Thermo-economic comparison of coal-fired boiler-based and groundwater-heat-pump based heating and cooling solution – A case study on a greenhouse in Hubei, China

2020 ◽  
Vol 223 ◽  
pp. 110214 ◽  
Author(s):  
Jin Luo ◽  
Wei Xue ◽  
Haibing Shao
Keyword(s):  
Heat Pump ◽  
Heating And Cooling ◽  
Groundwater Heat Pump ◽  
Economic Comparison

Numerical Modelling of a District Scale Groundwater Heat Pump Operation: Case Study from Colchester, UK

2021 ◽  
Author(s):  
Taha Sezer ◽  
Abubakar Kawuwa Sani ◽  
Rao Martand Singh ◽  
David P. Boon
Keyword(s):  
Large Scale ◽  
District Level ◽  
Thermal Plume ◽  
Injection Wells ◽  
Term Operation ◽  
Heating And Cooling ◽  
Groundwater Heat Pump ◽  
The Impact

<p>Groundwater heat pumps (GWHP) are an environmentally friendly and highly efficient low carbon heating technology that can benefit from low-temperature groundwater sources lying in the shallow depths to provide heating and cooling to buildings. However, the utilisation of groundwater for heating and cooling, especially in large scale (district level), can create a thermal plume around injection wells. If a plume reaches the production well this may result in a decrease in the system performance or even failure in the long-term operation. This research aims to investigate the impact of GWHP usage in district-level heating by using a numerical approach and considering a GWHP system being constructed in Colchester, UK as a case study, which will be the largest GWHP system in the UK. Transient 3D simulations have been performed pre-construction to investigate the long-term effect of injecting water at 5°C, into a chalk bedrock aquifer. Modelling suggests a thermal plume develops but does not reach the production wells after 10 years of operation. The model result can be attributed to the low hydraulic gradient, assumed lack of interconnecting fractures, and large (>500m) spacing between the production and injection wells. Model validation may be possible after a period operational monitoring.</p>

scholarly journals Design of Groundwater Heat Pump Systems. Principles, Tools, and Strategies for Controlling Gas and Precipitation Problems

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3657 ◽  
Author(s):  
Sondre Gjengedal ◽  
Lars A. Stenvik ◽  
Pål-Tore S. Storli ◽  
Randi K. Ramstad ◽  
Bernt O. Hilmo ◽  
...  
Keyword(s):  
System Design ◽  
Heat Pump ◽  
Precipitation Reaction ◽  
Pump System ◽  
Heat Pump System ◽  
Traditional System ◽  
Heating And Cooling ◽  
Groundwater Heat Pump ◽  
Town Center ◽  
The Town

The utilization of groundwater heat pump systems is increasing in Norway, which are currently widely employed for heating and cooling applications in the town center of Melhus. The investigations of the Melhus installations are detecting gas exsolution as a possible trigger for precipitation reaction that causes incrustation of iron and manganese compounds in the systems. This paper discusses risks associated with gas exsolution and considers gas exsolution triggers in a typical Norwegian groundwater heat pump (GWHP) system configuration. The concept of the solubility grade line (SGL) is developed and suggested as a tool for optimizing the design. Based on SGL analysis and the intention of avoiding gas exsolution during heat production, an alternative system design in the same aquifer is presented and compared. The analyses show that the traditional system design is predisposed to gas clogging risks and prone to vacuum pressures in parts of the system. The alternative design mediates the risks by adjusting the well and piping configuration and by applying a backpressure technique. The results demonstrate how the groundwater heat pump system design can be customized according to local aquifer conditions to avoid gas exsolution during operation. It is recommended that the presented method of analysis should be utilized in dimensioning of systems and included in the monitoring scheme of the systems.

The BSI indicator: preventing thermal interferences between groundwater heat pump systems

2020 ◽  
Author(s):  
Alejandro García-Gil ◽  
Miguel Ángel Marazuela ◽  
Miguel Mejías Moreno ◽  
Enric Vázquez-Suñè ◽  
Eduardo Garrido Schneider ◽  
...  
Keyword(s):  
Heat Pump ◽  
Energy Demand ◽  
Polynomial Regression ◽  
Energy Resource ◽  
Direct Calculation ◽  
Urban Environments ◽  
Geothermal Systems ◽  
Operational Conditions ◽  
Heating And Cooling ◽  
Groundwater Heat Pump

<p>Shallow geothermal systems are the most efficient and clean technology for the air-conditioning of buildings and constitutes an emergent renewable energy resource in the worldwide market. Undisturbed systems are capable of efficiently exchanging heat with the subsurface and transferring it to human infrastructures, providing the basis for the successful decarbonisation of heating and cooling demands of cities. Unmanaged intensive use of groundwater for thermal purposes as a shallow geothermal energy (SGE) resource in urban environments threatens the resources´ renewability and the systems´ performance, due to the thermal interferences created by a biased energy demand throughout the year. To ensure sustainability, scientifically-based criteria are required to prevent potential thermal interferences between geothermal systems. In this work, a management indicator (balanced sustainability index, BSI) applicable to groundwater heat pump systems is defined to assign a quantitative value of sustainability to each system, based on their intrinsic potential to produce thermal interference. The BSI indicator relies on the net heat balance transferred to the terrain throughout the year and the maximum seasonal thermal load associated. To define this indicator, 75 heating-cooling scenarios based in 23 real systems were established to cover all possible different operational conditions. The scenarios were simulated in a standard numerical model, adopted as a reference framework, and thermal impacts were evaluated. Two polynomial regression models were used for the interpolation of thermal impacts, thus allowing the direct calculation of the sustainability indicator developed as a function of heating-cooling ratios and maximum seasonal thermal loads. The BSI indicator could provide authorities and technicians with scientifically-based criteria to establish geothermal monitoring programs, which are critical to maintain the implementation rates and renewability of these systems in the cities.</p>

scholarly journals Energy balancing in ground heat exchanger for heat pump systems – a case study with simulations

2019 ◽  
Vol 100 ◽  
pp. 00076
Author(s):  
Ewelina Stefanowicz ◽  
Małgorzata Szulgowska-Zgrzywa
Keyword(s):  
Renewable Energy ◽  
Heat Pump ◽  
Negative Impact ◽  
Renewable Energy Sources ◽  
Cooling Load ◽  
Energy Balancing ◽  
Heating And Cooling ◽  
Large Heat ◽  
Heating Load

The negative impact of systems based on fossil fuel on the environment and the desire to promote sustainable development is increasingly encouraging building owners to invest in renewable energy sources. One of the possibilities of using a renewable energy source located in shallow soil layers is a brine-to-water heat pump. Ground energy can be used for both heating and cooling buildings. This article presents the advantages of balancing the supply and energy consumption from the ground for the large heat pump systems. Authors presented a case study and the simulation of the system operation with different cooling load share vs heating load. This was done on the basis of the analysis of data from several years of measurements from the actual installation as well as the simulation in Earth Energy Designer software. The results of the simulations shows that the most advantageous strategy for the operation of the analysed installation is to provide 50 to 75% of the cooling load in relation to the heating load.

scholarly journals Development of a Multi-Well Pairing System for Groundwater Heat Pump Systems

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3485 ◽  
Author(s):  
Hongkyo Kim ◽  
Yujin Nam ◽  
Sang mu Bae ◽  
Oun Jeoun
Keyword(s):  
Heat Pump ◽  
Coefficient Of Performance ◽  
Geothermal Systems ◽  
Groundwater Temperature ◽  
Groundwater Levels ◽  
Term Operation ◽  
Heating And Cooling ◽  
Air Source Heat Pump ◽  
Well Clogging ◽  
Groundwater Heat Pump

Groundwater heat pump systems (GWHPs) can achieve higher coefficient of performance (COP) than air-source heat pump systems by using the relatively stable temperature of groundwater. Among GWHPs, multi-well systems have lower initial investment costs than conventional closed-loop geothermal systems, because they typically require installation of fewer boreholes for the same building load. However, the performance of GWHPs depends significantly on the groundwater properties, such as groundwater temperature, permeability and water quality. Moreover, pumping and injecting of groundwater during long-term operation may lead to problems such as overflow or clogging of the wells. In order to ensure reliable energy from ground sources, the development of sustainable operation methods for multi-well systems is essential for preventing overflow and well clogging. In this study, we have developed a pairing technology that connects the injection and supply wells through a spillway. This pairing technology can be used to control groundwater levels in wells and can be sustainably operated. To accurately estimate the performance of a multi-well system with the proposed pairing technology, the heating and cooling performance of the developed system was compared to that of a standing column well (SCW) system in a field-scale experiment. Furthermore, the effects of the multi-well pairing system on groundwater levels in the injection well were analyzed by numerical simulation. Moreover, in order to decide the required conditions of the multi-well pairing system, case studies were conducted under various hydraulic conductivity and pumping conditions.

scholarly journals Hydrochemical and biotic control on iron incrustations in groundwater heat pump systems: Case study from a saline, anoxic aquifer in Melhus, Norway

Geothermics ◽  
2022 ◽  
Vol 100 ◽  
pp. 102349
Author(s):  
Lars A. Stenvik ◽  
Sondre Gjengedal ◽  
Randi K. Ramstad ◽  
Bjørn S. Frengstad
Keyword(s):  
Heat Pump ◽  
Groundwater Heat Pump ◽  
Biotic Control

Evaluation of measures to improve the performance of an open loop ground source heat pump system in the chalk aquifer: a case study

2021 ◽  
pp. qjegh2021-074
Author(s):  
D. Birks ◽  
C. Adamson ◽  
M. G. Woods ◽  
G. Holmes
Keyword(s):  
Heat Pump ◽  
Cooling System ◽  
Specific Capacity ◽  
Open Loop ◽  
Ground Source Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Ground Source ◽  
Groundwater Heat Pump

A case study documenting the development of a groundwater-fed district heat network in Colchester, UK, is presented. The performance of an open loop groundwater heating and cooling system (also known as a ground source heat pump (GSHP)) is a function of the performance of individual boreholes and interactions between the boreholes. When performance does not meet its design capacity or decreases with time, various measures can be undertaken to improve either the performance of individual wells or the performance of the system as a whole.Output from the first exploration borehole was less than expected, placing the business case for the development in jeopardy. Consequently, refinements to the remainder of the drilling programme were implemented including three to improve the performance of individual wells and two to improve performance of the system in its entirety. Results of these refinements are presented and may be used to inform the design of new open loop groundwater heat pump systems (GSHPs) and/or the rehabilitation of existing systems that have experienced diminished performance.Yields from three wells drilled using the reverse circulation method were more than double those drilled with the direct water flush method. A significant improvement in the performance of abstraction wells due to reinjection was observed. Specific capacity in abstraction wells increased by c. 40% due to reinjection, where the distance between abstraction and reinjection locations was 535–717 m. Allowing an excess pressure of up to 0.2 MPa in the reinjection boreholes meant that reinjection could be achieved with fewer wells.Outputs from abstraction wells were not increased by extending the depth of boreholes from 135 to 200 m or implementing additional acid treatments.

Clogging Problems in Groundwater Heat Pump Systems in Sweden

1988 ◽  
Vol 20 (3) ◽  
pp. 133-140 ◽  
Author(s):  
Annika Lindblad-Påsse
Keyword(s):  
Redox Potential ◽  
Heat Pump ◽  
Hydrogen Sulphide ◽  
Sludge Formation ◽  
Iron Bacteria ◽  
Iron Precipitation ◽  
Water Composition ◽  
Groundwater Heat Pump ◽  
And Control ◽  
System Knowledge

A number of groundwater heat pump systems have been investigated to determine the extent of problems caused by the chemistry of the groundwater used. The main purpose was to investigate sites using iron rich groundwater. Fifteen facilities were studied regularly for three years. Ten of these facilities had some kind of problem caused by iron precipitation. Four of the sites were rebuilt because of severe plugging due to iron sludge in wells, pumps and pipes. In all facilities with severe problems, iron bacteria were found. Low redox potential, indicated by hydrogen sulphide in the groundwater, seems to protect from iron bacteria. In some of the systems using groundwater with H2S the problems were corrosion and sludge formation caused by sulphur oxidizing bacteria. Rapid clogging was caused by aeration of the groundwater due to improper design of the system. Knowledge of the water composition, design of the systems to minimize aeration, and control of clogging turned out to be important factors to maintain operation safety.

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