In vitro propagation of Vitis x Muscadinia hybrids by microcuttings or axillary budding

Research Not

A putative NAP homolog specifically expressed during grapevine flower and berry development

Research Not

Application of magnetic cooling in electric vehicles

The features of an active magnetic regenerator refrigerator (AMRR) are determined for its application in mobile air-conditioning (MAC) systems. The thermal requirements of an electric vehicle have been firstly obtained and result in a cooling demand of 3.03 kW at a temperature span of 29.3 K. A comprehensive parametric study has been conducted in order to find the AMRR design and working parameters that fulfill the vehicle needs with a minimum electric consumption and device mass. Specifically, a permanent-magnet parallel-plate AMRR made of Gd-like materials is considered. According to the possibilities of current prototypes, in the study the cycle frequencies have been limited to 10 Hz and the applied magnetic fields, to 1.4 T. The results show that an AMRR made of plates between 30 and 40 µm thick and channels between 20 and 40 µm high could meet the vehicle demand with a COP between 2 and 4 and a total mass between 20 and 50 kg. Compared to vapor-compression devices for MAC systems (COP=2.5 and mass 12 to 15 kg), the AMRR works optimally with fluid flow rates at least 3 times larger. In order to integrate AMRRs into MAC systems, the hydraulic loops should be consequently redesigned.Barbara Torregrosa-Jaime acknowledges the Spanish Ministry of Education, Culture, and Sport (Ministerio de Educacion, Cultura y Deporte) for the Research Fellowship FPU ref. AP2010-2160.Torregrosa Jaime, B.; Payá Herrero, J.; Corberán Salvador, JM. (2016). Application of magnetic cooling in electric vehicles. Science and Technology for the Built Environment. 22(5):544-555. doi:10.1080/23744731.2016.1186459S54455522

Numerical approach for assessing combustion noise in compression-ignited Diesel engines

[EN] Diesel combustion noise has become a crucial aspect for the engine manufacturers due to its impact on human health and influence on the customer purchasing decision. The interaction of the pressure waves after mixture self-ignition induces cavity resonances inside the combustion chamber. This complex phenomenon produces high-frequency pressure oscillations, hence traditional in-cylinder measurements do not provide enough information to characterise the in-cylinder acoustic field. In this paper, a numerical methodology is proposed for assessing the Diesel combustion as a noise source and to overcome measurement limitations. An optimisation procedure is also presented in order to determine the numerical calculation parameters, boundary conditions definition and initialization. Results show that local flow conditions at the start of combustion have a strong influence on the acoustic response of the in-cylinder noise source. These particular conditions are only achievable by the proposed methodology which considers entire engine cycle simulations with the complete cylinder domain. Therefore, traditional Computational Fluid Dynamic (CFD) approaches, such those used for predicting combustion stability or pollutant emissions, are not suitable for reproducing the physical mechanisms of noise generation and they cannot be used for acoustic purposes. The reliability of the proposed methodology to simulate the acoustic field accurately inside the combustion chamber has been validated by comparison with experiments.The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energdtica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)", framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economia y Competitividad. J. Gomez-Soriano is partially supported through the "Programa de Apoyo para la Investigacion y Desarrollo (PAID)" of Universitat Politecnica de Valencia [Grant No. FPI-S2-2016-1353].Torregrosa, AJ.; Broatch, A.; Gil, A.; Gómez-Soriano, J. (2018). Numerical approach for assessing combustion noise in compression-ignited Diesel engines. Applied Acoustics. 135:91-100. https://doi.org/10.1016/j.apacoust.2018.02.006S9110013

Numerical Estimation of Wiebe Function Parameters Using Artificial Neural Networks in SI Engine

[EN] In modeling an Internal Combustion Engine, the combustion sub-model plays a critical role in the overall simulation of the engine as it provides the Mass Fraction Burned (MFB). Analytically, the Heat Release Rate (HRR) can be obtained using the Wiebe function, which is nothing more than a mathematical formulation of the MFB. The mentioned function depends on the following four parameters: efficiency parameter, shape factor, crankshaft angle, and duration of the combustion. In this way, the Wiebe function can be adjusted to experimentally measured values of the mass fraction burned at various operating points using a least-squares regression, and thus obtaining specific values for the unknown parameters. Nevertheless, the main drawback of this approach is the requirement of testing the engine at a given engine load/speed condition. Furthermore, the main objective of this study is to propose a predictive model of the Wiebe parameters for any operating point of the tested SI engine. For this purpose, an Artificial Neural Network (ANN) is developed from the experimental data. A criterion was defined to choose the best-trained network. Finally, the Wiebe parameters are estimated with the neural networks for different operating conditions. Moreover, the mass fractions burned generated from the Wiebe functions are compared with the respective experimental values from several operating points measured in the engine test bench. Small differences were found between the estimated and experimental mass fractions burned. Therefore, the effectiveness of the developed ANN model as a prediction tool for the engine MFB is verified.Torregrosa, AJ.; Broatch, A.; Olmeda, P.; Aceros, S. (2021). Numerical Estimation of Wiebe Function Parameters Using Artificial Neural Networks in SI Engine. SAE International. 1-10. https://doi.org/10.4271/2021-01-037911

Experiments on the influence of intake conditions on local instantaneous heat flux in reciprocating internal combustion engines

[EN] The present study tries to be a contribution for the development of more precise theoretical models for predicting the dissipation of heat through the combustion chamber walls of reciprocating (internal combustion) IC engines. A fast response thermocouple was embedded in the combustion chamber of a single cylinder engine to measure instantaneous wall temperatures. The heat flux was obtained by solving the one-dimensional transient energy equation with transient boundary conditions using the Fast Fourier Transform. The engine was tested under different operating conditions to evaluate the sensitivity of the measurement procedure to variations of three relevant combustion parameters: injection pressure, air temperature and oxygen concentration at the intake. The local heat flux obtained was compared with other relevant parameters that characterize the thermal behaviour of engines, showing, in most of the cases, correlation among them. The results showed that the instantaneous heat flux through the walls and hence the local wall temperatures are strongly affected by the ignition delay and the start of combustion. © 2010 Elsevier Ltd.Desantes, J.; Torregrosa, AJ.; Broatch, A.; Olmeda González, PC. (2011). Experiments on the influence of intake conditions on local instantaneous heat flux in reciprocating internal combustion engines. Energy. 36(1):60-69. doi:10.1016/j.energy.2010.11.011S606936

Bone Mineral Disease After Kidney Transplantation

Chronic kidney disease-mineral bone disorder (CKD-MBD) after kidney transplantation is a mix of pre-existing disorders and new alterations. The final consequences are reflected fundamentally as abnormal mineral metabolism (hypercalcemia, hypophosphatemia) and bone alterations [high or low bone turnover disease (as fibrous osteitis or adynamic bone disease), an eventual compromise of bone mineralization, decrease bone mineral density and bone fractures]. The major cause of post-transplantation hypercalcemia is the persistence of severe secondary hyperparathyroidism, and treatment options include calcimimetics or parathyroidectomy. On turn, hypophosphatemia is caused by both the persistence of high blood levels of PTH and/or high blood levels of FGF23, with its correction being very difficult to achieve. The most frequent bone morphology alteration is low bone turnover disease, while high-turnover osteopathy decreases in frequency after transplantation. Although the pathogenic mechanisms of these abnormalities have not been fully clarified, the available evidence suggests that there are a number of factors that play a very important role, such as immunosuppressive treatment, persistently high levels of PTH, vitamin D deficiency and hypophosphatemia. Fracture risk is four-fold higher in transplanted patients compared to general population. The most relevant risk factors for fracture in the kidney transplant population are diabetes mellitus, female sex, advanced age (especially > 65 years), dialysis vintage, high PTH levels and low phosphate levels, osteoporosis, pre-transplant stress fracture and high doses or prolonged steroids therapy. Treatment alternatives for CKD-MBD after transplantation include minimization of corticosteroids, use of calcium and vitamin D supplements, antiresorptives (bisphosphonates or Denosumab) and osteoformers (synthetic parathyroid hormone). As both mineral metabolism and bone disorders lead to increased morbidity and mortality, the presence of these changes after transplantation has to be prevented (if possible), minimized, diagnosed, and treated as soon as possible.info:eu-repo/semantics/publishedVersio

Assessment of the improvement of internal combustion engines cooling system using nanofluids and nanoencapsulated phase change materials

This is the author¿s version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087420917494[EN] In recent years, due to the increasing need to reduce consumption of reciprocating internal combustion engines, new researches on different subsystems have raised. Among them, the use of nanofluids as a coolant medium seems to be an interesting alternative. In this work, the potential benefits of using nanofluids in the cooling system using an engine lumped model are studied. The methodology of the study starts with a whole description and validation of the model in both steady and transient conditions by means of a comparison with experimental results. Then, the potential benefits that could be obtained with the use of nanofluids are studied in a theoretical way. After that, the model is used to estimate the behavior of the system using different nanofluids in both stationary and transient conditions. The main results show that the advantages of using these new refrigerants are limited.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT)'' (grant number FEDER-ICTS-2012-06), framed in the operational program of unique scientific and technical infrastructure of the Spanish Government.Torregrosa, AJ.; Broatch, A.; Olmeda, P.; Dreif-Bennany, A. (2021). Assessment of the improvement of internal combustion engines cooling system using nanofluids and nanoencapsulated phase change materials. International Journal of Engine Research. 22(6):1939-1957. https://doi.org/10.1177/1468087420917494S1939195722