scholarly journals The Effect of Different Absorber Configurations On The Exergy and The Energy of Parabolic Solar Dish

2020 ◽  
Vol 7 (3) ◽  
pp. 1-13
Author(s):  
A'laa Taghi Al-Azawi ◽  
Ali A. F. Al Hamadani
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Tracking System ◽  
Open Cavity ◽  
Solar Concentrator ◽  
International Conference ◽  
National University ◽  
Parabolic Dish

Abstract— The solar energy is the most important type of energy. The parabolic dish solar collector (PDSC) is the best type among other solar collectors because it is always tracking the sun movement. The exergy and the energy performances of a PDS were analyzed experimentally and numerically. The effect of different coil geometries and different mass flow rates of heat transfer fluid (HTF) were investigated. The PDS has parabolic dish and receiver with diameter (1.5) m and (0.2) m respectively. Concentration ratio is 56.25. The parabolic polar dish was supported by a tracking system with two axes. The types of the copper absorber were used which are: (spiral –helical) coil (SHC) and spiral-conical coil (SCC). The results showed that the useful energy and thermal efficiency are varying with solar radiation variation. The useful energy varying between (480-765) W for (SHC), the thermal efficiency varying between (35.2-39.8) % for (SHC). Exergy efficiency varying between (6.9 –8.6) %. It was shown that the higher values of useful energy for (spiral – helical) absorber was 0.1L/min flow rate. REFERENCES  1. T. Taumoefolau , K. Lovegrove ," An Experimental Study of Natural Convection Heat Loss from a Solar Concentrator Cavity Receiver at Varying Orientation. ", Australian National University,, Canberra ACT 0200 AUSTRALIA.2002  2. S. PAITOONSURIKARN and K. LOVEGROVE," On the Study of Convection Loss from Open Cavity Receivers in Solar Paraboloidal Dish Applications ", Australian National University Canberra ACT 0200, AUSTRALIA, pp 154,155,2003  3. Soteris A. Kalogirou*,"Solar thermal collectors and applications", Higher Technical Institute, Progress in Energy and Combustion Science 30 (2004) 231–295, pp237, 240, 241, 2004  4. M. Prakash, S.B. Kedare, J.K. Nayak," Investigations on heat losses from a solar cavity receiver", Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India,2008.  5. Shiva Gorjian1, Barat Ghobadian1, Teymour Tavakkoli Hashjin1, and Ahmad Banak ,"Thermal performance of a Point-focus Solar Steam Generating System ", 21st Annual International Conference on Mechanical Engineering-ISME201 7-9 May, 2013, School of Mechanical Eng., K.N.Toosi University, Tehran, Iran ,1ISME2013-1195,2013  6. Kailash Karunakaran1 Hyacinth J Kennady2 ,"Thermal Analysis of Parabolic Dish Snow Melting Device " ,International Journal for Research in Technological Studies| Vol. 1, Issue 3, February 2014 | ISSN (online): 2348-1439,2014  7. Charles-Alexis Asselineau, Ehsan Abbasi, John Pye "Open cavity receiver geometry influence on radiative losses" Australian National University (ANU), Canberra, ACT 0200 Australia. Solar2014: The 52nd Annual Conference of the Australian Solar Council 2014  8. Vahid Madadi, Touraj Tavakoli and Amir Rahimi First and second thermodynamic law analyses applied to a solar dish collector" DOI 10.1515/jnet-2014-0023 | J. Non-Equilib. Thermodyn. 2014; 39 (4):183–197  9. Yaseen. H. Mahmood , Mayadah K h. Ghaffar " Design of Solar dish concentration by using MATLAB program and Calculation of geometrical concentration parameters and heat transfer" , University of Tikrit , Tikrit , Iraq, Tikrit Journal of Pure Science 20 (4) ISSN: 1813 – 1662, 2015.  10. Vanita Thakkar, Ankush Doshi, Akshaykumar Rana "Performance Analysis Methodology for Parabolic Dish Solar Concentrators for Process Heating Using Thermic Fluid IOSR", Journal of Mechanical and Civil Engineering (IOSR-JMCE) eISSN: 2278-1684,p-ISSN: 2320-334X, Volume 12, Issue 1 Ver. II (Jan- Feb. 2015), PP 101-114  11. Saša R. pavlovi, Evangelos A. bellos, Velimir P. Stefanovi, Christos Tzivanidis and Zoran M. Stamenkovi "Design, Simulation ,and Optimiztion Of A Solar Dish Collector with spiral coil absorber ", , Nis, Serbia, thermal SCIENCE, Vol. 20, No. 4, pp. 1387-1397 1387,2016  12. Flávia V. Barbosa, João L. Afonso, Filipe B. Rodrigues, and José C. F. Teixeir," Development of a solar concentrator with tracking system", University of Minho,Guimarães, 4800-058, Portugal2016  13. O. López, A. Arenas, and A. Baños"Convective Heat Loss Analysis of a Cavity Receiver for a Solar Concentrator" International Conference on Renewable Energies and Power Quality (ICREPQ’17)Malaga (Spain), 4th to 6th April, 2017 ,ISSN 2172-038 X, No.15 April 2017 RE&PQJ, Vol.1, No.15, April 2017  14. D.R.Rajendran,E.GanapathySundaram,P.Jawahar "Experimental Studies on the Thermal Performance of a Parabolic Dish Solar Receiver with the Heat Transfer Fluids Sic water Nano Fluid and Water", Journal of Thermal Science Vol.26,  15. Muhammad Shoaib, Muhammad , Jameel Kabbir Ali ,Muhammad Usman1, Abdul Hannan " Analysis of thermal performance of parabolic dish collectors having different reflective" ,NFC institute of engineering &fertilizer research ,2018 .  16. Sasa PAVLOVIC, Evangelos BELLOS, Velimir STEFANOVIC ,Christos TZIVANIDIS " EXPERIMENTAL AND NUMERICAL INVESTIGATION OF A SOLAR DISH COLLECTOR WITH SPIRAL ABSORBER" A CTA TECHNICA CORVINIENSIS – Bulletin of Engineering Tome XI [2018] .   

Thermal Performance of Steam Receiver in Tower-Type Solar Power Plants

2017 ◽  
Author(s):  
Kai Yan ◽  
Xiaojiang Wu ◽  
Jianbin Liu
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Solar Power ◽  
Working Fluid ◽  
Receiver Design ◽  
Solar Power Plants ◽  
Performance Calculation

In this paper, the thermal performance of steam receiver in tower-type solar power plants has been performed using the tower-type solar receiver design program developed by Shanghai boiler works Co Ltd. In the program, the integrated effect of three types of heat transfer, i.e. heat conduction, convection and radiation, in the process of heat transfer of receivers has been considered. With integrating the characteristics and the working conditions of receivers of both steam and molten salt, the developed program can be used to perform the thermal performance calculations for the receivers of both working fluids. The proposed program was validated through Solar Two project and the satisfactory results achieve. A steam receiver in a tower-type solar power plant with double superheats is selected as an example for thermal performance calculation. In view of the receiver operating in subcritical status, the thermal performance calculation is carried out for two sections, the one for evaporation and that for superheat. In evaporation section, the working fluid is circulated with a circulating pump at a very high circulating ratio. At the outlet of panels, the qualities of working fluid can reach to maximum about 0.35. Besides, the great difference of qualities of working fluid at the outlet of panels is observed. Even for some pipes of some panels, the working fluid at the outlet is in liquid phase. The distribution of metal temperature at fin end of panels in the evaporation region varies dramatically from place to place and reaches to over 520 °C. In superheat region, the temperature of the outer front crown of tubes is concerned. The highest front point temperature of pipe, which reaches to maximum over 660 °C, is in the middle region of the last parts of the primary superheat pass. The thermal efficiency distribution of the receiver, including the evaporation and the superheat regions, are also performed. The results show that the averaged efficiency is about 86%. Besides, the phenomenon of negative thermal efficiency happens in both two regions. That is because the solar incidence cannot compensate the natural heat loss due to incident radiation reflection, the pipe wall infrared radiation and convective heat loss.

scholarly journals Effect of non-uniform temperature distribution on surface absorption receiver in parabolic dish solar concentrator

2017 ◽  
Vol 21 (5) ◽  
pp. 2011-2019 ◽  
Author(s):  
Ramalingam Senthil ◽  
Marimuthu Cheralathan
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Mild Steel ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Heat Transfer Fluid ◽  
Solar Concentrator ◽  
Surface Absorption ◽  
Heat Gain ◽  
Parabolic Dish

A flat surface absorption receiver was experimentally investigated with a parabolic dish solar concentrator in order to study the effect of receiver temperature distribution on heat gain and losses. The addition of specially designed metal fins in the inner surface of the receiver surface side the receiver transfers the incident heat flux to heat transfer fluid. The receiver surface temperature increased with increase in concentration ratio, intensity of beam radiation, and ambient temperature, but decrease with wind speed. The absorptivity of black coated mild steel of 0.85 and also the 0.15 emissivity of mild steel reduced the heat loss from the surface and improved heat gain to heat transfer fluid. The temperature gradient between the receiver periphery and centre is around 150?C. Fluid flow direction like straight and curved paths have been discussed for effective heat absorption and reduced operational duration. The thermal efficiency and operational duration were determined for a flow rate of 80 litres per hour through the receiver. Water flow though the curved path was observed with improved thermal efficiency of 3.8% and 20% reduction in operational duration when compared to the vertical flow through the receiver at same flow rate.

scholarly journals Effects of Absorber Emissivity on Thermal Performance of a Solar Cavity Receiver

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Jiabin Fang ◽  
Nan Tu ◽  
Jinjia Wei
Keyword(s):  
Heat Loss ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Radiative Heat ◽  
Slight Effect ◽  
Radiative Heat Loss ◽  
Total Heat Loss ◽  
Convective Heat Loss ◽  
Performance Curves ◽  
Variation Tendency

Solar cavity receiver is a key component to realize the light-heat conversion in tower-type solar power system. It usually has an aperture for concentrated sunlight coming in, and the heat loss is unavoidable because of this aperture. Generally, in order to improve the thermal efficiency, a layer of coating having high absorptivity for sunlight would be covered on the surface of the absorber tubes inside the cavity receiver. As a result, it is necessary to investigate the effects of the emissivity of absorber tubes on the thermal performance of the receiver. In the present work, the thermal performances of the receiver with different absorber emissivity were numerically simulated. The results showed that the thermal efficiency increases and the total heat loss decreases with increasing emissivity of absorber tubes. However, the thermal efficiency increases by only 1.6% when the emissivity of tubes varies from 0.2 to 0.8. Therefore, the change of absorber emissivity has slight effect on the thermal performance of the receiver. The reason for variation tendency of performance curves was also carefully analyzed. It was found that the temperature reduction of the cavity walls causes the decrease of the radiative heat loss and the convective heat loss.

scholarly journals Heat Transfer Augmentation of Concentrated Solar Absorber Using Modified Surface Contour

2021 ◽  
Vol 11 (1) ◽  
pp. 24-33
Author(s):  
Ramalingam Senthil ◽  
Arvind Chezian ◽  
Zackir Hussain Ajmal Arsath
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Cavity Surface ◽  
Solar Absorbers ◽  
Surface Contour ◽  
Parabolic Dish ◽  
Plain Surface ◽  
Surface Modified

This work aims to compare the cavity surface contour’s thermal performance to that of the solar absorber’s plain surface contour for Scheffler type parabolic dish collectors. The absorber is tested for the temperature range up to 600°C without working fluid and 180°C with the working fluid. The modified absorber surface's thermal performance is compared with the flat surface absorber with and without heat transfer fluid. The peak temperature reached by the surface modified absorber (534°C) is about 8.6% more than that of the unmodified absorber (492°C) during an outdoor test without fluid. The energy efficiency of cavity surface absorber and plain surface absorber are 67.65% and 61.84%, respectively. The contoured cavity surface produces a more uniform temperature distribution and a higher heat absorption rate than the plain surface. The results are beneficial to the design of high-temperature solar absorbers for concentrated solar collectors.

scholarly journals Prediction of the impact of climate change on the thermal performance of walls and roof in Morocco

2021 ◽  
Author(s):  
Yassine Kharbouch ◽  
Mohamed Ameur
Keyword(s):  
Climate Change ◽  
Heat Transfer ◽  
Heat Loss ◽  
Thermal Performance ◽  
Building Energy ◽  
Building Envelope ◽  
Heat Gain ◽  
Impact Of Climate Change ◽  
Summer Heat ◽  
The Impact

Abstract Climate change has become a real challenge in different fields, including the building sector. Understanding and assessing the impact of climate change on building energy performance is still necessary to elaborate new climate-adaptive design measures for future buildings. The building energy consumption for heating and cooling is mainly related to the building envelope thermal performance. In this study, the winter heat loss and summer heat gain indicators are proposed to assess and analyse the potential impact of climate change on opaque building envelope elements for different climate zones in Morocco over the next 40 years. For that purpose, a one-dimensional heat transfer model is used to simulate the heat transfer through the multi-layer structure of the wall/roof. A medium climate change scenario is considered in this study. The results showed that the current average walls and roof summer heat gain is expected to increase of about 19.2–54.3% by the 2060s depending on the climate zone, versus a less important decrease in winter heat loss varies between –10.6 and –20.6%. This paper provides a reliable evaluation of the climate change impact on building envelope thermal performance, which leads to better adjustments in future building envelope designs.

scholarly journals Thermal-Performance Evaluation of Bicycle Helmets for Convective and Evaporative Heat Loss at Low and Moderate Cycling Speeds

2019 ◽  
Vol 9 (18) ◽  
pp. 3672 ◽  
Author(s):  
Shriram Mukunthan ◽  
Jochen Vleugels ◽  
Toon Huysmans ◽  
Kalev Kuklane ◽  
Tiago Sotto Mayor ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Loss ◽  
Thermal Performance ◽  
Frontal Zone ◽  
Thermal Manikin ◽  
Evaporative Heat Loss ◽  
Cooling Efficiency ◽  
Bicycle Helmets ◽  
Evaporative Heat Transfer

The main objective of the study was to investigate the thermal performance of five (open and closed) bicycle helmets for convective and evaporative heat transfer using a nine-zone thermal manikin. The shape of the thermal manikin was obtained by averaging the 3D-point coordinates of the head over a sample of 85 head scans of human subjects, obtained through magnetic resonance imaging (MRI) and 3D-printed. Experiments were carried out in two stages, (i) a convective test and (ii) an evaporative test, with ambient temperature maintained at 20.5 ± 0.5 °C and manikin skin temperature at 30.5 ± 0.5 °C for both the tests. Results showed that the evaporative heat transfer contributed up to 51%–53% of the total heat loss from the nude head. For the convective tests, the open helmet A1 having the highest number of vents among tested helmets showed the highest cooling efficiency at 3 m/s (100.9%) and at 6 m/s (101.6%) and the closed helmet (A2) with fewer inlets and outlets and limited internal channels showed the lowest cooling efficiency at 3 m/s (75.6%) and at 6 m/s (84.4%). For the evaporative tests, the open helmet A1 showed the highest cooling efficiency at 3 m/s (97.8%), the open helmet A4 showed the highest cooling efficiency at 6 m/s (96.7%) and the closed helmet A2 showed the lowest cooling efficiency at 3 m/s (79.8%) and at 6 m/s (89.9%). Two-way analysis of variance (ANOVA) showed that the zonal heat-flux values for the two tested velocities were significantly different (p < 0.05) for both the modes of heat transfer. For the convective tests, at 3 m/s, the frontal zone (256–283 W/m2) recorded the highest heat flux for open helmets, the facial zone (210–212 W/m2) recorded the highest heat flux for closed helmets and the parietal zone (54–123 W/m2) recorded the lowest heat flux values for all helmets. At 6 m/s, the frontal zone (233–310 W/m2) recorded the highest heat flux for open helmets and the closed helmet H1, the facial zone (266 W/m2) recorded the highest heat flux for the closed helmet A2 and the parietal zone (65–123 W/m2) recorded the lowest heat flux for all the helmets. For evaporative tests, at 3 m/s, the frontal zone (547–615 W/m2) recorded the highest heat flux for all open helmets and the closed helmet H1, the facial zone (469 W/m2) recorded the highest heat flux for the closed helmet A2 and the parietal zone (61–204 W/m2) recorded the lowest heat flux for all helmets. At 6 m/s, the frontal zone (564–621 W/m2) recorded highest heat flux for all the helmets and the parietal zone (97–260 W/m2) recorded the lowest heat flux for all helmets.

scholarly journals Thermal Performance of a Low-Temperature Heat Exchanger Using a Micro Heat Pipe Array

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 675 ◽  
Author(s):  
Jingang Yang ◽  
Yaohua Zhao ◽  
Aoxue Chen ◽  
Zhenhua Quan
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Low Temperature ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Flue Gas ◽  
Thermal Efficiency ◽  
Heat Exchangers ◽  
Micro Heat Pipe

Domestic heat exchangers, even though widely used in industry, are not adequate for studies on low-temperature flue-gas use technologies. Despite spite their limitations, very few theoretical models have been investigated based on practical applications. Moreover, most of the existing studies on heat exchangers have focused particularly on one-dimensional and two-dimensional heat transfer models, while limited studies focus on three-dimensional ones. Therefore, this study aims at investigating the thermal performance of a low-temperature flue-gas heat recovery unit in the cold regions. Specifically, this study was conducted in the context of Changchun of Jilin Province, China, a city with the mean ambient temperature of −14 °C and mean diurnal temperature of −10 °C during winter. Experimental results showed that the thermal efficiency of the heat exchanger was higher than 60%. Through assessing the heat exchange coefficient and heat exchange efficiency of the heat exchanger, it is found that the thermal efficiency had been improved up to 0.77–0.83. Furthermore, the ICEPAK software and the standard k-ε RNG turbulence model were used to carry out simulations. The velocity and outlet temperature of fresh airflow and polluted airflow were simulated through setting different inlet temperatures of fresh air and polluted air inlet. Numerical results further indicated that the flow state was laminar flow. The micro heat pipe array side had small eddies and the heat transfer was significantly improved due to the flow of air along the surface of the micro heat pipe.

scholarly journals Solar Air Heater with W-Shaped Roughness on Absorber Plate

2019 ◽  
Vol 8 (9) ◽  
pp. 2218-2222
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Heat Input ◽  
Solar Irradiance ◽  
Smooth Surface ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Roughened Surface

The analysis is made for Reynolds number of 18000 – 21000. The thermal performance is investigated for W – shaped roughness of thickness (t) 5mm, length of 10.5 cm, with an angle of 25°. The simulation is carried out using solar irradiance as heat input at the location of Amravati 20.93°N 77.75°E. Comparison of Reynolds no and Nusselt no is made. The thermal efficiency is found to increase as the temperature goes on increasing simultaneously the pressure at outlet is greater than inlet pressure. The mechanical power which is required is increased due to the roughness present on absorber plate. The heat transfer between smooth and roughened surface is compared. The experimental results are compared with analytical results on ANSYS 18.1. The thermal efficiency for the smooth surface is around 40 – 45% at particular temperature after roughening the absorber plate the efficiency increased upto 50 – 60% for the same temperature.

Experimental investigation of the comparison of compound parabolic concentrator and ordinary heat pipe-type solar concentrator

2018 ◽  
Vol 29 (5) ◽  
pp. 770-783
Author(s):  
Fahim Ullah ◽  
Mansoor K Khattak ◽  
Kang Min
Keyword(s):  
Flat Plate ◽  
Heat Pipe ◽  
Heat Loss ◽  
Thermal Performance ◽  
Performance Comparison ◽  
Loss Coefficient ◽  
Fluid Temperature ◽  
Solar Concentrator ◽  
Average Heat ◽  
Compound Parabolic Concentrator

In this research study, we have compared between the two different concentrators with the flat absorber plate receiver of the compound parabolic concentrator heat pipe solar concentrator and ordinary heat pipe flat plate solar concentrator. For the reproduction of solar radiation in the experiment, iodine tungsten lamp was used. Thermal performance comparison of the two types of solar concentrator under different simulating radiation intensity conditions was carried out with including the fluid temperature, instantaneous efficiency, average efficiency, and average heat loss coefficient. The results of the experiment indicate that the compound parabolic concentrator heat pipe-type solar concentrator not only increased the fluid temperature and instantaneous efficiency but also decreased the average heat loss coefficient as compared with the ordinary heat pipe flat plate solar concentrator. It was noticed from the experimental results that the efficiency of compound parabolic heat pipe solar concentrator was higher than ordinary heat pipe solar concentrator up to 6 and 10°C with the light intensity, that is I = 679 W/m2 and I = 892 W/m2, respectively. From the results, it was concluded that the using of compound parabolic heat pipe solar concentrator increased the thermal performance of solar concentrator.

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