Cascade Use and Optimal Control of Solar Thermal Energy for Hybrid Solar Energy System

Author(s):  
Masashi Ohkura ◽  
Shunsuke Mori
2018 ◽  
Vol 11 (1) ◽  
pp. 30-43 ◽  
Author(s):  
Behnaz Rezaie ◽  
Bale V. Reddy ◽  
Marc A. Rosen

Background:District Energy (DE) is a technology capable of using renewable energy (e.g., solar thermal systems) and waste heat as energy sources efficiently. DE technology nonetheless has potential for improvement. Thermal Energy Storage (TES) can enhance DE performance significantly.Objective:An exergy analysis of a DE system which includes a solar thermal energy system and TES is performed, so as to improve understanding of its performance.Method:A case study based on the Friedrichshafen DE system in Germany is used to assess thermodynamically the role of solar energy and TES in a DE system. The system performance is separated into three modes: (1) fossil fuel is the only source of energy, (2) a discharging TES and fossil fuel provide heat for the DE system, and (3) solar energy and fossil fuels are the energy supplies. Exergy analyses are conducted for each performance mode and the overall DE system.Results:The results quantify the benefits of incorporating solar energy and TES on the performance of the Friedrichshafen DE system, and demonstrate that the overall exergy efficiency of the DE system increases from 23% to 27% with assistance of solar thermal collectors and TES, while the total energy efficiency increases from 83% to 87%.Conclusion:An increase of exergy efficiency is observed when TES is added to a DE system, due to a reduction in solar thermal energy loss by the TES, which allows more solar energy to be converted to useful energy to satisfy the DE system thermal energy demand.


2013 ◽  
Vol 24 (4) ◽  
pp. 51-62
Author(s):  
Shadreck M. Situmbeko ◽  
Freddie L. Inambao

Solar thermal energy (STE) technology refers to the conversion of solar energy to readily usable energy forms. The most important component of a STE technology is the collectors; these absorb the shorter wavelength solar energy (400-700nm) and convert it into usable, longer wavelength (about 10 times as long) heat energy. Depending on the quality (temperature and intensity) of the resulting thermal energy, further conversions to other energy forms such as electrical power may follow. Currently some high temperature STE technologies for electricity production have attained technical maturity; technologies such as parabolic dish (commercially available), parabolic trough and power tower are only hindered by unfavourable market factors including high maintenance and operating costs. Low temperature STEs have so far been restricted to water and space heating; however, owing to their lower running costs and almost maintenance free operation, although operating at lower efficiencies, may hold a key to future wider usage of solar energy. Low temperature STE conversion technology typically uses flat plate and low concentrating collectors such as parabolic troughs to harness solar energy for conversion to mechanical and/or electrical energy. These collector systems are relatively cheaper, simpler in construction and easier to operate due to the absence of complex solar tracking equipment. Low temperature STEs operate within temperatures ranges below 300oC. This research work is geared towards developing feasible low temperature STE conversion technology for electrical power generation. Preliminary small-scale concept plants have been designed at 500Wp and 10KWp. Mathematical models of the plant systems have been developed and simulated on the EES (Engineering Equation Solver) platform. Fourteen candidate working fluids and three cycle configurations have been analysed with the models. The analyses included a logic model selector through which an optimal conversion cycle configuration and working fluid mix was established. This was followed by detailed plant component modelling; the detailed component model for the solar field was completed and was based on 2-dimensional segmented thermal network, heat transfer and thermo fluid dynamics analyses. Input data such as solar insolation, ambient temperature and wind speed were obtained from the national meteorology databases. Detailed models of the other cycle components are to follow in next stage of the research. This paper presents findings of the system and solar field component.


2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Muhammad Irvan ◽  
Dewi Sri Jayanti ◽  
Raida Agustina

Abstrak.  Pengering hybrid merupakan pengering yang menggunakan dua atau lebih sumber energi untuk proses penguapan air. Tujuan dari penelitian ini adalah memodifikasi alat pengering surya sederhana menjadi alat pengering hybrid dengan tambahan energi panas dari pembakaran tempurung kelapa untuk melakukan uji pengeringan pada kacang hijau. Distribusi suhu rata-rata pada alat pengering hybrid pengeringan kacang hijau menggunakan energi panas matahari, kombinasi dan biomassa masing-masing adalah 49oC,50oC dan 35oC dengan iradiasi matahari masing-masing menggunakan energi panas matahari dan kombinasi adalah 360,47W/m2 dan 362,79W/m2. Kelembaban relatif pada alat pengering hybrid saat pengeringan kacang hijau menggunakan energi panas matahari, kombinasi dan biomassa masing-masing adalah 44,69%, 45,69% dan 57,75%. Kecepatan udara pada alat pengering hybrid saat pengeringan kacang hijau menggunakan energi panas matahari, kombinasi dan biomassa masing-masing adalah 0,11 m/s , 0,1 m/s dan 0,08 m/s. Pengeringan kacang hijau menggunakan sumber panas dari energi matahari, sumber panas kombinasi energi matahari dengan pembakaran biomassa dan menggunakan energi pembakaran biomassa menghasilkan kadar air akhir biji kacang hijau masing-masing sebesar 8,42%, 8,27% dan 10,75%. Besarnya energi biomassa yang dihasilkan saat pengering selama 10 jam adalah 272,142 MJ. Besarnya energi matahari saat pengeringan kacang hijau menggunakan sumber energi matahari dan sumber panas kombinasi energi matahari dengan pembakaran biomassa adalah 3,22 MJ dan 3,14 MJ.Testing of Simple and Modified Solar Dryers Become a Hybrid Dryer ToolAbstract. A hybrid dryer is a dryer that uses two or more sources of energy for the evaporation process of water. The purpose of this study is to modify the simple solar drying tool into a hybrid drying tool with additional heat energy from coconut shell combustion to test drying on green beans. The average temperature distribution of green peanut drying dryers using solar thermal energy, combination and biomass are respectively 49oC, 50oC and 35oC with solar irradiation each using solar thermal energy and the combination is 360,47W/m2 and                362, 79   W/m2. The relative humidity in the hybrid drier when drying green beans using solar thermal energy, combination and biomass are 44.69%, 45.69% and 57.75%, respectively. The air velocity in the hybrid drier when drying green beans using solar thermal energy, combination and biomass are 0.11 m/s, 0.1 m/s and       0.08 m/s respectively. Drying of green beans using a source of heat from solar energy, a combination of solar energy sources with biomass combustion and using biomass combustion energy to produce the final content of green beans seeds by 8.42%, 8.27% and 10.75% respectively. The amount of biomass energy produced during drying for 10 hours is 272,142 MJ. The amount of solar energy during drying of green beans using solar energy sources and the combined heat source of solar energy with biomass burning is 3.22 MJ and 3.14 MJ.


Author(s):  
Anagha Pathak ◽  
Kiran Deshpande ◽  
Sandesh Jadkar

There is a huge potential to deploy solar thermal energy in process heat applications in industrial sectors. Around 50 % of industrial heat demand is less than 250 °C which can be addressed through solar energy. The heat energy requirement of industries like automobile, auto ancillary, metal processing, food and beverages, textile, chemical, pharmaceuticals, paper and pulp, hospitality, and educational institutes etc. can be partially met with solar hybridization based solutions. The automobile industry is one of the large consumers of fossil fuel energy in the world. The automobile industry is major economic growth driver of India and has its 60 % fuel dependence on electricity and remaining on oil based products. With abundant area available on roof top, and need for medium temperature operation makes this sector most suitable for substitution of fossil fuel with renewable solar energy. Auto sector has requirement of heat in the temperature range of 80-140 oC or steam up to 2 bar pressure for various processes like component washing, degreasing, drying, boiler feed water preheating, LPG vaporization and cooling. This paper discusses use of solar energy through seamless integration with existing heat source for a few processes involved in automobile industries. Integration of the concentrated solar thermal technology (CST) with the existing heating system is discussed with a case study for commonly used processes in auto industry such as component washing, degreasing and phosphating. The present study is undertaken in a leading automobile plant in India. Component cleaning, degreasing and phosphating are important processes which are carried out in multiple water tanks of varying temperatures. Temperatures of tanks are maintained by electrical heaters which consumes substantial amount of electricity. Non-imaging solar collectors, also known as compound parabolic concentrators (CPC) are used for generation of hot water at required process temperature. The CPC are non-tracking collectors which concentrate diffuse and beam radiation to generate hot water at required temperature. The solar heat generation plant consists of CPC collectors, circulation pump and water storage tank with controls. The heat gained by solar collectors is transferred through the storage tank to the process. An electric heater is switched on automatically when the desired temperature cannot be reached during lower radiation level or during non-sunny hours/days. This solar heating system is designed with CPC collectors that generate process heating water as high as 90OC. It also seamlessly integrates with the existing system without compromising on its reliability, while reducing electricity consumption drastically. The system is commissioned in April, 2013 and since then it has saved ~ 1,75,000 units of electricity/year and in turn 164 MT of emission of CO2 annually.


2021 ◽  
Vol 16 ◽  
pp. 1-9
Author(s):  
NORHUDA ABDUL MANAF ◽  
Muhammad Hussin Abdul Jabar ◽  
Muhammad Hussin Abdul Jabar ◽  
Nor Ruwaida Jamian

Phase change material (PCM) features an attractive option due to its solar thermal storage capability to assist the cooling/heating process especially during night operation, thus contributing to the reduction of energy cost and carbon footprint. This study aims to analyse the emergence of PCM in the application of solar thermal energy. Subsequently, to envisage Technology Readiness Level (TRL) and commercialisation opportunity based on historical and contemporary research trends. This review encompasses of peer-reviewed literatures from Scopus database for one decade between 2010 and 2019. Based on the review, there is a moderate growth on the research related to PCM-solar thermal at 22% of emergence rate from the past one decade. China has dominated in this research development by concurring approximately 22% from the number of research articles published globally. It can be concluded that the application of PCM in solar thermal energy system is at TRL 5 which reflects research and development (R&D) progress is at intermediate prototypical development based on the trend of academic publication. Furthermore, based on the review, PCM features great potential in commercialisation opportunity due to its vital contribution as a frontier material/substance in overcoming the challenges of energy and environmental insecurity.


2016 ◽  
Vol 45 (21) ◽  
pp. 8740-8744 ◽  
Author(s):  
Anders Lennartson ◽  
Angelica Lundin ◽  
Karl Börjesson ◽  
Victor Gray ◽  
Kasper Moth-Poulsen

In a Molecular Solar–Thermal Energy Storage (MOST) system, solar energy is converted to chemical energy using a compound that undergoes reversible endothermic photoisomerization.


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