Parametric Analysis of Various Working Fluids for Solar Pond Electricity Generation

Parametric Analysis of Various Working Fluids for Solar Pond Electricity Generation

Piyush Jain11

M.Tech in Production Engg., RIET, Jaipur, Rajasthan (India)

Simple Agarwal 2

2 Assistant Professor, Mechanical department, Gurgaon Institute of Technology & Management, Bilaspur, Haryana (India)

Hemant Bansal 3

3 M.Tech in Production Engg., Poornima College, Jaipur, Rajasthan (India)

ABSTRACT-Solar-thermal power plants have enjoyed limited success in the energy market till date. The ability to better characterize the performance of existing solar-thermal technologies as well as investigate the potential of new technologies is a crucial step in developing more economically viable designs. Organic Rankine cycle is primarily used to generate power from low temperature applications. . Organic Rankine cycle similar to conventional Rankine cycle the only change is that instead of water as working fluid, organics fluids like refrigerates and azeotropes are used. ORC proves to be a good option for a small and medium sized plant, generally of less than 10 KW

The objective of this report is to evaluate the various working fluids to extract the energy from a low grade and low temperature heat sources like solar power, geothermal and waste heat recovery. Organic Rankine cycles have unique properties that are well suited to solar power generation. The thermodynamic potential of a variety Organic Rankine cycle working fluids and configurations are analyzed. To check for appropriate working fluid various working fluids have been analyzed like R-236fa,R-236ea,R-245ca and toluene

The parametric study of various working fluids on excel sheet for turbine inlet pressure is being done along with it, efficiency calculation based on recuperation and no recuperation is being done and the graphs are plotted as the result of the study

INTRODUCTION

The global demand for energy continues to increase while traditional energy resources are becoming scarcer. Exacerbating the situation is growing realization that the use of traditional fuels carries a significant environmental burden. Adoption of environmentally benign and renewable energy conversion technologies is essential if our society is to retain its advanced lifestyle in the face of global development

Economic opportunity drives the energy market just as it drives every market

Maximizing the economic opportunity associated with safe and renewable energy technologies is an essential step towards increasing their use. Taxes, penalties, incentives, public awareness and government mandates can all influence the economic opportunity associated with renewable energy technology. The principle focus of this thesis, however, is improving economic opportunity by providing tools for the evaluation and optimization of several specific renewable technologies: organic Rankine power cycles and thermal energy storage

Parabolic trough solar-thermal power generation is a proven technology. With several utility scale plants in operation for nearly 20 years. Current large-scale systems rely on traditional steam based Rankine cycles for power production. Organic Rankine cycle per plant are more compact and less costly than traditional steam cycle power plants and are able to better exploit lower temperature thermal resources. Utilizing organic Rankine cycles allows solar-thermal power generation to become a more modular versatile means of supplanting traditional fuels. While they have great potential, organic Rankine cycles have received relatively little attention

ORGANIC RANKINE CYCLE

Organic Rankine cycles are analogous to traditional steam Rankine cycles with an organic fluid as the working fluid in place of water. Many different organic fluids have been proposed and utilized as ORC working fluids, and fluids of particular interest for solar power applications .The following is a brief list of fluids that have been used or proposed for use in Rankine cycles: Toluene, Xylene, n- butane, R-11, R-22, R-248

The component processes that occur between the state points labeled as shown in fig are as follows:

1-2 The working fluid is expanded through a turbine

2-3 The turbine exhaust is used to preheat the working fluid exiting the pump

3-4 The working fluid is condensed

4-5 The working fluid is pumped from to high pressure 5-6 The working fluid is heated by turbine exhaust

6-1 Heat is added to the working fluid

SOLAR POND

They are large shallow bodies of water that are arrange so that the temperature gradient are reversed from the normal. This allows the use for collection and storage of solar energy which may, under ideal conditions, be delivered at temperature 40-50 C above normal

ZONE OF SOLAR POND

1. UCZ (Upper Convecting Zone) : Top layer

1. This is a zone, typically .3m thick, of almost low salinity which is almost close to ambient temperature

2. UCZ is the result of evaporation, wind induced mixing, and surface flushing

3. Usually this layer is kept as thin as possible by use of wave suppressing mesh or by placing wind breaks near the ponds

2. NCZ (Non Convecting Zone) : Middle layer

1. In this zone both salinity and temperature increases with depth

2. The vertical salt gradient in the NCZ inhibits convection and thus gives insulation effect

3LCZ (Lower Convecting Zone) : Top layer

1. This is a zone of almost constant, relatively high salinity (typically 20% by weight) at high temperature.

2. Heat is stored in the LCZ, which should be sized to supply energy continuously throughout the year

ORGANIC RANKINE MODEL

The model is designed to compare and evaluates the potential organic Rankine cycle configuration

THERMODYNAMIC ANALYSIS AND PARAMETRIC STUDY

In research work, thermodynamic analysis of various working fluids like toluene, R-236fa, R236ea, R-245fa and

R-134a is done. A parametric study was carried out to obtain the cycle efficiency of ORC along various saturation pressures. This is done to find the effect of turbine inlet pressure on the efficiency of the cycle

CALCULATIONS FOR DIFFERENT WORKING FLUIDS

CONCLUSION

Various working fluids were analyzed with varying turbine inlet pressure and various graphs were plotted to show the effect of turbine inlet pressure on various parameters

1. The fig 5.1 shows the plot for the efficiency of various working fluids at various turbine inlet pressure from the figure it can be said that the toluene reaches to the maximum efficiency but the effect of turbine pressure is more in case of toluene whereas the effect is much less on the rest of the fluids

2. Fig 5.2 shows the plot for mass flow rate of the various working fluids required for generation of nominal power 1MW.From the graph it is seen that the toluene requires the most minimal mass flow rate for the same R-236fa requires much more mass flow rate as compare to rest of fluids. Thus the toluene suits the most viable option according to mass flow rate

3. Fig 5.3 depicts the heat addition required in the boiler generation of the same turbine work under different turbine inlet pressure fig 5.3 toluene requires the less heat addition

4. From the above graphs, it is indicated that the toluene gives out to be the best option for a 1 MW solar operated power plant .The other important analysis done here is the effect of recuperate on the overall efficiency of the plant

5. Fig 5.4indicates the increase in the efficiency of the plant with use of recuperation for toluene

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