Entropy generation analysis of different solar thermal systems.

There is broad scientific agreement that anthropogenic greenhouse gases are contributing to global climate change and that carbon dioxide (CO2) is the primary contributor. Coal-based electricity generation produces over 30% of U.S. CO2 emissions; however, coal is also an available, secure, and low cost fuel that currently provides roughly half of U.S. electricity. As the world transitions from the existing fossil fuel-based energy infrastructure to a sustainable energy system, carbon dioxide capture and sequestration (CCS) will be a critical technology to allow continued use of coal-based electricity in an environmentally acceptable manner. Post-combustion amine absorption and stripping is one leading CO2 capture technology that is relatively mature, available for retrofit, and amenable to flexible operation. However, standard system designs have high capital costs and can reduce plant output by approximately 30% due to energy requirements for solvent regeneration (stripping) and CO2 compression. A typical design extracts steam from the power cycle to provide CO2 capture energy, reducing net power output by 11–40%. One way to reduce the CO2 capture energy penalty while developing renewable energy technologies is to provide some or all CO2 capture energy with a solar thermal energy system. Doing so would allow greater power plant output when electricity demand and prices are the highest. This study presents an initial review of solar thermal technologies for supplying energy for CO2 capture with a focus on high temperature solar thermal systems. Parabolic trough and central receiver (power tower) technology appear technically able to supply superheated steam for CO2 compression or saturated steam for solvent stripping, but steam requirements depend strongly on power plant and CO2 capture system design. Evacuated tube and compound parabolic collectors could feasibly supply heat for solvent stripping. A parabolic trough system supplying the energy for CO2 compression and solvent stripping at a gross 500 megawatt-electrical coal-fired power plant using 7 molal MEA-based CO2 capture would require a total aperture area on the order of 2 km2 or more if sized for an average direct normal solar insolation of 561 W/m2. The solar system’s capital costs would be roughly half that of the base coal-fired plant with CO2 capture. This analysis finds that irrespective of capital costs, relatively high electricity prices are required for additional electricity sales to offset the operating and maintenance costs of the solar thermal system, and desirable operational periods will be further limited by the availability of sunlight and thermal storage. At CO2 prices near 50 dollars per metric ton of CO2, bypassing CO2 capture yields similar operating economics as using solar energy for CO2 capture with lower capital cost. Even at high CO2 prices, any operating profit improvement from using solar energy for CO2 capture is unlikely to offset system capital costs. For high temperature solar systems such as power towers and parabolic troughs, direct electricity generation is likely a more efficient way to use solar energy to replace output lost to CO2 capture energy. However, low temperature solar systems might integrate more seamlessly with solvent stripping equipment, and more rigorous plant design analysis is required to definitively assess the technical and economic feasibility of using solar energy for CO2 capture.

Potential evaluation of hybrid nanofluids for solar thermal energy harvesting: A review of recent advances

Potential applications of inserts in solar thermal energy systems – A review to identify the gaps and frontier challenges

Potential of phase change materials and their effective use in solar thermal applications: A critical review

Nanofluids are fluids that contain nanoparticles that improve thermal characteristics. The thermal efficiency of systems that use nanofluids is higher than that of systems that use water as the working fluid. Solar thermal energy and systems, nanofluids and their structures, nanofluid integration into solar thermal systems, and the positive and negative consequences of nanofluid usage in these systems were all addressed in this study, emphasizing the importance of their integration. This study describes a study on using nanofluids in solar thermal systems. This research aims to examine the potential benefits of employing nanofluids, such as increased efficiency and lower prices. Furthermore, the study demonstrates that using nanofluids can reduce the size of the solar collector required to achieve the same performance level, which can lead to a decrease in the overall cost of the solar thermal system. This study's results indicate that using nanofluids in solar thermal systems can significantly enhance efficiency and reduce costs. However, further research is needed to fully explore the benefits and limitations of using nanofluids in solar thermal systems.

The efficient utilization of solar energy technology is significantly enhanced by the application of energy storage, which plays an essential role. Nowadays, a wide variety of applications deal with energy storage. Due to the intermittent nature of solar radiation, phase change materials are excellent options for use in several types of solar energy systems. This overview of the relevant literature thoroughly discusses the applications of phase change materials, including solar collectors, solar stills, solar ponds, solar air heaters, and solar chimneys. Despite the complexity of their availability and high costs, phase change materials are utilized in the majority of solar energy techniques because of the considerable technical improvements they provide. While numerous studies have investigated the progress of phase change materials used in solar energy applications such as photovoltaic systems, it is vital to understand the conceptual knowledge of employing phase change materials in various types of solar thermal energy systems. Investigations into the use of phase change materials in solar applications for the purpose of storing thermal energy are still being carried out to upgrade the overall performance. This paper briefly reviews recently published studies between 2016 and 2023 that utilized phase change materials as thermal energy storage in different solar energy systems by collecting more than 74 examples from the open literature. This study focuses on demonstrating the maturity of phase change materials and their integration into solar energy applications. Based on the findings, proposals for new research projects are made.

Availability of secure, sustainable and competitive sources of energy is essential to economic growth, prosperity and quality of life in Europe. In view of the expected growth in demand for energy, of the increasing evidence of the climate change and the aim to ensure the security of energy supply in Europe further reflections on nuclear and solar energy as best potential energy sources in the Europe energy mix is needed. Nuclear energy, supplying over 31 per cent of electricity demand, plays a key role in the EU's generation structure. Nonetheless, the current situation in the European nuclear sector is very diverse. Though the future prospect of nuclear energy is still uncertain in many member states, the general trend shows a renaissance of nuclear generation, hence the market is expected to witness solid growth over the medium and long term. The market growth of solar thermal systems and photovoltaics in Europe depends on the policy of the governments towards the use of solar energy systems, on the sensitivity of the people concerning environment and on the improvement of the technology combined with price reduction of solar systems. Considering the target of EU for 12% from renewables in 2010, solar energy systems can play a significant role in many countries. A renewed interest in Concentrating Solar Power is rapidly growing worldwide. Indeed, new commercial applications for electricity production are starting right now, 20 years after the deployment of the first plants in the Mojave desert, still operating since the early '80s

The Desert Research Institute (DRI) has developed a Renewable Energy Deployment and Display Facility (REDD) which utilizes solar and wind to create a net zero energy residence for research, education, and outreach. The facility is a demonstration of the integration of many renewable energy technologies into a residential setting such that technology developers can show proof-of-concept, students and trade workers can get hands-on experience, and public organizations can see renewable energy components implemented into a residential setting. A major technological aspect of the facility is the use of solar thermal energy to provide space heating, Domestic Hot Water (DHW), and solar cooling. Data are monitored from three separate solar thermal systems, each with their own hot water storage, to evaluate optimized utilization of solar thermal energy into residential applications. The three solar thermal systems differ in their working fluids. System 1 uses a conventional mixture of glycol and water in 200 ft2 of ground mounted collector area, System 2 uses DHW in 210 ft2 of roof mounted collector area, and System 3 uses air in a 578 ft2 collector built into the roof. Each system is configured to be used for space heating and DHW. Systems 1 and 2 are built into the HVAC system of the 1200 ft2 house, and System 3 is built into the HVAC system of the 600 ft2 detached workshop. Data collected from each system provide the basis for year-long energy and economic simulations using TRNSYS for comparison. The results from the simulations are used to demonstrate the effectiveness of site-built solar air collectors, which have the advantage of using conventional materials, and avoid the issues of liquid collectors associated with boiling and freezing. This paper describes the experimental setup of the solar thermal systems, how the data are used as inputs to the computer simulations, and the configuration of the computer simulations. The REDD Facility, as well as the use of TRNSYS will continue to be used by DRI researchers to investigate not only the most feasible integration of components for a solar thermal residential system, but also as a tool to properly size and implement solar thermal systems.

Growing population, depleting fossil fuels, economic expansions, and energy intensive life style demand are resulting in higher energy prices. We use energy as of heat and electricity, which can directly be obtained from sun using thermal collectors and solar cells. Solar thermal systems are gaining attention for water and space heating applications due to green aspects of solar energy. A solar thermal collector is a vital part of solar thermal energy system to absorb radiant energy from the sun. In this study, a solar water heating (SWH) system has been designed and simulated in the TRNSYS ® software using thermal and chemical properties of heat transfer fluids using REFPROP for dwellings located on ±31° latitudes (+31 Lahore in Pakistan and -31° Perth in Australia). We present an efficiency parametric optimization-based model for water and space heating. Simulation results for four types of solar thermal collectors are presented, and performance is analyzed on the basis of output temperature ( T out ), solar fraction ( f ), and collector efficiency ( η ). This study evaluates the comparative performance of evacuated tube collector (ETC), flat-plate collector (FPC), compound parabolic concentrator (CPC), and thermosiphon-driven systems. Our findings conclude the evacuated glass tube collector achieves the highest solar fraction, i.e., 50% of demand coverage during August in Pakistan and February in Australia, with an overall average of 43% annually.

Renewable energy technologies are in the centre of interest to narrow the gap between fossil fuels and clean energy systems. The dominant role of solar energy systems among the alternatives is beyond question owing to being associated with an infinite energy source, well-documented theory, simplicity, eco-friendly structure and notably higher energy and exergy efficiency range compared to other renewables. However, in solar energy systems, conventional working fluids with poor thermophysical properties are still utilised. In other words, further improvements are still available in the said systems by the use of unique nanoparticles with superior thermal, electrical, optical and mechanical properties. Within the scope of this research, the applications of nanofluids in various solar energy systems such as tracking and non-tracking solar collectors, photovoltaic/thermal systems, solar thermoelectric devices, solar stills, solar thermal energy storage systems, solar greenhouses and solar ponds are comprehensively analysed. Relevant comparisons and discussions are proposed for the potential impacts of various nanofluids on coefficient of performance (COP) and thermodynamic performance figures of solar energy systems such as energy and exergy efficiency, effectiveness and productivity. Some challenges of nanofluids are also addressed which need to be resolved in further works.

In the north of Graz, Austria, a large scale solar thermal system (gross collector area: 3885 m²) was installed in 2009 primarily to supply solar heat to a district heating (DH) network especially in summer and to cover part of the heat demand of the on-site buildings. In order to reduce the auxiliary heat needed for the on-site buildings and to prolong the operation time of the solar thermal system, a heat pump, which uses the solar collector loop as exclusive heat source, was installed later on. This way solar heat that is available at temperatures too low for direct solar charging of the TES (thermal energy storage) can still be used. After having performed dynamic system simulations of the installation without the heat pump in TRNSYS to validate the simulation model, the heat pump was implemented into the simulation model. Applying different control strategies to the solar heat pump system an increase of the solar fraction for the heating period (October to March) from 20.5 % without the heat pump up to 33.0 % with heat pump could be reached in the simulations. The interaction between solar thermal system and heat pump in this special configuration turned out to be challenging in terms of control optimization; hydraulic decoupling of the two units is recommended. Based on onsite measurements the performance of the system in February 2013 is evaluated

Work is broken down in the following areas: solar thermal central receiver systems analysis; advanced solar thermal systems analysis and engineering; thermal power systems support; total energy systems mission analysis; irrigation and small community mission analysis; photovoltaics mission analysis; Solar Thermal Test Facility and Central Receiver Pilot Plant systems engineering. (LEW)

RETRACTED: Development of correlations for Nusselt number and friction factor of packed bed solar thermal energy storage system having spheres with pores as packing elements

Experimental study on thermal performance of phase change material passive and active combined using for building application in winter

Mixed integer linear programming for the design of solar thermal energy systems with short-term storage