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Ericsson heat engine for small solar power plants

Ernst Kussul, O. Makeyev, T. Baidyk, O. Olvera

CCADET, UNAMekussul@unam.mx

tel.:56-22-86-02 ext.1204

At present, Stirling cycle and Rankine cycle heat engines are used to transform the heat energy of solar concentrators to mechanical and electrical energy. The Rankine cycle is used for large-scale solar power plants. The Stirling cycle can be used for small-scale solar power plants. The Stirling cycle heat engine has many advantages such as high efficiency, long service life, silent operation, etc. However, the Stirling cycle is good for high temperature difference (up to 700 C). It demands the use of expensive materials and has problems of lubrication. Its efficiency depends on the efficiency of the heat regenerator. The design and manufacture of a heat regenerator is not a trivial problem because the regenerator has to be placed in the internal space of the engine. It is possible to avoid this problem if we place the regenerator out of the internal engine space. To realize this idea it is necessary to develop the Ericsson cycle heat engine. We propose a structure of this engine. A computer simulation was made to evaluate the Ericsson engine parameters. In this article we discuss the obtained results.

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Map of solar energy of the world

Map of solar energy in Mexico

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This map shows the amount of solar energy in hours, received each day on an optimally tilted surface during the worst month of the year for sourthern USA, Mexico, Central America and northern South America. Source: NREL.

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Solar Concentrators

Concentrator “Parabolic Trough”

Solar Concentrator ”Parabolic Dish”

Concentrator “Tower”

Solar Concentrator “White Cliffs”, Australia

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G. Johnston, Focal region measurements of the 20 m2 tiled dish at the Australian National University, Solar Energy, Vol.63, No.2, 1998, pp. 117-124.

Prototype of solar concentrator,Mexico, 2012

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Publications (Solar Concentrator)• Kussul E., Baidyk T., Lara F., Saniger J., Bruce N.,

Estrada C., Micro facet solar concentrator, International Journal of Sustainable Energy, 2008, Vol.27, Issue 2, pp.61-71.

• Kussul E., Baidyk T., Lara-Rosano F., Jose M. Saniger Blesa, Neil Bruce, Concentrador Solar, UNAM, 18.04.2008, Instituto Mexicano de Propiedad Industrial, Solicitud MX/a/2008/005063, (en proceso).

• E. Kussul, T. Baidyk, O. Makeyev, F. Lara-Rosano, J. M. Saniger, N. Bruce, Development of Micro Mirror Solar Concentrator, WSEAS Transactions on Power Systems, Issue 8, Vol. 2, August 2007, pp. 188-194.

STIRLING ENGINE

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Ericsson engine

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Table 1. Ericsson engine parameters

Engineversion P1

(bar)

Tc

(°K)

Th

(°K)

Tc1

(°K)

Th6

(°K)

T3-2

(°K)

T5-4

(°K)

V1

(m3/s)

W

1 20 1.2 263 353 2 2 5 5 0.01 2889 0.186 0.255 0.73

2 20 1.1 263 353 2 2 5 5 0.01 1675 0.189 0.255 0.743

3 20 1.3 263 353 2 2 5 5 0.01 3740 0.174 0.255 0.682

4 20 1.2 263 353 1 1 2 2 0.01 2982 0.201 0.255 0.789

5 20 1.2 263 353 0.5 0.5 1 1 0.01 3030 0.207 0.255 0.814

6 20 1.2 300 673 2 2 5 5 0.01 12453 0.499 0.554 0.9

7 20 1.2 300 673 1 1 2 2 0.01 12567 0.515 0.554 0.93

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T C TC

Scheme of compressor/expander for Ericsson heat engine

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Intake wheel Exhaust wheel

Intake piston Exhaust piston

Intake port Exhaust port

Intake windows Exhaust windows

Main cylinder

Main piston

Main wheel

Time diagram of compressor windows

opening

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Time diagram of expander windows

opening

Conclusion

The Ericsson cycle heat engine can be used to transform heat energy of a solar concentrator to mechanical energy. At present the Stirling cycle and the Rankine cycle are used for this purpose. The problem of these cycles is relatively low Carnot efficiency. For practically developed Stirling and Rankine heat engines Carnot efficiency reaches 0.6. To obtain good overall efficiency it is necessary to increase the temperature of the concentrator up to 700 C. Special expensive materials are needed to create a heat engine working at such a temperature. If Carnot efficiency is higher, for example 0.8-0.9, the temperature of the solar concentrator can be as low as 400 C. This temperature permits us to make heat engines from low cost materials. A special computer program was developed for estimation of parameters for the Ericsson cycle heat engine. Experiments with this program show that Ericsson cycle can have Carnot efficiency more than 0.9.

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Thank you for your attention