Characterizing Long-Term Groundwater Conditions And Lithology For The Design Of Large-Scale Borehole Heat Exchangers

2018 ◽  
Author(s):  
David Smith ◽  
A.C. Elmore ◽  
Jordan Thompson
Keyword(s):  
Heat Exchangers ◽  
Large Scale ◽  
Borehole Heat Exchangers

scholarly journals Finite element modeling of geothermal source of heat pump in long-term operation

2020 ◽  
Vol 154 ◽  
pp. 04003
Author(s):  
Elżbieta Hałaj
Keyword(s):  
Finite Element ◽  
Heat Source ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Transport Model ◽  
Heat Pumps ◽  
Initial Temperature Distribution ◽  
Term Operation ◽  
Borehole Heat Exchangers

Heat pumps become more and more popular heat source. They can be an alternative choice for obsolete coal fired boilers which are emissive and not ecological. During heat pump installation designing process, especially for heat pumps with higher heating capacity (for example those suppling larger buildings), a simulation of heat balance of ground heat source must be provided. A 3D heat transport model and groundwater flow in the geothermal heat source for heat pump (GSHP) installation was developed in FEFLOW according to Finite Element Modelling Method. The model consists of 25 borehole heat exchangers, arranged with spacing recommended by heat pump branch guidelines. The model consists of both a homogeneous, non-layered domain and a layered domain, which reflected differences in thermal properties of the ground and hydrogeological factors. The initial temperature distribution in the ground was simulating according to conditions typical for Europe in steady state heat flow. Optimal mesh refinement for nodes around borehole heat exchangers were calculated according to Nillert method. The aim of this work is to present influence of geological, hydrogeological factors and borehole arrangement in the energy balance and long term sustainability of the ground source. The thermal changes in the subsurface have been determined for a long term operation (30 years of operation period). Some thermal energy storage applications have also been considered.

Development of Ceramic Heat Exchangers for Indirect Fired Gas Turbines

1982 ◽  
Author(s):  
W. T. Bakker ◽  
D. Kotchick
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
Large Scale ◽  
Working Fluid ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Short Term ◽  
The Status

Utilizing dirty fuels such as coal in gas turbine engines requires that heat input to the cycle working fluid occur through a heat exchanger. For high cycle efficiencies such a heat exchanger must operate in the 700–1400 KPA, 1100–1200°C (100–200 psi, 2000–2200°F) range. In this temperature range, ceramic heat exchangers are required. Ceramic heat exchangers that can operate in this regime have been under development for several years on a very modest scale. These programs are briefly reviewed. Major material issues are reviewed and the status of each is presented. Mechanical reliability and joining technology have been successfully demonstrated in short term tests. Long-term durability and the manufacturing technology to produce large scale components reproducibly remains to be demonstrated in the future.

scholarly journals Finite Element Modeling of Geothermal Source of Heat Pump in Long-Term Operation

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1341 ◽  
Author(s):  
Elżbieta Hałaj ◽  
Leszek Pająk ◽  
Bartosz Papiernik
Keyword(s):  
Heat Pump ◽  
Thermal Energy ◽  
Heat Exchangers ◽  
Thermal Recovery ◽  
Small Scale ◽  
Term Operation ◽  
Ground Source ◽  
Space Cooling ◽  
Borehole Heat Exchangers

Model simulation allows to present the time-varying temperature distribution of the ground source for heat pumps. A system of 25 double U-shape borehole heat exchangers (BHEs) in long-term operation and three scenarios were created. In these scenarios, the difference between balanced and non-balanced energy load was considered as well as the influence of the hydrogeological factors on the temperature of the ground source. The aim of the study was to compare different thermal regimes of BHEs operation and examine the influence of small-scale and short-time thermal energy storage on ground source thermal balance. To present the performance of the system according to geological and hydrogeological factors, a Feflow® software (MIKE Powered by DHI Software) was used. The temperature for the scenarios was visualized after 10 and 30 years of the system’s operation. In this paper, a case is presented in which waste thermal energy from space cooling applications during summer months was used to upgrade thermal performance of the ground (geothermal) source of a heat pump. The study shows differences in the temperature in the ground around different Borehole Heat Exchangers. The cold plume from the not-balanced energy scenario is the most developed and might influence the future installations in the vicinity. Moreover, seasonal storage can partially overcome the negative influence of the travel of a cold plume. The most exposed to freezing were BHEs located in the core of the cold plumes. Moreover, the influence of the groundwater flow on the thermal recovery of the several BHEs is visible. The proper energy load of the geothermal source heat pump installation is crucial and it can benefit from small-scale storage. After 30 years of operation, the minimum average temperature at 50 m depth in the system with waste heat from space cooling was 2.1 °C higher than in the system without storage and 1.6 °C higher than in the layered model in which storage was not applied.

Long-term thermal imbalance in large borehole heat exchangers array – A numerical study based on the Leicester project

2021 ◽  
Vol 231 ◽  
pp. 110518
Author(s):  
Shuang Chen ◽  
Wanlong Cai ◽  
Francesco Witte ◽  
Xuerui Wang ◽  
Fenghao Wang ◽  
...  
Keyword(s):  
Heat Exchangers ◽  
Numerical Study ◽  
Thermal Imbalance ◽  
Borehole Heat Exchangers

Geotechnical Considerations in the Design of Borehole Heat Exchangers

2020 ◽  
Author(s):  
Despina Maria Zymnis ◽  
Andrew J. Whittle
Keyword(s):  
Heat Exchanger ◽  
Parametric Study ◽  
Heat Exchangers ◽  
Design Parameters ◽  
Ground Source Heat Pumps ◽  
Heat Exchanger Design ◽  
Heating And Cooling ◽  
Adjacent Structures ◽  
Borehole Heat Exchangers

The use of ground source heat pumps to transfer heat to and from the ground via borehole heat exchangers (BHE) is among the most energy efficient techniques for space heating and cooling. Broader applications in urban environments require more careful evaluation of hydro-mechanical behavior of soil to ensure their reliable long-term performance and to minimize adverse effects on adjacent structures. An advanced soil model has been integrated within a finite difference (FD) framework, to solve coupled thermo-hydro-mechanical (THM) problems in an axisymmetric space. The FD simulator is applied to a prototype project and the ground conditions represent typical stress history profiles found in Geneva, Switzerland. An extensive parametric study is undertaken to study the long-term THM response of clay for a broad range of heat exchanger design parameters. The results show that significant settlements can be induced due to the long-term operation of BHEs (i.e., over periods from 10–50 years). The parametric study gives useful guidelines for heat exchanger design and identifies a design space of optimum solutions that meet pre-specified foundation settlement criteria. The study provides a qualitative investigation and a systematic framework for analyzing the long-term THM response of clay to seasonal heating and cooling.

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