Heat Pump Research Articles

Integrative analysis of the Aachen geothermal system (Germany) with an interdisciplinary conceptual model

Abstract The comprehension of geothermal systems involves the efficient integration of geological, geophysical and geochemical tools that are crucial in unraveling the distinct features inherent in geothermal reservoirs. We provide a first approach to comprehending the geologically complex geothermal system in the Aachen area, which has been known for its natural thermal spring occurrences since Roman times. Through a comprehensive analysis involving geochemical interpretation of water samples, a review of 2D seismic profiles, stress analysis, and surface geology, a dynamic model has been built, which serves as a conceptual framework providing a clearer understanding of the system. The model characterizes a non-magmatic, detachment fault-controlled convective thermal system, wherein the reservoir exhibits mixed properties of the mainly Devonian carbonate rocks. NW–SE directed fault lines play a pivotal role in fluid transport, enabling the ascent of thermal waters without the need for additional energy. We additionally conducted magnetotelluric (MT) surveys and analyzed apparent resistivity and impedance values obtained through forward modeling, along with an assessment of noise levels. These findings contribute to evaluating the potential use of MT methods in further evaluating the study area and for geothermal energy exploration in general.

Energy Saving Technologies and Practices in Facility Agriculture in Cold Regions

With the growth of the global population, energy demand continues to rise, making cross-regional energy transportation less viable as a sustainable solution. As a result, the construction of facilities for agriculture in cold regions has become increasingly important in the development of modern agriculture. However, cold region facility agriculture faces significant energy and environmental challenges, necessitating the advancement and application of energy saving technologies. This study addresses the high energy consumption in cold region facility agriculture by experimentally evaluating the integrated effects of geothermal heat pumps, solar collectors, intelligent light control systems, LED plant lamps, and smart ventilation systems in saving energy. The focus is on analyzing the technical adaptability and economic feasibility of these technologies under extremely cold conditions in Heilongjiang. The research findings indicate an overall energy saving rate of 17.8%, with energy savings in heating, lighting, and ventilation systems being 17.6%, 18.6%, and 17.4%, respectively. Economic analysis shows that geothermal heat pumps and high efficiency insulation materials have a short investment payback period and are suitable for widespread adoption, while solar collectors and intelligent light control systems are more appropriate for long-term application. This study demonstrates that intelligent and integrated energy saving technologies have significant potential in cold region facility agriculture, providing both data support and technical references for the efficient, low-carbon development of agriculture in cold climates. This study not only provides scientific evidence for the sustainable development of cold region facility agriculture but also highlights the practical implications of these technologies for reducing energy consumption and promoting low-carbon agriculture.

Effect of degassing on scaling in hypersaline system: Tuzla geothermal field, Turkey

A serious issue with geothermal power plants is the loss of production and decline in power plant efficiency. Scaling, also known as mineral precipitation, is one of the frequently-observed issue that causes this loss and decreasing efficiency. It is heavily observed in the production wells when the geothermal fluid rises from the depths due to a change in the fluid’s physical and chemical properties. Scaling issue in geothermal power plants result in significant output losses and lower plant effectiveness. In rare instances, it might even result in the power plant being shut down. The chemistry of the geothermal fluid, non-condensable gases, pH, temperature and pressure changes in the process from production to reinjection, power plant type and design, and sometimes the materials used can also play an active role in the scaling that will occur in a geothermal system. ICP–MS was used to evaluate the chemical properties of the fluids. On the other hand, XRD, XRF and SEM were used to investigate the chemical and mineralogical compositions of the scale samples in analytical methods. For the numerical approach, PhreeqC and GWELL codes were used to follow the chemical reactivity of the geothermal fluid in Tuzla production well. The novelty of this study is to determine potential degassing point and to characterize the mineralogical assemblage formed in the well because of the fluid composition, temperature and pressure variations. During production, geothermal fluids degas in the wellbore. This causes a drastic modification of the chemistry of the Tuzla fluids. This is why it is focused the calculations on the nature of the minerals that are able to precipitate inside the well. According to simulation results, the degassing point is estimated to be about 105 m depth, consistent with the field observations. If a small quantity of precipitated minerals is predicted before the boiling point, degassing significantly changes the fluid chemistry, and the model predicts the deposition of calcite along with smaller elements including galena, barite, and quartz. The simulation results are consistent with the mineral composition of scaling collected in the well.

Direct Air Capture by Monoethanolamine Absorption with Heat Pump Enhancements

Direct Air Capture by Monoethanolamine Absorption with Heat Pump Enhancements

Groundwater temperatures downstream from a large-scale geothermal collector system (LSC) in Bad Nauheim, Germany

Abstract The impact of horizontal geothermal systems on groundwater temperature has not been studied in detail due to their generally shallow installation depth. However, interactions between very shallow geothermal systems and groundwater are expected, especially at short groundwater distances. In this study, the effects of a large-scale geothermal collector system (LSC) in Bad Nauheim (Hesse, Germany) on the downstream shallow groundwater were analysed. For this purpose, subsurface and groundwater temperatures were measured over a period of two years. The results showed that in the immediate downstream area, the maximum degree of cooling of the groundwater temperature was between 4.2 and 5.2 K with a minimum temperature of 5.2 °C. Consequently, the presence of a temperature plume was demonstrated, whereby a significant regeneration of the subsurface temperature in comparison to measured values within the LSC area was also observed.

Charge and heat pumping in the Rice-Mele chain at finite temperature

Charge and heat pumping in the Rice-Mele chain at finite temperature

Solar Drying for Domestic and Industrial Applications: A Comprehensive Review of Innovations and Efficiency Enhancements

AbstractGlobal challenges such as energy scarcity and food security are intensified by a growing population and substantial post‐harvest food losses, contributing to alarming hunger levels. Solar drying is recognized as an effective, high‐quality, and sustainable method for food preservation, significantly aiding global food security. Dryers are essential in agriculture and the food industry for extending crop shelf life by removing moisture through thermal energy, with solar thermal energy being particularly suitable due to its environmental benefits and availability. This article reviews the classification of solar dryers, including direct (DSD), indirect (ISD), and hybrid (HSD) systems, examining key components like solar collectors, drying chambers, and auxiliary systems and the factors affecting their performance. The review highlights that the efficiency of solar dryers depends on dryer type, solar irradiation, drying duration, and operational conditions. Recent advancements to enhance solar dryers' energy efficiency include hybrid systems incorporating auxiliary heating sources (electric or biomass), solar‐assisted heat pump dryers, surface modification techniques, and heat storage systems utilizing sensible and latent heat storage. Findings suggest that HSD with auxiliary units can achieve up to 54% efficiencies, while solar collectors can reach up to 81%, yielding better product quality than traditional ones.

Innovative Approaches of Optimization Methods Used in Geothermal Power Plants: Artificial Neural Networks and Genetic Algorithms

In this study, a general description of geothermal power plants is provided, and the optimization methods used are summarized. Following the review of these optimization methods, the advantages of heuristic methods and the success of the developed models are demonstrated. The challenges in optimizing geothermal systems, including the limitations due to their complexity and the use of multiple parameters, are discussed. Heuristic methods, particularly the widely used artificial neural networks and genetic algorithms, are explained in general terms. Recent studies highlight that the combined use of artificial neural networks and genetic algorithms can produce faster and more consistent results. This demonstrates the benefits of using advanced methods for geothermal resource utilization and power plant optimization. An innovative optimization method has been developed using the operational data of an ORC geothermal power plant in the city of Izmir. The computational method, using genetic algorithms with artificial neural networks as the fitness function, has identified the optimal operating conditions, achieving a 39.41% increase in net power output. The plant’s gross power generation has increased from 4943 kW to 6624 kW.

Comprehensive Analysis and Emission Reduction Pathway of GHG Emissions at a Wastewater Treatment Plant in Suzhou

Taking a sewage treatment plant in Suzhou City, Jiangsu Province, as an example, the greenhouse gas （GHG） emissions generated in the sewage treatment system were calculated using the carbon balance method and the emission factor method. The environmental impacts and economic aspects of different treatment units in wastewater treatment plants were analyzed using life cycle assessment, cost-benefit analysis, and data envelopment analysis models, and emission reduction pathways were proposed. The results indicated that the total GHG emissions （in terms of CO2） from a certain municipal wastewater treatment plant in Suzhou were 6 653.08 kg·（104 m3）-1, with direct and indirect GHG emissions accounting for 29.22% and 74%, respectively. The reuse of treated effluent achieved a reduction of 3.3% in emissions. The biological treatment phase and the sludge treatment phase were the main impact stages for GHG emissions at a certain wastewater treatment plant in Suzhou, where the high-power equipment, specifically the blowers used in the biological treatment phase, and the use of polymeric ferric sulfate agents in the sludge treatment phase were the primary factors contributing to GHG emissions. Life cycle assessment analysis revealed that electricity consumption, direct CO2 emissions, pollutant concentration in the effluent, and the use of chemical agents at wastewater treatment plants had negative impacts on global warming, atmospheric acidification, and eutrophication of water bodies. Calculations indicated that for every 10 000 m3 of wastewater treated, the sewage treatment plant achieved a net benefit of 13 630 RMB. However, from April to May 2023, the scale efficiency of the sewage treatment plant was less than 1. This indicates that during this period, the proportion of output increase was less than that of input increase, demonstrating an irrational structure of input-output. After June, through enhancing the overall operational load, advancing technical improvements, and management efforts, the optimization of scale efficiency was achieved. A sewage treatment plant in Suzhou could achieve the goal of being "green and low-carbon" by installing high-efficiency pumps and fans, utilizing solar photovoltaic and water source heat pump systems, and making process improvements.

Optimization analysis of the performance of a ground source heat pump system based on air conditioning load forecasting

Optimization analysis of the performance of a ground source heat pump system based on air conditioning load forecasting

ASSESSING THE THERMAL EFFICIENCY OF HORIZONTAL AIR-GROUND HEAT EXCHANGERS FOR HEATING AND COOLING BUILDINGS IN THE NORTHWESTERN ALGERIA REGION

The earth-air heat exchanger is a geothermal system that exploits the thermal inertia of the ground. It is a promising environmentally friendly technique that can effectively reduce or cancel out heating and cooling loads in the building sector. This study presents a numerical simulation of horizontal ground-air heat exchange system to investigate the effectiveness of the ground in heating and cooling buildings. Given the climate of the region located in northwestern Algeria, the investigated system heats the air in winter and cools it in summer. A three-dimensional transient numerical model based on the finite element method is established using COMSOL Multiphysics software. The model takes into account the interaction between the ground and the atmosphere as a boundary condition at the ground surface, and all climatic and geological conditions of the region are considered. Next, the model evaluates the coupling of heat and moisture transfer for unsaturated soil. Finally, the interaction between the soil and the ground-air heat exchanger is examined to assess the energy performance of the shallow geothermal system in the study area. The results show that the air temperature drops by 4°C in cooling mode and rises by 2.5°C in heating mode. The heat exchange rate of the horizontal geothermal air heat exchanger system with the environment in cooling mode surpasses that in heating mode by 28%, yielding a performance coefficient of 5.9. These results offer valuable insights into optimizing the performance of geothermal systems for building climate control in Algeria's northwestern region.

Investigating the potential of geothermal heat pump and precision air supply system for heat stress abatement in dairy cattle barns.

Maintaining an optimal indoor thermal environment is crucial for enhancing the welfare and productivity of livestock in intensive breeding farms. This paper investigated the application of a combined geothermal heat pump with a precision air supply (GHP-PAS) system for cooling dairy cows on a dairy farm. The effectiveness of the GHP-PAS system in mitigating heat stress in lactating dairy cattle, along with its energy performance and local cooling efficiency in the free stalls were evaluated. A total of 140 multiparous lactating Holstein cows was tested in two groups. One group was housed in a barn equipped with a GHP-PAS system (GP barn, n=70), and the other was housed in a barn with a conventional fan-sprinkling system (FS barn, n=70). Results showed that the ambient temperature of both GP and FS barns were lower than that outside the barn (P<0.05), with no significant difference between the GP and FS barns (P>0.05). Compared to cows in the FS barn, those in the GP barn exhibited lower skin temperature, rectal temperature, and respiratory rate (P<0.05). The mean temperature difference between outflow and inflow water was 2.56°C of the GHP unit. The average energy efficiency ratios (EER) of the GHP unit and the GHP-PAS system were 5.03 and 2.92, respectively. The daily average electricity consumption was 20.4±1.0 kWh. The field test results indicated that the airflow from a single nozzle of the GHP-PAS system effectively covered a stall space with an average width of 1.84m at a cow reclining height of 0.5m, with an average air velocity of 1m/s. The per-cow hourly electricity consumption for cooling was 2.04 kWh for the GHP-PAS system and 0.36 kWh for the FS system, highlighting that the GHP-PAS system is approximately 5.6 times more energy-intensive than the FS system. In conclusion, the GHP-PAS system showed the potential for alleviating heat stress in dairy cows. Further research is needed to enhance the energy efficiency and cooling effectiveness of the current GHP-PAS system.

Determination of the maximum LV grid hosting capacity for a rapid integration of photovoltaics, electric vehicles and heat pumps

Determination of the maximum LV grid hosting capacity for a rapid integration of photovoltaics, electric vehicles and heat pumps

Grid-related control measures for electric vehicle charging stations and heat pumps: implementation and impact analysis

Grid-related control measures for electric vehicle charging stations and heat pumps: implementation and impact analysis

Thermodynamic performance of organic rankine cycle based pumped thermal energy storage system with different working fluids.

In the context of global efforts toward energy transition and carbon neutrality, thermal integrated pumped thermal energy storage (TIPTES) systems, especially those utilizing low-grade heat sources, have garnered significant attention due to their large capacity, flexibility, and environmental advantages. This paper explores a TIPTES system that harnesses industrial waste heat as a heat source. The system's heat pump (HP) subcycle and Organic Rankine Cycle (ORC) subcycle are equipped with regenerators to optimize system configuration and enhance efficiency. Five working fluids-R245fa, isobutane, isopentane, MM, and R1336mzz(Z)-are selected for analysis based on parametric evaporation temperature (T 1) and thermal storage temperature (T 8).Parameter analysis results reveal that both round-trip efficiency (η ptp) and exergy efficiency (η ex) increase with rising T 1, with the system using MM demonstrating optimal performance: at T1 of 70°C, η ptp reaches 71.34%, and η ex is 37.42%. The η ptp for each system decreases as T8 increases, with the isobutane-based system showing the slowest decline; η ptp remains relatively unaffected by T 8, while η ex for the isobutane- and R245fa-based systems initially decreases and then increases with rising T 8.Key system parameters-T 1, T 8, and cold thermal storage temperature (T 7)-are further analyzed in a single-objective optimization focused on round-trip efficiency. Results indicate that the isopentane-based system performs optimally at T 8 of 388.65K, T 7 of 359.15K, and T 1 of 338.15K, achieving a maximum round-trip efficiency of 71.60%. This study offers theoretical insights to support the future development and application of TIPTES systems.

Design of Geothermal Groundwater Heating and Cooling Plant: A Trial Study in Eleme Fertilizer Company in Niger Delta Region

A geothermal groundwater heating and cooling plant consisting of a heat pump and heat exchanger has been designed. Geothermal heating and cooling systems play a crucial role in the decarbonization of the environment, helping to prevent global warming and promote energy savings due to the reduced energy required to power the plant, which in turn generates more geothermal energy for the heating and cooling needs of the fertilizer company. This study considered Eleme Fertilizer as a case study for the scaled-up and installation of the prototype designed of the geothermal groundwater heating and cooling plant. Both manual and software simulation designs were conducted based on material and energy balance principles. Error analysis and deviations were used to validate the design results. The results of the plant's unit design showed that the power drive, overall efficiency, and coefficient of performance for heating and cooling were 354.1 kW, 402%, and 2.82 &amp; 1.05, respectively. For the heat exchanger, design type 10-E-01, the values for heat duty, overall heat transfer coefficient, exchanger area, and tube pressure drop were 309.5 kW, 0.2104 kW/m²°C, 60.32 m², and 390 MPa, respectively. Error analysis conducted on the design work showed negligible values of RMSE (0.02, 0.025, 20 and 0.656) and deviation (0.014, 0.05, 0.05, 0.002) for coefficient of performance of heating and cooling, heat pump efficiency and the drive power of the plant respectively. The values obtained from the design of the units in the geothermal plant were reasonable and are thus recommended for academic and industrial applications

The Future of Structural Geology in the 21st Century – Moving from Mesoscale to Nanoscale Observations in Tectonically Deformed Rocks

ABSTRACT The importance of integrating field studies with various micro-and nano-scale structural geological investigations using petrographic microscope, scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) is highlighted in this paper. The author’s past studies dealing with SEM-EBSD and TEM investigations to decipher deformation mechanism of magnetite are taken as examples to support the robustness of investigating nanostructures in thin films excavated parallel to the kinematic reference frame. In addition, the author also shares a work flow involving collection of oriented field samples, followed by petrophysical investigations (e.g., porosity, permeability, P-wave velocity of oriented samples, etc.), 3D fabric analysis (e.g., AMS, X-ray micro-CT of oriented samples), 2D-microstructural analysis in oriented thin sections (petrography, SEM imaging including in-lens, EBSD, etc.) and finally nanostructural studies in oriented thin films using TEM (in that order). The importance of this integrated approach to evaluate structures at different scales and utilize the results for fundamental research as well as applications such as in the field of understanding fluid flow, mineralization, geothermal systems and radioactive waste management is discussed. Hence the paper provides an overview to the reader about some of the possibilities that exist today (21st century) in the field of structural geology.

Graded heating operation strategy study of geothermal ice melting system considering the temperature gradient of bridge concrete structures

Graded heating operation strategy study of geothermal ice melting system considering the temperature gradient of bridge concrete structures

Exploring the Integration of Renewable Energy in Building Cooling Systems: A Review of Articles

As the earth’s global warming and other environmental problems keep getting worst, the world is moving towards sustainable practices both passive and technologically, especially in energy production and consumption. An important step towards these sustainable practices is the incorporation of renewable energies into our systems. The integration of renewable energy in building cooling systems represents an important shift towards sustainable energy practices. There have been recent research works on the integration of wind, geothermal, and solar energy systems into buildings cooling system in order to minimize environmental effects and increase efficiencies, while making the world more sustainable. This paper seeks to explore the feasibility and effectiveness of using sustainable technologies of solar-powered or geothermal cooling systems in commercial or residential buildings, by reviewing articles on these sustainable practices, aimed to provide a comprehensive overview of existing literature, highlight trends, and identify gaps in the articles. These articles to be reviewed are valuable resources for understanding the current state of research on sustainable cooling systems.

Performance investigation of a solar-assisted ground source heat pump system coupled with novel offset pipe energy piles and solar PVT collectors for cold climate applications

Performance investigation of a solar-assisted ground source heat pump system coupled with novel offset pipe energy piles and solar PVT collectors for cold climate applications