Preprint written by and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: To better understand the heat production, electricity generation performance and economic viability of closed loop geothermal systems in hot-dry-rock, the Closed Loop Geothermal Group, a consortium of several national labs and academic institutions has tabulated time-dependent numerical solutions and levelized cost results of two popular closed loop heat exchanger designs (u-tube and co-axial). The heat exchanger designs were evaluated for two working fluids (water and super-critical CO2) while varying seven continuous independent parameters of interest (i.e., mass flow rate, vertical depth, horizontal extent, borehole diameter, formation gradient, formation conductivity, and injection temperature). The corresponding numerical solutions (approximately 1.2 million per heat exchanger design) are stored as multi-dimensional HDF5 datasets and can be queried at off-grid points using multi-dimensional linear interpolation. A Python script was developed to query this database and estimate time-dependent electricity generation using an Organic Rankine cycle (for water) or direct turbine expansion cycle (for CO2) and perform a cost assessment. This document aims to give an overview of the HDF5 database file and highlights how to read, visualize, and query quantities of interest (e.g., levelized cost of electricity, levelized cost of heat) using the accompanying python scripts. Details regarding the capital, operation, and maintenance and levelized cost calculation using the TEA (techno-economic analysis) script are provided.

Download or read book Geothermal Heat Pumps What You Need To Know Before You Buy One written by Jerry Scherer and published by Createspace Independent Publishing Platform. This book was released on 2014-06-11 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the majority of geothermal heat pump contractors do not size, design, or install geothermal heat pumps correctly one would be wise to follow the steps in this book so you don't end up with a geothermal heat pump system that is nothing but trouble. This book tells you the steps you need to take so you can get a geothermal heat pump correctly installed either by doing it yourself or having a contractor install it for you. It also has many other articles about energy saving things you can do to have a more energy efficient home. Here are the chapters that are in the book; TABLE OF CONTENTS Page 8 Preface Page 11 Chapter One Geothermal heat pump tax credits. Page 13 Chapter Two About geothermal heat pumps. Page 14 Chapter Three The three loops in a geothermal heat pump system. Page 16 Chapter Four The air has problems, The earth has solutions. Page 18 Chapter Five How do heat pumps move heat from cooler areas into warmer areas? Page 20 Chapter Six Any geothermal heat pump is better than an air source heat pump. Page 24 Chapter Seven What do geothermal heat pumps have to do with renewable energy? Page 26 Chapter Eight Will a geothermal heat pump keep me comfortable? YOU BET IT WILL!!! Page 27 Chapter Nine Geothermal heat pumps: Keeping maintenance simple. Page 28 Chapter Ten Which efficiency ratings should I compare? SEER, EER, COP? Page 29 Chapter Eleven Efficiency: Geothermal heat pumps compared to electric resistant heaters Page 30 Chapter Twelve Does running a ceiling fan lower my cooling bills? Page 32 Chapter Thirteen Can ceiling fans lower my heating bills? Page 34 Chapter Fourteen Properly sizing your geothermal heat pump will make a big difference. Page 36 Chapter Fifteen Rules of thumb for sizing are out!!! Page 38 Chapter Sixteen Closed earth loops. Page 40 Chapter Seventeen Horizontal earth loops. Page 48 Chapter Eighteen Slinky loops. Page 49 Chapter Nineteen Naeem's slinky earth loop installation. Page 72 Chapter Twenty Pond loops. Page 73 Chapter Twenty-one Vertical bore loops. Page 80 Chapter Twenty-two Using well water for an open loop. Page 84 Chapter Twenty-three Geothermal heat pump earth loop antifreeze. Page 89 Chapter Twenty-four What is insulation R-value? Page 90 Chapter Twenty-five Best insulation R-value per dollar: Stop the largest losses/leaks first. Page 94 Chapter Twenty-six What is a desuperheater? Page 96 Chapter Twenty-seven Single stage, Two stage, and Variable speed geothermal heat pumps. Page 99 Chapter Twenty-eight Water-to-Water VS. Water to Air Geothermal heat pumps. Page 102 Chapter Twenty-nine Geothermal heat pumps: Packaged units VS. Split systems. Page 104 Chapter Thirty ClimateMaster's ClimaDry geothermal heat pump dehumidification system. Page 106 Chapter Thirty-one Geothermal heat pump thermostat: Don't set it back. Page 109 Chapter Thirty-two Duel Fuel geothermal heat pump systems. Page 111 Chapter Thirty-three About heat distribution. Page 112 Chapter Thirty-four Sizing and designing your forced air ducting system (duct work). Page 117 Chapter Thirty-five Sizing and designing your Geothermal heat pump. Page 119 Chapter Thirty-six Designing your closed earth loop. Page 123 Chapter Thirty-seven What we need from you so we can size and design your horizontal earth loop. Page 125 Chapter Thirty-eight How to test your soil. Page 129 About the Author

Download or read book Encyclopedia of Renewable Energy Sustainability and the Environment written by and published by Elsevier. This book was released on 2024-08-09 with total page 4061 pages. Available in PDF, EPUB and Kindle. Book excerpt: Encyclopedia of Renewable Energy, Sustainability and the Environment, Four Volume Set comprehensively covers all renewable energy resources, including wind, solar, hydro, biomass, geothermal energy, and nuclear power, to name a few. In addition to covering the breadth of renewable energy resources at a fundamental level, this encyclopedia delves into the utilization and ideal applications of each resource and assesses them from environmental, economic, and policy standpoints. This book will serve as an ideal introduction to any renewable energy source for students, while also allowing them to learn about a topic in more depth and explore related topics, all in a single resource.Instructors, researchers, and industry professionals will also benefit from this comprehensive reference. - Covers all renewable energy technologies in one comprehensive resource - Details renewable energies' processes, from production to utilization in a single encyclopedia - Organizes topics into concise, consistently formatted chapters, perfect for readers who are new to the field - Assesses economic challenges faced to implement each type of renewable energy - Addresses the challenges of replacing fossil fuels with renewables and covers the environmental impacts of each renewable energy

Download or read book Particle scale Simulations for Geothermal Energy Applications written by Faras Al Balushi and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geothermal energy has the potential to develop into a reliable source of clean and renewable energy due to its widespread availability and minimal carbon dioxide emission during electricity generation. Due to the high temperature of such reservoirs, technologies are continuously being developed to reduce the cost of extracting heat and extend the lifetime of the geothermal systems for profitable heat production. One of the main challenges hindering the further development of geothermal systems is the low heat extraction efficiency characterized by low-temperature produced fluids. In enhanced geothermal systems, where fluid injected flows directly through the geothermal formation, thermal breakthrough or "short-circuiting" causes fast cooling of the geothermal formation due to the presence of shortcut paths connecting the injector well to the producer well. Such an occurrence may lead to the temporary shutdown of the geothermal plant, leaving an enormous amount of untapped heat behind. Efforts to tackle this issue have been focused on delaying thermal breakthrough rather than achieving uniform heat sweeping from the geothermal systems. No technologies or methods are currently available to achieve uniform heat extraction from EGS. To fill this gap, we propose a novel concept of temperature-sensitive proppants to achieve self-adjustable fracture conductivity. Through particle-scale numerical simulations, we evaluate the performance of such proppants for different operating conditions and material properties. My numerical results showed that the permeability of such proppants is affected by in-situ conditions, material properties, and geometric properties. The developed model can be utilized to comprehensively understand the performance of such temperature-sensitive proppants at different operating conditions. Field-scale simulations confirmed the feasibility of using the proposed temperature-sensitive proppants in enhancing heat extraction from EGS by ~50% over 50 years of production when the proposed proppants are used compared to typical proppants with no temperature dependency. Alternatively, closed-loop geothermal systems can be considered, where the working fluid is circulated inside the wellbore. The heat exchange efficiency of such systems is typically low, which limits the use of the produced heat for direct heating applications. In this study, we introduce a method of improving heat exchange between the wellbore and the geothermal formation utilizing coated proppants. Based on numerical simulations, the enhancement of proppant thermal conductivity is discussed. Particle-scale analysis showed that coating sand proppants with a thin layer of copper coating may increase its effective thermal conductivity seven times. Increasing proppant particulate coating thickness further increases the effective thermal conductivity by an order of magnitude. In addition, smaller proppants showed higher effective thermal conductivity compared to larger proppants due to the increased contact with the neighboring particles, resulting in lower resistance to heat conduction. Such conductive proppants can enhance heat conduction between the geothermal formation and the wellbore, increasing the heat extraction efficiency of closed-loop geothermal systems. Drilling costs account for the majority of the cost of developing a geothermal system. During drilling, thief zones (permeable zones) may be encountered. Moreover, fractures may be induced due to the high circulating density of the drilling fluid. If such fractures are left unplugged, excessive fluid loss may occur, which may cause well instability issues or may lead to losing the well in extreme cases. Using lost circulation material (LCM) is a cheap and effective way to prevent further drilling fluid loss to the formation. Granular particles are typically used due to their cost and their ability to form a tight and stable seal. Understanding the performance of such particles after bridging is essential to ensure their stability under fluctuating operating conditions. Here, the sealing performance of granular particles after bridging is discussed. Our analysis revealed that the shape of the particles is one of the most influential factors that impact the sensitivity of such particles to closure stress. Furthermore, the sensitivity of the particle pack permeability to friction is influenced by the particle shape. Numerical simulations offer considerable advantages over laboratory experiments, especially for geothermal systems due to the difficulty in accurately reproducing the elevated temperature. In this study, different numerical tools are utilized to model and design particulates that can enhance the heat extraction efficiency of both open- and closed-loop geothermal systems. Using numerical simulations allows easier control of the design parameters as well as operating conditions to avoid repetitive and costly laboratory experiments that may require different samples from different vendors. The numerical workflow used is validated against laboratory experiments and analytical as well as empirical equations.

Download or read book Thermal Systems Design written by Richard J. Martin and published by John Wiley & Sons. This book was released on 2022-01-19 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal Systems Design Discover a project-based approach to thermal systems design In the newly revised Second Edition of Thermal Systems Design: Fundamentals and Projects, accomplished engineer and educator Dr. Richard J. Martin offers senior undergraduate and graduate students an insightful exposure to real-world design projects. The author delivers a brief review of the laws of thermodynamics, fluid mechanics, heat transfer, and combustion before moving on to a more expansive discussion of how to apply these fundamentals to design common thermal systems like boilers, combustion turbines, heat pumps, and refrigeration systems. The book includes design prompts for 14 real-world projects, teaching students and readers how to approach tasks like preparing Process Flow Diagrams and computing the thermodynamic details necessary to describe the states designated therein. Readers will learn to size pipes, ducts, and major equipment and to prepare Piping and Instrumentation Diagrams that contain the instruments, valves, and control loops needed for automatic functioning of the system. The Second Edition offers an updated look at the pedagogy of conservation equations, new examples of fuel-rich combustion, and a new summary of techniques to mitigate against thermal expansion and shock. Readers will also enjoy: Thorough introductions to thermodynamics, fluid mechanics, and heat transfer, including topics like the thermodynamics of state, flow in porous media, and radiant exchange A broad exploration of combustion fundamentals, including pollutant formation and control, combustion safety, and simple tools for computing thermochemical equilibrium when product gases contain carbon monoxide and hydrogen Practical discussions of process flow diagrams, including intelligent CAD, equipment, process lines, valves and instruments, and non-engineering items In-depth examinations of advanced thermodynamics, including customized functions to compute thermodynamic properties of air, combustion products, water/steam, and ammonia right in the user’s Excel workbook Perfect for students and instructors in capstone design courses, Thermal Systems Design: Fundamentals and Projects is also a must-read resource for mechanical and chemical engineering practitioners who are seeking to extend their engineering know-how to a wide range of unfamiliar thermal systems.