Energy, exergy and thermoeconomic analysis of an industrial solar pond

This study evaluates the viability of an industrial salinity gradient solar pond during two operating seasons (2014 and 2015). The Granada solar pond was built to supply low-temperature heat (up to 60 °C) to satisfy the temperature requirements of the flotation unit in a mineral processing plant (Solvay Minerales in Granada (Spain)). Energy analysis indicates that the non-convective zone (NCZ) and the upper convective zone (UCZ) have low efficiencies because these zones have a low capacity to store heat, and no heat extractions are carried out from these zones. In contrast, heat extraction in the lower convective zone (LCZ) has a positive impact on the system because it increases the capacity of the solar pond to store energy. Higher efficiencies were achieved in the second operation period in the LCZ, since higher amount of heat was extracted during this period. The overall exergy efficiency of the LCZ after the first and second operation periods was 1.6% and 2.3%, respectively. The solar pond works at temperatures close to room temperature and thus the exergetic efficiency decreases significantly. Regarding the thermoeconomic analysis, the cost of exergy stored is studied in this work, using two different approaches, by estimating the minimum price for exergy stored or the minimum surface area that ensure the thermoeconomic viability. The price of the stored exergy tends to decrease inversely to the price of fuel oil. Thus, the cost of the stored exergy must be four to five times higher than the price of fuel oil for the solar pond system to be feasible. On the other hand, solar pond technology is affected by economies of scale; the larger the solar pond, the higher the inflation rates and the lower the cost reduction rates that can be accommodated. This implies that estimating the cost of the stored exergy is complex due to the variability of the processes involved and can lead to erroneous interpretations when evaluating the viability of a solar pond from a thermoeconomic perspective.Peer ReviewedPostprint (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

Síndrome de Gitelman y condrocalcinosis. Revisión de un caso clínico

El síndrome de Gitelman es una tubulopatía de herencia autosómica recesiva que cursa, entre otras manifestaciones, con hipomagnesemia e hipocalciuria. Se presenta el caso de una paciente mujer de 68 años que acudió a consulta por artritis de grandes articulaciones en ausencia de otra sintomatología. En el estudio radiológico se observaron depósitos de pirofosfato cálcico en rodillas, sínfisis púbica y otras articulaciones. En la analítica destacaba hipomagnesemia e hipocalciuria compatibles con síndrome de Gitelman que se confirmó tras estudio genético

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 Reviewe