Numerical and experimental analysis of a salt gradient solar pond performance with or without reflective covered surface (original) (raw)
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Performance investigation of a solar pond
Applied Thermal Engineering, 2006
This work consists of both experimental and theoretical parts. In the experimental part, an insulated solar pond with a surface area of 4 m 2 and a depth of 1.5 m was built at Cukurova University in Adana, Turkey to conduct performance experiments. The system was filled with salty water of various densities to form three salty water zones (upper convective, non-convective and heat storage). During the months of January, May and August, a data acquisition device was used to measure and record the temperature readings at various locations in the pond (distributed vertically within and at the bottom of the pond, and horizontally and vertically within the insulated side-walls). In the theoretical part, we developed a performance model to determine the thermal efficiencies of the pond and its various zones. Temperature difference was seen to be the key driving force in heat transfer, particularly in heat rejection. As expected, the highest thermal efficiency was obtained for August as follows: 4.5% for the upper convective zone, 13.8% for the non-convective zone and 28.1% for the heat storage zone, respectively.
Effect of Insulation and Transparent Glass Cover on the Performance of Salt Gradient Solar Pond
In this study a salt gradient solar pond of 6ftx4ftx2ft was constructed whose surface was insulated and covered with transparent glass. The effect of insulation and transparent glass cover on the performance was investigated. Several sensors and thermo couples were placed at different height within the pond to predict to thermal behavior. By measuring of various points of the pond on different dates the temperature profiles of the wall as well as of salt water within the pond were obtained the result shows good agreement with the expected production of solar energy reaching to the reason and metrological air conditions
PLOS ONE
A salinity gradient solar pond (SGSP) is capable of storing a significant quantity of heat for an extended period of time. It is a great option for providing hot water at a reduced energy cost. Additionally, SGSP is used in low-temperature industrial applications such as saltwater desalination, space heating, and power generation. Solar pond thermal performance is dependent on a variety of operational variables, including the soil conditions, the climate of the particular site, the thickness of the solar pond layers, the depth of the water table, and the salt content of the pond. As such, this study examines the thermal performance of a solar pond under a variety of operational conditions. The solar pond model is used to test the thermal performance by simulating two-dimensional heat and mass transport equations. The equations are solved using the finite difference technique utilizing MATLAB® scripts. Salt distributions and temperature profiles are computed for a variety of factors ...
The purpose of this analysis is the development of salt gradient solar pond design to improve the performance of solar pond. The study of previous treatment of internal reflection is considered by dividing the spectrum into a finite no. of spectral wavelength bands. To evaluate the performance of solar pond various method of augmentation are included. Such as based on depth cold sea water as heat sink, auxiliary heat source at high temperature, waste heat, fossil fuels and biomass fuels. In this paper the heat extraction from the lower convective zone or storage zone of salt gradient solar pond with corrugated bottom is investigated with the aim of increasing the overall efficiency of collecting solar radiation. A theoretical analysis is conducted to obtain expression for the variation of temperature with depth of solar pond. The efficiency of the solar ponds depends on thickness of storage zone, temp of delivered heat, the analysis suggests that heat extraction from the storage zone has potential to increase the overall efficiency of solar pond delivering heat at a relatively high temp up to 50% compared with the conventional solar pond the potential gain in efficiency using storage zone heat extraction is attributed to the storage zone that can be achieved with this method. The effects of system and operating parameters of the soar ponds like area enhancement factor (), heat extraction rate, heat capacity rate, depth of the pond on the temp distribution and efficiency have been developed.
New Method for Predicting the Performance of Solar Pond in any Sunny Part of the World
ep.liu.se
The solar pond is considered one of the most reliable and economic solar systems. The collecting and storing of the solar energy is in one system, so the heat in summer can be utilised in winter in the same system. To predict the potential of solar pond at any part of the world a mathematical model is established to calculate the parameters affecting the performance of the solar pond through a computer programme.. The solar radiation input to the pond is calculated using the daily monthly average method. One dimensional steady state and transient assumptions in the gradient zone are used to predict the effect of any parameter on the solar pond performance. The results show excellent agreement with the experimental data under the steady state assumption. Many parameters affecting the performance of the solar pond such as shading effect, depths of the upper, gradient and storage zones, ground temperature and covered insulation for different climates and different latitudes have been studied. The results show that the solar pond has high potential even for colder climates such as that of the UK, where the heat could be used for a number of applications including domestic and industrial.
Modeling and testing a salt gradient solar pond in northeast Ohio
Solar Energy, 1981
A dynamic computer model of a salt gradient solar pond as an annual-cycle solar energy collection and storage system was developed. The model was validated using experimental results of a solar pond located at the Ohio Agricultural Research and Development Center (OARIX~), Wooster, Ohio. The model was then used to analyze the transient energy phenomena which occurred within the storage zone of the pond. Generalized daily weather functions used were the incident solar radiation upon a horizontal surface, the daylight length and the daily maximum and minimum ambient air temperatures. Various simulations were performed to evaluate the OARDC solar pond and to improve its overall effective capacity of heat storage. It was found that 4.6 weeks variation in start-up time and 5-10°C variation in start-up temperature had no effect on late summer peak storage temperature. The pond operated at a 20 per cent collection efficiency with a 1.5-m deep gradient. Insulating the pond in the winter would be beneficial if no heat was removed during the fall. Reducing the gradient zone thickness to I m and enlarging the storage zone could improve the performance of a 3-m deep pond. The model could be used to predict and analyze the transient thermal response of large storages associated with solar heating system for a variety of purposes and climatic conditions.
Performance comparison of aboveground and underground solar ponds
Thermal Science, 2016
This paper deals with the modeling of two different solar ponds which has some different structural parameters such as aboveground and underground, and its performance evaluation. The solar pond system generally consists of three zones, and the densities of these zones decrease from the bottom of the pond to the surface. The most significant decrease in the density distribution of the salt between bottom and up of the pond is the gradient zone. The convective heat loss in the solar pond is prevented with this zone. In this study, aboveground and underground solar ponds were modeled at the same dimensions, but different structural parameters in the same conditions. In this model, the temperature distributions of the solar pond were obtained during a year. The thermal performances of the solar pond were calculated and the results were compared with an experiment. This study shows that the efficiency of the aboveground solar pond is observed to be a maximum of 25.93% in July, a minimum...
Journal of Energy Technologies and Policy, 2013
A numerical investigation on the non-convective salt-gradient solar pond was carried out to study the effect of different variables on the solar pond performance. A numerical computer program was performed to show the relations between the different pond variables. The investigation analysis was performed at selected days (1, 15, and 20 th) of December 2012 at Jordan-Amman climate. The results of investigation show that the temperature of storage zone will increase by decreasing the depth of both UCZ and LCZ and increasing the depth of NCZ.
Thermal behaviour of salt gradient solar ponds
Journal of Physics D-applied Physics, 1987
A numerical model has been developed to study the thermal behaviour of salt gradient solar ponds under different operating conditions. A cylindrical solar pond system with a thermal sink below and around the pond is also modelled to determine the heat losses to the earth. In these calculations, the solar pond is considered as a steady-state flat-plate collector. The effects of the thickness of three different zones and insulating materials below and around the pond on the overall thermal performance of the pond are studied. There is an optimum thickness of the non-convective zone for which the heat storage is maximum. The pond bottom and side heat losses are reduced using some low-cost insulating building materials such as dry dune sand, dry mica powder and dry marble dust below and around the pond. The results of a comparative study indicate that heat losses are considerably reduced with marble dust insulation and the solar thermal energy retaining capability of the pond is improved.
A salinity gradient solar pond (SGSP), termed in this work "solar pond", is a simple and effective way of capturing and storing solar energy. This paper presents the results of temperature developed in the inner zones of a salinity gradient solar pond model (SGSPM) under Egyptian solar radiation climate conditions during 2010. An insulated solar pond model with a surface area of 1.5 m × 1.5 m and a depth of 1.44 m was constructed at Faculty of Agriculture, Zagazig University, Sharkia Governorate, Egypt (Latitude 30o 35/N, Longitude 31o 31/E). SGSPM filled with prepared different concentrations of sodium chloride salt in water of densities to form salty water zones (upper convective zone, UCZ, the non-convective zone, NCZ, and the lower convective zone, LCZ, with thickness of 0.1, 0.6 and 0.74 m, respectively). The salinity difference between UCZ and LCZ was 6% for 1st experiment, 10% for 2nd experiment and 15 % for 3rd experiment. Twelve temperature sensors (thermocouples type "T") were distributed vertically at different locations along the centered inner zones of the pond to measure temperature variations during day times. Temperature difference was an important indicator for forced heat transfer. The highest stored temperature was obtained from 3rd experiment as follow: 38.3, 49.9 and 53.5oC for UCZ, NCZ and LCZ, respectively in April; 39.1, 52.6 and 58.8oC in June; 24.7, 31.8 and 37.9oC in December. A mathematical analysis was conducted to calculate the efficiency of the solar pond in collecting solar energy. It is noticed that, the collection efficiency of the solar pond was about 29.2 % by SGSPM with a depth of 1.44 m under Egyptian climate conditions.