scholarly journals Comparative Experiment of Wellbore Self-Circulation Heat Mining Capacity with Different Heat-Carrying Fluids

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 5) ◽  
Author(s):  
Liang Zhang ◽  
Linchao Yang ◽  
Songhe Geng ◽  
Shaoran Ren
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Convective Heat Transfer Coefficient ◽  
Similarity Criterion ◽  
Injection Pressure ◽  
Outlet Temperature ◽  
Field Scale ◽  
Horizontal Wellbore ◽  
Mining Capacity ◽  
Criterion Method

Abstract Based on the principle of wellbore self-circulation heat mining, the evaluation experiments of local wellbore self-circulation heat exchange laws and influencing factors were carried out. Water, SCCO2, R134a, and heat transfer oil were screened as the heat-carrying fluids. The heat exchange laws and heat mining capacity of these four heat carrying fluids were analyzed and compared, and their heat mining rates at the field scale were estimated using the similarity criterion method according to the experimental results. The results show that R134a and heat transfer oil can obtain the largest outlet temperature and the largest heat loss ratio, while the water can achieve a higher heat mining rate and a larger convective heat transfer coefficient than the other three fluids. The heat mining capacity of CO2 is significantly affected by the injection pressure. It is necessary to optimize the injection pressure larger than critical point to achieve the best heat mining performance. When the water is selected as the heat-carrying fluid, the heat mining rate can reach more than 1 MW if a horizontal wellbore with a length of 2000 m is applied for wellbore self-circulation at the field scale.

scholarly journals Experimental Study on the Heat Exchange Mechanism in a Simulated Self-Circulation Wellbore

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2918
Author(s):  
Liang Zhang ◽  
Songhe Geng ◽  
Jun Kang ◽  
Jiahao Chao ◽  
Linchao Yang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Exchange ◽  
Convective Heat Transfer Coefficient ◽  
Injection Rate ◽  
Circulation Rate ◽  
Similarity Analysis ◽  
Published Data ◽  
Outlet Temperature ◽  
Hot Dry Rocks ◽  
Mining Capacity

Self-circulation wellbore is a new technique for geothermal development in hot dry rocks (HDR), which uses a U-shape channel composed of tubing and casing as the heat exchanger. In this study, a self-circulation wellbore in HDR on a laboratory scale was built, and a serial of experiments were conducted to investigate the heat exchange law and the influencing factors on the heat mining rate of the wellbore. A similarity analysis was also made to estimate the heat-mining capacity of the wellbore on a field scale. The experimental results show that the large thermal conductivity and heat capacity of granite with high temperature can contribute to a large heat-mining rate. A high injection rate can cause a high convective heat transfer coefficient in wellbore, while a balance is needed between the heat mining rate and the outlet temperature. An inner tubing with low thermal conductivity can significantly reduce the heat loss to the casing annulus. The similarity analysis indicates that a heat mining rate of 1.25 MW can be reached when using a 2000 m long horizontal well section in a 150 °C HDR reservoir with a circulation rate of 602.8 m3/day. This result is well corresponding to the published data.

Development of a Computer Program for the Numerical Investigation of Heat Transfer in a Gasketed Plate Heat Exchanger

2010 ◽  
Author(s):  
Gizem Gulben ◽  
Selin Aradag ◽  
Nilay Sezer-Uzol ◽  
Ufuk Atamturk
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Computer Program ◽  
Working Conditions ◽  
Convective Heat Transfer Coefficient ◽  
Plate Heat Exchanger ◽  
Design Parameters ◽  
Outlet Temperature ◽  
Pressure Drops ◽  
Plate Heat

In this study, a computer program is developed to calculate characteristics of a Chevron type gasketed plate heat exchanger (CTGPHEX) such as: the number of plates, the effective surface area and total pressure drops. The main reason to prefer the use of CTGPHEXs to other various types of heat exchangers is that the heat transfer efficiency is much higher in comparison. Working conditions such as the flow rates and inlet and outlet temperature of both flow sides and plate design parameters are used as an input in the program. The Logarithmic Mean Temperature Method and the different correlations for convective heat transfer coefficient and Fanning factor that are found in the literature are applied to calculate the minimum necessary effective heat transfer area, the number of plate and pressure drops due to friction for both fluid sides of fulfill the desired heat transfer rate. This Turkish / English language optioned user friendly computer program is targeted to be used in domestic companies to design and select CTGPHEXs for any desired working conditions.

scholarly journals Horizontal earth-air heat exchanger for preheating external air in the mechanical ventilation system

2018 ◽  
Vol 13 (1) ◽  
pp. 71-76
Author(s):  
Vasyl Zhelykh ◽  
Olena Savchenko ◽  
Vadym Matusevych
Keyword(s):  
Heat Transfer ◽  
Mechanical Ventilation ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Exchangers ◽  
Convective Heat Transfer Coefficient ◽  
Ventilation System ◽  
Heat Pipes ◽  
Heat Exchanger Tube ◽  
Exchanger Tube

Abstract To save traditional energy sources in mechanical ventilation systems, it is advisable to use low-energy ground energy for preheating or cooling the outside air. Heat exchange between ground and outside air occurs in ground heat exchangers. Many factors influence the process of heat transfer between air in the heat exchanger and the ground, in particular geological and climatic parameters of the construction site, parameters of the ventilation air in the projected house, physical and geometric parameters of the heat exchanger tube. Part of the parameters when designing a ventilation system with earth-air heat exchangers couldn’t be changed. The one of the factors, the change which directly affects the process of heat transfer between ground and air, is convective heat transfer coefficient from the internal surface of the heat exchanger tube. In this article the designs of a horizontal earthair heat exchanger with heat pipes was proposed. The use of heat pipes in designs of a horizontal heat exchanger allows intensification of the process of heat exchange by turbulence of air flow inside the heat exchanger. Besides this, additionally heat transfer from the ground to the air is carried out at the expense of heat transfer in the heat pipe itself.

Investigation of Heat Transfer Efficiency of Improved Intermig Impellers in a Stirred Tank Equipped with Vertical Tubes

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Leizhi Wang ◽  
Yongjun Zhou ◽  
Zhaobo Chen
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Heat Exchange ◽  
Convective Heat Transfer Coefficient ◽  
Simulation Software ◽  
Related Factors ◽  
Temperature Boundary Layer ◽  
Temperature Boundary ◽  
Vertical Tubes

AbstractThe heat transfer of a reactor with improved Intermig impellers was numerically investigated by the finite element method (FEM) simulation software Fluent (V.19). A turbulence model utilized the standard k-ε model, and the turbulent flows in two large vortexes between vertical tubes were collided to form a strong convection. The influence of heat and mass transfer developing from the impeller diameters, the distance between the two impellers (C1), the rotational speed and the installation height of the bottom impeller (C2) were studied. The reactor was equipped with special structure vertical tubes to increase the heat exchange areas. The rate of heat transfer, including criteria such as the convective heat transfer coefficient, the Nusselt number of outside vertical tubes, and the temperature boundary layer thickness, assured the accurate control of the heat exchange mixing state. The experimental testing platform was designed to validate the simulated results, which revealed the influence order of related factors. The Nusselt number Nu was affected by various related factors, resulting in the rotation and diameter of impellers extending far beyond the distance between the two impellers (C1) and the installation height of the impeller (C2). The average temperature boundary layer thicknesses of the symmetrical and middle sections were 3.24 mm and 3.48 mm, respectively. Adjusting the appropriate parameters can accurately control the heat exchange process in such a reactor, and the conclusions provide a significant reference for engineering applications.

Comparative Thermal Analyses Between Theoretical Mode and RELAP5 Code Simulation for OTSG of a Small PWR

2020 ◽  
Author(s):  
Baihui Jiang ◽  
Zhiwei Zhou ◽  
Zhaoyang Xia ◽  
Qian Sun
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Nuclear Reactors ◽  
Heat Transfer Analysis ◽  
Tube Length ◽  
Outlet Temperature ◽  
Steam Generators ◽  
Inclined Tube ◽  
Heat Transfer Calculation ◽  
Relap5 Code

Abstract Due to the low nuclear safety risk, low initial investment cost and short construction period, integrated small nuclear reactors have received wide attention from all over the world. As advanced new type of nuclear reactors, the technologies of integrated small nuclear reactors are in the process of exploration and development. Steam generators are used as the heat transfer system for energy exchange between the primary and secondary circuit in reactors, and their heat transfer analysis is very important for reactor design and development. Due to the simple structure, strong heat exchange capacity and timely load following, Once-Through Steam Generators (OTSGs) are the mainly used steam generators in the design of integrated small nuclear reactors. RELAP5/MOD4.0 is a commercial software developed by Innovative System Software, LLC for transient analysis of light water reactors (LWR). After years of development and improvement, RELAP5 has been a basic tool for analysis and calculation of various simulators of nuclear power plants. However, when RELAP5 models steam generators, only structural models related to straight pipes can be established, which is very inconvenient for the heat transfer research of Once-Through Steam Generators. In this paper, Once-Through Steam Generators with specified structural parameters are taken as the research object. The heat transfer calculation is performed on the simplified inclined tube models by RELAP5 code and the theoretical calculation of the spiral tube heat transfer models is also carried out. Comparing the steam outlet temperature on the primary and secondary sides, the heat exchange power, the average heat transfer coefficient and the tube length of different heat exchange zones under given primary and secondary side inlet fluid conditions, it is confirmed that the RELAP5 heat transfer calculation is verified for simplifying Once-Through Steam Generators with inclined tube models.

Research on Energy and Environment Engineering with Heat Transfer in the Geothermal Heating System with Horizontal Wells

2014 ◽  
Vol 908 ◽  
pp. 461-464 ◽  
Author(s):  
Ming Ming Lv ◽  
Shu Zhong Wang ◽  
Xiang Rong Luo ◽  
Ming Luo
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Flow Rate ◽  
Horizontal Well ◽  
Horizontal Wells ◽  
Heating System ◽  
Transfer Model ◽  
Outlet Temperature ◽  
Linear Change ◽  
Geothermal Heating

Geothermal heating system with horizontal wells doesnt extract ground water and is not affected by the distribution of geothermal resources, which is a closed-loop and environment-friendly system. In this paper, the heat exchange between the horizontal well and rock in the geothermal heating system with horizontal wells has been studied, the heat transfer model has been built, and the heat transfer at different flow rates of water has been calculated. The results show that the outlet temperature of the horizontal well increases with the decrease of the flow rate, and the flux of heat exchange decreases with the decrease of the flow rate. The outlet temperature and the flux of heat transfer have basically the same tendency with time. The three stages are respectively rapidly change stage, moderate change stage and linear change stage.

Heat Transfer Enhancement by Ultrasound Pressure Waves in Liquid Water: A Cooling Method for New Electronic Components

2014 ◽  
Vol 556-562 ◽  
pp. 1968-1974
Author(s):  
Carlo Bartoli ◽  
F. Baffigi ◽  
Andrea Brunini
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Ultrasonic Waves ◽  
Ultrasonic Power ◽  
Experimental Apparatus

The objective of this work is to study the increase of the convective heat transfer coefficient in the presence of ultrasound waves and, in particular, to find a relationship between the ultrasonic power and the effective pressure of water. The tests have focused on the heat exchange by natural convection, in single-phase conditions, at atmospheric pressure, between a cylinder, heated by means of the Joule effect, and distilled water, with and without the action of ultrasonic waves. The variables involved in the heat exchange have been varied within the range allowed by the experimental apparatus and the convective heat transfer coefficient has been maximized. The specific thermal flow has been chosen in a range compatible with applications in the field of electronics. For the first time the pressure of water at various ultrasonic power levels has been measured, in the vicinity of the cylindrical surface, thanks to the collaboration with the Naval Experimentation and Support Center (CSSN) of the Italian Navy in La Spezia, Italy.

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