Simulation analysis of a single well geothermal system with open-loop structure

The energy reserves in hot dry rock and hydrothermal systems are abundant in China, however, the developed resources are far below the potential estimates due to immature technology of enhanced geothermal system (EGS) and scattered resources of hydrothermal systems. To circumvent these problems and reduce the thermal resistance of rocks, here a shallow depth enhanced geothermal system (SDEGS) is proposed, which can be implemented by fracturing the hydrothermal system. We find that, the service life for SDEGS is 14 years with heat output of 4521.1 kW. To extend service life, the hybrid SDEGS and solar energy heating system is proposed with 10,000 m2 solar collectors installed to store heat into geothermal reservoir. The service life of the hybrid heating system is 35 years with geothermal heat output of 4653.78 kW. The novelty of the present work is that the hybrid heating system can solve the unstable and discontinuous problems of solar energy without building additional back-up sources or seasonal storage equipment, and the geothermal thermal output can be adjusted easily to meet the demand of building thermal loads varying with outside temperature.

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A novel demodulation algorithm for VHF Data Broadcast signals in multi-sources augmentation navigation system

International Journal of Distributed Sensor Networks ◽

10.1177/1550147720914770 ◽

2020 ◽

Vol 16 (3) ◽

pp. 155014772091477

Author(s):

Hongwei Zhao ◽

Zichun Zhang ◽

Xiaozhu Shi ◽

Yihui Yin

Keyword(s):

Navigation System ◽

Signal To Noise Ratio ◽

Open Loop ◽

Timing Recovery ◽

Loop Structure ◽

Frame Synchronization ◽

Source Information ◽

Carrier Synchronization ◽

Data Broadcast ◽

Training Symbol

The augmentation navigation system based on multi-source information fusion can significantly improve position accuracy, and the multi-source information is usually transmitted through VHF Data Broadcast . Aiming at the burst characteristics of VHF Data Broadcast, this article proposed a novel demodulation algorithm based on open-loop structure. When a VHF Data Broadcast burst is detected, the timing recovery should be finished first, and the value of cross-correlation between the timing-recovered signal and the local training symbol is calculated to complete the frame synchronization. Then, the data-aided and non-data-aided algorithms are used to estimate the frequency offset. Finally, the phase offset is estimated and the carrier synchronization is accomplished. The simulation results demonstrate that the proposed algorithm can quickly accomplished carrier synchronization without using feedback-loop structure, and the bit error rate is less than 10−4 when the signal-to-noise ratio is greater than 17 dB, which satisfy the requirement of receiving VHF Data Broadcast signals in augmentation navigation system. Therefore, the proposed algorithm can be used for receiving VHF Data Broadcast signals.

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Error Uncertainty Analysis in Planar Closed-Loop Structure with Joint Clearances

Metals ◽

10.3390/met11111872 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1872

Author(s):

Yushu Yu ◽

Jinglin Li ◽

Xin Li ◽

Yi Yang

Keyword(s):

Joint Distribution ◽

Error Probability ◽

Closed Loop ◽

Open Loop ◽

Distribution Functions ◽

Positional Error ◽

Loop Structure ◽

Virtual Link ◽

Joint Clearances ◽

Probability Density Function Pdf

For planar closed-loop structures with clearances, the angular and positional error uncertainties are studied. By using the vector translation method and geometric method, the boundaries of the errors are analyzed. The joint clearance is considered as being distributed uniformly in a circle area. A virtual link projection method is proposed to deal with the clearance affected length error probability density function (PDF) for open-loop links. The error relationship between open loop and closed loop is established. The open-loop length PDF and the closed-loop angular error PDF both approach being Gaussian distribution if there are many clearances. The angular propagation error of multi-loop structures is also investigated by using convolution. The positional errors of single and multiple loops are both discussed as joint distribution functions. Monte Carlo simulations are conducted to verify the proposed methods.

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Dipole and Convergent Single-Well Thermal Tracer Tests for Characterizing the Effect of Flow Configuration on Thermal Recovery

Geosciences ◽

10.3390/geosciences9100440 ◽

2019 ◽

Vol 9 (10) ◽

pp. 440 ◽

Cited By ~ 1

Author(s):

Jérôme de La Bernardie ◽

Olivier Bour ◽

Nicolas Guihéneuf ◽

Eliot Chatton ◽

Laurent Longuevergne ◽

...

Keyword(s):

Fractured Rock ◽

Tracer Tests ◽

Crystalline Rock ◽

Industrial Applications ◽

Thermal Recovery ◽

Geothermal System ◽

Distributed Temperature Sensing ◽

Flow Configuration ◽

Single Well ◽

Flow Configurations

Experimental characterization of thermal transport in fractured media through thermal tracer tests is crucial for environmental and industrial applications such as the prediction of geothermal system efficiency. However, such experiments have been poorly achieved in fractured rock due to the low permeability and complexity of these media. We have thus little knowledge about the effect of flow configuration on thermal recovery during thermal tracer tests in such systems. We present here the experimental set up and results of several single-well thermal tracer tests for different flow configurations, from fully convergent to perfect dipole, achieved in a fractured crystalline rock aquifer at the experimental site of Plœmeur (H+ observatory network). The monitoring of temperature using Fiber-Optic Distributed Temperature Sensing (FO-DTS) associated with appropriate data processing allowed to properly highlight the heat inflow in the borehole and to estimate temperature breakthroughs for the different tests. Results show that thermal recovery is mainly controlled by advection processes in convergent flow configuration while in perfect dipole flow field, thermal exchanges with the rock matrix are more important, inducing lower thermal recovery.

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Thermoporoelastic Analysis of a Single-Well Closed-Loop Geothermal System

Poromechanics VI ◽

10.1061/9780784480779.074 ◽

2017 ◽

Author(s):

Milad Ahmadi ◽

Arash Dahi Taleghani

Keyword(s):

Closed Loop ◽

Geothermal System ◽

Single Well

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A Novel Open Loop Structure for Phase Shifting and Frequency Synthesizing

IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences ◽

10.1093/ietfec/e91-a.2.491 ◽

2008 ◽

Vol E91-A (2) ◽

pp. 491-496 ◽

Cited By ~ 1

Author(s):

S. KAZEMINIA ◽

K. HADIDI ◽

A. KHOEI

Keyword(s):

Open Loop ◽

Phase Shifting ◽

Loop Structure

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Performance Analysis of Single-Well Enhanced Geothermal System for Building Heating

The Scientific World JOURNAL ◽

10.1155/2020/7927052 ◽

2020 ◽

Vol 2020 ◽

pp. 1-8

Author(s):

Haijun Liang ◽

Xiaofeng Guo ◽

Tao Gao ◽

Lingbao Wang ◽

Xianbiao Bu

Keyword(s):

Volume Flow Rate ◽

Water Reservoir ◽

Hot Water ◽

Heat Extraction ◽

Geothermal System ◽

Enhanced Geothermal System ◽

Artificial Reservoir ◽

Reservoir Volume ◽

Thermal Output ◽

Single Well

Deep borehole heat exchanger (DBHE) technology does not depend on the existence of hot water reservoir and can be used in various regions. However, the heat extraction from DBHE can hardly be improved due to poor thermal conductivity of rocks. Here, a single-well enhanced geothermal system (SWEGS) is proposed, which has a larger heat-exchange area of artificial reservoir created by fracturing hydrothermal technology. We find that, due to heat convection between rocks and fluid, the extracted thermal output for SWEGS is 4772.73 kW, which is 10.64 times of that of DBHE. By changing the injection water temperature, volume flow rate, and artificial reservoir volume, it is easy to adjust the extracted thermal output to meet the requirement of building thermal loads varying with outdoor air temperature. Understanding these will enable us to better apply SWEGS technology and solve the fog and haze problem easily and efficiently.

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