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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Results are reported of work on: characterizing flow in wells with perforated casings with and without downhole heat exchangers (DHE) installed, determining energy extraction rates for conventional DHES in both cased and uncased wells, and modeling of DHE systems to predict effects of heat exchangers and well variable changes.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Results are reported of work on: characterizing flow in wells with perforated casings with and without downhole heat exchangers (DHE) installed, determining energy extraction rates for conventional DHES in both cased and uncased wells, and modeling of DHE systems to predict effects of heat exchangers and well variable changes.
Author: Charles Ray Miles Publisher: ISBN: Category : Geothermal engineering Languages : en Pages : 128
Book Description
The low temperature geothermal deposits in the Klamath Falls area are commonly used for heating buildings. The system often used to accomplish this consists of a heat exchanger that extends the full length of the casing within the well. This casing has slots cut in it to allow geothermal water from the aquifer to circulate through the casing and past the heat exchanger. A mathematical model for the thermosyphoning in this system was developed. The model was extended to include: a partial-length heat exchanger, the effects of the mixing of the fluid from inside the casing with that from the aquifer, and the effects on heat transfer coefficients caused by the scaling of the casing and heat exchanger. A parametric study of the system showed that the energy extraction rate from the heat exchanger is largely dependent upon: the temperature of the reservoir, the surface area of the heat exchanger, the ratio of the flow area inside the casing to the area of the annulus between the casing and the well bore, and the degree of mixing between the water from the aquifer and the cooler water from inside the casing. Flow measurements were made to verify the mathematical model. A hot-film anemometer was used to measure the convective flows within the casing but its use is greatly limited because the coating that protects the hot-film does not hold up at the temperatures encountered in a geothermal well. Construction of an energy balance around the heat exchanger in the well made it possible to estimate the convective flows within the well. Alternative designs for heat exchangers were examined. A short multi-loop heat exchanger was designed, built, and tested. Initial results indicate that this type of heat exchanger could be used to replace the full-length heat exchangers.presently in use for residences.
Author: Fritz Stauffer Publisher: CRC Press ISBN: 1466560193 Category : Technology & Engineering Languages : en Pages : 306
Book Description
The thermal use of the shallow subsurface is increasingly being promoted and implemented as one of many promising measures for saving energy. A series of questions arises concerning the design and management of underground and groundwater heat extraction systems, such as the sharing of the thermal resource and the assessment of its long-term potential. For the proper design of thermal systems it is necessary to assess their impact on underground and groundwater temperatures. Thermal Use of Shallow Groundwater introduces the theoretical fundamentals of heat transport in groundwater systems, and discusses the essential thermal properties. It presents a complete overview of analytical and numerical subsurface heat transport modeling, providing a series of mathematical tools and simulation models based on analytical and numerical solutions of the heat transport equation. It is illustrated with case studies from Austria, Germany, and Switzerland of urban thermal energy use, and heat storage and cooling. This book gives a complete set of analytical solutions together with MATLAB® computer codes ready for immediate application or design. It offers a comprehensive overview of the state of the art of analytical and numerical subsurface heat transport modeling for students in civil or environmental engineering, engineering geology, and hydrogeology, and also serves as a reference for industry professionals.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Downhole heat exchangers are widely used at Klamath Falls, Oregon, for low temperature heating applications. The design of such systems leads to the consideration of several interesting problems of buoyancy driven heat transfer in enclosures. Two models are considered: (i) free convection in the uncased wellbore and (ii) thermosyphoning through and around the wellbore casing which is perforated at two or more depths. Preliminary temperature measurements in the uncased well indicate little bulk vertical flow in the upper part of the well and possible circulation in the lower part. An analytical model is formulated to investigate this problem, and the results are compared with the results of some previous investigations of natural convection in similar enclosures. An analytical model is developed for the thermosyphoning case to determine the limitations of energy extraction for downhole heat exchangers that rely on thermosyphoning as the major mechanism of circulation in the well. Theoretical results from the model are presented showing that observed energy extraction rates are possible as a result of thermosyphoning only.
Author: Ingrid Stober Publisher: Springer Nature ISBN: 3030716856 Category : Science Languages : en Pages : 392
Book Description
The internal heat of the planet Earth represents an inexhaustible reservoir of thermal energy known as Geothermal Energy. The 2nd edition of the book covers the geologic and technical aspects of developing all forms of currently available systems using this "renewable" green energy. The book presents the distribution and transport of thermal energy in the Earth. Geothermal Energy is a base load energy available at all times independent of climate and weather. The text treats the efficiency of diverse shallow near surface installations and deep geothermal systems including hydrothermal and petrothermal techniques and power plants in volcanic high-enthalpy fields. The book also discusses environmental aspects of utilizing different forms of geothermal energy, including induced seismicity, noise pollution and gas release to the atmosphere. Chapters on hydraulic well tests, chemistry of deep hot water, scale formation and corrosion, development of geothermal probes, well drilling techniques and geophysical exploration complete the text. This book, for the first time, covers the full range of utilization of Geothermal Energy.
Author: Haibing Shao Publisher: Springer ISBN: 3319450573 Category : Technology & Engineering Languages : en Pages : 99
Book Description
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.
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Author: Charles Ray Miles
Author: Fritz Stauffer
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Author: Ingrid Stober
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Author: Haibing Shao
Author: M. Fukuda
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Author: Shuang Chen