79 results on '"Mahkamov, Khamid"'
Search Results
2. Development of a smart control unit for small-scale concentrated solar combined heat and power systems for residential applications
- Author
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Cioccolanti, Luca, Tascioni, Roberto, Moradi, Ramin, Pirro, Matteo, Bartolini, Carlo Maria, Makhkamova, Irina, Mahkamov, Khamid, Cabeza, Luisa F., De Gracia, Alvaro, Pili, Piero, Mintsa, André C., and Mullen, David
- Published
- 2022
- Full Text
- View/download PDF
3. Development and experimental investigation of a novel solar-powered cooling system
- Author
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Hashem, Gamal, Mahkamov, Khamid, Belgasim, Basim, Elsharif, Nabil, and Makhkamova, Irina
- Published
- 2021
- Full Text
- View/download PDF
4. Selection and testing of phase change materials in the physical models of buildings for heating and curing of construction elements made of precast concrete
- Author
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Yu, Nan, Chen, Chao, Mahkamov, Khamid, Makhkamova, Irina, Li, Qiong, and Ma, Jing
- Published
- 2021
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- View/download PDF
5. Numerical and experimental study of laboratory and full-scale prototypes of the novel solar multi-surface air collector with double-receiver tubes integrated into a greenhouse heating system
- Author
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Chen, Chao, Han, Fengtao, Mahkamov, Khamid, Wei, Shen, Ma, Xinglong, Ling, Haoshu, and Zhao, Chen
- Published
- 2020
- Full Text
- View/download PDF
6. Selection of a phase change material and its thickness for application in walls of buildings for solar-assisted steam curing of precast concrete
- Author
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Yu, Nan, Chen, Chao, Mahkamov, Khamid, Han, Fengtao, Zhao, Chen, Lin, Jie, Jiang, Lixing, and Li, Yaru
- Published
- 2020
- Full Text
- View/download PDF
7. Melting and solidification of PCMs inside a spherical capsule: A critical review
- Author
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Kenisarin, Murat M., Mahkamov, Khamid, Costa, Sol Carolina, and Makhkamova, Irina
- Published
- 2020
- Full Text
- View/download PDF
8. Theoretical and experimental study on selection of physical dimensions of passive solar greenhouses for enhanced energy performance
- Author
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Chen, Chao, Yu, Nan, Yang, Fengguang, Mahkamov, Khamid, Han, Fengtao, Li, Yaru, and Ling, Haoshu
- Published
- 2019
- Full Text
- View/download PDF
9. Analysis of labour market needs for engineers with enhanced knowledge in renewable energy in some European and Latin-American Countries
- Author
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Comodi, Gabriele, Cioccolanti, Luca, Mahkamov, Khamid, Penlington, Roger, Lapuerta, Magin, Hernandez, Juan José, Silva Lora, Electo Eduardo, Venturini, Osvaldo, Melian Cobas, Vladimir Rafael, Escobar Palacio, Jose Carlos, Mendonça Freires, Francisco Gaudêncio, Torres, Ednildo Andrade, da Silva, Julio Augusto Mendes, Kafarov, Viatcheslav, Chacon Velasco, Jorge Luis, Solano Martinez, Javier Enrique, Lizarazo Salcedo, Gladys Yolanda, Serna Suárez, Iván David, Jaen, Rene Lesme, Gonzalez, Josue Imbert, Fernandez, Maria, Garcia Faure, Luis Jerónimo, Oliva-Merencio, Deny, Reyes, Ileana Pereda, Salas, Joel Morales, and Ramírez, Cesar Cisneros
- Published
- 2019
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10. Simulation analysis of an innovative micro-solar 2kWe Organic Rankine Cycle plant coupled with a multi-apartments building for domestic hot water supply
- Author
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Arteconi, Alessia, Zotto, Luca Del, Tascioni, Roberto, Mahkamov, Khamid, Underwood, Chris, Cabeza, Luisa F., Gracia, Alvaro de, Pili, Piero, Mintsa, André C., Bartolini, Carlo M., Gimbernat, Toni, Botargues, Teresa, Halimic, Elvedin, and Cioccolanti, Luca
- Published
- 2019
- Full Text
- View/download PDF
11. Analysis of Natural Convection During the Melting Process of Hydrogenated Palm Stearin for use as Phase-Change Material.
- Author
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Lizcano-González, Víctor A., Kafarov, Viatcheslav, Mahkamov, Khamid, Aguilera-Duarte, Valentina, and Blanco-Beltran, Anamaria
- Subjects
NATURAL heat convection ,MELTING ,STEARIN ,PHASE change materials ,HEAT exchangers - Abstract
There are three main alternatives for the improvement of heat transfer in phase change materials (PCM) such as the use of additives, support matrices and customized designs for heat exchangers. The first two alternatives imply incurring additional material costs, as well as a decrease in the specific heat storage capacity by using components that remain solid during the process. The present work therefore sought to study the effect of the use of a coil shell heat exchanger with a square cross section on natural convection during the melting process of hydrogenated palm stearin. Three different sections of the profile called square profile, U-profile, and L-profile and two types of material, copper, and stainless steel, were studied. A test bench was built with a capacity of 5 kg of this PCM, implementing a hot water recirculation system with flow and temperature measurement and including 9 temperature sensors inside the PCM. The melting process was conducted by recirculating water with a temperature of 75° C and a flow rate of 2 L/min. The results show a marked effect of natural convection on the melting process, presenting characteristic profiles for this phenomenon. It was found that the highest temperatures are recorded in the upper part of the PCM and that the heat transfer in the solid material is appreciably low. The results allow us to identify for each profile, the zones in which heat transfer is relatively high because of natural convection and those zones that require the use of additives or support matrices. It is therefore expected to contribute to the design of more efficient and lower commercial cost configurations. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
12. Thermal Performance of Hydrogenated Palm Stearin as Phase Change Material in a Pilot Solar Thermal Energy Storage System.
- Author
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Lizcano-González, Víctor A., Kafarov, Viatcheslav, and Mahkamov, Khamid
- Subjects
STEARIN ,PHASE change materials ,HEAT storage ,PARAFFIN wax ,RENEWABLE energy sources - Abstract
The search for new phase change materials (PCM) of renewable origin and low cost, as an alternative to the use of paraffin wax, contributes to the environmental resilience of solar thermal energy systems. An important source of PCMs of renewable origin are vegetable oils and fats, especially those with established agro-industrial chains. Globally, palm oil has positioned as an indispensable product in many industrial sectors. One of the main by-products of palm oil refining is palm stearin, which can be hydrogenated to improve its thermal properties. This paper presents the results of the performance of a Solar thermal energy storage system (STESS) located in a Colombian paramo area with an altitude of 3,200 m.a.s.l. The system store heat in 550 kg of Hydrogenated Palm Stearin (HPS), contained in a rectangular vessel, which allow to supply hot water and space heating for a country house. The average ambient temperature is 12°C during the day and 7°C at night. This experimental station implements a robust measurement and control system including 39 PT-100 type temperature sensors, and different actuators connected to a control system based on Arduino and Raspberry Pi devices. This configuration permit also to implement a remote monitoring system. The constructed STESS employs 140 collector tubes, running at a maximum temperature of 95°C. According to the energy load tests during a period of 7 hours of operation, approximately 40.0 MJ were stored as heat in the hydrogenated palm stearin. For the same period, the heat transfer fluid received approximately 170 MJ of energy. In subsequent discharge tests, the heat stored in the HPS allowed the ambient temperature inside the room to be maintained 8°C above the external ambient temperature for up to 8 hours during the night, demonstrating the technical feasibility of using this new PCM from renewable sources. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
13. Methods of heat transfer intensification in PCM thermal storage systems: Review paper
- Author
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Al-Maghalseh, Maher and Mahkamov, Khamid
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- 2018
- Full Text
- View/download PDF
14. Financial Analysis of Low-Temperature Solar Thermal Energy Storage Systems to Supply Hot Water and Heating for Rural Colombian Households.
- Author
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León-Esteban, Andrés F., Lizcano-González, Víctor Alexis, Mahkamov, Khamid, and Kafarov, Viatcheslav
- Subjects
HEAT storage ,HOUSEHOLDS ,ECONOMIC activity ,ECONOMIC development ,ECONOMIC recovery - Abstract
In order to mitigate the effects of climate change, contribute to energy autarky and improve the quality of life of the population, Colombia has adopted the energy transition to renewable energy as a state policy. In this context, the use of solar thermal energy, which is abundant in the tropical zone, should be considered as one of the alternatives to be prioritised. A solar thermal energy storage system (STESS) has been developed for the supply of hot water and heating in paramo areas. The system is capable of storing energy in the form of latent heat using a renewable phase change material (PCM). The PCM reaches a maximum temperature of 70° C, allowing enough energy to be stored to take several hot showers and maintain a comfortable temperature in a room. This paper evaluates the performance of the developed STESS from a financial point of view, analysing the associated capital and operational costs. It is also compared with alternative technologies available in the area based on electric heaters and propane gas heaters. The operating cost analysis concludes that the performance of the STESS allows savings of variable operation cost up to 90 % compared to electric energy-based systems. These results become even more relevant considering that many of these areas are not connected to the national electricity grid and almost none of them have a reliable supply of propane gas. Regarding capital costs, although STESS requires an initial investment up to 20 times the value of alternative systems, its long lifetime, low operating costs and reliability make it an attractive alternative in this scenario. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
15. Passive thermal control in residential buildings using phase change materials
- Author
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Kenisarin, Murat and Mahkamov, Khamid
- Published
- 2016
- Full Text
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16. Prediction of the time constant of small-scale concentrated solar CHP plants
- Author
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Tascioni Roberto, Pirro Matteo, Arteconi Alessia, Del Zotto Luca, Bartolini Carlo M., Mahkamov Khamid, Mahkamova Irina, Cabeza Luisa F., De Gracia Alvaro, Pili Piero, Mintsa André C., Gimbernat Toni, Botargues Teresa, Mullen David, and Cioccolanti Luca
- Subjects
Environmental sciences ,GE1-350 - Abstract
The operation of a power plant based on solar energy can vary significantly with time because of the intrinsic intermittency of the energy resource. Hence, a smart management is required to deal with the complex dynamic variations of the different subsystems. In order to do that, different control logics can be implemented but their effectiveness strictly depends on the temporal evolution of the parameters considered. For a given plant configuration, their exact estimation can be obtained through experimental tests during the commissioning of the plant. However, any change in the design parameters of the plant reflects in a different time constant, whose preliminary knowledge may be of support in tuning the control logic of the plant during the design stage. Therefore, based on the configuration of a small-scale concentrated solar combined heat and power plant as designed and built under the EU funded project Innova MicroSolar by several universities and companies, in this study a prediction of the time constant of several plant configurations with varying solar multiple and size of the storage tank is performed. By making use of the dynamic simulator previously developed by some of the authors, an estimation of such characteristic is assessed in case of potential redesign of the plant, providing also useful suggestions into the design of the control logic.
- Published
- 2021
- Full Text
- View/download PDF
17. Analysis of labour market needs for engineers with enhanced knowledge in sustainable renewable energy solutions in the built environment in some Asian countries
- Author
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Cioccolanti Luca, Moglie Matteo, Mahkamov Khamid, Paksoy Halime, Chen Chao, Lin Jie, Li Caiyun, Guan Yong, Zhou Wenhe, Abdullah Ermira, Mohd Radzi Mohd Amran, Shafie Suhaidi, Alimuddin Zainal, Yusof Idroas Mohamad, Yew Heng Teoh, Azmier Ahmad Mohd, Azman Miskam Muhamad, Kraitong Kwanchai, Wongsapai Wongkot, Chaichana Chatchawan, and Damronsak Det
- Subjects
Environmental sciences ,GE1-350 - Abstract
Despite the rapid growth in the uptake of renewable energy technologies, the educational profile and the skills gained at University level do not always comply with the practical needs of the organisations working in the field. Furthermore, even though the residential sector has very high potential in curbing its CO2 emissions worldwide thus meeting the challenging goals set out by the international agreements, such reduction has been limited so far. Within this context, the ‘Skybelt’ project, co-funded by the EU under the framework of the Erasmus + programme aims at enhancing in several Universities of Asia and Europe the engineering skills of students of all level for application of sustainable renewable energy solutions in the built environment. With the target of increasing the employability of graduates and the impact of the project, a survey on the labour market needs for specialists with enhanced knowledge and skills in the topic of the project has been conducted in the related Asian countries. Hence, relevant industries, labour market organisations and other stakeholders have been interviewed and the main results of this analysis is reported in the present paper. As first outcome of this activity, the obtained results have been considered in the selection of the modules to be improved according to a student centred study approach.
- Published
- 2021
- Full Text
- View/download PDF
18. A novel small dynamic solar thermal desalination plant with a fluid piston converter
- Author
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Mahkamov, Khamid, Orda, Eugene, Belgasim, Basim, and Makhkamova, Irina
- Published
- 2015
- Full Text
- View/download PDF
19. 3 - Low and high-temperature phase change materials
- Author
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Kenisarin, Murat, Mahkamov, Khamid, Combrinck, Madelein, and Makhkamova, Irina
- Published
- 2023
- Full Text
- View/download PDF
20. Prediction by mathematical modeling of the behavior of an internal combustion engine to be fed with gas from biomass, in comparison to the same engine fueled with gasoline or methane
- Author
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Centeno González, Felipe O., Mahkamov, Khamid, Silva Lora, Electo E., Andrade, Rubenildo V., and Jaen, René Lesme
- Published
- 2013
- Full Text
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21. CFD thermal modelling of Lynx overhead conductors in distribution networks with integrated Renewable Energy Driven Generators
- Author
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Makhkamova, Irina, Mahkamov, Khamid, and Taylor, Philip
- Published
- 2013
- Full Text
- View/download PDF
22. Potential Application of Renewable Eutectic Mixtures as Phase Change Materials for Thermal Energy Storage.
- Author
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Lizcano-González, Víctor Alexis, Kafarov, Viatcheslav, Mahkamov, Khamid, Carvajal Arciniegas, María Paula, and Socha Rojas, Nelcy Daniela
- Subjects
RENEWABLE energy sources ,ORGANIC wastes ,TEMPERATURE ,THERMOGRAVIMETRY ,STEARIN - Abstract
Many energies management and storage technologies use phase change materials (PCM) to increase process efficiency. Technologies such as solar thermal energy storage, passive temperature management in buildings, even the development of high-performance sportswear employ various types of PCM. Phase change materials can be classified according to the working temperature, their nature or the phase transition, highlighting the use of materials of renewable origin. There are different methodologies to modify the properties of PCM, among which the preparation of eutectic mixtures stands out. This is a technique that allows obtaining PCM with a lower melting temperature than that of the initial components. Considering the above, this work presents the thermal characterization of mixtures of palm stearin, hydrogenated palm stearin, beeswax, and paraffin wax in order to evaluate the heat storage potential of the resulting products. Mixing ratios of 80:20, 65:35, 50:50, 35:65 and 20:80 were evaluated. Melting and crystallisation temperatures and enthalpies and their solid and liquid heat capacities were measured by differential scanning calorimetry. The thermal stability of the mixtures was also determined by thermogravimetric analysis. From the results obtained, the PCM obtained by mixing beeswax and hydrogenated palm stearin, which presents its eutectic melting point for the mixture ratio of 50:50 with a temperature of 56 °C and an enthalpy of fusion of 264 kJ/kg, stands out. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
23. Syngas production in downdraft biomass gasifiers and its application using internal combustion engines
- Author
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Martínez, Juan Daniel, Mahkamov, Khamid, Andrade, Rubenildo V., and Silva Lora, Electo E.
- Published
- 2012
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- View/download PDF
24. Theoretical and experimental investigations of a downdraft biomass gasifier-spark ignition engine power system
- Author
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Centeno, Felipe, Mahkamov, Khamid, Silva Lora, Electo E., and Andrade, Rubenildo V.
- Published
- 2012
- Full Text
- View/download PDF
25. 'Комп'ютерне моделювання і керування в техніці та технологіях КМКТТ-2021', Дев’ята міжнародна науково-практична конференція
- Author
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Lizcano-González, V. A., Kafarov, Viatcheslav, and Mahkamov, Khamid
- Published
- 2021
26. Analysis of labour market needs for engineers with enhanced knowledge in sustainable renewable energy solutions in the built environment in some Asian countries
- Author
-
Desideri, U., Cioccolanti, Luca, Moglie, Matteo, Mahkamov, Khamid, Paksoy, Halime, Chen, Chao, Lin, Jie, Li, Caiyun, Guan, Yong, Zhou, Wenhe, Abdullah, Ermira, Mohd Radzi, Mohd Amran, Shafie, Suhaidi, Alimuddin, Zainal, Yusof Idroas, Mohamad, Yew Heng, Teoh, Azmier Ahmad, Mohd, Azman Miskam, Muhamad, Kraitong, Kwanchai, Wongsapai, Wongkot, Chaichana, Chatchawan, Damronsak, Det, Ferrari, L., and Yan, J.
- Subjects
lcsh:GE1-350 ,Market needs ,business.industry ,020209 energy ,H300 ,Context (language use) ,02 engineering and technology ,Employability ,Environmental economics ,021001 nanoscience & nanotechnology ,Residential sector ,Renewable energy ,0202 electrical engineering, electronic engineering, information engineering ,Asian country ,0210 nano-technology ,business ,Erasmus+ ,lcsh:Environmental sciences ,Built environment - Abstract
Despite the rapid growth in the uptake of renewable energy technologies, the educational profile and the skills gained at University level do not always comply with the practical needs of the organisations working in the field. Furthermore, even though the residential sector has very high potential in curbing its CO2 emissions worldwide thus meeting the challenging goals set out by the international agreements, such reduction has been limited so far. Within this context, the ‘Skybelt’ project, co-funded by the EU under the framework of the Erasmus + programme aims at enhancing in several Universities of Asia and Europe the engineering skills of students of all level for application of sustainable renewable energy solutions in the built environment. With the target of increasing the employability of graduates and the impact of the project, a survey on the labour market needs for specialists with enhanced knowledge and skills in the topic of the project has been conducted in the related Asian countries. Hence, relevant industries, labour market organisations and other stakeholders have been interviewed and the main results of this analysis is reported in the present paper. As first outcome of this activity, the obtained results have been considered in the selection of the modules to be improved according to a student centred study approach.
- Published
- 2021
27. Prediction of the time constant of small-scale concentrated solar CHP plants
- Author
-
Desideri, U., Tascioni, Roberto, Pirro, Matteo, Arteconi, Alessia, Del Zotto, Luca, Bartolini, Carlo M., Mahkamov, Khamid, Makhkamova, Irina, Cabeza, Luisa F., De Gracia, Alvaro, Pili, Piero, Mintsa, André C., Gimbernat, Toni, Botargues, Teresa, Mullen, David, Cioccolanti, Luca, Ferrari, L., and Yan, J.
- Subjects
lcsh:GE1-350 ,Power station ,business.industry ,Computer science ,020209 energy ,Scale (chemistry) ,Control engineering ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,02 engineering and technology ,H800 ,Solar energy ,law.invention ,Resource (project management) ,020401 chemical engineering ,law ,Intermittency ,Storage tank ,0202 electrical engineering, electronic engineering, information engineering ,0204 chemical engineering ,Control logic ,business ,Energy (signal processing) ,lcsh:Environmental sciences - Abstract
The operation of a power plant based on solar energy can vary significantly with time because of the intrinsic intermittency of the energy resource. Hence, a smart management is required to deal with the complex dynamic variations of the different subsystems. In order to do that, different control logics can be implemented but their effectiveness strictly depends on the temporal evolution of the parameters considered. For a given plant configuration, their exact estimation can be obtained through experimental tests during the commissioning of the plant. However, any change in the design parameters of the plant reflects in a different time constant, whose preliminary knowledge may be of support in tuning the control logic of the plant during the design stage. Therefore, based on the configuration of a small-scale concentrated solar combined heat and power plant as designed and built under the EU funded project Innova MicroSolar by several universities and companies, in this study a prediction of the time constant of several plant configurations with varying solar multiple and size of the storage tank is performed. By making use of the dynamic simulator previously developed by some of the authors, an estimation of such characteristic is assessed in case of potential redesign of the plant, providing also useful suggestions into the design of the control logic.
- Published
- 2021
28. Production of Fatty Esters from Palm Oil By-Products for use as Phase Change Materials.
- Author
-
Lizcano-González, Víctor A., Kafarov, Viatcheslav V., and Mahkamov, Khamid
- Subjects
PALM oil ,STEARIN ,PHASE change materials ,ESTERS ,NEAR infrared reflectance spectroscopy - Abstract
Palm stearin is the heavy fraction obtained during palm oil refining. It consists mainly of saturated fatty acids and is often an unwanted by-product that reduces the economic efficiency of the processes. Although it is currently used in the manufacture of margarine or industrial vegetable fats, the increase in palm oil production will lead to higher production of palm stearin. The composition, low cost and physicochemical characteristics of palm stearin make it an ideal raw material for obtaining phase change materials for thermal energy storage in solar thermal energy systems. This work explores the esterification of hydrogenated palm stearin (HPS) for obtaining phase change materials with suitable properties for application. The esterification conditions were studied using low and high molecular weight alcohols, like ethanol, butanol and cetyl alcohol, according to Fischer's esterification principles. The esters formation was characterized by attenuated total reflectance infrared spectroscopy. For both HPS and products obtained, melting and solidification temperatures and enthalpies, and heat capacity were determined by DSC according to ASTME793-06(2018) and ASTME1269-11(2018). A crude wax was obtained by esterification of the fatty acids present in palm stearin in all cases. Among the esters produced, the one obtained by using cetyl alcohol, which has a melting temperature of 55.9 °C and an enthalpy of fusion of 257.26 kJ/kg, stands out. This novel PCM is presumed to have an optimal performance for heat storage applications in low temperature solar thermal systems (50°C - 90°C), for hot water supply and space conditioning. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
29. Numerical investigation of pipelines modeling in small-scale concentrated solar combined heat and power plants
- Author
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Tascioni, Roberto, Arteconi, Alessia, Del Zotto, Luca, Habib, Emanuele, Bocci, Enrico, Moradi, Ramin, Mahkamov, Khamid, Costa, Carolina, Cabeza, Luisa F., Gracia Cuesta, Alvaro de, Pili, Piero, Mintsa, André Charles, Pirro, Matteo, Gimbernat, Toni, Botargues, Teresa, Halimic, Elvedin, and Cioccolanti, Luca
- Subjects
numerical analysis ,renewable energy ,dynamic simulation ,concentrated solar power plant ,organic Rankine cycle system ,thermal losses ,Work (thermodynamics) ,Renewable energy ,Control and Optimization ,Power station ,020209 energy ,Energy Engineering and Power Technology ,02 engineering and technology ,lcsh:Technology ,7. Clean energy ,Organic Rankine cycle system ,020401 chemical engineering ,0202 electrical engineering, electronic engineering, information engineering ,Mass flow rate ,Fluid dynamics ,organic rankine cycle system ,0204 chemical engineering ,Electrical and Electronic Engineering ,Engineering (miscellaneous) ,Concentrated solar power plant ,Organic Rankine cycle ,lcsh:T ,Renewable Energy, Sustainability and the Environment ,business.industry ,Mechanics ,Dynamic simulation ,Temperature gradient ,Thermal losses ,Environmental science ,business ,Energy (miscellaneous) ,Numerical analysis - Abstract
In this paper four different detailed models of pipelines are proposed and compared to assess the thermal losses in small-scale concentrated solar combined heat and power plants. Indeed, previous numerical analyses carried out by some of the authors have revealed the high impact of pipelines on the performance of these plants because of their thermal inertia. Hence, in this work the proposed models are firstly compared to each other for varying temperature increase and mass flow rate. Such comparison shows that the one-dimensional (1D) longitudinal model is in good agreement with the results of the more detailed two-dimensional (2D) model at any temperature gradient for heat transfer fluid velocities higher than 0.1 m/s whilst the lumped model agrees only at velocities higher than 1 m/s. Then, the 1D longitudinal model is implemented in a quasi-steady-state Simulink model of an innovative microscale concentrated solar combined heat and power plant and its performances evaluated. Compared to the results obtained using the Simscape library model of the tube, the performances of the plant show appreciable discrepancies during the winter season. Indeed, whenever the longitudinal thermal gradient of the fluid inside the pipeline is high (as at part-load conditions in winter season), the lumped model becomes inaccurate with more than 20% of deviation of the thermal losses and 30% of the organic Rankine cycle (ORC) electric energy output with respect to the 1D longitudinal model. Therefore, the analysis proves that an hybrid model able to switch from a 1D longitudinal model to a zero-dimensional (0D) model with delay based on the fluid flow rate is recommended to obtain results accurate enough whilst limiting the computational efforts.
- Published
- 2020
30. Solar energy storage using phase change materials
- Author
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Kenisarin, Murat and Mahkamov, Khamid
- Published
- 2007
- Full Text
- View/download PDF
31. Contributors
- Author
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Alkan, Cemil, Arumuga Perumal, D., Biswas, Prasanta K., Castelain, Cathy, Chavan, Santosh, Combrinck, Madelein, Confalonieri, Chiara, Deshpande, Madhura D., Faraj, Jalal, Faraj, Khaireldin, Gariboldi, Elisabetta, Gumtapure, Veershetty, Hachem, Farouk, Hakami, Abdullatif, Jain, Pawan Kumar, Kali, Ravi, Kenisarin, Murat, Khaled, Mahmoud, Kizildag, Nuray, Kulkarni, Prashant S., Mahkamov, Khamid, Makhkamova, Irina, Militky, Jiri, Padya, Balaji, Pielichowska, Kinga, Pielichowski, Krzysztof, Rao, Akshay, Raut, Sandesh S., Ravikiran, Nowduru, Savvakis, Nikolaos, Selvaraj, M., Silva, Tiago, Srinivasan, Sesha S., Stefanakos, Elias K., Szatkowski, Piotr, Tsoutsos, Theocharis, Venkataraman, Mohanapriya, Vicente, Romeu, Wiener, Jakub, and Yang, Kai
- Published
- 2023
- Full Text
- View/download PDF
32. Numerical investigation of the smart energy management of modular latent heat thermal storage on the performance of a micro-solar power plant
- Author
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Tascioni, Roberto, Cioccolanti, Luca, Del Zotto, Luca, Mahkamov, Khamid, Kenisarin, Murat, Costa, Carolina, Cabeza, Luisa F., Gracia Cuesta, Alvaro de, Maldonado, José Miguel, Halimic, Elvedin, Mullen, David, Lynn, Kevin, and Arteconi, Alessia
- Subjects
Fuzzy logic ,Micro-scale ORC system ,Micro combined heat and power plant ,Concentrated solar power ,Renewable energy systems - Abstract
Solar energy is widely considered as one of the most attractive renewable energy source to curb CO2 emissions at residential level where micro-cogeneration has a very interesting potential. One promising application of solar energy is in combination with Organic Rankine Cycle (ORC) plants due to the ability to utilize low-medium temperature heat sources. However, because of the intermittent availability of solar energy, thermal energy storage (TES) systems are required to improve the performance of such systems and assure their prolonged operation. At medium temperatures, latent heat thermal energy storage (LHTES) systems allow to effectively store and release the collected thermal energy from the solar field. However, room for improvements exists to increase their efficiency when in operation. For this reason, in this work the authors have numerically investigated the performance of a 2 kWe micro-solar ORC plant coupled with an innovative LHTES system that is going to be built and tested under the EU funded project Innova MicroSolar. The novel LHTES, developed and designed by some partners of the Consortium, is subdivided into six modules and consists of 3.8 tons of high-temperature phase change material. In this study the effect of the storage volume partialization on the performance of the integrated plant is evaluated using a fuzzy logic approach. Main aim of the storage management is to achieve a reduction of the thermal losses and improve the plant overall efficiency. Annual dynamic simulations are performed in order to determine the optimal storage volume needed in different operating conditions. Results clearly show a remarkable annual increase in electric and thermal energy production of 8 % and 6 % respectively, in comparison with the configuration without fuzzy logic control: this achievement was obtained decreasing the working LHTES modules in winter and conversely increasing them in summer. This study is a part of the Innova MicroSolar Project, funded in the framework of the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement No 723596).
- Published
- 2019
33. Thermodynamic Analysis and Sizing of a Small Scale Solar Thermal Power System Based on Organic Rankine Cycle.
- Author
-
Hossin, Khaled, Mahkamov, Khamid, and Belgasim, Basim
- Subjects
SOLAR thermal energy ,RANKINE cycle ,HEAT transfer fluids ,SOLAR energy ,SOLAR collectors ,ENTHALPY ,ORGANIC bases ,SOLAR heating - Abstract
This paper presents the feasibility analysis of a small-scale low-temperature solar organic Rankine cycle power system. The heat transfer fluid for running the organic Rankine cycle system is hot water with a temperature of 120 °C provided by an array of evacuated tube solar collectors. The performance of the solar organic Rankine cycle system was investigated using two different working fluids over a wide range of the evaporation temperature. Technical and economic indicators such as the required solar collector aperture area, the total heat transfer surface area of the heat exchangers and the volume flow ratio between the outlet and inlet of the expander are among the key parameters used to evaluate the solar organic Rankine cycle. Thermolib toolbox 5.2 in conjunction with MATLAB/Simulink was used to predict the variation of the system performance. The results showed that the solar organic Rankine cycle system is able to achieve an overall system efficiency of 6.75% using a relatively low-temperature heat source. The results also showed that the solar organic Rankine cycle system requires smaller evacuated tube solar collector and heat exchanger areas when R245fa is used as the working fluid. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
34. Evaluation of domestic electrical demand and its effect on low voltage network performance
- Author
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Karmacharya, Samir, Putrus, Ghanim, Underwood, Chris, and Mahkamov, Khamid
- Subjects
H600 ,H900 - Abstract
Electrical demand in a house depends on various factors mainly being the user’s behaviour and the rating of the appliances. Some researchers have used daily domestic electrical demand profile at half hour time resolution for the energy management. When data of half hour time interval is used for the analysis of on-site generation, it can lead to over/under -estimates of the proportion of generated energy used on site. As a consequence, this could lead to over/under-estimating in the import and export of power from and to the power grid. In this paper, domestic electricity use profile recorded at high time resolution of one minute is used to analyse the profile obtained at different time resolution and its effect on on-site generation.\ud Daily load profile for summer and winter at time resolution of 30 minute is generated from a data set of 22 houses consisting data of a whole year which is then compared with the daily load curve obtained after diversity maximum demand from the literature. The generated daily load profile is then used to see effect on the low voltage network. For the analysis on the low voltage network, a typical UK low voltage network is developed in the Matlab/Simulink software
- Published
- 2012
35. Salt hydrates as latent heat storage materials:Thermophysical properties and costs.
- Author
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Kenisarin, Murat and Mahkamov, Khamid
- Subjects
- *
HYDRATES , *HEAT storage , *THERMOPHYSICAL properties , *ENERGY conversion , *TEMPERATURE effect , *PHASE change materials - Abstract
Thermal energy storage is considered as one the most perspective technologies for increasing the efficiency of energy conversion processes and effective utilization of available sources of heat. Advantages and technical attractiveness of the thermal energy storing have resulted in continuously increasing numbers of research activities, especially in the last four decades. Among various applications of thermal energy storage, the heat or cold accumulation in the temperature range from −50 °C to 120 °C has a greater market potential and this can be carried out using a wide range of phase change latent heat materials. Among these materials the salt hydrates deserve a special attention and currently a large number of phase change compositions based on salt hydrates are produced commercially and available on the market. However, reliable data on thermophysical properties as well as their thermal stability over their lifetime is required to build effective storage systems. Currently this data is insufficient and is scattered across numerous sources that are often difficult to access for potential consumers. This paper summarises practically all available original experimental data on the phase change diagram of salt–water systems, melting temperatures, heat of fusion, specific heat, density, thermal conductivity, and thermal diffusivity in solid and liquid states and viscosity in the liquid state for 18 salt hydrates. The above information is provided for major market products on the basis of the salt hydrates for latent heat storage. The wholesale prices for pure salt, salt hydrates, and salt hydrate heat storage compositions are also additionally discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
36. Stirling conversions: recent developments in power generation technology imply that domestic combined heat and power may be feasible in the near future. Dr Khamid Mahkamov * describes the significant progress made with the Stirling engine in the past decade Wards this. (Domestic CHP conference)
- Author
-
Mahkamov, Khamid
- Subjects
Motor industry -- Product information ,Stirling engines -- Design and construction ,Stirling engines -- Maintenance and repair ,Industrial equipment and supplies industry -- Product information ,Business ,Business, international ,Petroleum, energy and mining industries - Published
- 2003
37. Experimental Investigations of a Solar Water Treatment System for Remote Desert Areas of Pakistan.
- Author
-
Jamil, Muhammad Ahmad, Yaqoob, Haseeb, Farooq, Muhammad Umar, Teoh, Yew Heng, Xu, Ben Bin, Mahkamov, Khamid, Sultan, Muhammad, Ng, Kim Choon, and Shahzad, Muhammad Wakil
- Subjects
WATER purification ,SOLAR stills ,WATER shortages ,WATERBORNE infection ,MARITIME shipping ,DRINKING water - Abstract
Pakistan is among the countries that have already crossed the water scarcity line, and the situation is worsened due to the recent pandemic. This is because the major budget of the country is shifted to primary healthcare activities from other development projects that included water treatment and transportation infrastructure. Consequently, water-borne diseases have increased drastically in the past few months. Therefore, there is a dire need to address this issue on a priority basis to ameliorate the worsening situation. One possible solution is to shift the focus/load from mega-projects that require a plethora of resources, money, and time to small domestic-scale systems for water treatment. For this purpose, domestic-scale solar stills are designed, fabricated, and tested in one of the harshest climatic condition areas of Pakistan, Rahim Yar Khan. A comprehensive overview of the regional climatology, including wind speed, solar potential, and ambient temperature is presented for the whole year. The analysis shows that the proposed system can adequately resolve the drinking water problems of deprived areas of Pakistan. The average water productivity of 1.5 L/d/m
2 is achieved with a total investment of PKR 3000 (<$20). This real site testing data will serve as a guideline for similar system design in other arid areas globally. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
38. Theoretical and experimental studies for improving the design of the solar field and organic Rankine cycle turbine in a small linear Fresnel reflector solar thermal power plant
- Author
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Mustafa, Abba Imam, Mahkamov, Khamid, and Rahmati, Mohammad
- Subjects
H300 Mechanical Engineering ,H800 Chemical, Process and Energy Engineering - Abstract
Providing sustainable, cost-effective and environmentally friendly energy for consumer societies and industrial economies has been a major concern for industrialized and developing countries. For that reason, there is a renewed interest in the generation of energy from various solar technologies. Among others, Concentrated Solar Power (CSP) technologies has the potential to meet such demands. However, most recent solar energy harnessing technologies require substantial energy to attain efficient power production with compact plant size and the least payback time. Linear Fresnel coupled with organic Rankine cycle solar thermal power plant may prove to be a promising choice due to its capacity to overcome techno-commercial constraints related with conventional reflector based CSP Technologies. Theoretical and experimental studies for improving the design of a solar field and organic Rankine cycle turbine in a small Linear Fresnel Reflector solar thermal power plant is performed in this study. In the initial stage, the design and optimization of the 3D optical model of the LFR solar field is presented in an attempt to minimize the drift and variation in ray concentration and improve the optical performance. In the solar field optimization, key variables such as the mirror curvature, width, length, the distance between consecutive mirror centre lines and height were selected. Subsequently, a Monte Carlo Raytracing and thermal analysis were performed to investigate the impact of the optimized mirror elements on the optical performance of the solar field. A comparative analysis between two LFR configurations, Central LFR (CenLFR) and Compact LFR (ComLFR) is put forward by adopting a similar approach. Furthermore, a small-scale organic Rankine cycle turbine used for low-temperature applications capable of generating electrical power was theoretically and experimentally investigated. A single-stage axial turbine expander deploying R365mfc, and the new environmentally friendly Novec649 organic working fluids were selected. Modelling of the turbine and comparative analysis of the two working fluids is performed adopting a simple CFD approach proposed. The effect of the range of inlet definition variables such as temperature, pressure, rotational speed and key thermodynamic properties of the fluids on the work output and isentropic efficiency as well as the influence of rotor tip clearance (rotor gap) on the turbine power were investigated and analysed. In the closing stage, the shading analysis of the solar field and environs is performed using different approaches. In this context, shading resulting mainly from structures such as buildings and vegetation is considered. The analysis considers sun and shadow effects that can be easily and dynamically improved or even animated within the program to evaluate the timing and effect of obstructions and the resulting consequence on the optical performance of the solar field. The numerical approaches were validated with optical and thermal experimental data gathered from a linear Fresnel plant erected in Almatret, Spain. Results show a good correlation between the numerical approach and experimental study. Findings from the solar field study show that optimising key mirror elements such as the curvature, width, length, receiver height from the mirror plane, and the distance between two consecutive mirror centrelines can significantly impact the LFR solar field optical performance. This leads to an improved concentration factor which can enhance the energy conversion efficiency of LFR plants and greatly minimize the cost of thermal storage, which results in a low Levelized cost of electricity (LCOE) and offers LFR the economic potential to compete with other CSP power plants. Next to that, results of the comparative analysis show minimized drift in ray concentration and the computed energy efficiency for separate mirror elements, and the overall solar field show improved optical performance for the central configuration. Despite blocking and shading effect minimized in the compact configuration, findings show lower optical efficiency, mainly due to the receiver being fixed and its distance away from the primary mirrors. In both solar field studies, it was observed that losses are greatly influenced by the solar field orientation. As per the ORC turbine, it was observed that the inlet turbine temperature and pressure have the greatest effect on the power, work output and isentropic efficiency. The selection of an organic working fluid and its application in ORC turbine is a crucial aspect mainly due to the dependence of its categorization on the temperature of the heat source, defined by the fluid thermodynamic and thermophysical. As expected, the computed peak power output is generated by the "ideal" turbine expander design with zero clearance of blade tips. Exceeding the 200 μm rotor gap results in a sharp detrimental effect on the turbine performance. Shading analysis was found to be a fundamental step in the phase of design, installation and operation of a solar field. Shading of any form can have a negative influence on the performance of an entire solar field. Such estimations are significant, especially when designing collectors for places where the available land strip does not align with a particular orientation, as in the case of the north-south configuration.
- Published
- 2022
39. Comparative life cycle and technical-economic analysis of renewable energy technologies and numerical modelling of heat pipes for application in solar thermal plants
- Author
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Nkor, John Vurebari Koko and Mahkamov, Khamid
- Subjects
H300 Mechanical Engineering ,H800 Chemical, Process and Energy Engineering - Abstract
This research presents a comparison between mainstream and emerging solar-thermal renewable energy technologies (RETs) using an integrated environmental and techno- economic assessment framework and the numerical modelling of heat pipes for solar thermal applications. Using the framework, the overall sustainability potential is quantified in terms of a novel environmental and techno-economic index (ETEI), combining the Levelised Life Cycle Impact (LLCI) with the Levelised Cost of Energy (LCOE). A set of three 'mainstream' (Photovoltaic-PV, Wind Turbine-WT, Bioenergy) and three 'solar- thermal' (Parabolic Trough Steam-driven turbine, Parabolic Trough and Linear Fresnel Reflectors, the latter two with Organic Rankine Cycle, respectively PT-ORC and LFR- ORC) RETs are used. Economic and environmental evaluation of the RETs for technological innovation is relevant in making an informed decision as to the value these technologies present. Hence, this study also assesses the efficiency of technical innovations of the six RETs, using the eco-efficiency approach by integrating life cycle assessment and life costing. A demonstration case study is presented for two sites with favourable renewable resources over 25-year operational life. The results show improved overall sustainability scores for solar-thermal, attributed mainly to the additional thermal energy recovery from the ORC. PV emerges as the most preferred option when only electricity generation is considered, whereas accounting for the additional thermal energy outputs makes PT-ORC as the most preferred option during to its technological maturity and LFR-ORC the second preferred option. The transient behaviour of a heat pipe, designed by an industrial partner of the Northumbria University team, leading Horizon 2020 R & I Activity Project on the development of a small solar thermal plant, was investigated numerically. The heat pipe is a part of the plant, and its operation was studied for different tilt angles (0 = 0°, 45°, 90°). The numerical solutions were obtained using a fully implicit Finite Difference Method that considered the motion of the liquid and a known time-varying temperature boundary condition at the liquid front. The liquid front position was found to be dependent on the applied heat flux, the initial conditions, and the thermophysical properties of the working fluid. Additionally, the distribution of power output and wall temperatures was predicted. The temperature distribution of the working fluid was consistent with experimental results from the previous literature and provided valuable insight into the room-temperature start- up phenomenon.
- Published
- 2021
40. Theoretical modelling of components of a solar thermal power plant for performance enhancement
- Author
-
Mahmood, Hassan and Mahkamov, Khamid
- Subjects
H800 Chemical, Process and Energy Engineering - Abstract
Solar power is a renewable energy source and can meet the growing world demand for electricity. The thermal energy produces by solar is an attractive solution to handle the environmental issues caused by fossil fuels. This research focuses on the theoretical modelling of components of solar thermal power plants for performance enhancement. It involves the modelling of the solar collector and organic Rankine power cycle. The overall solar thermal power plant comprises such components as a collector, evaporator, turbine, condenser, pump, heat exchanger, and thermal storage system. The present research studies the Linear Fresnel Reflector's performance in providing the heat input to the Organic Rankine Cycle and investigate the annual energy production of the power plant, located at the testing site in Almatret, Catalonia, Spain. The work includes step-by-step modification of the actual system design with a performance analysis of the non-concentrating and concentrating power plant systems. The mathematical model of the ORC was developed based on the thermodynamic equations with simulations performed using MATLAB/Thermolib software. The ORC system performance was investigated for different working fluids at their critical operating conditions. The considered working fluids include the HCFC-245fa, HCFC-134a, Propane, butane, ethanol, and methanol. The ORC model was upgraded by taking into account the heat exchanger to recover the system waste heat, and results were compared to that from a simple ORC model. The recovery of the heat in the cycle increases the thermal efficiency of the ORC, but its benefits depend on the critical parameters of the working fluid. The effect is considerable for R134a and negligible for Ethanol. The Solar Organic Rankine Cycle (SORC) mathematical model was developed, and simulation designed on the MATLAB/Thermolib software. The evacuated tube collector designed for the Almatret latitude position and supplied the power input to the Rankine system. The model based on the water heat transfer fluid of the solar field, and it is transferring the heat to HCFC-134fa, the working fluid of the Rankine cycle via a heat exchanger without a tracking and thermal storage system. The thermal performance of the model investigated base on the day scan results. The solar organic Rankine cycle has an area 600 m2 to generate peak thermal power 71 kW, and the mechanical output power of the Rankine cycle is 4.274 kW using 30 bar evaporation pressure and 10 bar condensation pressure. The Generic Algorithm code developed on MATLAB and connected with the Thermolib model to operate the SORC system with optimum variables and thermal efficiency increases from 10.58 % to 11.87 % using the peak value solar irradiance. Fresnel solar reflector model simulated by using the light tools simulation software and have a one-axis tracking system. The actual weather data was imported to the simulation software to investigate the system performance using the day scan results. The theoretical model derived to determine the system thermal energy and conduction, convection, and radiation heat transfer of the receiver tube. The thermal losses of the model investigated and derived solar angles of the specific day. The tracking system based on the incidence angle modifier model (IAM) and calculated the system optical efficiency corresponds to the IAM in terms of the longitudinal and transverse components of the incidence of rays. The analysis performed from ambient conditions to determine the peak value by using the Therminol-62 working fluid. The LFR field produces 106.425 kW thermal energy during peak hour using a high value of IAM, and the reflector area is 214.38 m2. The thermal losses during the peak time of day at 1:00 PM is 7.872 kW. The system advisor simulation software used to validate the solar power linear Fresnel system. The complete model simulated with the thermal storage system. The actual weather data and Therminol-62 heat transfer fluid and NOVECTM649 working fluid import to the simulation model. The simulation model based on the exact power plant is located in the Almatret location and investigated the model thermal performance. The results show that the LFR field with a tracking system and Therminol-62 working fluid increases the system thermal performance. The Therminol-62 have high-temperature ranges at low operating pressure as compare to the steam working fluid. The ORC has a higher value of thermal efficiency NOVECTM649 than HCFC-134a and produces 7.2 kW output power of the ORC plant during the peak hour of solar irradiance with specific operating conditions. The two-tank thermal storage system extends the Plant four hours of operation and produces the highest power output of 2160 kWh in July.
- Published
- 2020
41. Mathematical modelling of a small biomass gasifier for synthesis gas production
- Author
-
Mbikan, Atainu and Mahkamov, Khamid
- Subjects
662 ,F100 Chemistry ,H700 Production and Manufacturing Engineering ,H800 Chemical, Process and Energy Engineering - Abstract
The depletion of fossil fuels coupled with the growing demands of the world energy has ignited the interest for renewable energies including biomass for energy production. A reliable affordable and clean energy supply is of major importance to the environment and economy of the society. In this context, modern use of biomass is considered a promising clean energy alternative for the reduction of greenhouse gas emissions and energy dependency. The use of biomass as a renewable energy source for industrial application has increased over the last decade and is now considered as one of the most promising renewable sources. The direct combustion of biomass in small scales often results in incomplete and inconsistent burning process which could produce carbon monoxide, particulates and other pollutants. Therefore, biomass is required to be transformed into more easily handled fuel such as gases, liquids and charcoal using technologies such as pyrolysis, gasification, fermentation, digestion etc. Biomass gasification upon which this thesis focuses is one of the promising routes amongst the renewable energy options for future deployment. Gasification is a process of conversion of solid biomass into combustible gas, known as producer gas by partial oxidation. This research work is carried out to investigate various methods employed for modelling biomass gasifiers, it also studies the chemistry of gasification and reviews various gasification models. In this work, a mathematical model is developed to simulate the behaviour of downdraft gasifiers operating under steady state and determine the synthesis gas composition. The model distinctly analyses the processes in each of the three zones of the gasifier; pyrolysis, oxidation and reduction zones. Air is used as the gasifying agent and is introduced into the pyrolysis and oxidation zones of the gasifier for both single and double air operations. These zones have been modelled based on thermodynamic equilibrium and kinetic modelling; the model equations are solved in MATLAB. Given the biomass properties, consumption, air input, moisture content and gasifier specifications, the MATLAB model is able to accurately predict the temperature and distribution of the molar concentrations of the synthesis gas constituents. The downdraft gasifier is also represented in Aspen HYSYS based on the same models to study the effect of both single and double air gasification operation. For known biomass properties, consumption, air input, moisture content and gasifier operating conditions, the Aspen HYSYS model can accurately predict the distributions of the molar concentrations of the syngas constituents (CO, CO2, H2, CH4, and N2). The models were validated by comparing obtained theoretical results with experimental data published in the open literature. Parametric studies were carried out to study the effects of equivalence ratio, moisture content, temperature on the gas compositions and its energy content. The proposed equilibrium model displayed a variable ability for the prediction of various product yields with this being a function of the feedstock studied. It also demonstrated the ability to predict product gases from various biomasses using both single and double stage air input. In the case of gasification with double air stage supply, higher amounts of methane are obtained with specific tendencies of the gases reaching a peak at certain conditions. The kinetic model was partially successful in predicting results and comparable with experimentally published results for a range of conditions. There were discrepancies particularly with CH4 formation and the operating temperatures predictions which were usually consistently lower than those actually measured experimentally. The use of the PFR, however, did show a greater potential for the use in further modelling.
- Published
- 2019
42. Intensification of heat transfer in thermal energy storage systems with phase change materials
- Author
-
Ismail, Mohammad, Mahkamov, Khamid, and Kenisarin, Murat
- Subjects
621.47 ,F200 Materials Science ,H800 Chemical, Process and Energy Engineering ,J500 Materials Technology not otherwise specified - Abstract
This research work aims to develop low- and medium-temperature thermal energy storage (TES) systems using metallic alloys and solar salt as phase change materials (PCMs) for accumulating thermal energy in the temperature ranges between 120 and 140 °C and 215 and 250 °C, respectively. The low purity metallic alloy Bi 58%-Sn 42% was selected as the PCM for low-temperature applications because it is non-hazardous, relatively inexpensive, and it has a suitable melting temperature range. Commercially available high-purity metallic alloys (99.99%) are expensive, whereas lower purity alloys can be a cost-competitive alternative for PCM applications. The sample of a low purity metal alloy, namely Bi 58%-Sn 42% with a purity of 97% was sintered in the laboratory, and its thermal properties were characterized for application as a PCM. Experimental investigations demonstrated that deterioration of the thermal properties of the low purity metal alloy is not substantial in comparison to the pure metallic alloy and that it can be efficiently used as a PCM. Solar salt (NaNO3 60% - KNO3 40%), selected as the PCM for medium-temperature applications due to its high latent heat value, has a relatively low thermal conductivity. Therefore, two techniques were adopted to improve the heat transfer in TES: deploying metallic fins and using graphite as an additive. The experimental tests demonstrate that both methods considerably improve heat transfer and data obtained was used to quantify these effects. In addition, the computational fluid dynamics (CFD) simulations were carried out to evaluate the thermal performance of the metallic alloy and solar salt TES systems with different concentrations of additives and number of fins in terms of the evolution of the liquid fraction and amount of energy stored and released during charging and discharging processes as a function of time. The comparison of numerical and experimental results demonstrated the acceptable accuracy of the developed CFD models. Both experimental and numerical results were used to derive dimensionless correlations for estimation of the heat transfer intensity and time required for charging and discharging of the studied TES systems. These generated dimensionless correlations can be successfully used in engineering practice to design TES systems.
- Published
- 2019
43. Solar water desalination using multi-effect water stills with reduced internal pressure
- Author
-
Elsharif, Nabil and Mahkamov, Khamid
- Subjects
621.47 ,H300 Mechanical Engineering ,H800 Chemical, Process and Energy Engineering - Abstract
The application of solar energy is one prospective solution to meet the sharp increase in global energy demand and alleviate the environmental issues, caused by the use of fossil fuels. Solar thermal energy has been actively utilized to operate small-scale desalination systems and solar water stills, which are one of the most promising technologies in the field of seawater desalination. A desalination system, consisting of multi-effect solar water still coupled to evacuated tube solar collectors and a novel modification of small fluid piston energy converter has been studied at Northumbria University. The task in this research was to experimentally test the possibility of the operation of system with capability to self-reduce the internal pressure inside the still in order to increase its productivity. It was demonstrated that the system was able to achieve vacuum conditions and maintain this level of pressure without using an external vacuum pump. In the theoretical investigation a thermodynamic mathematical model of the proposed system has been developed and used to solve the governing equations in a Matlab/Simulink environment. The output data was obtained in terms of variation of the pressure and temperatures inside the system as well as its distillate productivity. In the experimental investigation, the above described distillation system was developed at Northumbria University based on a laboratory prototype of a dynamic solar multi-effect water still and fluid piston energy converter designed and built previously by Prof K. Mahkamov. Series of experimental tests and numerical simulations were performed for the climatic conditions of Benghazi city in Libya. After validation of the mathematical model against previously published theoretical results and the experimental data obtained in this study, further investigations of the influence of decreasing internal pressure on the performance of the system was conducted. Overall, investigations confirm that this novel system demonstrates considerable improvement in the distillate productivity when compared to conventional solar stills.
- Published
- 2018
44. Dynamic modelling and thermo-economic optimization of a small-scale hybrid solar/biomass Organic Rankine Cycle power system
- Author
-
Hossin, Khaled, Mahkamov, Khamid, and Belgasim, Basim
- Subjects
620 ,H800 Chemical, Process and Energy Engineering - Abstract
The use of solar thermal energy to drive both large and small scale power generation units is one of the prospective solutions to meet the dramatic increase in the global energy demand and tackle the environmental problems caused by fossil fuels. New energy conversion technologies need to be developed or improved in order to enhance their performance in conversion of renewable energy. The Organic Rankine Cycle (ORC) is considered as one of the most promising technologies in the field of small and medium scale combined heat and power (CHP) systems due to its ability to efficiently recover low-grade heat sources such as solar energy. This technology is especially in demand in isolated areas where connection to the grid is not a viable option. The present research provides thermodynamic performance evaluation and economic assessment for a small-scale (10 kW) hybrid solar/biomass ORC power system to operate in the UK climate conditions. This system consists of two circuits, namely organic fluid circuit and solar heating circuit in which thermal energy is provided by an array of solar evacuated tube collectors (ETCs) with heat pipes. A biomass boiler is also integrated to compensate for solar energy intermittence. A dynamic model for the hybrid ORC power system has been developed to simulate and predict the system behaviour over a day-long period for different annual seasons. In the thermodynamic investigation, an overall thermodynamic mathematical model of the proposed power system has been developed. The calculation model of the ORC plant consists of a number of control volumes and in each volume the mass and energy conservation equations are used to describe energy transfer processes. The set of equations were solved numerically using a toolbox called Thermolib which works in the MATLAB/Simulink® environment. The numerical results obtained on the performance of the ORC plant were validated against the theoretical and experimental data available in the open literature. The predicted results were in very good agreement with the data published in the literature. The comparison demonstrated that the developed simulation model of the ORC plant accurately predicts its performance with a maximum deviation of less than 7%. The developed mathematical model then has been used to carry out the parametric analysis to investigate the effect of different operating conditions on the system performance. The economic analysis has been performed with the use of equipment costing technique to estimate the system’s total capital investment cost. This approach is based on the individual costing correlation of each component in the system, considering all the direct and indirect costs of the proposed components. The system cost calculations have been conducted for a range of operating parameters and different working fluids for a fixed value of net power output. At the final stage of the research, a thermo-economic optimization procedure has been developed using Genetic Algorithm (GA) approach for selection of the rational set of design parameters and operating conditions for optimum system performance.
- Published
- 2017
45. Numerical and experimental study of dynamic solar cooling system with a liquid piston converter
- Author
-
Hashem, Gamal and Mahkamov, Khamid
- Subjects
621.47 ,H300 Mechanical Engineering - Abstract
Solar energy has been actively used to drive cooling cycles for domestic and industrial applications, especially in remote areas with a lack of electricity supply for running conventional refrigeration or air-conditioning systems. A number of solar cooling technologies exists but their market penetration level is relatively low due to the high capital costs involved and a long pay-back period. Extensive R & D activities are underway at Universities and industrial companies across many countries to improve performance and reduce capital and running costs of solar cooling systems. Systems based on application of a liquid piston converter for solar water pumping and dynamic water desalination have been developed at Northumbria University. Some preliminary work has been completed on the development of a new solar cooling system built around the above fluid piston converter. In this work, the task is to experimentally and numerically investigate performance of the solar cooling system with the fluid piston converter. The developed theoretical model then can be used for determination of its rational design parameters. Experimental tests were conducted in the Energy Laboratory of the Faculty. The test rig consisted of a solar simulator and evacuated tube solar collector, coupled to the liquid piston converters, equipped with a heat exchanger. Three different configurations of the solar cooling unit were tested and a data acquisition system with pressure, temperature and liquid piston displacement sensors was used to evaluate the experimental performance on the cooling capacity. In the theoretical part of the study, the thermodynamic model of the solar cooling system was developed. In the calculation scheme, the system was split into a number of control volumes and ordinary differential equations of energy and mass conservation were used to describe mass and heat transfer in each such volume. The system of ordinary equations then was solved numerically in MATLAB/Simulink environment and information on the variations of pressure and temperatures in the control volumes of the system over the cycle were obtained. Calibration of the mathematical model with the use of experimental data demonstrated that the model predicts the performance of the system with accuracy acceptable for engineering purposes. Experimental investigations showed that laboratory prototypes of the system demonstrate a stable operation during the tests with an amplitude and frequency of liquid piston oscillations being about 4- 6 cm and 3 Hz, respectively. The reduction in the air temperature in the cooling space was about 1 and 2 K, compared to the ambient temperature. The cooling effect increases with the raise in the heat input into the solar collector and in the flow rate of cooling water. The developed mathematical model of the system describes the pressure variation in the cycle, amplitude and frequency of oscillation of pistons with a level accuracy sufficient for performing engineering design calculations. Overall, both experimental and theoretical investigations confirm that the system demonstrates a capacity to produce a cooling effect with utilisation of solar energy. However, further R & D is required to enhance its performance.
- Published
- 2016
46. Stirling conversions.
- Author
-
Mahkamov, Khamid
- Subjects
STIRLING engines ,THERMODYNAMIC cycles ,COMBUSTION - Abstract
Discusses the dynamic changes of Stirling engines as an external combustion heat engine that works on a closed regenerative cycle. Changes in the compresion and expansion of thermodynamic cycle; Introduction of combustion of air-fuel mixture; Enhancement of combustion products.
- Published
- 2003
47. Experimental and theoretical analysis of the performance of micro co-generation systems based on various technologies
- Author
-
Gkounis, George and Mahkamov, Khamid
- Subjects
621.43 ,H300 Mechanical Engineering - Abstract
This research is focused on the performance evaluation of micro Combined Heat and Power (mCHP) systems based on modern prime mover technologies using both theoretical and experimental analysis. Estimations of the environmental and economic impact associated with their deployment in residential conditions were also carried out. Experimental work was performed on assessing the dynamic and steady-state performance of the 1 kWe Stirling based mCHP system (Whispergen), the 0.75 kWe Proton Exchange Membrane Fuel Cell (PEMFC, PA Hilton Ltd) and the 5.5 kWe Internal Combustion Engine (ICE) based mCHP (Dachs). Results obtained from experiments (such as partial efficiencies, nominal capacities etc.) were fed directly in a theoretical model. Primary energy requirements corresponding to average UK domestic conditions were simulated based on real life technical data. All theoretical work was conducted using EnergyPlus building simulation tool in which the operation of several hydronic heating systems was modelled. Furthermore, attained experimental data and previously published research results were used to validate the theoretical modelling process. Several operating strategies of the Stirling based mCHP unit were simulated in order to determine the regime which offers highest reduction in carbon emissions and household expenditures. In addition, variations in a number of parameters that significantly affect the performance of the system were investigated including energy consumption profiles, occupancy characteristics, dwelling thermal requirements, domestic hot water tank volume, etc). For the optimum performance strategy, several configurations of co-generation systems with nominal capacity in the range from 1 to 3 kWe were simulated. All simulated mCHP scenarios were compared against a conventional heating equipment. Finally, the advantages of a mass installation on a district level, consisting of 60, 120 and 240 dwellings and utilising a mixture of different mCHP units (ICE, Stirling, PEMFC), were estimated.
- Published
- 2015
48. Modelling and optimisation of a free piston stirling engine for micro-CHP applications
- Author
-
Sowale, Ayodeji and Mahkamov, Khamid
- Subjects
621.43 ,H300 Mechanical Engineering - Abstract
This study is carried out to investigate the solar thermal energy conversion for generating power. This form of renewable energy can be utilised for power production deploying the free piston Stirling engines, which convert thermal energy into mechanical energy. Such systems have an advantage of production of work using low and high temperature differences in the cycle which could be created by different sources of heat including solar energy, combustion of a fuel, geothermal energy, nuclear energy or waste heat. The thermodynamic analysis of the free piston Stirling engine have been carried out and implemented in past studies with different methods of approach with various difficulties exhibited. In the present study isothermal, ideal adiabatic and Quasi steady flow models have been produced and used for investigation of the engine performance. The approach in this study deals with simultaneous mathematical modelling of thermodynamic processes and pistons dynamics. The steady state operation of the engine depends on the values of damping coefficients, spring stiffness and pressure drop within the heat exchangers during the engine’s operation, which is also a result of the energy transfer in each engine’s component. In order to design effective high performance engines it is necessary to develop such advanced mathematical models to perform the analysis of the engine’s operation and to predict its performance satisfactorily. The aim of this study was to develop several levels of mathematical models of free piston Stirling engines and to evaluate their accuracy using experimental and theoretical results available in published sources. The validation of the developed free piston Stirling engine models demonstrates a good agreement between the numerical results and experimental data. The validated model then was used for optimisation of the engine, deploying Genetic Algorithm approach with the purpose to determine its optimal design parameters. The developed optimisation procedure provides a noticeable improvement in the engine’s performance in terms of power output and efficiency.
- Published
- 2015
49. Compact solar thermal energy storage systems using phase change materials
- Author
-
Al-Maghalseh, Maher and Mahkamov, Khamid
- Subjects
621.47 ,H800 Chemical ,Process and Energy Engineering ,J500 Materials Technology not otherwise specified - Abstract
The present research explores numerically and experimentally the process of melting and solidification of Phase Change Materials (PCM) in a latent heat thermal energy storage system (LHTESS). Further, the study will investigate various methods of intensification of heat transfer in such materials by means of metallic fins, filling particles or nanoparticles and by choosing the optimal system geometry for a rapid development of free convection flows during the melting process. The study includes three main parts. First, 3D CFD modelling was performed for the melting performance of a shell-and-tube thermal storage system with n-Octadecane as a PCM. The predicted model was in very good agreement with experimental data published in open literature. A series of numerical calculations were then undertaken to investigate the effect of nanoparticles on the heat transfer process. Dimensionless heat transfer correlations were derived for the system with Pure PCM and PCM mixed with nano-particles. In the second part of this study the experimental studies were carried out in order to investigate the performance of the laboratory thermal storage system with paraffin as the PCM. The thermal storage system was connected to evacuated tube solar collectors and its performance was evaluated in various conditions. 3D CFD model of the system was developed and numerical simulations were run for constant heat source conditions. Computational results were compared with experimental data obtained on the test rig at Northumbria University. Comparison revealed that the developed CFD model is capable to describe process of heat transfer in the system with high accuracy and therefore can be used with high confidence for modelling further cases. Finally, 3D CFD model was developed to predict the transient behaviour of a latent heat thermal energy storage system (LHTESS) in the form of a rectangular container with a central horizontal pipe surrounded by paraffin as PCM (melting temperature is 60 oC). Water was used as a heat transfer fluid (HTF). The enhancement of heat transfer in specific geometries by using external longitudinal fins on the tube and metallic porous matrix were numerically investigated. The influence of the number of fins and porosity of the matrix on the temperature distribution, melting process, melting time and natural convection phenomena were studied. Dimensionless heat transfer correlations were derived for calculation of the Nusselt number as function of Fourier, Stefan and Rayleigh numbers. These correlations to be used in the further designing process of similar thermal storage units at Northumbria University.
- Published
- 2014
50. CFD modelling of Stirling engines with complex design topologies
- Author
-
Alexakis, Thanos and Mahkamov, Khamid
- Subjects
621.4 ,H300 Mechanical Engineering - Abstract
This research is in the field of CFD modelling of heat engines, particularly the advanced CFD methodologies for the performance characterization of solar Stirling Engines with complex geometrical topologies. The research aims to investigate whether these methods can provide a more inclusive picture of the engine performance and how this information can be used for the design improvement of Stirling engines and the investigation of more complex engine topologies.
- Published
- 2013
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