EFFECTIVE UTILIZATION OF PARABOLIC DISH SOLAR COLLECTORS FOR THE HEATING AND THERMO-ELECTRIC POWER GENERATION

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 2, February 2018, pp , Article ID: IJMET_09_02_067 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed EFFECTIVE UTILIZATION OF PARABOLIC DISH SOLAR COLLECTORS FOR THE HEATING AND THERMO-ELECTRIC POWER GENERATION R. Senthil and P. Sundaram Department of Mechanical Engineering, SRM Institute of Science and Technology, Kattankulathur, Chennai, India ABSTRACT The power generation from the heat into electricity are mainly Stirling engines and thermoelectric generator modules. Thermoelectric power generation using parabolic dish solar collectors are mainly operated as the stand-alone systems with the dish aperture area varies from the few square meters to several thousand square meters. The major parameters affecting the electrical output of the thermoelectric system are the receiver surface temperature, the sink temperature, tracking accuracy of the dish collector, solar beam radiation, wind speed and ambient temperature at the site. Stirling engine technology provides higher energy conversion whereas the thermoelectric generator (TEG) generates electricity around 5%. The selection of materials for the hot and cold junction and the nanofluids for enhanced cooling of such modules will pave the way to the improved energy conversion efficiency of the thermoelectric modules. The thermoelectric power generators driven by the parabolic dish is one of the better option for the remote applications. The thermal storage based solar receivers are one of the effective utilization of concentrated solar thermal energy for domestic and industrial applications. Key words: Parabolic dish, solar collector, Stirling engines, thermoelectric generators, phase change materials, heat engines, integrated receiver storage, thermal battery Cite this Article: R. Senthil and P. Sundaram, Effective Utilization of Parabolic Dish Solar Collectors for the Heating and Thermo-Electric Power Generation, International Journal of Mechanical Engineering and Technology 9(2), 2018, pp INTRODUCTION The concentrated solar collectors are producing the temperature of fluid up to 1000 C. The concentrated solar thermal power plants are operating in USA, Spain, Brazil, Turkey and India. Most of the solar thermal technologies are supplying the temperature between 50 C and 450 C. The increasing popularity of solar systems is visible from the growth rate of deployment of solar collectors. The renewable energy sources are encouraged in every potential country for various domestic and industrial applications. Renewable energy editor@iaeme.com

2 R. Senthil and P. Sundaram conversion is already gained momentum and the installations have been increasing for the past few decades. The continuing trend in research and developments of renewable energy technologies, cost effectiveness and market dynamics reveals the awareness of the climate change and associated impacts on the society. The utilization of renewable sources accounts 14% of the total power generation globally. The solar energy is one of the fast-growing energy market potentials for thermal and electric power applications. Various power generation option are available to harness the solar power in the standalone or grid-connected power generation. Parabolic dish technologies are useful to provide the power for a small scale to large scale. The useful thermal output of the parabolic dish depends on the aperture area, optical properties of reflector and absorber materials. Kalogirou [1] proposed the solar parabolic trough power system should be located near the sea to combine with solar desalination system to produce fresh water from seawater which is also a precious commodity for Cyprus. Steam cooking Parabolic dish collector Thermal Applications Electric power generation Domestic heating Industrial process heating Heat engines Thermoelectric power generation Figure 1 Applications of parabolic dish collectors Sahoo et al. [2] discussed the advanced selective coating for solar dish for industrial process heat, solar thermal between generation in the temperature range of C and low-cost polymer materials for solar thermal applications. The decentralized power generation is the feasible with the combined deployment of various solar thermal technologies. Abid et al. [3, 4] compared the thermal performance of the parabolic dish and parabolic trough with the nanofluids and molten salts. They observed the higher thermal output for the parabolic dish when compared to the parabolic dish at the same operating conditions. The hydrogen production was faster with the nanofluids as solar absorbers. The hydrogen production rate for parabolic dish thermal power plant and parabolic trough thermal power plant varies from g/s to g/s and from g/s to g/s, respectively. Figure 1 shows the various major applications of parabolic dish solar collectors. Loni et al. [5] showed the net power output increased for higher solar irradiation, smaller tube diameter, and for the case of cubical cavity receiver (i.e. cavity depth h equal to the receiver aperture side length a). Li et al. [6] showed the optimal system performance is editor@iaeme.com

3 Effective Utilization of Parabolic Dish Solar Collectors for the Heating and Thermo-Electric Power Generation strongly dependent on the temperatures of absorber, cooling water and working fluid, and the effectiveness of regenerator in Brayton cycle based solar parabolic dish system using sensitivity analysis. 2. HEAT ENGINES Parabolic dish collectors are operating at the higher temperatures. Heat engines are mostly coupled to the parabolic dish collector to generate electric power. The recent research works are focused over the application-specific design of parabolic dish collectors. A variety of applications are ranges from the standalone to field level applications. From the industrial process heat to large scale power generation are demonstrated using the parabolic dish collectors. The concentration ratio of such collectors plays a vital role in the thermal and electrical applications. Gholamalizadeh and Chung [7] mathematically modelled the Stirling engine system to improve its performance by taking the design main factors of the collector into account. To analyze the performance of the system a thermodynamic model was developed to predict the thermal efficiency of the dish-stirling engine based on factors such as fluid and mechanical friction, finite regeneration process time, and heat transfer, including the effects of cycle internal and external losses. The increase in the dish diameter increases the system performance and the annual energy production. The effect of solar dish design features and factors were studied by Hafez et al. [8]. 3. THERMOELECTRIC GENERATORS (TEG) Thermoelectric power generation is the electricity generation due to the thermoelectric effect while maintaining a temperature difference across two terminals. Shanmugam et al. [9] fabricated a low-cost parabolic dish collector and tested with commercial thermoelectric modules made of bismuth telluride for electricity generation on its focal plane. They determined the energy end exergy efficiencies. Shanmugam et al. [10] modelled a thermoelectric power generator driven by a solar parabolic dish collector. The system is modeled by a set of steady state energy balance equations from the first law of thermodynamics for two main components of the solar parabolic dish collector and thermoelectric power generator. Muthu et al. [11-13] demonstrated the hot-side temperature reaches the optimum value, the conversion efficiency is reduced, although the power increases. Lertsatitthanakorn et al. [14] investigated a rectangular fin heat sink coupled with a fan was used to release heat from the cold side of TEG module and a tracking system was used to continuously track the sun. The effects of fan orientation and air flow rate were investigated. Eswaramoorthy and Shanmugam [15] evaluated the standard efficiencies of PDC based TEG based on the annual average solar radiation data at site. It found that the proposed system is generating 24 and 7% of excess electricity at maximum and minimum radiation data respectively. The effective temperature gradient across the thermoelectric module are vital to improve the heat to electricity conversion. An effective cooling technology using nanofluids are not only improves the overall performance of TEG but also the heat recovered for further process heating applications. 4. INTEGRATED SOLAR RECEIVER STORAGE The effect of PCM incorporated in the concentrated solar receiver has also to be experimentally investigated to improve the usability of the solar receiver. An attempt is editor@iaeme.com

4 R. Senthil and P. Sundaram undertaken to increase the thermal capacity of such solar thermal systems for later and convenient use. Incorporating PCM in the thermal storage is widely investigated with different application-specific phase change material. The concentrated solar receivers are operating at elevated temperatures and more prone to heat losses on the focus as well as the transport of heat transfer fluid to the applications. The heat losses are observed mainly due to the receiver aperture, orientation and optical properties. The phase change materials (PCM) are having a larger phase change enthalpy values to store the thermal energy of the solar thermal collectors and are capable of releasing the heat to the specific applications. Such materials are possessing a lower thermal conductivity and this has been significantly improved using the nanoparticles dispersion into the PCM [16, 17]. The effect of non-uniform temperature distribution on the parabolic dish concentrated solar receiver has been studied experimentally and various methods are employed to improve the thermal performance [18 21]. Optical analysis of parabolic dish solar collector and the flat surface absorption receivers are carried out to predict the overall thermal and optical performances [22, 23]. Figure 2 shows the receiver-storage with the parabolic dish collector. Figure 2 Parabolic dish collector and receiver-storage system [19] Inorganic and organic phase change materials have their unique thermal properties. Organic PCM have a larger phase change enthalpy and a lower thermal conductivity. However, the inorganic PCM possess a higher thermal conductivity with a lower phase change enthalpy. The use of PCM in the high temperature solar receivers are one of the way of storing the energy at the focus and further the stored energy can be effectively utilized with a convenience [24-31]. The heat battery is useful in the short-term applications due to the heat loss from the collector-storage. Several studies are carried out on the different size parabolic dish and the integrated receiver-storage for the standalone thermal applications. 5. CONCLUSIONS Parabolic dish solar collectors produce an elevated temperature and easily coupled to the heat engines, thermoelectric generators and receiver integrated thermal storage. The first two categories are used to generate the electricity directly. The third category is primarily used to generate heat output and the PCM storage can be conveniently used to operate the thermoelectric modules with the effective heat transport mechanisms. The combination of editor@iaeme.com

5 Effective Utilization of Parabolic Dish Solar Collectors for the Heating and Thermo-Electric Power Generation these three systems will effectively optimize the overall thermo-electrical energy management of the heat energy available at the focus of the PDSC. The improvement in the reflector design and receiver design are most important to satisfy the thermal needs at reduced cost. The reflector design involves the optics design and optical materials. The thermal battery receiver is useful to capture and store the incident solar energy at the focus of the receiver using suitable PCM (a high latent and appropriate phase transition temperature). REFERENCES [1] Kalogirou SA. Solar thermoelectric power generation in Cyprus: Selection of the best system. Renew Energy 2013; 49: [2] Sahoo U, Kumar R, Pant PC, Singh SK, Saxena P. Evaluation of solar thermal technologies and applications in India. Advances in Energy Research; p [3] Abid M, Ratlamwala TAH, Atikol U. Performance assessment of parabolic dish and parabolic trough solar thermal power plant using nanofluids and molten salts. Int J Energy Res 2016; 40(4): [4] Abid M, Ratlamwala TAH, Atikol U. Solar assisted multi-generation system using nanofluids: A comparative analysis. Int J Hydrogen Energy 2017; 42(33): [5] Loni R, Kasaeian AB, Mahian O, Sahin AZ. Thermodynamic analysis of an organic rankine cycle using a tubular solar cavity receiver. Energy Convers Manage 2016; 127: [6] Li Y, Liu G, Liu X, Liao S. Thermodynamic multi-objective optimization of a solardish Brayton system based on maximum power output, thermal efficiency and ecological performance. Renew Energy 2016; 95: [7] Gholamalizadeh E, Chung JD. Design of the Collector of a Solar Dish-Stirling System: A Case Study. IEEE Access 2017; 5: [8] Hafez AZ, Soliman A, El-Metwally KA, Ismail IM. Solar parabolic dish Stirling engine system design, simulation, and thermal analysis. Energy Convers Manage 2016; 126: [9] Shanmugam S, Veerappan AR, Eswaramoorthy M. An experimental evaluation of energy and exergy efficiency of a solar parabolic dish thermoelectric power generator. Energy Sources Recovery Util Environ Eff 2014; 36(17): [10] Shanmugam S, Eswaramoorthy M, Veerappan AR. Modeling and analysis of a solar parabolic dish thermoelectric generator. Energy Sources Recovery Util Environ Eff 2014; 36(14): [11] Muthu G, Shanmugam S, Veerappan AR. Energy and exergy analysis of solar parabolic dish thermoelectric generator. Appl Mech Mater 2014; : [12] Muthu G, Shanmugam S, Veerappan AR. Numerical Modeling of Year-Round Performance of a Solar Parabolic Dish Thermoelectric Generator. J Electron Mater 2015; 44(8): [13] Muthu, G., Shanmugam, S., Veerappan, A.R., Solar parabolic dish thermoelectric generator with acrylic cover. Energy Procedia; [14] Lertsatitthanakorn, C., Jamradloedluk, J., Rungsiyopas, M. 2014, Electricity generation from a solar parabolic concentrator coupled to a thermoelectric module. Energy Procedia; [15] Eswaramoorthy M, Shanmugam S. Solar parabolic dish thermoelectric generator: A technical study. Energy Sources Recovery Util Environ Eff 2013; 35 (5): editor@iaeme.com

6 R. Senthil and P. Sundaram [16] Senthil R, Cheralathan M. Natural heat transfer enhancement methods in phase change material based thermal energy storage. International Journal of ChemTech Research, 2016; 9 (5): [17] Senthil R, Cheralathan M. Enhancement of heat absorption rate of direct absorption solar collector using graphite nanofluid. International Journal of ChemTech Research, 2016; 9(9): [18] Senthil R, Cheralathan M. Effect of non-uniform temperature distribution on surface absorption receiver in parabolic dish solar concentrator. Thermal Science, 2017; 21 (5): [19] Senthil R, Rath C, Gupta M. Enhancement of uniform temperature distribution on the concentrated solar receiver with integrated phase change material. International Journal of Mechanical Engineering and Technology, 2017; 8 (9): [20] Senthil R. Recent developments in the design of high temperature solar receivers. International Journal of Mechanical Engineering and Technology, 2017; 8 (8): [21] Senthil R, Prabhu S, Cheralathan M. Effect of heat transfer fluid input parameters on thermal output of parabolic dish solar receiver using design of experiment techniques. International Journal of Mechanical Engineering and Technology, 2017; 8 (8): [22] Senthil R, Araavind S, Vigneshwar K, Athreya AS. Optical and thermal analysis of concentrated solar thermal collectors: A review. International Journal of Mechanical Engineering and Technology, 2017; 8 (12): [23] Senthil R, Nishanth AP. Optical and thermal performance analysis of solar parabolic concentrator. International Journal of Mechanical and Production Engineering Research and Development, 2017; 7(5): [24] Senthil R, Sundaram P. Effect of phase change materials for thermal management of buildings. International Journal of Civil Engineering and Technology, 2017; 8 (9): [25] Senthil R, Cheralathan M. Simultaneous testing of a parabolic dish concentrated PCM and non-pcm solar receiver. International Journal of Mechanical and Production Engineering Research and Development, 2017; 7(6): [26] Senthil R, Senguttuvan P, Thyagarajan K. Experimental study on a cascaded pcm storage receiver for parabolic dish collector. International Journal of Mechanical Engineering and Technology, 2017; 8(11): [27] Senthil R, Thyagarajan K, Senguttuvan P. Experimental study of a parabolic dish concentrated cylindrical cavity receiver with PCM. International Journal of Mechanical Engineering and Technology, 2017; 8(11): [28] Senthil R, Gupta M, Rath C. Parametric analysis of a concentrated solar receiver with Scheffler reflector. International Journal of Mechanical and Production Engineering Research and Development, 2017; 7(5): [29] Senthil R, Muthuveeran M, Harish SM, Kumar NR. Experimental investigation on a PCM integrated concentrated solar receiver for hot water generation. International Journal of Mechanical Engineering and Technology, 2017; 8(9): [30] Senthil R, Cheralathan M. Effect of the Phase Change Material in a solar receiver on thermal performance of parabolic dish collector. Thermal Science, 2017; 21 (6B): [31] Senthil R, Araavind S, Ghosh N. Optimization techniques for solar photovoltaicwind turbine hybrid energy systems. International Journal of Mechanical Engineering and Technology, 2018; 9(1): editor@iaeme.com