Supported by National Nature Science Foundation of China (NSFC)
Time: Aug., 2008 ~ Jul., 2009
The applications of renewable energies (such as solar energy, wind energy, and biomass) to electricity generation become more and more important, and have received increasing attentions. In this research, a low-temperature solar Rankine system utilizing zeotropic refrigerant as the working fluid is proposed and an experimental system is designed, constructed and tested. Both the evacuated solar collectors and the flat plate solar collectors are compared in the experimental system, meanwhile, a stable rolling-piston expander is designed for the system.
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| Schematic program of the low-temperature solar Rankine cycle system |
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(a) Solar collector arrays. (b) Gas tank, liquid tank, condenser and evaporator. (c) Cooling tower and equipment room. (d) R245fa feed pump and expander. |
In this team, my job was to reveal the heat transfer characteristics of solar collector and working fluid. In this research, I chose R245fa as working fluid for the follow reasons:
1. R245fa has a lowe GWP;
2. R245fa belongs B1 safety class which means non-inflammability;
3. R245fa has high molecular weight to minimize the rotational speed or the number of turbine stages and to allow for reasonable mass flow rates and turbine nozzle areas;
R245fa possesses its own advantage in the operation of the low-temperature solar Rankine cycle system. Comparing with CO2 and R134a, R245fa has a lower pressure level, thus cheaper solar collectors and equipments could be used. Comparing with pentane and ammonia, R245fa’s advantage is the non-flammability, thus the safety of the system is certifiable. However, the experimental research of R245fa utilized in low-temperature solar Rankine cycle is still blank. Therefore, a low-temperature solar powered Rankine cycle system is designed and built by the authors in Tianjin, China. Utilizing a tailor-made R245fa expander, solar energy can be converted into shaft power in the system, and the remainder heat is still available for other uses. The objective of this paper is to introduce the proposed low-temperature solar Rankine cycle system and to investigate the performance of R245fa utilized in the system by experimental work with the typical weather conditions in Tianjin, China.
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| Rankine cycle efficiency of the experiment system |
Publication:
[1] X.D. Wang, L. Zhao, J.L. Wang, W. Wu, etal. Performance evaluation of a low-temperature solar Rankine cycle system utilizing R245fa. Solar energy, 2010, 84:353-364.