scholarly journals Simulations of Heat Supply Performance of a Deep Borehole Heat Exchanger under Different Scheduled Operation Conditions

Processes ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 121
Author(s):  
Jiaqi Zhang ◽  
Xinli Lu ◽  
Wei Zhang ◽  
Jiali Liu ◽  
Wen Yue ◽  
...  
Keyword(s):  
Heat Supply ◽  
Operation Mode ◽  
Continuous Operation ◽  
Heat Extraction ◽  
Formation Temperature ◽  
Deep Borehole ◽  
Borehole Heat Exchanger ◽  
Electricity Cost ◽  
Mode 2 ◽  
Mode 3

With the changing world energy structure, the development of renewable energy sources is gradually accelerating. Among them, close attention has been given to geothermal energy because of its abundant resources and supply stability. In this article, a deep borehole heat exchanger (DBHE) is coupled with a heat pump system to calculate the heat supply and daily electricity consumption of the system. To make better use of the peaks and valleys in electricity prices, the following three daily operating modes were studied: 24-h operation (Mode 1), 8-h operation plus 16-h non-operation (Mode 2), and two cycles of 4-h operation and 8-h non-operation (Mode 3). Simulation results show that scheduled non-continuous operation can effectively improve the outlet temperature of the heat extraction fluid circulating in the DBHE. The heat extraction rates of Mode 1 is 190.9 kW for mass flowrate of 9 kg/s; in Mode 2 and Mode 3 cases, the rates change to 304.7 kW and 293.0 kW, respectively. The daily operational electricity cost of Mode 1 is the greatest because of 24-h operation; due to scheduled non-continuous operation, the daily operational electricity cost of Mode 3 is only about 66% of that of Mode 2. After an 8-month period without heating, the formation-temperature can be restored within 4 °C of its original state; 90% recovery of the formation-temperature can be achieved by the end of the second month of the non-operation season.

Heat extraction model and characteristics of coaxial deep borehole heat exchanger

2021 ◽  
Vol 169 ◽  
pp. 738-751
Author(s):  
Ji Li ◽  
Wei Xu ◽  
Jianfeng Li ◽  
Shuai Huang ◽  
Zhao Li ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Extraction ◽  
Deep Borehole ◽  
Borehole Heat Exchanger ◽  
Extraction Model

Analysis of heat extraction performance and long-term sustainability for multiple deep borehole heat exchanger array: A project-based study

2021 ◽  
Vol 289 ◽  
pp. 116590
Author(s):  
Wanlong Cai ◽  
Fenghao Wang ◽  
Shuang Chen ◽  
Chaofan Chen ◽  
Jun Liu ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Extraction ◽  
Deep Borehole ◽  
Borehole Heat Exchanger ◽  
Extraction Performance

scholarly journals A Fast Simulation Approach to the Thermal Recovery Characteristics of Deep Borehole Heat Exchanger after Heat Extraction

2020 ◽  
Vol 12 (5) ◽  
pp. 2021
Author(s):  
Yazhou Zhao ◽  
Zhibo Ma ◽  
Zhonghe Pang
Keyword(s):  
Source Model ◽  
Thermal Recovery ◽  
Heat Extraction ◽  
Deep Borehole ◽  
Heating Season ◽  
Fast Simulation ◽  
Borehole Heat Exchanger ◽  
Cyclic Operation ◽  
Finite Line ◽  
Finite Line Source

Necessary intermittence after heat extraction for a deep borehole heat exchanger (DBHE) is beneficial for sustainable operation. This paper centers on the fast simulation for thermal recovery characteristics of DBHE under intermittent condition. First of all, in view of the existing temperature gradient and multi-layer heterogeneity of rock underground that could never be ignored for DBHE, we extend the classical finite line source model based on heat source theory and superposition principle to account for the vertical heat flux distribution varying along depth and heterogeneous thermal conductivities in the multi-layer rock zone. Moreover, a fast simulation approach for heat transfer analysis inside the borehole coupled with the extended finite line source model is put forward to depict the transient thermal response and dynamic thermal recovery of rock outside borehole. To the authors’ knowledge, no such algorithm for deep BHE has yet been suggested in the previous literature. This approach has proven to be reliable and efficient enough for DBHE simulation under the intermittent condition. Simulation results show that at least 65 days of intermittence for the model in study should be spared after the heating season to achieve sustainable heat extraction in the next cyclic operation. Compared to the detailed solution based on full discretization numerical schemes, the relative error for borehole bottom temperature was 0.79%. In addition, comparison of the simulation results for thermal performance during the heating season in a three-year cyclic operation with 205 days intermittence shows that both the outflow temperature and heat extraction rate in the subsequent cycle after intermittence are in good agreement with the full 3D numerical solution in the reference (with a relative error of 6.36% for the outflow temperature and 9.3% for the heat extraction rate). Regarding the calculation speed, around a 13 times acceleration can be achieved. Finally, it is also promising to be applicable for thermal recovery simulation after heat extraction of vertical closed loop borehole heat exchangers at arbitrary length from shallow to deep.

Performance Evaluation and Operation Mechanism of Deep Borehole Heat Exchanger with Different Types of Boundary Conditions

2020 ◽  
Author(s):  
Wanlong Cai ◽  
Chaofan Chen ◽  
Fenghao Wang ◽  
Jun Liu ◽  
Olaf Kolditz ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Boundary Conditions ◽  
Urban Areas ◽  
Geothermal Energy ◽  
Heat Fluxes ◽  
Heat Extraction ◽  
Neumann Condition ◽  
Deep Borehole ◽  
Borehole Heat Exchanger ◽  
Different Types

<p>Due to its sustainability, continuity and low carbon emissions, the utilization of geothermal energy is gaining more attention all around the world. Shallow geothermal energy is usually extracted through borehole heat exchangers (BHE) with a maximum length up to 150 m. Such systems typically require large space areas, thus limiting its application in built-up urban areas. This study presents a case where deep borehole heat exchanger (DBHE) with a depth down to 2500 m was constructed to extract geothermal energy for building heating purposes. A double-continuum finite element based numerical model was set up to simulate the heat transport process within and around the DBHE. The model has been validated by the experimental data in a demonstration project located in Fengxi, Xi’an China. The heat extracting performance of DBHE under different types of boundary conditions (including the Dirichlet condition and Neumann condition) are evaluated. The amount of thermal recharges from top, sides and bottom of the domain were differentiated and quantified. It is found that different types of boundary conditions will lead to deviations in the simulated heat fluxes and corresponding thermal recharge. The numerical simulations also suggest that the sustainable heat extract capacity of DBHE is mainly determined by the stored heat from the surrounding subsurface, and thermal recharge takes only a limited contribution. According to the calibrated modelling results, the proper heat extraction rate of DBHE in the long-period operation modes is analyzed.</p>

scholarly journals Sustainability of the Exploitation of Campi Flegrei Geothermal Area Using a Zero-mass Extraction Device

2020 ◽  
Author(s):  
Claudio Alimonti ◽  
Elena Soldo ◽  
Gennaro Sepede ◽  
Salvador Ángel Gómez-Lopera
Keyword(s):  
Heat Exchanger ◽  
Coupled Model ◽  
Heat Extraction ◽  
Campi Flegrei ◽  
Geothermal System ◽  
Volcanic Area ◽  
Deep Borehole ◽  
Borehole Heat Exchanger ◽  
Zero Mass ◽  
Extraction Device

Abstract In this paper, the use of a zero-mass extraction device has been simulated in the volcanic area of CampiFlegrei (Italy),one of the most promising geothermal districts of Italy.The sustainability of the heat extraction has been studied with a coupled model of the geothermal reservoir and the deep borehole heat exchanger. The reservoir model has been built using the SHEMAT software, the heat transfer in the deep borehole heat exchanger has been simulated using GEOPIPE, a pure conductive semi-analytical model. An iterative approach has been used to couple the two simulators. The work has demonstrated that the area of CampiFlegrei is a promising candidate to produce sustainable geothermal energy with a zero-mass extraction device. It is also demonstrated that the coupled model of reservoir and deep borehole heat exchanger is the best modelling approach when convective structures are present in the geothermal system, which can generate heat recovery effects.

HUBUNGAN ANTARA CONSUMPTION ABROAD (MODA 2) DENGAN COMMERCIAL PRESENCE (MODA 3) DI SEKTOR JASA PARIWISATA INDONESIA

2016 ◽  
Vol 10 (1) ◽  
pp. 45-62
Author(s):  
Muhammad Fawaiq
Keyword(s):  
Vector Error Correction Model ◽  
Short Term ◽  
Correction Model ◽  
Vector Error Correction ◽  
Vector Error ◽  
Mode 2 ◽  
Variable Mode ◽  
Causality Relationship ◽  
Mode 3

Penelitian ini bertujuan untuk menganalisis hubungan antara Moda 2 dan Moda 3 dalam perdagangan internasional di sektor jasa pariwisata. Metode penelitian yang digunakan dalam penelitian ini adalah Panel Vector Error Correction Model (VECM) Granger. Data yang digunakan adalah data kedatangan wisatawan mancanegara dan Foreign Direct Investment (FDI) jasa hotel dan restoran tahun 1997-2014 di Bali, Jakarta, Kepulauan Riau dan Sumatera Utara. Daerah-daerah ini berkontribusi sebesar 81,26% dari total kedatangan wisatawan mancanegara di Indonesia dan 68% terhadap total FDI di jasa hotel dan restoran Indonesia. Hasil penelitian menunjukkan bahwa tidak terdapat hubungan kausalitas jangka pendek antara kedua variabel tetapi terdapat hubungan jangka panjang satu arah yaitu variabel Moda 3 dipengaruhi oleh variabel Moda 2. Hasil pengujian pada gabungan antara jangka panjang dan jangka pendek menujukkan bahwa variabel Moda 3 secara kuat dipengaruhi oleh variabel Moda 2. Dengan demikian diketahui bahwa semakin banyak jumlah wisatawan mancanegara yang datang ke Indonesia maka akan mendorong meningkatnya FDI di jasa hotel dan restoran, tetapi meningkatnya FDI di jasa tersebut tidak signifikan berpengaruh terhadap masuknya jumlah wisatawan mancanegara. This paper examines the relationship between Mode 2 and Mode 3 of international trade in tourism sector. The method used is the Panel Vector Error Correction Model (VECM) Granger. The data used in this study were the number of foreign tourist arrivals and the Foreign Direct Investment (FDI) in some hotels and restaurants during 1997-2014 in Bali, Jakarta, Riau Islands and Nort Sumatera.These regions contributed for 81.26% out of the total tourist arrivals in Indonesia and 68% of the total FDI in the services of hotels and restaurants Indonesia. The results using VECM Granger demonstrated that there was no short-term causality relationship between these two variables but they had a long-term causality relationship that the Moda 3 was affected by the variable mode 2. Test results on a combination of long-term and short-term showed that the variable mode 3 was strongly influenced by variable mode 2. Thus, it is known that the more foreign tourists coming to Indonesia, the more FDI we gained from the service of hotels and restaurants, but this increase does not significantly affect the number of foreign tourists.

Sign in / Sign up

Export Citation Format

Share Document