A solar pond is a large body of water having a varying salinity gradient (halodi
ID: 106152 • Letter: A
Question
A solar pond is a large body of water having a varying salinity gradient (halodine) which traps the sun's energy such that the storage layer at the bottom of the pond can reach high temperatures. The bottom zone of a pond can be used as a heat source since that zone has a concentrated salt solution with a higher temperature from absorbing solar radiation. Consider a solar pond power plant operating on a closed Rankine cycle using the storage layer as the boiler heat source, and the upper layer as the heat sink. Using R-134a as the working fluid, specify the operating temperatures and pressures in the cycle, and estimate the required mass flow rate of refrigerant for a net power output of 50 kW. Also estimate the surface area of the pond for this level of continuous power production. Assume that the solar energy is incident on the pond at a rate of 500 W per m^2 of pond area at noontime, and that the pond is capable of storing 15 percent of the incident solar energy in the storage zone. Some Design Considerations (a) Discuss the proposed system with respect to its environmental impact and feasibility, and the sensitivity of selected temperatures and pressures on the thermal efficiency of the power plant. What do you consider to be the major advantages and disadvantages of this system? Your discussion should include the practical aspects of maintaining the system under salinity conditions. In this regard you may have to go through some Internet sites. (b) Justify all values used and derive all equations used starting from the basic energy equation for a flow system (C) Also, discuss the possibility of adding a superheater in proposed system as shown in the figure above.Explanation / Answer
1. A solar pond power plant tells that the maximum thermal power generation with efficiency of 27.94 % and 16.852 kW/m2 of specific power can done by the effective closed Rankine cycle power generator. To do in minimal quantity of making power and constant power production from solar energy supply, a closed Rankine cycle solar power system is a really smart choice. But other factors like maintenance, working cost and broadcast, etc, were overlooked in this analysis and so these have an impact on upcoming power plants propose. Additional research is required in order to test the efficiency achieved from solar power energy removal before going to working applications in these part. The approach is particularly attractive for rural areas in developing countries. Very large area collectors can be set up for just the cost of the clay or plastic pond liner. The accumulating salt crystals have to be removed and can be both a valuable by-product and a maintenance expense. Its efficiency of energy gained is in the type of low grade heating between 70 - 80 °C balanced to an 20 °C ambient temperatures.
Advantage and Disadvantages:
No need for a separate collector for this thermal storage system.
The extremely large thermal mass means power is generated night and day.
Relatively low-temperature operation means solar energy conversion is typically less than 2%.[2]
Due to evaporation non-saline water is constantly required to maintain salinity gradients.
3.The wood-fired, fossil or fuel burning are used as a superheater in which the steam at the outlet of the boiler is heated from 100°C to 250°C.
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