Browsing by Author "Lamba, Ravita"

Now showing 1 - 8 of 8
  • No Thumbnail Available
    Item
    A bidirectional solar thermoelectric generator combining heat storage for daytime and nighttime power generation
    (2023) Montero, Francisco J.; Lamba, Ravita; Ortega, Alfonso; Jahn, Wolfram; Chen, Wei-Hsin; Guzman, Amador M.
    A solar thermoelectric generator (STEG) is a promising technology for harvesting solar energy for standalone applications. However, the STEG cannot generate electricity during nighttime due to unavailability of solar energy. The efficiency of thermoelectric generator (TEG) is also low that limits its application areas. This low efficiency can be improved by partially utilizing the waste heat from its cold side using phase change materials (PCMs). Further, the STEG systems operating during day and nighttime are not proposed so far. Therefore, an experimental test rig of a bidirectional (operative in day and night both) STEG coupled with latent heat storage and cooling system (LHSCS) has been developed in this paper. The LHSCS acts as a sink by storing waste heat from the TEG cold side in a phase change material during the daytime and regulates its temperature effectively. During nighttime, LHSCS acts as a heat source for TEG power generation. This proposed bidirectional model aims to provide non-intermittent electricity generation for 24 h. An experimental setup was tested under laboratory conditions and adjusted using a numerical model previously developed in COMSOL Multiphysics software. Once both models are mutually adjusted and verified, the proven numerical model is used to simulate the prototype in the environmental conditions of the Atacama Desert in Chile. The transient effects of solar radiation, ambient temperature and wind speed of the selected location on the hot and cold side temperatures, voltage, power output and efficiency of STEG have been analyzed. A maximum temperature difference of 120 degrees C is obtained between the TEG hot and cold sides. The experimental results showed TEG efficiency of 5%. The system generated average annual electricity of 5735 Wh. The STEG generated around 0.6 % of the total electricity during the night in the Atacama Desert location. The levelized cost of energy and storage have also been calculated for the proposed system and compared with PV and STEG systems. The LCOE and LCOS of the proposed system are 8850 and 566 USD/MWh respectively. The proposed configuration may provide a reference study for design and development of an efficient and cost-effective STEG coupled LHSCS system.
  • No Thumbnail Available
    Item
    A novel 24-h day-night operational solar thermoelectric generator using phase change materials
    (2021) Montero, Francisco J.; Lamba, Ravita; Ortega, Alfonso; Jahn, Wolfram; Guzman, Amador M.
    To improve the energy matrix using solar energy, the intermittency and variation of the solar resource must be resolved for effective implementation of solar operated electricity generation systems. Solar thermoelectric generators (STEG) can be used for electricity generation in non-grid and grid connected applications. However, to use the STEG systems extensively, the limitations of lower conversion efficiency of around 7%, effective passive thermal management of the thermoelectric generator (TEG) and storage of residual heat of the thermoelectric generator need to be solved. In this study, a conceptual theoretical model of latent heat storage and cooling system (LHSCS) is proposed for the effective thermal management and enhanced electricity generation from the solar thermoelectric generator. The numerical model of the proposed system has been developed in COMSOL Multiphysics software for the climatic conditions of the Atacama Desert, Chile. The effect of phase change material (PCM) volume, heat sink and container geometry on the performance of the system has been studied. It is found that the desert locations are the best geographical locations for operating the solar thermoelectric generator coupled latent heat storage and cooling system due to higher solar radiation resource and favorable environmental conditions. The results showed that with 6 kg of phase change material, a temperature difference of 120 degrees C has been achieved between the hot and cold sides of the thermoelectric generator without using an active cooling system and the stored residual heat in phase change material generated 0.6% more electricity during the off-sunshine hours. Further, it has been found that the natural convection has a relevant impact on the melting of the phase change material and must be considered in the designing of a latent heat container. This proposed numerical model can be used to demonstrate the solar thermoelectric generator coupled latent heat storage and cooling system for any geographical location. (c) 2021 Elsevier Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    Energy and exergy analysis of a bidirectional solar thermoelectric generator combining thermal energy storage
    (2023) Montero, Francisco J.; Lamba, Ravita; Singh, Sarveshwar; Jahn, Wolfram; Chen, Wei-Hsin
    In this paper, energy and exergy analysis of a bidirectional solar thermoelectric generator (STEG) coupled to a latent heat storage and cooling system (LHSCS) has been carried out. The effect of various parameters of LHSCS on energy and exergy efficiencies of STEG have been analysed under climatic conditions of Chile's Atacama Desert. It is found that the most relevant design parameter to improve the energy and exergy efficiencies of the thermoelectric generator (TEG) is the container insulation, followed by heat sink at the TEG hot side, fin thickness and the aspect ratio of the container. The results showed that an optimally designed insulation container can improve the energy and exergy efficiencies of LHSCS by 30% and 200%, respectively, and the TEG conversion efficiency by 30% during nighttime. Further, inclusion of heat sink at TEG hot side during reverse operation of TEG at night can improve the TEG efficiency by 20%. The optimal fin thickness can improve the TEG conversion efficiency by 20% during the night and LHSCS energy and exergy efficiencies by 30% and 23%, respectively. The container geometry should have higher aspect ratios. This study may help in optimal design of LHSCS for solar energy conversion applications in the desert locations.
  • No Thumbnail Available
    Item
    Hybrid photovoltaic-thermoelectric system: Economic feasibility analysis in the Atacama Desert, Chile
    (2022) Montero, Francisco J.; Kumar, Ramesh; Lamba, Ravita; Escobar, Rodrigo A.; Vashishtha, Manish; Upadhyaya, Sushant; Guzman, Amador M.
    Desert areas are the favorable geographical locations for desired solar resource and temperature variations for improving the performance of hybrid photovoltaic-thermoelectric generator (HPV-TEG) systems. Therefore, economic feasibility analysis of HPV-TEG system is carried out under real environment and market conditions for the Atacama Desert, Chile. The thermal, electrical and economic models of HPV-TEG system are developed and analyzed in MATLAB. Five different possible scenarios are considered for economic feasibility based on energy losses, system costs, nominal efficiencies of TEG and photovoltaic module and their contribution in the economic feasibility of HPV-TEG system is identified and payback period for all scenarios is determined at minimum and maximum PV temperatures for Atacama Desert including residential and industrial electricity prices. The results showed that with existing market costs and TEG efficiency, HPV-TEG system could not be economically competitive with photovoltaic system for environmental conditions of the Atacama Desert. However, the calculated levelized cost of energy (LCOE) of the HPV-TEG system is 0.071 USD/kWh which is relatively close to current LCOEs for PV systems in Chilean energy market. Further, LCOE analysis economically quantifies the advantages of HPV-TEG system over PV system and opens the possibility for HPV-TEG systems to be competitive in desert locations. (c) 2021 Elsevier Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    Metaheuristic based single and multiobjective optimization of thermoelectric generator
    (2024) Jacob, Irene; Lamba, Ravita; Kumar, Rajesh; Montero, Francisco J.
    Analytical optimization methods are not applicable for some complex practical problems that lead to explore the numerical/metaheuristic optimization methods. Thermoelectric devices are also complex systems and need metaheuristic methods for their performance optimization. This paper analyses various metaheuristic techniques for performance optimization of thermoelectric generator (TEG). Single and multiobjective optimizations of TEG have been performed to optimize its power output and efficiency. The hot and cold side temperatures, load resistance, length of semiconductor legs, and fill factor of the TEG are used as performance parameters. Single objective optimization is performed using 13-metaheuristic algorithms and their results are compared in terms of solution optimality and computational time acceptability. It has been observed that the cuckoo search (CS) algorithm is the most suitable in terms of accuracy and speed. CS produced the optimum power output and efficiency of 19.20837 W and 2.4427 % respectively in minimum time. The multiobjective optimization is also performed for simultaneous optimization of the power output and efficiency. Shannon entropy approach is found to be the best technique to determine optimal point on the Pareto front for multiobjective optimization. The optimal values of decision variables, Th Tc, RL, L and FF for multiobjective optimization are found to be 321.195 K, 281.195 K, 0.14250 omega, 0.5 mm and 0.9 respectively and it produced optimum power output and efficiency of 19.20837 W and 2.25932 % respectively. The statistical and box plot analysis have also been carried out for all the algorithms. The determination of the most suitable algorithm for the faster performance optimization of the TEG, hereby provides the pathways to ascertain the most accurate solution for the power output and efficiency obtainable from the TEG system and hence, delivering the ability to decide the right parameters for the construction of the TEG system with the best performance.
  • No Thumbnail Available
    Item
    PCM-based hybrid thermal management system for photovoltaic modules: A comparative analysis
    (2023) Lamba, Ravita; Montero, Francisco Javier; Rehman, Tauseef-ur; Singh, Sarveshwar; Manikandan, Sundararaj
    Proper temperature regulation of photovoltaic (PV) modules increases their performance. Among various cooling techniques, phase change materials (PCMs) represent an effective thermal management route, thanks to their large latent heat at constant temperatures. Radiative cooling (RC) is also recently explored as a passive option for PV temperature regulation. In this paper, a heat sink (HS), phase change materials, and radiative cooling are integrated with photovoltaic modules to achieve low and uniform temperature distribution along the PV module and improved performance. Eight different combinations are considered for the proposed system, including HS, PCM, and RC, and their various combinations. The PCM is selected according to the environmental conditions of the selected location. A comprehensive 2-D model is developed and analyzed in COMSOL-Multiphysics software by solving the governing equations using the finite element method. The performance analysis is carried out for the climatic conditions of the Atacama Desert, having high solar radiation and ambient temperature. The effects of PCM height, ambient temperature, wind velocity, and solar radiation on the performance of the proposed system are studied. The performance of eight different configurations is also compared. The maximum reductions in PV temperature, maximum PV power, and a minimum drop in PV conversion efficiency are observed to be 22 C-o, 152 W, and 14% using a combined heat sink and radiative cooling systems, among all other configurations. The findings of this study can be used to select the best PV cooling method among different configurations.
  • No Thumbnail Available
    Item
    Radiative cooling system integrated with heat sink for the thermal management of photovoltaic modules under extreme climate conditions
    (2023) Kumar, Ramesh; Montero, Francisco J.; Rehman, Tauseef-ur; Lamba, Ravita; Vashishtha, Manish; Upadhyaya, Sushant
    Suitable thermal management of photovoltaic (PV) modules can increase their efficiency. Alongside, the extra amount of energy needed for their thermal management should also be minimized to improve the overall efficiency of the PV system. This leads to exploring passive thermal management techniques. Recently, radiative cooling (RC) has been explored widely as a passive thermal management technique for PV systems. This paper explores radiative cooling and heat sink (HS) as passive methods for thermal regulation of the photovoltaic systems to get lower and uniform temperature distribution along the PV module. A comprehensive two-dimensional model of the proposed system is developed and analyzed in commercial COMSOL Multiphysics software. The governing equations are solved numerically using finite element methods, and simulations are carried out. Four different configurations, namely Case-0: photovoltaic-only system, Case-1: photovoltaic + heat sink, Case-2: photovoltaic + radiative cooling, and Case-3: photovoltaic + heat sink + radiative cooling systems, are considered in this analysis. The performance of four cases has been compared regarding PV temperature reduction, power output, and conversion efficiency. The performance analysis is carried out for the climatic conditions of the Atacama Desert. The results indicated that the photovoltaic + heat sink + radiative cooling system, i.e., Case-3, is the most efficient among all cases. The reduction in the maximum PV operating temperature and improvements in the maximum PV power output and minimum PV conversion efficiency of the photovoltaic + heat sink + radiative cooling system compared to that of the photovoltaic system alone are 6.63%, 8.57%, and 11.11%, respectively. The findings of this study can be used to effectively design the cooling system for the thermal management of photovoltaic modules installed in desert locations.
  • No Thumbnail Available
    Item
    Thermal management of photovoltaic-thermoelectric generator hybrid system using radiative cooling and heat pipe
    (2023) Kumar, Ramesh; Montero, Francisco J.; Lamba, Ravita; Vashishtha, Manish; Upadhyaya, Sushant
    Temperature regulation of photovoltaic modules is crucial for improving their efficiency. Nowadays, radiative cooling is a widely adopted passive thermal management technique for photovoltaic systems. Heat pipe and radiative cooling are two primary passive photovoltaic cooling methods employed in photovoltaic-thermoelectric generator hybrid systems. Therefore, this study proposes a novel photovoltaic-heat pipe-thermoelectric generator-radiative cooling hybrid system by applying heat pipe and radiative cooling simultaneously to control the temperature of the photovoltaic-thermoelectric generator hybrid system. A detailed computational model of the proposed system is developed and analyzed in the COMSOL Multiphysics. A comparative analysis of the photovoltaic module temperature drop and its efficiency enhancement between the proposed and the reference system consisting of only a photovoltaic module is performed. The effects of solar radiation, ambient tempera-ture, and wind speed on both systems are studied under the Atacama Desert and Las Vegas climatic conditions. This proposed configuration reduced the photovoltaic temperature by efficiently evacuating its residual heat using a heat pipe and then rejecting it to the atmosphere using a radiative cooler. Results show that in contrast to the reference system, the proposed system reduced the average photovoltaic operating temperature by 2 degrees C for both the summer and winter seasons of the Atacama Desert and by 13 degrees C for Les Vegas. The maximum and minimum reductions of the photovoltaic temperature in the proposed system, as compared to the reference system, are 4 degrees C and 1.5 degrees C respectively, in June and 9 degrees C and 1 degrees C respectively, in January for the Atacama Desert. The maximum PV conversion efficiency and energy production improvements as compared to the reference system are 0.8% & 1.03% respectively, (for summer), and 0.3% & 0.94% respectively, (for winter) for the Atacama Desert, and 1.8% & 7.2% respectively, for the Las Vegas environment. The expected range of LCOE for a hybrid PV-HP-TEG-RC system is found to be between 0.065-0.089 USD/kWh. This study can help in improving the energy conversion efficiency by controlling the photovoltaic temperature using passive cooling methods in harsh environmental conditions such as the desert locations.