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>

Geo.KW, a coupled hydrothermal and infrastructure model at urban scale

2021 ◽  
Author(s):  
Thilo Schramm ◽  
Fabian Böttcher ◽  
Viktoria Pauw ◽  
Leonhard Odersky ◽  
Smajil Halilovic ◽  
...  
Keyword(s):  
Energy Demand ◽  
Transport Model ◽  
Linear Optimization ◽  
Urban Environments ◽  
Optimization Approach ◽  
Geothermal Systems ◽  
Iterative Coupling ◽  
Energy Infrastructure ◽  
Heating And Cooling ◽  
High Level

<p>To reduce anthropogenic climate change, our energy demand needs to be met by renewable energies, wherever possible. So far, only a minor part of heating and cooling is met by such sources. Shallow geothermal energy, powered by green electricity, can close this gap at a high level of efficiency, while reducing intermittency problems current renewables have. As there are various competing uses of the underground in urban environments, e.g. drinking water protection and infrastructure, local authorities are more and more restrictive in granting licenses for new shallow geothermal systems.</p><p>In the project Geo.KW we created a coupling approach, which combines hydrothermal and infrastructure modeling to efficiently position shallow geothermal systems between existing uses and other conflicting groundwater usage, optimized by economical and ecological constraints. This should act as a planning tool for water authorities and policymakers.</p><p>We are using PFLOTRAN, a finite volume Darcy-Richards model as our flow and heat transport model.<br>The energy infrastructure optimization is done with urbs, a linear optimization model for distributed energy systems.<br>For our iterative coupling, we are using preCICE, a multi-physics coupling library, which facilitates fully parallel peer-to-peer exchange between these modeling domains.</p><p>The city of Munich is the pilot-region for the implementation of our tool, supported by local government and water authorities. The size and complexity of the model makes it necessary to run the optimization approach on a supercomputer, i.e. the SuperMUC-NG of the Leibniz Supercomputing Centre. Even there, the model needs to be partitioned for the energy infrastructure optimization to be feasible.</p>

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 Study of a Heat Pump for Simultaneous Cooling and Desalination

2016 ◽  
Vol 819 ◽  
pp. 152-159 ◽  
Author(s):  
Paul Byrne ◽  
Yacine Ait Oumeziane ◽  
Laurent Serres ◽  
Thierry Mare
Keyword(s):  
Heat Pump ◽  
Energy Demand ◽  
Energy Resource ◽  
Coupled System ◽  
Data File ◽  
Cooling Capacity ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Weather Data ◽  
Air Gap Membrane Distillation

Access to freshwater and energy resource management are two of the major concerns of the next decades. The global warming indicator, the decrease of rainfalls and the growing energy demand for cooling are correlated in the most populated agglomerations of the world. For industrial and social purposes, it seems vital to develop energy efficient systems for cooling and desalination. A heat pump can produce energy for space cooling and heat for desalination. Among the different desalination systems available, membrane distillation seems the most suitable solution to the condensing temperature level of a standard heat pump.This article presents the development of a model of heat pump for simultaneous cooling and desalination by air-gap membrane distillation. The model was first developed using EES software and validated with experimental results from our laboratory and from the literature. The desalination unit was then optimised by numerical means in terms of dimensions and operating conditions using a bi-dimensional model with Matlab. A coupled system with a heat pump was finally simulated. The objective is to estimate the freshwater production depending on the cooling loads of a refrigerator placed in a building submitted to the conditions given by a weather data file in the Trnsys environment. The energy consumptions are compared to those of a standard reverse osmosis plant producing the same amount of freshwater associated to a chiller of same cooling capacity as the heat pump. The results show that the heat pump for simultaneous cooling and desalination offers interesting perspectives.

scholarly journals A European Database of Building Energy Profiles to Support the Design of Ground Source Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2496 ◽  
Author(s):  
Laura Carnieletto ◽  
Borja Badenes ◽  
Marco Belliardi ◽  
Adriana Bernardi ◽  
Samantha Graci ◽  
...  
Keyword(s):  
Heat Pump ◽  
Energy Demand ◽  
Residential Buildings ◽  
Building Energy ◽  
Heat Pumps ◽  
Climatic Conditions ◽  
Ground Source Heat Pumps ◽  
Heating And Cooling ◽  
Energy Profiles ◽  
Ground Source

The design of ground source heat pumps is a fundamental step to ensure the high energy efficiency of heat pump systems throughout their operating years. To enhance the diffusion of ground source heat pump systems, two different tools are developed in the H2020 research project named, “Cheap GSHPs”: A design tool and a decision support system. In both cases, the energy demand of the buildings may not be calculated by the user. The main input data, to evaluate the size of the borehole heat exchangers, is the building energy demand. This paper presents a methodology to correlate energy demand, building typologies, and climatic conditions for different types of residential buildings. Rather than envelope properties, three insulation levels have been considered in different climatic conditions to set up a database of energy profiles. Analyzing European climatic test reference years, 23 locations have been considered. For each location, the overall energy and the mean hourly monthly energy profiles for heating and cooling have been calculated. Pre-calculated profiles are needed to size generation systems and, in particular, ground source heat pumps. For this reason, correlations based on the degree days for heating and cooling demand have been found in order to generalize the results for different buildings. These correlations depend on the Köppen–Geiger climate scale.

scholarly journals Comparison between Measured and Calculated Thermal Conductivities within Different Grain Size Classes and Their Related Depth Ranges

Soil Systems ◽  
2018 ◽  
Vol 2 (3) ◽  
pp. 50 ◽  
Author(s):  
David Bertermann ◽  
Johannes Müller ◽  
Simon Freitag ◽  
Hans Schwarz
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Bulk Density ◽  
Energy Resource ◽  
Fundamental Property ◽  
Geothermal Systems ◽  
Research Activity ◽  
Heating And Cooling ◽  
Very Shallow Geothermal Energy ◽  
Thermal Conductivities

In the field of the efficiency of very shallow geothermal energy systems, there is still a significant need for research activity. To ensure the proper exploitation of this energy resource, the decisive geophysical parameters of soil must be well-known. Within this study, thermal conductivity, as a fundamental property for evaluating the geothermal potential of very shallow geothermal systems, was analyzed and measured with a TK04 device. A dataset, consisting of various geophysical parameters (thermal conductivity, bulk density, water content, and porosity) determined for a large range of different textural soil classes, was collated. In a new approach, the geophysical properties were visualized covering the complete grain size range. The comparison between the measured and calculated thermal conductivity values enabled an investigation with respect to the validity of the different Kersten equations. In the course of this comparison, the influence of effective bulk density was taken into account. In conclusion, both Kersten formulas should be used as recommended and regular bulk density corresponded better to the reference dataset representing the outcomes of the TK04 laboratory measurement. Another objective was to visualize the relation of thermal conductivities within their corresponding textural classes and the validity of Kersten formulas for various bulk densities, depths, and soils. As a result, the accessibility to information for expedient recommendations about the feasibility of very shallow geothermal systems will be improved. Easy, accessible know-how of the fundamentals is important for a growing renewable energy sector where very shallow geothermal installations can also cover heating and cooling demands.

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.

scholarly journals Thermo-Chemical Instability and Energy Analysis of Absorption Heat Pumps

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1966
Author(s):  
Gábor L. Szabó
Keyword(s):  
Heat Pump ◽  
Energy Demand ◽  
Energy Analysis ◽  
Heat Pumps ◽  
Condensation Temperature ◽  
Heat Sources ◽  
Evaporation And Condensation ◽  
Chemical Instability ◽  
Heating And Cooling ◽  
Points Of View

This paper presents the results of energy analysis of absorption heat pumps. The thermo-chemical instability term was introduced for absorption heat pumps used for heating or cooling or heating and cooling. A higher thermo-chemical instability results in the equipment being more sensitive with regard to the variation of the heat source flux. This sensitivity can be taken into account when heat sources are chosen for a certain absorption machine. Absorption heat pumps having thermo-chemical compressors were compared from energy demand and energy efficiency points of view with heat pumps having mechanical compressors. As it is shown, for certain evaporation and condensation temperature values, an absorption heat pump with similar efficiency to that of the heat pump with a mechanical compressor can always be found.

scholarly journals Energy Analysis of a Dual-Source Heat Pump Coupled with Phase Change Materials

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2933
Author(s):  
Michele Bottarelli ◽  
Francisco Javier González Gallero
Keyword(s):  
Phase Change ◽  
Heat Pump ◽  
Energy Demand ◽  
Phase Change Materials ◽  
Weather Conditions ◽  
Heat Pumps ◽  
Ground Heat Exchangers ◽  
Heating And Cooling ◽  
Air Source Heat Pump ◽  
Dual Source

Installation costs of ground heat exchangers (GHEs) make the technology based on ground-coupled heat pumps (GCHPs) less competitive than air source heat pumps for space heating and cooling in mild climates. A smart solution is the dual source heat pump (DSHP) which switches between the air and ground to reduce frosting issues and save the system against extreme temperatures affecting air-mode. This work analyses the coupling of DSHP with a flat-panel (FP) horizontal GHE (HGHE) and a mixture of sand and phase change materials (PCMs). From numerical simulations and considering the energy demand of a real building in Northern Italy, different combinations of heat pumps (HPs) and trench backfill material were compared. The results show that PCMs always improve the performance of the systems, allowing a further reduction of the size of the geothermal facility. Annual average heat flux at FP is four times higher when coupled with the DSHP system, due to the lower exploitation. Furthermore, the enhanced dual systems are able to perform well during extreme weather conditions for which a sole air source heat pump (ASHP) system would be unable either to work or perform efficiently. Thus, the DSHP and HGHE with PCMs are robust and resilient alternatives for air conditioning.

scholarly journals Archetype definition for analysing retrofit solutions in urban areas in Europe

2019 ◽  
Vol 111 ◽  
pp. 03027
Author(s):  
Michele De Carli ◽  
Laura Carnieletto ◽  
Antonino Di Bella ◽  
Samantha Graci ◽  
Giuseppe Emmi ◽  
...  
Keyword(s):  
Urban Areas ◽  
Energy Demand ◽  
Peak Power ◽  
Heat Pumps ◽  
Urban Environments ◽  
Cold Climate ◽  
Ground Source Heat Pumps ◽  
Heating And Cooling ◽  
Set Up ◽  
Different Levels

Ground Source Heat Pumps (GSHP) are gaining interest for many applications and a very difficult task is to look at their affordability in urban environments with limited spaces. For this reason, the EU project GEO4CIVHIC has been funded. In order to set up different cases with different levels of retrofit and try to generalize results, the project focuses the activity on archetypes, i.e. buildings which may represent the usual type of building which may be found more frequently in urban environments around Europe. The analysis of the archetypes has been based on literature review and analysing the existing databases of buildings in Europe. The work allowed to determine a reference building for single family house and a building representing an apartment block for multi-users. In this latest case two types of possible uses have been examined: residential building and office building. In order to set up different levels of retrofit and cost-effective solutions, three different climates have been defined: warm climate, mild climate and cold climate. The climatic conditions do not only affect the energy demand of the building and the peak power needed for heating and cooling, but also determine different ways of buildings’ construction and define different levels of insulation. Last but not least, the buildings have been also subdivided into existing buildings, i.e. built up from 1960 to 2000 and historic buildings, i.e. buildings earlier than 1960. The paper presents the first step of the research which permitted to define the different archetypes, their dimensions and way they are constructed. Moreover, the different simulations allowed to define the energy needs of the buildings as well as the peak power for heating and cooling. This allows to create a matrix for the different levels of retrofit solutions which will be associated to related costs for a cost-benefit analysis to check the most achievable solutions.

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