Temperature evolution of an experimental salt-gradient solar pond

2010 ◽  
Vol 1 (4) ◽  
pp. 246-250 ◽  
Author(s):  
F. Suárez ◽  
A. E. Childress ◽  
S. W. Tyler
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Thermal Evolution ◽  
Low Cost ◽  
Heat Extraction ◽  
Low Grade ◽  
Distributed Temperature Sensing ◽  
Solar Pond ◽  
Thermal Desalination ◽  
Salt Gradient

A salt-gradient solar pond is a low-cost, large-scale solar collector with integrated storage that can be used as a source of energy in low-grade-heat thermal desalination systems. This work presents the thermal evolution of an experimental solar pond for both the maturation and heat extraction time periods. The temperature profile was measured every 1.1 cm using a vertical high-resolution distributed temperature sensing (DTS) system, with a temperature resolution of 0.04ºC. Temperatures of 34 and 45ºC were achieved in the bottom of the pond when the lights were on for 12 and 24 hours per day, respectively. Heat was extracted at a rate of 139 W from the solar pond, which corresponded to an efficiency of 29%. Stratification and mixing were clearly observed inside the solar pond using the vertical high-resolution DTS system.

scholarly journals Assessment of a vertical high-resolution distributed-temperature-sensing system in a shallow thermohaline environment

2011 ◽  
Vol 15 (3) ◽  
pp. 1081-1093 ◽  
Author(s):  
F. Suárez ◽  
J. E. Aravena ◽  
M. B. Hausner ◽  
A. E. Childress ◽  
S. W. Tyler
Keyword(s):  
High Resolution ◽  
Temperature Sensing ◽  
Distributed Temperature Sensing ◽  
Temperature Resolution ◽  
Spatial And Temporal Scales ◽  
Solar Pond ◽  
Salt Gradient ◽  
Time Averages ◽  
Corrosive Environments ◽  
And Storage

Abstract. In shallow thermohaline-driven lakes it is important to measure temperature on fine spatial and temporal scales to detect stratification or different hydrodynamic regimes. Raman spectra distributed temperature sensing (DTS) is an approach available to provide high spatial and temporal temperature resolution. A vertical high-resolution DTS system was constructed to overcome the problems of typical methods used in the past, i.e., without disturbing the water column, and with resistance to corrosive environments. This paper describes a method to quantitatively assess accuracy, precision and other limitations of DTS systems to fully utilize the capacity of this technology, with a focus on vertical high-resolution to measure temperatures in shallow thermohaline environments. It also presents a new method to manually calibrate temperatures along the optical fiber achieving significant improved resolution. The vertical high-resolution DTS system is used to monitor the thermal behavior of a salt-gradient solar pond, which is an engineered shallow thermohaline system that allows collection and storage of solar energy for a long period of time. The vertical high-resolution DTS system monitors the temperature profile each 1.1 cm vertically and in time averages as small as 10 s. Temperature resolution as low as 0.035 °C is obtained when the data are collected at 5-min intervals.

scholarly journals Assessment of a vertical high-resolution distributed-temperature-sensing system in a shallow thermohaline environment

2011 ◽  
Vol 8 (1) ◽  
pp. 29-58
Author(s):  
F. Suárez ◽  
J. E. Aravena ◽  
M. B. Hausner ◽  
A. E. Childress ◽  
S. W. Tyler
Keyword(s):  
High Resolution ◽  
Temperature Sensing ◽  
Distributed Temperature Sensing ◽  
Temperature Resolution ◽  
Spatial And Temporal Scales ◽  
Solar Pond ◽  
Salt Gradient ◽  
Corrosive Environments ◽  
First Time ◽  
And Storage

Abstract. In shallow thermohaline-driven lakes it is important to measure temperature on fine spatial and temporal scales to detect stratification or different hydrodynamic regimes. Raman spectra distributed temperature sensing (DTS) is an approach available to provide high spatial and temporal temperature resolution. A vertical high-resolution DTS system was constructed to overcome the problems of typical methods used in the past, i.e., without disturbing the water column, and with resistance to corrosive environments. This system monitors the temperature profile each 1.1 cm vertically and in time averages as small as 10 s. Temperature resolution as low as 0.035 °C is obtained when the data are collected at 5-min intervals. The vertical high-resolution DTS system is used to monitor the thermal behavior of a salt-gradient solar pond, which is an engineered shallow thermohaline system that allows collection and storage of solar energy for a long period of time. This paper describes a method to quantitatively assess accuracy, precision and other limitations of DTS systems to fully utilize the capacity of this technology. It also presents, for the first time, a method to manually calibrate temperatures along the optical fiber.

1-D Model Analysis of Tesla Turbine for Small Scale Organic Rankine Cycle (ORC) System

2017 ◽  
Author(s):  
Jian Song ◽  
Chun-wei Gu
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Organic Rankine Cycle ◽  
Axial Flow ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Working Fluid ◽  
Small Scale ◽  
Low Grade ◽  
D Model

Energy shortage and environmental deterioration are two crucial issues that the developing world has to face. In order to solve these problems, conversion of low grade energy is attracting broad attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be one of the most effective methods for the utilization of low grade heat sources. Turbine is a key component in ORC system and it plays an important role in system performance. Traditional turbine expanders, the axial flow turbine and the radial inflow turbine are typically selected in large scale ORC systems. However, in small and micro scale systems, traditional turbine expanders are not suitable due to large flow loss and high rotation speed. In this case, Tesla turbine allows a low-cost and reliable design for the organic expander that could be an attractive option for small scale ORC systems. A 1-D model of Tesla turbine is presented in this paper, which mainly focuses on the flow characteristics and the momentum transfer. This study improves the 1-D model, taking the nozzle limit expansion ratio into consideration, which is related to the installation angle of the nozzle and the specific heat ratio of the working fluid. The improved model is used to analyze Tesla turbine performance and predict turbine efficiency. Thermodynamic analysis is conducted for a small scale ORC system. The simulation results reveal that the ORC system can generate a considerable net power output. Therefore, Tesla turbine can be regarded as a potential choice to be applied in small scale ORC systems.

Transient heat extraction modeling method for a rectangular type salt gradient solar pond

2017 ◽  
Vol 132 ◽  
pp. 316-326 ◽  
Author(s):  
Mohamad Aramesh ◽  
Fathollah Pourfayaz ◽  
Alibakhsh Kasaeian
Keyword(s):  
Modeling Method ◽  
Heat Extraction ◽  
Solar Pond ◽  
Salt Gradient

scholarly journals Heat extraction from the ANL research salt gradient solar pond

1986 ◽  
Author(s):  
J. Hull ◽  
A. Scranton ◽  
J. Mehta ◽  
S. Cho ◽  
K. Kasza
Keyword(s):  
Heat Extraction ◽  
Solar Pond ◽  
Salt Gradient

scholarly journals Design and Development of Low-Cost Solar Electricity Generation System with Heliostat to Ensure the Optimum Uses of Rated Capacity of Solar Cells

2020 ◽  
pp. 113-116
Keyword(s):  
Flat Plate ◽  
Electricity Generation ◽  
Large Scale ◽  
Tracking System ◽  
Low Cost ◽  
Low Grade ◽  
The Sun ◽  
Solar Panels ◽  
Generation System ◽  
Solar Electricity

Almost all solar electricity generation systems are now operated with flat plate solar panels. These flat plate solar panels have a lot of expensive collector area although still deliver only low-grade temperature which is a boundless problem for assuring the optimum uses of the rated capacity of solar panels. Using heliostats can reduce this problem significantly. Heliostats consist of a single or a set of mirrors that track the sun’s position and reflect the sun rays into a central receiving point. With the movement of the sun, these mirrors are adjusted accordingly to track the sun to ensure the highest amount of sunlight reflected onto the same collection point. The system is cheaper than any other solar tracking system presently used in our country. This paper describes an improved design of a solar electricity generation system having a capacity of 1Wp with heliostats on an experimental basis. It will also demonstrate a comparison of a generation of a 1Wp solar system with and without heliostats. Successful outcomes of this experiment will lead us to implement the heliostats-based tracking system into the large-scale solar electricity generation systems.

scholarly journals Effect of heat extraction on the thermal efficiency of salt gradient solar pond

2018 ◽  
Vol 37 (5) ◽  
pp. 1502-1515
Author(s):  
Qi Wu ◽  
Hua Wang ◽  
Shukuan Xie ◽  
Liugang Zhang ◽  
Jie Wang ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Heat Extraction ◽  
Solar Pond ◽  
Salt Gradient

scholarly journals A Novel Low-Cost, High-Resolution Camera System for Measuring Peat Subsidence and Water Table Dynamics

2021 ◽  
Vol 9 ◽  
Author(s):  
Chris D. Evans ◽  
Nathan Callaghan ◽  
Adi Jaya ◽  
Alistair Grinham ◽  
Sofie Sjogersten ◽  
...  
Keyword(s):  
High Resolution ◽  
Water Table ◽  
Large Scale ◽  
Low Cost ◽  
Ghg Emissions ◽  
Time Lapse ◽  
Surface Elevation ◽  
Carbon Loss ◽  
Camera System ◽  
Peat Surface

Peatlands are highly dynamic systems, able to accumulate carbon over millennia under natural conditions, but susceptible to rapid subsidence and carbon loss when drained. Short-term, seasonal and long-term peat surface elevation changes are closely linked to key peatland attributes such as water table depth (WTD) and carbon balance, and may be measured remotely using satellite radar and LiDAR methods. However, field measurements of peat elevation change are spatially and temporally sparse, reliant on low-resolution manual subsidence pole measurements, or expensive sensor systems. Here we describe a novel, simple and low-cost image-based method for measuring peat surface motion and WTD using commercially available time-lapse cameras and image processing methods. Based on almost two years’ deployment of peat cameras across contrasting forested, burned, agricultural and oil palm plantation sites in Central Kalimantan, Indonesia, we show that the method can capture extremely high resolution (sub-mm) and high-frequency (sub-daily) changes in peat surface elevation over extended periods and under challenging environmental conditions. WTD measurements were of similar quality to commercially available pressure transducers. Results reveal dynamic peat elevation response to individual rain events, consistent with variations in WTD. Over the course of the relatively severe 2019 dry season, cameras in deep-drained peatlands recorded maximum peat shrinkage of over 8 cm, followed by partial rebound, leading to net annual subsidence of up to 5 cm. Sites with higher water tables, and where borehole irrigation was used to maintain soil moisture, had lower subsidence, suggesting potential to reduce subsidence through altered land-management. Given the established link between subsidence and CO2 emissions, these results have direct implications for the management of peatlands to reduce high current greenhouse gas (GHG) emissions. Camera-based sensors provide a simple, low-cost alternative to commercial elevation, WTD and GHG flux monitoring systems, suitable for deployment at scale, and in areas where existing approaches are impractical or unaffordable. If ground-based observations of peat motion can be linked to measured GHG fluxes and with satellite-based monitoring tools, this approach offers the potential for a large-scale peatland monitoring tool, suitable for identifying areas of active carbon loss, targeting climate change mitigation interventions, and evaluating intervention outcomes.

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