Como usar Atenea en la gestión de grupos en una asignatura de laboratorio de Química

En esta propuesta se presenta la experiencia de utilización del campus virtual ATENEA como herramienta de comunicación y de gestión de la interacción tanto profesorado-alumnado como alumnado-alumnado en la asignatura de Experimentación en Química II de segundo curso de la titulación de Ingeniería Química, que se imparte en la ETSEIB. Atenea ha demostrado ser una herramienta eficaz que ha permitido, durante el curso 2009-10, facilitar la información general y la planificación temporal de todas las actividades de la asignatura, además de gestionar el seguimiento y retroacción de las tareas de los grupos de trabajo cooperativo.Peer Reviewe

Enhancing the efficiency of solar pond heat extraction by using both lateral and bottom heat exchangers

In this study, heat extraction from both the gradient and heat storage zones of a salinity-gradient solar pond (SGSP) has been evaluated. For this purpose, an experimental solar pond pilot plant was constructed in 2009 in Barcelona (Spain). The structure of the pond is a cylindrical tank of 3-m height and 8 m diameter with a total area of 50 m(2). The main objective was to evaluate a heat-extraction system from the SGSP designed to enhance the system efficiency under different conditions. Thus, an in-pond heat exchanger covering all of the lateral wall area of the pond was installed, and its performance was compared with the traditional in-pond heat exchanger situated on the bottom of the pond. Heat extraction experiments were performed using both heat exchangers individually or both at the same time. The study covers the experiments performed at three different seasonal temperature conditions: winter (December), summer (July) and autumn (October and November). The variations of the temperature inside the pond during the heat extraction were measured and analyzed. The results demonstrated that the efficiency of the pond increases when the heat is removed from the lateral heat exchanger alone compared to either using the bottom heat exchanger or using both heat exchangers simultaneouslyPostprint (author's final draft

Design, construction, and operation of the first industrial salinity-gradient solar pond in Europe: An efficiency analysis perspective

A 500 m2 industrial salinity-gradient solar pond (SGSP) was constructed in a mineral processing plant (Solvay Minerales) in Granada (Spain). This renewable energy technology was designed to supply a low-temperature heat (up to 60 °C) to achieve the temperature requirements of the flotation mineral purification stage. The low-temperature source was integrated to partially replace the fuel oil boiler used to heat the water used in the flotation stage. Theoretical calculations based on solar radiation indicated that the use of the SGSP would reduce the annual fuel consumption by more than 50%, thus providing a significant improvement at both economic and environmental levels. Two months after the SGSP was established, in August 2014, the temperature in the storage zone of the SGSP reached approximately 90 °C. The overall performance was evaluated in two periods (2014 and 2015) in terms of the retrofitting of mining facility with a solar pond and a new method to assess the thermal efficiency of the solar pond in a long-term perspective has been proposed. The overall efficiencies obtained after the first and second operation periods were 10 and 12%, respectively, with maximum values of 28 and 24% obtained during the first operation months. Regarding the economic savings, the fuel oil cost of the flotation unit was reduced by a higher percentage than the fuel oil consumption, due to the decreasing tendency of fuel oil prices during 2014 and 2015. Reductions of 52 and 68% were obtained in the first and second periods of operation, respectively, when compared to 2013. In addition, not only does the SGSP have considerably reduced operating costs but also the environmental costs are clearly reduced when considering the reduction of CO2 emissions.Peer ReviewedPostprint (author's final draft

Increasing the storage capacity of a solar pond by using solar thermal collectors: heat extraction and heat supply processes using in-pond heat exchangers

In this study, an experimental investigation of the performance of a salinity gradient solar pond (SGSP) integrating solar collectors is presented. The SGSP is located in Barcelona (Spain) and has a cylindrical tank 3¿m in height and 8¿m in diameter with a total area of 50¿m2. For this purpose, four solar thermal collectors (10¿m2) are integrated, as an external source of heat, with the solar pond pilot plant in order to increase the storage capacity and its overall efficiency. The aim of this study is to evaluate heat extraction and heat supply processes from and to the SGSP under different seasonal conditions. Two in-pond heat exchangers are used, a conventional one situated on the bottom of the pond and a second one covering the lateral wall area of the pond. Heat extraction and supply experiments are performed using both heat exchangers individually or both at the same time. The experiments are conducted under two different seasonal temperature conditions: winter (February and March) and summer (July). The variations of the temperature inside the pond during the heat extraction/supply tests are monitored and analyzed. The results have indicated that the use of solar collectors as an extra source of heat for the solar pond led to a 50% increase in the daily efficiency during the cold season tests, while heat extraction only appeared as the best option during the warm season tests. Higher daily efficiency and heat supply results can only be obtained if large amounts of heat are extracted, otherwise, the daily efficiency of the solar pond could decrease. Finally, the solar collectors can be considered a good alternative for avoiding a significant decrease in solar pond temperatures (especially during the cold season), which would not only result in a significant energy storage efficiency improvement but also increase the capacity of the solar pond to supply heat to an external application.Peer ReviewedPostprint (author's final draft

Simultaneous phosphate and ammonium removal from aqueous solution by a hydrated aluminum oxide modified natural zeolite

A natural zeolite (Z-N), rich in clinoptilolite, was modified (Z-Al) by incorporation of hydrated aluminium oxide (HAlO) for the simultaneous phosphate and ammonium removal. The incorporation of surface hydroxyl groups (ffiAl-OH) into the zeolite structure, as active groups for phosphate removal, was characterized by acid–base titrations (pHPZC= 4.5 ± 0.2). The phosphate sorption increases from 0.6 mg-P/g for Z-N up to 7.0 mg-P/g while only a slight decrease on the ammonium sorption capacity from 33 mg-N/g of Z-N to 30 mg-N/g for Z-Al was observed. The HAlO modified zeolite sorption capacity for both phosphate and ammonium was slightly reduced by common ions typically present in secondary waste water effluents. Column experiments revealed higher enrichment factor for ammonium (120) than for phosphate (50) using 1 M NaOH as elution solution. A reduction of zeolite phosphate capacity with regeneration cycles was observedPostprint (author’s final draft

Thermal performance of 500m2 salinity gradient solar pond in Granada, Spain under strong weather conditions

In this study, an experimental investigation of temperature performance and efficiency of an industrial solar pond during strong winter conditions is presented. Several temperature sensors connected to a data logger were used to measure the temperature gradient in a 500¿m2 solar pond. During the winter 2015 there was a snowfall in the solar pond of Granada (Spain), reaching a minimum air ambient temperature of -2.4¿°C. The temperature of the storage zone in Granada solar pond remained constant (around 40¿°C) indicating the system responds positively to weather variations and confirming the fundamental role of the salinity gradient as a thermal insulation layer. The stored energy during January 2015 was 13.3¿GJ, the weekly efficiency reached 10% and finally, the solar pond was able to provide 247.1¿MJ to the flotation unit during the week of the snowfall.Peer ReviewedPostprint (author's final draft

Recovery of ammonium and phosphate from treated urban wastewater by using potassium clinoptilolite impregnated hydrated metal oxides as N-P-K fertilizer

A natural clinoptilolite in its potassium form (KNC) was modified by impregnation of hydrated metal oxides (HMO) of aluminium (III) (KAlC), iron (III) (KFeC) and manganese (IV) (KMnC) for the simultaneous ammonium and phosphate recovery from urban wastewaters. The resulting pHpzc of the HMOs on the modified zeolites (7.3 ± 0.3 for KAlC, 6.4 ± 0.4 for KFeC and 6.9 ± 0.3 for KMnC) are suitable for phosphate sorption at pH of treated urban wastewaters (6–8). The sorption capacity for phosphate for KAlC and KFeC zeolites is higher at the lower pH range while for KMnC is higher at the upper pH range. Differences were associated to the intrinsic complexing properties of the MOH groups to form outer and inner sphere MOH-phosphate complexes. The maximum phosphate sorption capacity for the three zeolites were 6.8 mg-P/g for KAlC, 7.2 mg-P/g for KFeC and 8.2 mg-P/g for KMnC. Contrary maximum ammonium sorption capacity is kept constant between pH 4–9 for the tree zeolites as the main sorption mechanism is the ion-exchange reaction with K+ ions of the zeolite. The maximum ammonium sorption capacity for the three zeolites ranged from 29 to 33 mg-N/g. These differences on the nature of the sorption processes are also reflected in a much faster sorption kinetic for ammonium than for phosphate although for both species the rate determining step was ions diffusion on the zeolite particles. Modified zeolites shown high selectivity towards ammonium and phosphate in the presence of the dissolved organic matter as well as other ionic species present in the treated wastewaters. Finally, phosphorous (P) fractionation assays of the loaded zeolites confirmed a high phosphate bioavailability if these are applied as phosphate slow release fertilizers in soil applicationsPostprint (author's final draft

Producciones digitales para la fase pre-laboratorio de experimentación en química

Postprint (published version

Eina informàtica basada en el guiatge de l’alumne, per l’anivellament dels coneixements previs de química, de primer curs de la UPC de la titulació d’Enginyeria Industrial, mitjançant la plataforma de suport a la docència (Atenea v.4.0)

Durant aquest projecte s’ha recopilat i estructurat un material didàctic adequat perquè l’alumnat, en especial el que no hagi cursat assignatures de química abans del seu ingrés a la universitat, pugui aconseguir uns coneixements de química convenients per poder seguir eficaçment l’assignatura de Química I, corresponent a la fase selectiva de la titulació d’Enginyeria Industrial impartida a la ETSEIB. A continuació, aquest material s’ha desenvolupat i adaptat dins del recurs de la plataforma de suport docent Atenea v 4.0 la “lliçó”, que permet el guiatge de l'alumnat per la resolució de problemes, afavorint així el seu auto-aprenentatge i per tant l’anivellament dels coneixements de química dels grups de Química I, finalitat principal d’aquest projecte de millora docent. En total s’han creat 4 lliçons diferents : 1: Formulació i nomenclatura de química inorgànica. 2: Gasos i dissolucions. 3: Reaccions químiques. Igualació de reaccions. 4: Estequiometria. Cadascuna d’aquestes lliçons s’ha plantejat amb una part de teoria amb exemples resolts per mostrar-los com a models de resolució, i una altra part amb una sèrie d’exercicis proposats perquè l’alumnat pugui practicar els conceptes associats. Finalment, s’ha implementat durant el primer quadrimestre del curs 2008-09 en els 7 grups (aproximadament 500 alumnes) de l’assignatura mencionada.Peer Reviewe

Materiales digitales para experimentación en química en abierto: UPCommons

Peer ReviewedPostprint (published version