A discussion of “Heat pumps as a source of heat energy for desalination of seawater”

Systematic Analysis Reveals Thermal Separations Are Not Necessarily Most Energy Intensive

Heat pumps as a source of heat energy for desalination of seawater

Geothermal is a source of heat energy contained in hot water, rocks, water vapor as well as gases and minerals and others that cannot be genetically separated from a geothermal system. Geothermal energy is a renewable natural resource with high potential. The source of this energy comes from heating magma against water rocks together with elements contained in the earth's crust. North Sulawesi has the potential to become a geothermal development area, both directly and indirectly. The existence of hot springs shows that the research location in Sawangan Village has geothermal potential. This research aims to determine the fluid type and molecular functional groups of hot springs in Sawangan Village, North Minahasa Regency, North Sulawesi Province. Using geochemical methods using Cl-SO2-HCO3 and FTIR diagrams, it is known that the type of hot spring fluid in Sawangan Village is Bicarbonate (HCO3) and the molecular functional group is C=O, where the parent chain C binds HCO3 (Bicarbonate) which corresponds to fluid type results.

In this study, four new indirect heat pump assisted mechanical vapor compression humidification-dehumidification (HDH) systems are proposed and their superiorities over the reference system are demonstrated from thermodynamics and thermoeconomics viewpoints. The proposed models are configured based on an HDH unit and a simple cascade heat pump, an HDH unit and a heat pump with an ejector, an HDH unit and a cascade heat pump with an ejector, and an HDH unit and a vapor injection heat pump. Although employing a heat pump with cascade and ejector configurations improved gain-output-ratio (GOR) and specific power consumption (SPC) values in comparison with the base system, the performance metrics of such layouts are still inferior to those of the HDH unit coupled with the vapor injection heat pump. It is found that the desalination unit with vapor injection mechanism has the highest GOR and the lowest SPC values of 9.22 and 71.29 kWh/m3, respectively, under constant electrical power of 31.26 kW. Overall, proposal of the cascade heat pump, heat pump with an ejector, cascade heat pump with an ejector, and a vapor injection heat pump instead of the conventional heat pump improved GOR by 4.83%, 10.03%, 11.52%, and 14.25%, respectively. Meantime, the SPC of the HDH unit coupled with a simple heat pump decreased by 4.6%, 9.1%, 10.26%, and 12.46% when a cascade heat pump, a heat pump with an ejector, a cascade heat pump with an ejector, and a vapor injection heat pump were used instead of the conventional heat pump, respectively. Also, it is found that a maximum improvement of 14.13% can be achieved in exergy efficiency with a cost penalty of only 1.59 $/m3. Also, it was found that with the use of a simple cascade heat pump instead of the simple heat pump, the exergy efficiency can be enhanced by 4.9%, while the unit cost of the distilled water (UCDW) was degraded by 51.32%. Likewise, the HDH unit coupled with the cascade heat pump with an ejector was resulted in high UCDW compared to the base system, while its exergy efficiency was not enhanced so significantly. Variation of exergy efficiency versus the intermediate temperature had a maximum value of 1.93% (for the HDH unit coupled with a simple cascade heat pump) and 2.05% (for the HDH unit coupled with a cascade heat pump with an ejector) at Tint = 315 K. Moreover, it was found that the UCDW can be decreased with the rise of the intermediate temperature and cascade heat exchanger temperature difference as the fresh water cost rate decreases as a result, while the exergy efficiency can be increased with the rise of the cascade heat exchanger temperature difference.

The exploration of subsurface geothermal reservoirs has gained significant attention in recent years as a sustainable solution for energy storage and extraction. These reservoirs, ranging from shallow to deep geological conditions, offer immense potential to meet the growing demand for renewable energy while reducing reliance on fossil fuels. By leveraging the Earth's natural heat or over-seasonal waste heat, geothermal systems provide a reliable and environmentally friendly energy source for heating, cooling, and electricity generation. Recent advancements in technology and improved understanding of subsurface geological conditions have expanded the scope of geothermal applications, positioning them as a vital component of the global energy transition.In this study, various geothermal systems in porous and fractured reservoirs are modeled using flow, heat, and mass transport processes implemented in the open-source software OpenGeoSys (OGS), such as Borehole Heat Exchangers (BHEs). The performance, sustainability, and efficiency of these geothermal systems are analyzed through scenarios involving inter-seasonal multi-cycles of energy use. Additionally, surface energy utilization systems designed for low- and mediate-grade geothermal heat sources, such as geothermal heat pumps and Organic Rankine Cycle (ORC) power plants, are modeled and optimized using the open-source simulation toolkit TESPy (Thermal Engineering Systems in Python).This work also investigates the mechanisms of interaction between subsurface and surface facilities by coupling geothermal reservoir with thermodynamic process simulation. The integrated simulations enable further optimization of the entire system. This study aims to summarize progress made in modeling geothermal systems for energy extraction and storage using OGS, while also outlining future directions for developing large-scale integrated models that incorporate other renewable energy sources.

Currently, at the current stage in the field of application of heat pumps in heat supply systems, it is promising to use low-potential heat from natural sources. The purpose of the work is to study the thermodynamic energy efficiency of heat transformation in the "water-water" heat pump (HР) cycle, the working agent of which is propane. A thermodynamic analysis of the energy efficiency of the use of modern heat pump technologies for the heat supply system when using natural, ecologically clean energy sources was performed. Factors that directly affect the energy efficiency of HР “W-W” have been identified, and the features of the operation of a water HР have been evaluated. Increasing the energy efficiency of a water HР depends not only on the perfection of the HР operation cycle and the choice of the HР working agent, but also on the process of heat transformation in the heat pump cycle. The results of the thermodynamic calculation of the energy efficiency indicators of the operation of the water heating plant using the natural energy source of water are presented. The energy efficiency of the water HР cycle, which implements the reverse thermodynamic Carnot cycle using a low-potential water heat source, is shown. The heat pump cycle "W-W" is accompanied by minimal losses when throttling the liquid working agent propane, and also solves the problem of useful heat use to increase the temperature of the coolant, which is heated for heat supply. A thermodynamic and exergy analysis of the energy efficiency indicators of the water HР with the environmentally safe agent propane (R290) was performed. The energy efficiency of the water HР cycle is estimated by the heat transformation coefficient HР (COP), which is calculated to be 3.72. The thermodynamic efficiency of the water HР in heat supply systems is considered using the exergy efficiency, it is 44 %. A comparative analysis of the thermodynamic energy efficiency of a water-based heat pump with other heat pumps operating on low-potential natural heat sources, such as ground and air, was conducted. For a ground-based heat pump, the coefficient of thermal transformation (COP) of the heat pump is 3.53, for an air-based heat pump 3.37. The thermodynamic efficiency of a ground-based heat pump is 40 %, for an air-based heat pump 36 %. Therefore, the thermodynamic energy efficiency of a water-based heat pump, based on the comparative thermodynamic analysis, is higher than the use of ground and air heat pumps in heat supply systems. Therefore, the use of water НР in heat supply systems is more appropriate in comparison with air and ground НР. Bibl. 42, Fig. 2, Tab. 1.

The article "The use of heat pumps in combined heating systems for urban infrastructure" delves into the potential of integrating heat pumps into modern urban heating systems, with a focus on energy efficiency and environmental sustainability. As urban areas expand and energy consumption continues to rise, the integration of heat pumps presents a promising solution to address both environmental and economic challenges. The introduction emphasizes the growing demand for energy-saving technologies, underscoring the need to reduce environmental impacts associated with traditional heating systems. Keywords such as heat pumps, combined heating systems, energy efficiency, and environmental sustainability are central to the discussion. The relevance of the topic is particularly justified by the increasing costs of traditional energy sources, which are often based on fossil fuels. As global concerns about climate change grow, cities are under pressure to reduce greenhouse gas emissions, which are a significant byproduct of conventional heating methods. The adoption of more sustainable technologies like heat pumps is critical to reducing urban areas’ carbon footprints. The problem statement in the article highlights the excessive energy consumption of conventional systems, as well as their significant contribution to greenhouse gas emissions. By transitioning to heat pumps, cities can not only address these environmental concerns but also ensure a more sustainable and energy-efficient future. The section on the analysis of studies and publications reviews the advantages and challenges of implementing heat pumps in urban environments. One of the key advantages of heat pumps is their ability to harness renewable energy from the environment, such as air, water, or the ground, to generate heating and cooling. This process drastically reduces reliance on fossil fuels and cuts down on emissions. However, several challenges are identified, including the high upfront costs of installation and the modernization of existing heating networks to accommodate these systems. Moreover, there is limited long-term data on the operational efficiency of heat pumps in urban settings, making it difficult to predict their performance over time in various urban climates and infrastructure types. The research aims to provide recommendations for the adoption of heat pumps in urban conditions. The tasks outlined include performing energy efficiency analyses to determine the optimal systems for different types of urban environments. Additionally, the research will explore integration schemes that combine heat pumps with existing heating infrastructure, as well as how to incorporate other renewable energy sources such as solar and wind to enhance overall system efficiency. The main body of the article elaborates on the technical aspects of heat pump operations. Heat pumps work by transferring heat from one location to another, typically from the ground or air to a building, which makes them highly energy-efficient. Their ability to both heat and cool spaces makes them versatile for year-round use in urban infrastructures. The economic feasibility of implementing heat pumps is also addressed. While initial installation costs may be high, the long-term savings on energy bills, coupled with the environmental benefits, make heat pumps a viable option for cities looking to reduce their energy costs and carbon emissions. Finally, the conclusions underscore the promising nature of heat pumps as a solution for urban heating and cooling needs. However, the article stresses the necessity of significant investments in both technology and infrastructure to ensure the successful integration of heat pumps into urban systems. The adaptation of existing heating networks, retrofitting older buildings, and overcoming technological limitations are key challenges that need to be addressed. In summary, the article suggests that while heat pumps offer a promising future for urban infrastructure, they require careful planning, significant investments, and continued research to fully realize their potential for long-term environmental and economic sustainability.

Desalination plant with absorption heat pump for power station

This essay briefly introduces the solar energy- ground source heat pump, respectively analyzes advantages and disadvantages of the solar energy and ground source heat pump, illustrates necessities of integrated applications of the solar energy and ground source heat pump in Changchun, and finally points out problems which exist in the technology.

A review on Heat Pumps implementation in Lithuania in compliance with the National Energy Strategy and EU policy

This study presents an energetic, exergetic and environmental (3E) evaluation of different source heat pump systems for heating. For the first time, three different systems, namely ground, solar energy-assisted ground and solar source heat pump systems, have been modeled for Kocaeli climate conditions and thermodynamic analyses have been performed. The calculation procedure has been given for the correct design and evaluation of the models of these systems. The energy and exergy analyses have been made of these systems. The compressor work of the solar-assisted ground source heat pump (GSHP) system is 5.4% lower than the GSHP system. The solar source heat pump has the highest exergy destruction at 14.29 kW. In addition, the collector areas have been calculated for the solar energy-assisted ground and solar energy source heat pumps. The solar radiation values according to the months have been calculated for Kocaeli. This study shows that the heat pump systems can be used in residential heating in Kocaeli. Thus, it is possible to achieve more efficient and economical heating using alternative energy sources in heat pumps. The heat pumps are an effective environmental protection and energy-saving technology.

Modeling of geothermal power system equipped with absorption refrigeration and solar energy using multilayer perceptron neural network optimized with imperialist competitive algorithm

Concentrated solar driven thermochemical hydrogen production plant with thermal energy storage and geothermal systems

Geothermal (ground source) heat pumps (GHP) and permeable pavement systems (PPS) have demonstrated their effectiveness in both industry and academic research during recent decades. To meet the rising demand for sustainable, recyclable and energy efficient techniques, research has focused on the combination of techniques to enhance existing or develop new applications. This paper reports on an experimental programme that combined GHP with PPS for nutrient removal and system energy balancing. Experimental data collected over a 3-year period have provided evidence of highly efficient removal rates of up to 99% for ammonia–nitrate and biochemical oxygen demand; and 96% removal rates were obtained for orthophosphate–phosphorus. This paper also contains energy efficiency ratio (EER) and coefficient of performance (COP) calculations. Cyclic heat removal and heat rejection allowed for stable temperature and pump COP and EER sustainability. The results prove that PPS systems are appropriate for GHP installation, delivering high and stable pollutant removal with EER efficiencies between 1.5 and 5.5. The combination of GHP with PPS has the potential to provide a new sustainable and eco-friendly practice.

Hybrid Geothermal and Biomass Energy Systems