Minimum Number of Experimental Data for the Thermal Characterization of a Hot Water Storage Tank

[EN] This paper demonstrates that it is possible to characterize the water temperature profile and its temporal trend in a hot water storage tank during the thermal charge process, using a minimum number of thermocouples (TC), with minor differences compared to experimental data. Four experimental tests (two types of inlet and two water flow rates) were conducted in a 950 L capacity tank. For each experimental test (with 12 TC), four models were developed using a decreasing number of TC (7, 4, 3 and 2, respectively). The results of the estimation of water temperature obtained with each of the four models were compared with those of a fifth model performed with 12 TC. All models were tested for constant inlet temperature. Very acceptable results were achieved (RMSE between 0.2065 degrees C and 0.8706 degrees C in models with 3 TC). The models were also useful to estimate the water temperature profile and the evolution of thermocline thickness even with only 3 TC (RMSE between 0.00247 degrees C and 0.00292 degrees C). A comparison with a CFD model was carried out to complete the study with very small differences between both approaches when applied to the estimation of the instantaneous temperature profile. The proposed methodology has proven to be very effective in estimating several of the temperature-based indices commonly employed to evaluate thermal stratification in water storage tanks, with only two or three experimental temperature data measurements. It can also be used as a complementary tool to other techniques such as the validation of numerical simulations or in cases where only a few experimental temperature values are available.This research was supported by the Plan Nacional de I+D+i del Ministerio de Ciencia e Innovacion (ENE2009-13376).Gasque Albalate, M.; Ibáñez, F.; González Altozano, P. (2021). Minimum Number of Experimental Data for the Thermal Characterization of a Hot Water Storage Tank. Energies. 14(16):1-16. https://doi.org/10.3390/en14164741S116141

Reducción a una fuerza puntual de la carga distribuida que actúa sobre una viga por analogía con un sistema continuo de vectores deslizantes. Aplicación a una carga triangular

Se explica resumidamente el procedimiento para la reducción de un sistema continuo de vectores deslizantes y se aplica a la resolución de un caso práctico sencillo.Gasque Albalate, MC.; Llopis Cosin, JV. (2018). Reducción a una fuerza puntual de la carga distribuida que actúa sobre una viga por analogía con un sistema continuo de vectores deslizantes. Aplicación a una carga triangular. Universitat Politècnica de València. http://hdl.handle.net/10251/101488DE

Particularización de la teoría de la cinemática del sólido rígido al estudio del movimiento plano. Aplicación a un caso práctico

Se resuelve un caso práctico de cinemática del sólido rígido en el que se estudia el modelo de un mecanismo. La resolución del problema implica la particularización a un sistema con movimiento plano.Gasque Albalate, MC.; Llopis Cosin, JV. (2020). Particularización de la teoría de la cinemática del sólido rígido al estudio del movimiento plano. Aplicación a un caso práctico. Universitat Politècnica de València. http://hdl.handle.net/10251/142184DE

Cálculo de momentos de inercia mediante el teorema de Steiner. Aplicación a la superficie de un triángulo rectángulo

Mediante la resolución de un caso práctico se propone una guía para la determinación de momentos de inercia de superficies planas básicas aplicando el teorema de Steiner.Gasque Albalate, MC.; Llopis Cosin, JV. (2018). Cálculo de momentos de inercia mediante el teorema de Steiner. Aplicación a la superficie de un triángulo rectángulo. Universitat Politècnica de València. http://hdl.handle.net/10251/101489DE

New Approaches for Teaching Irrigation Scheduling. Improving Understanding through Modeling Applications

[EN] This paper presents a teaching methodology for introducing specific modeling tools and their methods in the contents of the subject Irrigation Engineering, corresponding to the degree of Agricultural Engineering in Spanish universities. Modeling tools can be powerful educational resources allowing for a better understanding of the physical problems addressed in different subjects of scientific-technological careers. In particular, a Gene Expression Programming based approach is applied for estimating stem water potential, a key variable in irrigation scheduling, and, consequently, a crucial issue for Agricultural Engineers. This activity is scheduled in three practical sessions for the mentioned subject. Students learn a crucial topic in irrigation engineering and the fundamentals of a very robust modeling tool. The application of this methodology for solving a specific problem contributes to improving the understanding of the theoretical topic scheduled in the subject program. At the same time, students learn a new way of facing specific problems that might be encountered in their professional practice.Martí Pérez, PC.; Shiri, J.; Gasque Albalate, M.; González Altozano, P. (2017). New Approaches for Teaching Irrigation Scheduling. Improving Understanding through Modeling Applications. International Journal of Information and Education Technology. 7(2):95-99. doi:10.18178/ijiet.2017.7.2.848S95997

Simple inlet devices and their influence on thermal stratification in a hot water storage tank

[EN] Thermal energy storage is a technology used mostly in buildings and industries in order to preserve thermal energy so that the stored energy can be used at a later time. Thermal stratification during the charge process in a cylindrical water tank was investigated using tools of Computational Fluid Dynamics (CFD). Simulations were validated by means of experimental measurements of time-dependent temperature profiles. The results showed that the model was able to adequately capture the experimental temperature evolution in the tank for all the validation cases. Once validated the model, simple modifications of the usual inlet devices and inflow rate by CFD techniques were accomplished with the intention of improving the tank performance. It was found that the modifications of the simulated inlet devices affected the stratification level. This could lead to improve designs and optimize system efficiency. The analyses confirmed numerically the results obtained experimentally, and it was evidenced that a sintered bronze conical diffuser can improve stratification compared to a conventional bronze elbow inlet. Therefore, CFD techniques proved to be quite a valuable complement of experimental studies. The use of low inflow, smooth out inlet velocity and operate inflow upwards near the top of the tank enhanced stratification. (C) 2017 Published by Elsevier B.V.This research was supported by the Plan Nacional de I+D+i del Ministerio de Ciencia e Innovacion (ENE2009-13376). The authors would like to thank L.H. Sanchis for his valuable and constructive suggestions during the planning and development of this research.Moncho Esteve, IJ.; Gasque Albalate, M.; González Altozano, P.; Palau-Salvador, G. (2017). Simple inlet devices and their influence on thermal stratification in a hot water storage tank. Energy and Buildings. 150:625-638. https://doi.org/10.1016/j.enbuild.2017.06.012S62563815

Comparative evaluation of two photovoltaic multi-pump parallel system configurations for optimal distribution of the generated power

[EN] The suitability of a strategy for distributing the power generated by a photovoltaic pumping system equipped with two equal pumps working in parallel is proven. This strategy aims to improve energy management and consists of feeding a single pump with all the power generated until it exceeds a threshold value from which the power distribution must be at 50% between the two pumps. This pumping method was compared with the operation mode usually applied in parallel PV pumping facilities (50% of the power always assigned to each pump). A system equipped with two 0.75 kW pumps was employed. The assessment of the facility's performance under the two alternative working conditions and several pumping heads was conducted using simulation techniques. Both the pumped annual volume and the annual efficiency of the motor-pump group increased when the strategy was applied compared to operation with power distribution at 50%. This increase was greater the higher the head (6.21% at H = 18 m vs. 57.60% at H = 48 m for pumped annual volume and 6.42% at H = 18 m vs. 57.51% at H = 48 m for annual efficiency). The halving of the irradiance threshold and the improved efficiency (36.4% vs. 34.8%) may explain this increase.Gasque Albalate, M.; González Altozano, P.; Gutiérrez-Colomer, RP.; García-Marí, E. (2021). Comparative evaluation of two photovoltaic multi-pump parallel system configurations for optimal distribution of the generated power. Sustainable Energy Technologies and Assessments. 48:1-11. https://doi.org/10.1016/j.seta.2021.1016341114

Sustainable development goals and their implementation in Physics

[EN] Sustainable Development Goals (SDGs) currently represent a challenge for the future and are already being implemented in different working areas. That is why, from the moment a student starts university education, professors must take the lead to include them in the different subjects offered in the curricula of the different Degrees. Physics is a subject that represents a fundamental basis in many engineering degrees studies. On the one hand, the importance of this subject for the future of students is well known. However, this fundamental nature means that it is perceived by the students as a subject with no connection with the degree they aspire to achieve. Additionally, the heterogeneous level of training of the students, especially in the first courses, is a limitation. This makes it difficult to relate the content of the subject with the everyday phenomena and favours the lack of interest in them. One way to motivate students and use the active and constructive teaching methodology is to introduce SDGs within the subject, given the high sensitivity of current generations on Planet Earth. The introduction of these new training tools is not easy because the teaching of the fundamental bases requires most of the available time. This work aims to bring Physics closer to society through SDGs. For this purpose, a challenge is incorporated into the subject¿s curriculum for each thematic block that students must overcome. In this way, two important training actions are combined, efficient teaching is carried out, and the students become aware of SDGs, which are necessary for their future work. PoliformaT, the e-learning platform implemented in the Universitat Politècnica de València, facilitates the use of these new teaching methodologies that combine traditional on-site laboratory tasks with other learning assignments carried out autonomously online by students.The authors would like to thank the educational innovation group Multidisciplinary Teaching Innovation Methodology (Teach- Inn) (GIE-64) from Universidad de Las Palmas de Gran Canaria.Castiñeira Ibáñez, S.; Tarrazó-Serrano, D.; Gasque Albalate, M.; Rubio Michavila, C.; Uris Martínez, A. (2022). Sustainable development goals and their implementation in Physics. IATED. 9378-9383. https://doi.org/10.21125/edulearn.2022.22639378938

La reducción de un sistema de vectores deslizantes como metodología para la simplificación del cálculo de cargas estructurales reales. Aplicación a un caso práctico

Se explica resumidamente el procedimiento para la reducción de un sistema discreto de vectores deslizantes y se aplica a la resolución de un caso práctico sencillo.Llopis Cosin, JV.; Gasque Albalate, MC.; Rubio Michavila, C. (2017). La reducción de un sistema de vectores deslizantes como metodología para la simplificación del cálculo de cargas estructurales reales. Aplicación a un caso práctico. Universitat Politècnica de València. http://hdl.handle.net/10251/80754DE

Application of the finite element method to the understanding of a non-steady state heat transport problem

[EN] Nowadays, the search for new active and constructive learning methodologies is one of the pedagogical objectives in universities and other educational institutions. In the degrees taught at the Escola Tècnica Superior d'Enginyeria Agronòmica i del Medi Natural (ETSEAMN), the phenomena associated with heat transport and the underlying physics are studied. In the master classes, within the framework of food science and technology subjects, the phenomenon of this energy balance in a one-dimensional system is explained. In the present work, the analytical solution is developed and evaluated, and a numerical model achieving the same solution is shown. One of the advantages of using numerical tools is that more complex solutions can be obtained, even if the corresponding analytical solution does not exist or is not known, which is useful for engineering students. In this work, it is shown that changing the boundary conditions, geometry, or dimension in the system and the mathematical model, and solving it by applying a numerical solution method is easier and more comprehensive for students rather than facing the complexity of the analytical solutions. To demonstrate the applications and possibilities of this approach, a simple way of modifying the degrees of freedom of the same problem applied in the case of a vegetable subjected to a heat treatment is shown. Thus, the students can understand how these modifications affect the solution and comprehend that the dimension of some problems can be simplified in order to contextualize them. The development of PoliformaT, the e-learning platform implemented in the Universitat Politècnica de València facilitates the use of these new teaching models that combine traditional on-site laboratory tasks assignments with other learning assignments carried out autonomously online by students.The authors would like to thank the educational innovation group Multidisciplinary Teaching Innovation Methodology (Teach- Inn) (GIE-64) from Universidad de Las Palmas de Gran Canaria. In addition, we greatly appreciate José Bon Corbín his invaluable support and time.Tarrazó-Serrano, D.; Castiñeira Ibáñez, S.; Sánchez-García, E.; Gasque Albalate, M.; Uris Martínez, A.; Rubio Michavila, C. (2022). Application of the finite element method to the understanding of a non-steady state heat transport problem. IATED. 9370-9377. https://doi.org/10.21125/edulearn.2022.22629370937