Development of a Geothermal-Based Integrated Plant for Generating Clean Hydrogen and Other Useful Commodities

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Yunus Emre Yuksel ◽  
Murat Ozturk ◽  
Ibrahim Dincer
Keyword(s):  
Geothermal Energy ◽  
Hydrogen Generation ◽  
Positive Impact ◽  
Exergy Efficiency ◽  
Integrated System ◽  
Operating Conditions ◽  
Hot Water ◽  
Fluid Temperature ◽  
Geothermal Fluid ◽  
Energy And Exergy

Abstract In this study, geothermal energy is considered as a renewable energy source to finally provide various useful outputs such as electricity, hydrogen, fresh and hot water, drying, heating, and cooling. In this regard, a new geothermal power-based multigenerational system is proposed to meet these demands in an environmentally benign manner and studied thermodynamically by considering energy and exergy approaches and investigating parametrically. A combination of geothermal energy is used to achieve the most promising hydrogen generation rates and high plant performances. The results of this study indicate that the energy and exergy efficiency values of the entire plant for the selected operating conditions become 38.41% and 42.57%. In addition to the thermodynamic analysis performed, numerous parametric studies are performed to reveal how operating conditions and state parameters affect the overall system performance. According to the parametric analyses results, for given ranges, an increase in ambient temperature, separator working temperature, geothermal fluid temperature, and geothermal fluid mass flowrate have positive impact on both energy and exergy efficiency of the integrated system and useful products generation rate as well.

Design of a Multigenerational System With Absorption Cooling for a Residential Community: A Case Study

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Andre Bolt ◽  
Branson Chea ◽  
Ibrahim Dincer ◽  
Martin Agelin-Chaab ◽  
Marc Rosen
Keyword(s):  
British Columbia ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Residential Community ◽  
Heating And Cooling ◽  
Absorption Cooling ◽  
Energy And Exergy

Abstract In this paper, a multigeneration system is proposed, which utilizes geothermal energy and a lithium-bromide absorption cooling cycle. The proposed system is capable of providing electricity, heating, cooling, and domestic hot water to a small residential community in Vancouver, British Columbia, Canada. The performance of the system's heating and cooling capabilities were evaluated energetically and exergetically. A case study is presented by considering human occupancy loads and the impact of building material conditions on heating and cooling. System performance was investigated using parametric studies, where the operating conditions and ambient conditions were varied. Similar systems in the open literature were found to have an energetic and exergetic coefficient of performance (COP) of 0.8 and 0.3 for heating, while the proposed multigeneration system resulted in an energetic and exergetic coefficient of performance of 1.14 and 0.63 for heating, an increase of 30–52%. Additionally, the literature revealed that some systems resulted in an energy and exergy efficiency of 26.2% and 36.6%. The proposed multigeneration system achieved an energy and exergy efficiency of 31.86% and 63.33%, an improvement of 5.66–26.73%. The study was able to utilize the existing recommendations made by British Columbia to determine the necessary heating and cooling loads while also being able to successfully generate four useful outputs with a smaller footprint than those in the literature.

scholarly journals Energetic and exergetic analysis of a convective drier: A case study of potato drying process

2020 ◽  
Vol 5 (1) ◽  
pp. 563-572
Author(s):  
Iman Golpour ◽  
Mohammad Kaveh ◽  
Reza Amiri Chayjan ◽  
Raquel P. F. Guiné
Keyword(s):  
Energy Consumption ◽  
Research Work ◽  
Specific Energy Consumption ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Energy Utilization ◽  
Convective Drying ◽  
Drying Time ◽  
Energy And Exergy ◽  
Exergy Losses

AbstractThis research work focused on the evaluation of energy and exergy in the convective drying of potato slices. Experiments were conducted at four air temperatures (40, 50, 60 and 70°C) and three air velocities (0.5, 1.0 and 1.5 m/s) in a convective dryer, with circulating heated air. Freshly harvested potatoes with initial moisture content (MC) of 79.9% wet basis were used in this research. The influence of temperature and air velocity was investigated in terms of energy and exergy (energy utilization [EU], energy utilization ratio [EUR], exergy losses and exergy efficiency). The calculations for energy and exergy were based on the first and second laws of thermodynamics. Results indicated that EU, EUR and exergy losses decreased along drying time, while exergy efficiency increased. The specific energy consumption (SEC) varied from 1.94 × 105 to 3.14 × 105 kJ/kg. The exergy loss varied in the range of 0.006 to 0.036 kJ/s and the maximum exergy efficiency obtained was 85.85% at 70°C and 0.5 m/s, while minimum exergy efficiency was 57.07% at 40°C and 1.5 m/s. Moreover, the values of exergetic improvement potential (IP) rate changed between 0.0016 and 0.0046 kJ/s and the highest value occurred for drying at 70°C and 1.5 m/s, whereas the lowest value was for 70°C and 0.5 m/s. As a result, this knowledge will allow the optimization of convective dryers, when operating for the drying of this food product or others, as well as choosing the most appropriate operating conditions that cause the reduction of energy consumption, irreversibilities and losses in the industrial convective drying processes.

scholarly journals A Project To Estimate The Power Capacity Of Geothermal Power Plants Based On The Enthalpy Of Geothermal Fluid And Plant Design

2021 ◽  
Author(s):  
Obumneme Oken
Keyword(s):  
Power Plant ◽  
Geothermal Energy ◽  
Electricity Generation ◽  
Power Plants ◽  
Hot Water ◽  
Power Capacity ◽  
Geothermal Fluid ◽  
Direct Heating ◽  
Single Flash ◽  
Geothermal Power

Nigeria has some surface phenomena that indicate the presence of viable geothermal energy. None of these locations have been explored extensively to determine the feasibility of sustainable geothermal energy development for electricity generation or direct heating. In this context, the present study aims to provide insight into the energy potential of such development based on the enthalpy estimation of geothermal reservoirs. This particular project was conducted to determine the amount of energy that can be gotten from a geothermal reservoir for electricity generation and direct heating based on the estimated enthalpy of the geothermal fluid. The process route chosen for this project is the single-flash geothermal power plant because of the temperature (180℃) and unique property of the geothermal fluid (a mixture of hot water and steam that exists as a liquid under high pressure). The Ikogosi warm spring in Ekiti State, Nigeria was chosen as the site location for this power plant. To support food security efforts in Africa, this project proposes the cascading of a hot water stream from the flash tank to serve direct heat purposes in agriculture for food preservation, before re-injection to the reservoir. The flowrate of the geothermal fluid to the flash separator was chosen as 3125 tonnes/hr. The power output from a single well using a single flash geothermal plant was evaluated to be 11.3 MW*. This result was obtained by applying basic thermodynamic principles, including material balance, energy balance, and enthalpy calculations. This particular project is a prelude to a robust model that will accurately determine the power capacity of geothermal power plants based on the enthalpy of fluid and different plant designs.

scholarly journals ENERGY AND EXERGY ANALYSIS OF A CYLINDRICAL HOT WATER STORAGE TANK: EXPERIMENTAL AND CFD ANALYSIS

2020 ◽  
Author(s):  
Tomas Kropas ◽  
Giedrė Streckienė
Keyword(s):  
Numerical Model ◽  
Storage Tank ◽  
Exergy Analysis ◽  
Water Storage ◽  
Exergy Efficiency ◽  
Hot Water ◽  
Water Storage Tank ◽  
Environment Temperature ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

Active solar water heating systems typically include hot water storage tanks. The selection of the storage system strongly affects the performance of the entire system. This article presents a detailed analysis of a hot water storage tank during charging and dynamic charging-discharging mode. A numerical model using computational fluid dynamics for the storage tank was developed to investigate the temperature distribution inside of it. Transient thermal analysis was carried using ANSYS Fluent. The numerical model was validated with the experimental results. The energy and exergy analysis as an important tool for the evaluation of the thermal systems quantitatively and qualitatively was performed. The calculation procedures were described. The energy and exergy efficiencies, heat losses were calculated for steady and dynamic processes. Effect of mass flow rate was analysed. The results from parametric analysis showed that charging dynamics reduced the thermocline and efficiency of the hot water storage tank. The dependency of the exergy efficiency of the heat storage tank on the reference environment temperature during the dynamic operation was analysed. Exergy efficiencies for two cities with different climates were compared. This indicated that the higher envi-ronmental temperature gave lower exergy efficiency of the storage tank.

scholarly journals A Project To Estimate The Power Capacity Of Geothermal Power Plants Based On The Enthalpy Of Geothermal Fluid And Plant Design

2021 ◽  
Author(s):  
Obumneme Oken
Keyword(s):  
Power Plant ◽  
Power Output ◽  
Geothermal Energy ◽  
Power Plants ◽  
Hot Water ◽  
Geothermal Resource ◽  
Power Capacity ◽  
Geothermal Fluid ◽  
Single Flash ◽  
Geothermal Power

Surface phenomena that signal the presence of viable geothermal energy can be found in various locations in Nigeria. None of these locations have been explored extensively to determine the feasibility of sustainable geothermal energy development for electricity generation or direct heating purposes. In this context, the present study aims to provide insight into the energy potential of such development based on the enthalpy estimation of geothermal reservoirs. This particular project was conducted to determine the power output from a geothermal resource given an estimated enthalpy of the geothermal fluid. The process route chosen for this project is the single-flash geothermal power plant because of the temperature (180℃) and unique property of the geothermal fluid (a mixture of hot water and steam that exists as a liquid under high pressure). The Ikogosi warm spring in Ekiti State, Nigeria was chosen as the site location for this power plant. To support food security efforts in Africa, this project proposes the cascading of a hot water stream from the flash tank to serve direct heat purposes in agriculture for food preservation, before re-injection to the reservoir. The flowrate of the geothermal fluid to the flash separator was chosen as 3125 tonnes/hr. The power output from a single well using a single flash geothermal plant was evaluated to be 11.3 MW*. This result was obtained by applying basic thermodynamic principles, including material balance, energy balance, and enthalpy calculations. This particular project is a prelude to a robust model that will accurately determine the power capacity of geothermal power plants based on the enthalpy of geothermal fluid, size of the geothermal resource, and different plant designs. I hope that the knowledge gained from the study will promote best practices in geothermal engineering and emphasize appropriate planning for, and implementation of, geothermal plants.

Analysis and Assessment of Tower Solar Collector Driven Trigeneration System

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Abdul Khaliq ◽  
Mathkar A. Alharthi ◽  
Saeed Alqaed ◽  
Esmail M. A. Mokheimer ◽  
Rajesh Kumar
Keyword(s):  
Energy Efficiency ◽  
Solar Collector ◽  
Lithium Bromide ◽  
Rankine Cycle ◽  
Significant Rise ◽  
Exergy Efficiency ◽  
Integrated System ◽  
Operating Conditions ◽  
Heating And Cooling ◽  
And Performance

Abstract This paper describes the development and performance assessment of a tower solar collector driven integrated system operating in trigeneration mode to generate electricity, heating, and cooling, in a carbon-free manner. The proposed system applies a heliostat-based central receiver unit as a base of solar energy input to drive the steam Rankine cycle which is combined with the process heater and the lithium bromide-water operated absorption chiller. An analysis is performed to monitor the behavior of energy and exergy efficiency at various operating conditions of the proposed trigeneration system. The computed results are authenticated with the reported literature. A comparison is made between the present findings and reported results in the form of exergy efficiency, total exergy destroyed, and energy efficiency. Consideration of process heat and cold along with electricity provides a promising increase in energy efficiency from 15.8% to 64.1% while the exergy efficiency is enhanced from 16.9% to 24.4%. Variation in direct normal irradiations from 600 W/m2 to 1000 W/m2 results in the significant rise of energetic and exergetic outcomes of the proposed trigeneration system. Out of 100% solar exergy supplied to the proposed trigeneration, 24% is generated as the exergetic output, 1.6% is lost to ambient, and the remaining 74.4% is the exergy destroyed in the system components.

scholarly journals Performance Analysis of a RED-MED Salinity Gradient Heat Engine

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3385 ◽  
Author(s):  
Patricia Palenzuela ◽  
Marina Micari ◽  
Bartolomé Ortega-Delgado ◽  
Francesco Giacalone ◽  
Guillermo Zaragoza ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Power Density ◽  
Waste Heat ◽  
Salinity Gradient ◽  
Heat Engine ◽  
Exergy Efficiency ◽  
Integrated System ◽  
Operating Conditions ◽  
Membrane Properties ◽  
Recovery Ratio

A performance analysis of a salinity gradient heat engine (SGP-HE) is presented for the conversion of low temperature heat into power via a closed-loop Reverse Electrodialysis (RED) coupled with Multi-Effect Distillation (MED). Mathematical models for the RED and MED systems have been purposely developed in order to investigate the performance of both processes and have been then coupled to analyze the efficiency of the overall integrated system. The influence of the main operating conditions (i.e., solutions concentration and velocity) has been quantified, looking at the power density and conversion efficiency of the RED unit, MED Specific Thermal Consumption (STC) and at the overall system exergy efficiency. Results show how the membrane properties (i.e., electrical resistance, permselectivity, water and salt permeability) dramatically affect the performance of the RED process. In particular, the power density achievable using membranes with optimized features (ideal membranes) can be more than three times higher than that obtained with current reference ion exchange membranes. On the other hand, MED STC is strongly influenced by the available waste heat temperature, feed salinity and recovery ratio to be achieved. Lowest values of STC below 25 kWh/m3 can be reached at 100 °C and 27 effects. Increasing the feed salinity also increases the STC, while an increase in the recovery ratio is beneficial for the thermal efficiency of the system. For the integrated system, a more complex influence of operating parameters has been found, leading to the identification of some favorable operating conditions in which exergy efficiency close to 7% (1.4% thermal) can be achieved for the case of current membranes, and up to almost 31% (6.6% thermal) assuming ideal membrane properties.

scholarly journals Theoretical and Experimental Evaluation of the Working Fluid Temperature Levels in a CPV/T System

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3077
Author(s):  
Carlo Renno
Keyword(s):  
Thermal Energy ◽  
Integrated System ◽  
Hot Water ◽  
Experimental Comparison ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Cooling Fluid ◽  
Operation Conditions ◽  
Temperature Levels ◽  
T System

A linear focus Concentrator Photovoltaic and Thermal (CPV/T) system can match the thermal demands of a user. The evaluation of the cooling fluid temperature levels of a CPV/T system is fundamental to understand if this system is capable of satisfying the typical thermal requirements of a residential user (heating, cooling and domestic hot water). First, an experimental line-focus CPV/T system, realized in the Laboratory of Applied Thermodynamics of the University of Salerno (Italy), has allowed to determine the cooling fluid temperature at the CPV/T system outlet. Successively, the cooling fluid temperatures, experimentally obtained, have been compared with the same temperatures calculated by means of a theoretical model under the same operation conditions. A deviation in terms of the percentage relative error between theoretical and experimental results included between about 0.5% and 5%, has been found. The goodness of the theoretical–experimental comparison in terms of the temperature of the operation fluid at the CPV/T system outlet has represented a fundamental point to evaluate theoretically, by means of the TRNSYS software, the other levels of temperature of an integrated system, constituted by CPV/T system, thermal tank and user, for different temporal scenarios (hourly, weekly, monthly and yearly). The input data of the TRNSYS model are: Direct Normal Irradiance (DNI), Triple-Junction (TJ) cell temperature and environmental conditions. A tank model is also adopted to satisfy the thermal energy demand peaks, and the temperature stratification in the tank linked to the CPV/T system, as function of the height, is obtained in winter and summer. It is important to define these thermal levels to verify if a CPV/T system is capable to satisfy the residential user energy demands or a thermal energy integration is necessary in some periods of the year. A good stratification has been noted in the summer season, with temperature values that are variable between about 40 and 90 °C. From April to October, the tank average temperature is generally resulted about 10 °C higher than the temperature required by the fluid sent to the residential user, and a very low integration is then necessary. It has been verified that the CPV/T system covers a large part of the thermal energy needs of the residential user during the year; the coverage is limited only in the winter months.

scholarly journals Energy and Exergy Analysis of the Air Source Transcritical CO2 Heat Pump Water Heater Using CO2-Based Mixture as Working Fluid

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4470
Author(s):  
Yikai Wang ◽  
Yifan He ◽  
Yulong Song ◽  
Xiang Yin ◽  
Feng Cao ◽  
...  
Keyword(s):  
Exergy Analysis ◽  
Heat Pumps ◽  
Exergy Efficiency ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Domestic Hot Water ◽  
Practical Applications ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

Given the large demand nowadays for domestic hot water, and its impact on modern building energy consumption, air source transcritical CO2 heat pumps have been extensively adopted for hot water production. Since their system efficiency is limited by significant irreversibility, a CO2-based mixture could offer a promising drop-in technology to overcome this deficiency without increasing system complexity. Although many CO2 blends have been studied in previously published literature, little has been presented about the CO2/R32 mixture. Therefore, a proposed mixture for use in transcritical CO2 heat pumps was analyzed using energy and exergy analysis. Results showed that the coefficient of performance and exergy efficiency variation displayed an “M” shape trend, and the optimal CO2/R32 mixture concentration was determined as 0.9/0.1 with regard to flammability and efficiency. The irreversibility of the throttling valve was reduced from 0.031 to 0.009 kW⋅kW−1 and the total irreversibility reduction was more notable with ambient temperature variation. A case study was also conducted to examine domestic hot water demand during the year. Pure CO2 and the proposed CO2 blend were compared with regard to annual performance factor and annual exergy efficiency, and the findings could provide guidance for practical applications in the future.

Evaluation of an Integrated Photovoltaic-Thermal Option for HVAC Cooling System in UAE

2015 ◽  
Author(s):  
Mohamed Gadalla ◽  
Amani Al Hammadi ◽  
Dina Gadalla
Keyword(s):  
Alternative Energy ◽  
Cooling System ◽  
Cooling Capacity ◽  
Commercial Buildings ◽  
Integrated System ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Energy Output ◽  
Energy And Exergy ◽  
New Interpretation

This paper investigates the integration of a photovoltaic-Thermal Collector (PV/T) and a Triple Effect Absorption System (TEAS) for cooling residential as well as commercial buildings. Energy and exergy analyses are conducted to examine the performance of the recommended system and to investigate the variation of different operating conditions and PV/T characteristics on the overall performance of the PV/T collector. Power and heat generated by the PV/T system are used to mainly drive mainly the TEAS by supplying power and heat to the HTG. This paper studies the effect of the of average solar radiation for different months during the year on the Coefficient of Performance (COP) and/or the overall efficiency of the (PV/T) collector integrated with TEAS to produce 10 kW of cooling capacity. This paper also investigates how the rate of energy output of the PV/T collector. It is found that energetic and exergetic efficiencies of the PV/T collector as well as the overall energetic and exergetic efficiencies of the integrated system decrease with increasing the solar irradiance. The analyses show that the maximum energetic and exergetic COPs obtained for PV/T integrated with TEAS are 2.32 and 2.06; respectively. Finally, this paper provides a new interpretation in which alternative energy is utilized in operating HVAC cooling systems and presents a new insight into one of the most sustainable integrated systems that can be applied in residential and commercial buildings in the UAE.

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