Thermodynamic evaluation of solar integration into a natural gas combined cycle power plant

The term integrated solar combined-cycle (ISCC) has been used to define the combination of solar thermal energy into a natural gas combined-cycle (NGCC) power plant. Based on a detailed thermodynamic cycle model for a reference ISCC plant, the impact of solar addition is thoroughly evaluated for a wide range of input parameters such as solar thermal input and ambient temperature. It is shown that solar hybridization into an NGCC plant may give rise to a substantial benefit from a thermodynamic point of view. The work here also indicates that a significant solar contribution may be achieved in an ISCC plant, thus implying substantial fuel savings and environmental benefits.     

The potential of concentrating solar power in South Africa

In this paper all provinces of South Africa with a good potential for the implementation of large-scale concentrating solar power plants are identified using geographic information systems. The areas are assumed suitable if they get sufficient sunshine, are close enough to transmission lines, are flat enough, their respective vegetation is not under threat and they have a suitable land use profile. Various maps are created showing the solar resource, the slope, areas with “least threatened” vegetation, proximity to transmission lines and areas suitable for the installation of large concentrating solar power plants. Assuming the installation of parabolic trough plants, it is found that the identified suitable areas could accommodate plants with a nominal capacity of 510.3 GW in the Northern Cape, 25.3 GW in the Free State, 10.5 GW in the Western Cape and 1.6 GW in the Eastern Cape, which gives a total potential nominal capacity of 547.6 GW for the whole country.     

Experimental investigation of an indirect-type solar cooker for indoor cooking based on a parabolic dish collector

In the present research article, an indirect type solar cooking system has been developed for indoor cooking. In the proposed cooking system, a cooking pot has been placed at a distance of 5 m from the parabolic dish collector, and the heat has been transmitted from the collector to the cooking pot by means of heat transfer fluid. A gear pump of 40 W and insulated pipes have been used to circulate the fluid. A number of experiments have been performed to analyze the performance of the cooking system. During the investigation, the system achieved the temperature of the heat transfer fluid up to 175°C. The time taken for cooking the rice and the black grams has been observed 21 and 68min, respectively. The average thermal efficiency of the proposed system for the entire day has been achieved at 13.11%.     

Performance investigation of a solar water distiller integrated with a parabolic collector using fuzzy technique

A recent study of the design of solar distillation with solar radiation concentration was carried out by an independent device. Transformer oil was used as a fluid to transfer heat to the distilled basin. The design and operational variables are essential, such as distiller dimensions, concentration ratio, pressure, and temperature. A mathematical model was proposed to simulate the system for 2 July 2018 from 10 am to 4 pm  in the climatic conditions of the city of Kirkuk, Iraq. Fuzzy logic (FL) was used to select the affected parameters: water temperature (T_w), water pressure (P_w), glass temperature (T_g), and vapor pressure (P_g) which have a separated membership function that control the linguistic variables. The results showed that the best performance of the distiller is at T_w = 100°C, P_g = 10 000 Pa, T_g = 20°C, and P_w = 20 000 Pa, and concentration ratio of 30. This study used FL to analyze solar distiller performance and identify optimum temperature, pressure, and concentration ratio on the productivity of solar distiller.     

Experimental study of a refrigerant charged solar collector

The performance of a heat-pipe solar collector was investigated experimentally using refrigerants R11 as the working fluid. The unit is fabricated locally and its performance is evaluated under Beirut Solar conditions. The heat transfer from the heat pipes to the hot-water storage tank took place through a circular end condenser section of the heat-pipe integrated within the collector frame. Tests of single heat pipes showed that the thermal performance of the heat pipe were dependent on its tilt angle, condenser section length and configuration, and type of internal wick used. A circular condenser end of the heat-pipe performed better than a straight condenser due to increased surface area for heat transfer. The R11-charged solar collector with integrated condenser for secondary cooling of water had an efficiency in early operation hours that reached values higher than 60% for the forced circulation mode. The instantaneous system efficiencies varied from 60 to 20%, which are in the range of conventional water solar collectors. System response was fast and sensitive to the incident solar radiation. The thermosyphonic mode of the system operation generated build up of stored energy in the condenser, resulting in oscillating-type flow thus reducing system efficiency below values obtained with forced circulation. © 1998 John Wiley & Sons, Ltd.     

Thermodynamic optimization of solar flat-plate collector

Second-law modeling of flat-plate collectors is performed with the objective of describing collector performance when entropy generation is minimum. Effects of irreversibility are demonstrated. Factors mostly effecting the generation of entropy are discussed.     

Selection of metal hydrides for a thermal energy storage device to support low-temperature concentrating solar power plants

Metal hydrides have become more and more significant both as hydrogen storage devices and as basic elements in energy conversion systems. Besides the well-known rare earth hydrides, magnesium alloys are very promising in the field of thermal energy storage for concentrating solar power plants. There is interest in analysing the performances of such materials in this context; for this purpose, a numerical model to describe hydrogen absorption and desorption processes of a metal hydride has been connected to a model elaborated with the help of Cycle-Tempo software to simulate a CSP plant operation. The integration of this plant with four metal hydride systems, based on the combination of two low-temperature hydrides (LaNi₅, LaNi_4.8Al_0.2) and two high-temperature hydrides (Mg, Mg₂Ni) has been studied. The investigation has taken into account CSP overall performances, transfer surfaces and storage efficiencies, to determine the feasibility of designed plants. Results show that the selection of the optimal hydrides must take into account hydride operation temperatures, reaction enthalpies, storage capacities and kinetic compatibility. In the light of the calculated parameters, a solar ORC plant using R134a as the working fluid is a valuable choice if matched to a storage system composed of LaNi₅ and Mg₂Ni hydrides.     

Methods for probabilistic modeling of concentrating solar power plants

Probabilistic modeling of concentrating solar power technologies provides important information regarding uncertainties and sensitivities not available from deterministic models. Benefits of using probabilistic models include quantification of uncertainties inherent in the system and characterization of their impact on system performance and economics. This paper presents the tools necessary to conduct probabilistic modeling of concentrating solar technologies. The probabilistic method begins with the identification of uncertain variables and the assignment of appropriate distributions for those variables. Those parameters are then sampled using a stratified method (Latin Hypercube Sampling) to ensure complete and representative sampling from each distribution. Models of performance, reliability, and/or cost are then simulated multiple times using the sampled set of parameters. The results yield a cumulative distribution function that can be analyzed to quantify the probability of achieving a particular metric (e.g., net energy output or levelized energy cost) and to rank the importance of the uncertain input parameters.     

Optical performance of an asymmetric inverted absorber compound parabolic concentrating solar collector

A computer-based numerical model has been developed utilising ray trace techniques, to simulate the optical characteristics of asymmetric inverted absorber line axis compound parabolic concentrating solar collectors (IACPCs). Cognisance is taken of the separate effects of the beam and diffuse properties of the total insolation on the optical performance. Increasing absorber gap height was expected to increase convection heat loss suppression and overall collector performance at the expense of a reduction in optical efficiency. The results are presented as graphical analyses of optical efficiency versus height of absorber gap, reflectivity and, acceptance and ray input angles.     

Parametric study of a thermal trap solar energy collector

A parametric study of a thermal trap solar energy collector with the help of a modified Hottel-Whillier-Bliss equation, is presented. The developed analysis is used to optimize the typical parameters, namely the trap's thickness and the number of flowing channels. The variation of the rating parameters of a collector with typical quantities, such as the fin distance, mass flow rate and thickness of the absorber plate, is discussed in detail.     

Performance evaluation of water and air based PVT solar collector for hydrogen production application

This study aims to investigate the performance of the Photovoltaic Thermal (PVT) collector based hydrogen production system. For this purpose, a solar assisted water splitting system is fabricated. This system comprises the array of photovoltaic (PV) cells with 0.303 m² surface area, a spiral flow thermal collector with 12.7 mm outer diameter, 10.26 mm internal diameter, 10 m length copper tube and Hoffman voltameter. The results have been taken for three different mass flow rates (0.008, 0.01 and 0.011 kg/s) and compared with the reference PV module. This study results clearly show that the collector outlet temperature, output voltage and output power increase as the flow rate increases and the PV module temperature decreases with an increase of flow rate. The maximum thermal and electrical efficiency of 33.8% and 8.5% are observed for water based PVT solar collector with 0.011 kg/s flow rate at 12.00. It is also noted that the hydrogen yield rate increases significantly with an increase in flow rate. The highest hydrogen yields of 17.1 ml/min are obtained at a fluid flow rate of 0.011 kg/sec at 12.00.     

Techno-economic evaluation of concentrating solar power generation in India

The Jawaharlal Nehru National Solar Mission (JNNSM) of the recently announced National Action Plan on Climate Change (NAPCC) by the Government of India aims to promote the development and use of solar energy for power generation and other uses with the ultimate objective of making solar competitive with fossil-based energy options. The plan includes specific goals to (a) create an enabling policy framework for the deployment of 20,000 MW of solar power by 2022; (b) create favourable conditions for solar manufacturing capability, particularly solar thermal for indigenous production and market leadership; (c) promote programmes for off grid applications, reaching 1000 MW by 2017 and 2000 MW by 2022, (d) achieve 15 million m² solar thermal collector area by 2017 and 20 million by 2022, and (e) deploy 20 million solar lighting systems for rural areas by 2022. The installed capacity of grid interactive solar power projects were 6 MW until October 2009 that is far below from their respective potential.     

Flower-type pulsating heat pipe for a solar collector

Inspired by the sunflower, we report a new structure of a solar collector that integrates a pulsating heat pipe (PHP) into a flat-plate collector. The proposed flower-type PHP solar collector is designed after a sunflower with petals that absorb sunlight and transfer nutrients to the stem after photosynthesis. The evaporator section adopts the shape of a flower to absorb sunlight fully, and the condenser section is rolled into a cylinder and placed in the lower part of the structure. A systematic experimental study is conducted upon start-up, and the performance characteristics, with acetone as the working fluid, are evaluated. We also did a heat loss analysis, which has a deviation of 8%. The effects of the mass flow rate of cooling water, filling ratio, length of the condenser section, and solar intensity are assessed. As the temperature of the heat absorber plate increases, the thermal resistance of the PHP can decrease to a minimum of 0.14°C/W. Under sunny weather conditions, the instantaneous thermal efficiency of the system with a filling ratio of 50% reaches 50%. Besides, we discussed the unstable operation conditions and possible dryout phenomenon that happened inside the PHP.     

Potential application of concentrating solar power systems for the generation of electricity in Thailand

This study aims to investigate a potential application of concentrating solar power (CSP) systems for producing electricity in the tropical environment of Thailand. An 8-year period (1995–2002) of satellite data was used to generate the direct normal irradiation map of the country. The map reveals that the areas which receive the highest irradiation are mainly in the Northeast and the Central regions of the country, with the yearly sum of direct normal irradiation in the range of 1350–1400 kW h/m² year. The location of Ubon Ratchathani (15.25 °N, 104.87 °E) situated in the Northeast was selected as a target area for investigating the potential application of CSP systems. The performance of three 10 MW CSP systems, namely the parabolic trough, the tower and the dish/Stirling engine systems was investigated. A software named TRNSYS together with the solar thermal electric components (STEC) subroutines were used to simulate the systems. The yearly production of electricity from these systems was estimated and used for the economic evaluation of the systems. It was found that the parabolic trough system afforded the lowest levelized electricity cost of 0.30 USD/kW h. Based on the technical and economic considerations, this system has a sufficient potential for producing electricity in this region.     

The potential of metal hydrides paired with compressed hydrogen as thermal energy storage for concentrating solar power plants

Concentrating solar power (CSP) plants require thermal energy storage (TES) systems to produce electricity during the night and periods of cloud cover. The high energy density of high-temperature metal hydrides (HTMHs) compared to state-of-the-art two-tank molten salt systems has recently promoted their investigation as TES systems. A common challenge associated with high-temperature metal hydride thermal energy storage systems (HTMH TES systems) is storing the hydrogen gas until it is required by the HTMH to generate heat. Low-temperature metal hydrides can be used to store the hydrogen but can comprise a significant proportion of the overall system cost and they also require thermal management, which increases the engineering complexity. In this work, the potential of using a hydrogen compressor and large-scale underground hydrogen gas storage using either salt caverns or lined rock caverns has been assessed for a number of magnesium- and sodium-based hydrides: MgH₂, Mg₂FeH₆, NaMgH₃, NaMgH₂F and NaH. Previous work has assumed that the sensible heat of the hydrogen released from the HTMH would be stored in a small, inexpensive regenerative material system. However, we show that storing the sensible heat of the hydrogen released would add between US$3.6 and US$7.5/kWh_th to the total system cost for HTMHs operating at 565 °C. If the sensible heat of released hydrogen is instead exploited to perform work then there is a flow-on cost reduction for each component of the system. The HTMHs combined with underground hydrogen storage all have specific installed costs that range between US$13.7 and US$26.7/kWh_th which is less than that for current state-of-the-art molten salt heat storage. Systems based on the HTMHs Mg₂FeH₆ or NaH have the most near term and long term potential to meet SunShot cost targets for CSP thermal energy storage. Increasing the operating temperature and hydrogen equilibrium pressure of the HTMH is the most effective means to reduce costs further.     

Thermodynamic and economic investigation of an innovative multigeneration plant integrated with the solar collector and combustion chamber

Today, effective and low-emission energy systems have been needed to combat environmental problems and to satisfy the growing energy requirement in a sustainable way. In this case, it has gained importance to the production of different useful commodities with the multigeneration plant that is obtained by integrating different systems. With this viewpoint, the key objective of this work is to design and analyze the solar collector and combustion chamber-assisted multigeneration model for power, heating, hydrogen, ammonia and freshwater generation. A newly designed plant comprises a gas turbine cycle, which includes a parabolic dish solar collector and combustion chamber, a Rankine power plant, a multi-effect desalination part, a hydrogen generation part, an ammonia generation part, and a solid oxide fuel cell unit. Comprehensive thermodynamic modeling, economic analysis and multiobjective optimization are executed to observe the performance of the whole plant and sub-system by employing energetic and exergetic approaches. Moreover, a parametric investigation is addressed to review the impacts of some important point changes on the modeled plant's efficiency. Analyses consequences display that the power and hydrogen generation amounts are 12,835 kW and 0.0607 kgs^?1. Also, freshwater generation capacity with desalination unit is computed as 4.89 kgs^?1. Moreover, total cost rate of the modeled plant is computed as 1074 $/h. Finally, the evaluated plant's energetic and exergetic efficiency is 58.38% and 54.21%, respectively.     

Thermodynamic studies of a novel heat pipe evacuated tube solar collectors based integrated process for hydrogen production

In this study, the detailed thermodynamic assessment of an integrated process based on heat pipe evacuated tube solar collectors for hydrogen production is provided for more efficiently process designs. An integrated process consists of the solar heat pipe collector, photovoltaic panels, PEM electrolyzer and Linde-Hampson hydrogen liquefaction process are considered and analyzed thermodynamically for hydrogen production and liquefaction aims. The energetic and exergetic efficiencies of this integrated process are calculated as 0.2297 and 0.1955, respectively. Based on the parametric study, the effectiveness of the solar energy based integrated process is also highly dependent on the solar flux and ambient conditions.     

The effective size of the solar cone for solar concentrating systems

In this paper we define a virtual solar cone, whose principle axis is aligned with the solar vector, having a radial angular displacement containing a pre-defined proportion of the terrestrial solar radiation. By simulating various sunshape profiles, the angular extent of the energy distribution is established to give the effective size of the solar cone for a range of atmospheric conditions. Then, by simulating the reflection of these solar distributions off a set of non-ideal mirrored surfaces, accounting for non-specular reflection and mirror shape errors, the combined effect of sunshape and mirror properties on the solar image is obtained. Clear trends are presented that show the dependence of the effective size of the solar image on the accuracy of a mirrored surface for different sunshapes. We then identify the effective size of the solar image at the absorber plane that must be accommodated in the design and optimisation of solar concentrating systems.     

Simulation of a solar concentrating dish for steam generation

This research work aims to design theoretically through computer programming a solar concentrating dish using flat mirrors as reflectors to be fixed in pieces on a steel framed dish. The simulation program determines design dimensions, economical factors and thermal performance, relating them to each other and to be controlled through specific preliminary inputs. A model of concentrating dish having 1?m diameter was constructed and tested to achieve design optimisation of such types of systems. A prototype of 8?m diameter was also constructed and tested to verify the reliability of the program and workability of the system to be used for steam generation.