Comparative analysis of domestic water heating thermosiphon systems tested according to the Standard ISO 9459-2

Permiso concedido para subir el documentoThe Standard ISO 9459-2 is a standard for the characterization of thermal performance of domestic water heating systems without auxiliary heating. In this study, 18 domestic water heating thermosiphon systems have been tested according to this international standard. The objective of the paper is to carry out a comparative analysis of the results obtained in these systems as a function of their volume and type of heat exchanger (tubular and double jacket). A comparative analysis of systems performance will be carried out by calculating the performance without thermal loss (a1/A) and solar fraction fSOL in different reference locations for different volume/area ratios. Also, a comparative analysis of systems performance and solar fraction will be carried out at different locations between a tubular heat exchanger tank and a double jacket heat exchanger tank. The different values obtained will be compared for the storage tank’s heat loss coefficient (Us). It will determinate the useful energy (energy with temperature above 45ºC) for the degree of mixing in the storage tank during a draw-off test

Thermodynamic Limits of the Use of PCM Simultaneously in Photovoltaic Modules and in Building

Permiso obtenido por la institución para subir el documentoThe paper quantifies the thermodynamic limits on the energy and exergy use that would result from the use of PCM in photovoltaic BIPV modules versus not using PCM, by limiting module temperature to 298 K and the thermal energy use in buildings according to a set of hypotheses. The results obtained have been extended to six different climates. The results show that the maximum use of PCM depends heavily on the climate, therefore in hot climates as Seville, Cairo and Nairobi, the improvements in energy efficiency are very important (multiplied from 6 to 9 times), while in cold climates as London and Helsinki, the improvements are not that significant (multiplied from 1.5 to 2 times). The exergetic efficiency improvements range of about 5% for all climates, due to the low operating temperature of the PCM. These materials requirements are significant, ranging between 31 and 193 kg/m2, with thicknesses between 3.9 and 24.2 cm/m2

Thermodynamic Limits of the Use of Solar Energy for Cold Production

Permiso obtenido de la institución para subir este documetnoThe paper quantifies the thermodynamic limits on the energy and exergy use that would result from the use of PCM in photovoltaic BIPV modules versus not using PCM, by limiting module temperature to 298 K and the thermal energy use in buildings according to a set of hypotheses. The results obtained have been extended to six different climates. The results show that the maximum use of PCM depends heavily on the climate, therefore in hot climates as Seville, Cairo and Nairobi, the improvements in energy efficiency are very important (multiplied from 6 to 9 times), while in cold climates as London and Helsinki, the improvements are not that significant (multiplied from 1.5 to 2 times). The exergetic efficiency improvements range of about 5% for all climates, due to the low operating temperature of the PCM. These materials requirements are significant, ranging between 31 and 193 kg/m2, with thicknesses between 3.9 and 24.2 cm/m

Integration of solar thermal energy in a conventionaf power plant: The Colon solar project

This paper reports on the first phase of the Colón Solar Project, originally conceived as the hybrid repowering of an existing thermal power plant, with the addition of a gas turbine in a topping configuration integrating thermal energy (steam) produced by a solar system. However, the project developed in a changing economic environment, in which a new legal structure, still incomplete, as of January, 1998 has liberalized the electricity generation market. This forced the original configuration to be modified, resulting in an all-new combined cycle with solar energy integrated into a Heat Recovery Boiler. Basic plant engineering placed special emphasis on the most important solar components (heliostat and receiver), and an economic analysis showed that the plant is profitable under the assumptions of the analysis. Nevertheless, the relatively low IRR, as well as the uncertainty of realization of some of those assumptions, made the utility postpone its decision to build the plant

Experimental Comparison of Different Global Irradiation Models with and without Sun Tracking for the South of Spai

Permiso obtenido por la institución para subir este documentoIt is very unusual to have global irradiance data for a tilted surface and even more for a surface with a perfect sun tracking. The most common available data is the global horizontal irradiance, thus it is necessary to convert the available data into the desirable inclination. The purpose of this paper is to analyse the different response of the radiation models that are used to calculate the global irradiance in static surfaces and in surfaces with a perfect sun tracking (two axis). For that end 10 years of measured data has been utilized. The combination of methods that better approaches to the experimental values is the one formed by Orgill - Hollands and Perez for stationary surfaces and mode- Temps-Coulson for two-axis tracking

Reliability of photovoltaic solar systems through real O&M follow-up data

Permiso obtenido por la institución para subir el documentoThis paper provides a detailed analysis of failures and incidents that occurred in 218 PV systems, in 24 PV plants and 17 PV parks, for 15 months of performance, located in Spain and Italy. The results show that the photovoltaic technology is the cause of the 20.3% of the incidents while the 44% of failures are caused due to external causes of the PV system installation. The 56.7% of the failures affected the energy production of the PV system. The major cause of failure is given by the monitoring systems, followed by low power inverters (between 5- 90 kW). Despite these failures, the efficiency of the facilities is high with a performance ratio between 69% and 83%

Benefits of Medium Temperature Solar Concentration Technologies as Thermal Energy Source of Industrial Processes in Spain

This paper analyses the possible applications of medium temperature solar concentration technologies, Compound Parabolic Collector, Linear Fresnel Collector and Parabolic Trough Collector in the Spanish industrial sector. Results of this study allow evaluating whether or not solar technologies are an alternative to conventional sources. This possibility is analyzed energetically, economically and environmentally. Results show that the percentage of solar use is decisive in determining the true thermal energy generation cost. The other essential parameter is the solar field area due to produce economy of scale that reduces investment costs. Fluid temperature has significant influence mainly in Compound Parabolic Collector technology. Results obtained in this paper collect multiple alternatives and allow comparing for different scenarios the suitability to replace conventional energy sources by thermal energy obtained from medium temperature solar concentration technologies from an economic perspective. For instance, for percentage of solar use equal to 100%, the lowest thermal energy generation costs for each technology are 1.3 c /kWh for Compound Parabolic Collector technology, fluid temperature of 100º C and industrial process located in Seville, 2.4 c /kWh for Linear Fresnel Collector technology, fluid temperature of 170º C and industrial process located in Jaen, 3.3 c /kWh for technology, fluid temperature of 350º C and industrial process located in Jaen. These costs are lower than conventional energy sources costsPlataforma Tecnológica Solar Concentra ES-130

Conditions in which a photovoltaic system is more viable than a low-temperature solar thermal system.

Permiso para subir el documento obtenido por la instituciónPhotovoltaic (PV) and low-temperature solar thermal (LT-STH) are the most widely used technologies in the building sector. This study determines, depending on the most influential parameters, the conditions in which a PV system is more beneficial than a LT-STH system from an economical, energetic and environmental point of view. The parameter used for economically evaluated both technologies is the levelized cost of energy (LCOE). Moreover the Greenhouse Gas Emissions factor is employed for an environmental evaluation. The main results shown on this study reveal that in most cases PV is economically and environmentally more viable than LT-STH, although it would be necessary to analyze the particular conditions of each site

Direct radiation estimates from horizontal global irradiance values

One of the main factors determining the economic feasibility of a solar thermal power plant is the availability of direct radiation at the plant site. During last years, two Central Receiver Power Plants (Solgas and Colon Solar) have been proposed in the South West of Spain (Huelva). For this area only global solar radiation data are available in a historical representative database. Based on an 11 years radiation database gathered at a nearby location, distance less than 100 km, 12 correlations, (one per month), between Mt and Md have been obtained. Solar global radiation data from the power plant site and generated correlations have allowed the "construction" of a Direct Radiation Design year that has been used both to design the solar plant heliostat field and receiver and to estimate annual energy produced by the solar plant

Process Heat Generation Potential from Solar Concentration Technologies in Latin America: The Case of Argentina

This paper evaluates the potential of solar concentration technologies—compound parabolic collector (CPC), linear Fresnel collector (LFC) and parabolic trough collector (PTC)—as an alternative to conventional sources of energy for industrial processes in Latin America, where high levels of solar radiation and isolated areas without energy supply exist. The analysis is addressed from energy, economic and environmental perspective. A specific application for Argentina in which fourteen locations are analyzed is considered. Results show that solar concentration technologies can be an economically and environmentally viable alternative. Levelized cost of energy (LCOE) ranges between 2.5 and 16.9 c /kWh/m2 and greenhouse gas (GHG) emissions avoided range between 33 and 348 kgCO2/(m2 year). CPC technology stands out as the most recommendable technology when the working fluid temperature ranges from 373 K to 423 K. As the working fluid temperature increases the differences between the LCOE values of the CPC and LFC technologies decrease. When 523 K is reached LFC technology is the one which presents the lowest LCOE values for all analyzed sites, while the LCOE values of PTC technology are close to CPC technology values. Results show that solar concentration technologies have reached economic and environmental competitiveness levels under certain scenarios, mainly linked to solar resource available, thermal level requirements and solar technology cos