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Science Bulletin

, Volume 60, Issue 4, pp 460–469 | Cite as

Energy analysis of a hybrid solar concentrating photovoltaic/concentrating solar power (CPV/CSP) system

  • Xue Han
  • Chao XuEmail author
  • Xing Ju
  • Xiaoze DuEmail author
  • Yongping Yang
Article Engineering Sciences

Abstract

This study presents a novel solar concentrating photovoltaic/concentrating solar power (CPV/CSP) hybrid system, which mainly contains CPV modules with an evaporative cooling subsystem, a thermal receiver and an organic Rankine cycle (ORC). The cooling fluid is boiled when cooling the CPV modules, and superheated vapor that is effective for power generation with an ORC is generated after absorbing low-concentration solar radiation in the thermal receiver. A steady-state physical model is developed to carry out energy analysis of the hybrid system. The results show that when saturated vapor is fed into the thermal receiver, the peripheral low-concentration solar radiation that is discarded in conventional CPV or CPV/thermal systems is effective to get a high-temperature superheated vapor (e.g., above 120 °C). The overall solar-to-electricity efficiency can be increased from 28.4 % for the conventional CPV system to 44 % for the hybrid system with 500 suns. Even though the overall efficiency decreases from 44.0 % to 36.8 % when the concentration ratio increases from 500 to 2,000 suns, there is still a considerable efficiency improvement compared with the conventional CPV systems. The results indicate that the proposed hybrid system provides a viable solution for solar power generation with high efficiencies.

Keywords

Hybrid CPV/CSP system Annular solar thermal receiver Evaporative cooling Organic Rankine cycle 

List of symbols

A

Area (m2)

d

Diameter (m)

err

Error

\( \varvec{h} \)

Enthalpy (\( {\text{kJ}}/({\text{kg K}}) \)) or convective heat transfer coefficient (\( {\text{W}}/({\text{m}}^{2} \;{\text{K}}) \))

\( \varvec{I} \)

Current (A)

\( \varvec{k}_{{\mathbf{B}}} \)

Boltzmann’s constant \( ( {\text{m}}^{2} \;{\text{kg}}/({\text{s}}^{2} \;{\text{K}}) ) \)

\( \varvec{n} \)

Diode ideality factor

\( \varvec{Nu} \)

Nusselt number

\( \varvec{N}/\varvec{ X} \)

Concentration ratio

\( \varvec{P} \)

Electricity energy (W)

\( \varvec{Pr} \)

Prandtl number

\( \varvec{Q} \)

Energy (W)

\( \varvec{q} \)

Elementary charge (C) or heat flux (W/m2)

\( \varvec{q}_{\varvec{m}} \)

Mass flow (kg/s)

\( \varvec{R} \)

Series resistance (Ω) or heat resistance (\( {\text{K m}}^{2} /{\text{W}} \))

\( \varvec{r} \)

Radius (m)

\( \varvec{Re} \)

Reynolds number

\( \varvec{T} \)

Temperature (°C)

\( \varvec{V} \)

Voltaic (V)

\( \varvec{v}\text{/}\varvec{u} \)

Velocity (m/s)

\( \varvec{v}_{\varvec{f}} \)

Kinematic viscosity (m2/s)

\( \varvec{W} \)

Output power (W)

x

Quality

Greek symbols

η

Efficiency

ε

Emissivity

σ

Standard deviation or Stefan–Boltzmann constant

β

Temperature coefficient

ρ

Reflectivity or density (kg/m3)

λ

Thermal conductivity (W/(m K))

Subscripts

ab

Absorbed

air

Air

ave

Average

c

Concentration ratio

conv

Convective heat loss

CPV

DA-CPV (dense-array concentrated photovoltaic)

CSP

Concentrating solar power

em

Emissive heat loss

g

Gas

I

Current

in

Incident or inlet

l

Liquid

loss

Heat loss

m

Mass

max

Maximum

n

Natural convection

oc

Open circuit

out

Output or outlet

p

Pipes

R

R134a

r

Reference point

ref

Reflective heat loss

s

Surface

sc

Short circuit

sky

Sky

so

Solar cells

V

Voltage

w

Wall surface

一种聚光光伏/光热混合发电系统能量分析

摘要

为了提高聚光光伏系统的能量利用效率, 本文提出了一种新型的聚光光伏/光热混合发电系统, 该系统主要由带有蒸发冷却装置的聚光光伏模块、光热接收器和有机朗肯循环组成. 液体有机工质在冷却聚光光伏模块时吸热蒸发, 而后流经外围低聚光光热接收器时加热成为过热蒸汽, 最终经由有机朗肯循环发电. 针对该混合发电系统, 本文提出了稳态模型, 并进行了系统能量分析. 结果表明利用聚光光伏模块外围的低聚光能量可以有效产生较高温度 (例如, 大于 120 °C) 的过热蒸汽. 当聚光比为500倍时, 该系统可以将整体光电转换效率从传统的聚光光伏电池的28.4 %显著提高到44 %. 因此, 该混合发电系统为太阳能的更高效率发电提供了新的发展方向.

Notes

Acknowledgments

This work was supported by the National Natural Science Foundation of China (51106149 and 51406051), the Fundamental Research Funds for the Central Universities and the Foundation of Key Laboratory of Thermo-Fluid Science and Engineering (Xi’an Jiaotong University), Ministry of Education, Xi’an 710049, China.

Conflict of interest

The authors declare that they have no conflict of interest.

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Copyright information

© Science China Press and Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education, School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijingChina

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