A Calculation Method of Average Fluid Temperature in Solar Collector

doi:10.12096/j.2096-4528.pgt.21071

Abstract

Abstract:

The solar collector is an important equipment for photo-thermal conversion. It can be used not only for centralized energy utilization by tower thermal power generation technology, but also for distributed energy utilization by disc thermal power generation technology. Therefore, it is necessary to evaluate the thermal performance of solar collectors. A new method was proposed to calculate the average fluid temperature of solar collectors. The experimental results show that the calculation results are in good agreement with the experimental data, which proves that the method can predict the average fluid temperature of solar collector. The effect of different parameters on thermal efficiency was also investigated to better acquire the thermal performance of solar collectors. The results show that when the input power is constant, increasing the flow rate can effectively improve the efficiency of solar collector. When the flow rate is constant, the efficiency of solar collector increases first and then decreases with the increase of input power. The efficiency of solar collector is inversely proportional to the inlet temperature and proportional to the ambient temperature.

Key words: solar thermal power generation, solar collector, average fluid temperature, thermal performance

CLC Number:

TK 51

Li XU, Feihu SUN, Zhi LI, Qiangqiang ZHANG. A Calculation Method of Average Fluid Temperature in Solar Collector[J]. Power Generation Technology, 2022, 43(3): 405-412.

Figures/Tables 15

Fig. 1 Structure of solar collector

Fig. 2 Structure of receiver panel

Fig. 3 Structure of experimental platform

Tab. 1 Structural parameters of solar collector

结构	管板数	单个管板吸热管数	外径/mm	壁厚/mm	采光口面积/m²
腔式太阳能集热器	7	4	14	1.4	0.12

Tab. 2 Parameter values under reference condition

m ˙

/(kg·s^-1)

v_w/(m·s^-1)

ε_p

ε_r

k_p/

(W·m^-1·K^-1)

Tab. 2 Parameter values under reference condition

参数

Q_net,in/kW

T_a/K

T_fi/K

m ˙

/(kg·s^-1)

v_w/(m·s^-1)

ε_p

ε_r

k_p/

(W·m^-1·K^-1)

数值

140

293.15

493.15

0.5

0.66

0.8

Tab. 3 Ranges and uncertainties of test parameters

参数	范围	不确定度
输入功率	0~200 kW	±0.5%
入口温度	0~510 ℃	±1.5 ℃
出口温度	0~510 ℃	±1.5 ℃
环境温度	5~40 ℃	±1.5 ℃
体积流量	0~24 L/min	±1%

Fig. 4 Inlet temperature and input power of solar collector

Fig. 5 Ambient temperature and mass flow rate of solar collector

Fig. 6 Comparison between calculation results and experimental data of average fluid temperature

Fig. 7 Maximum relative error between calculation results and experimental data of average fluid temperature under different working conditions

Fig. 8 Distribution of input power of solar collector

Fig. 9 Thermal efficiency of solar collector under different input power distributions

Fig. 10 Effect of inlet and ambient temperature on thermal efficiency of solar collector

Fig. 11 Effect of input power and mass flow rate on thermal efficiency of solar collector

Fig. 12 Sensitivity analysis of different parameters on thermal efficiency

References 23

1	张哲旸，巨星，潘信宇，等.太阳能光伏‒光热复合发电技术及其商业化应用[J]．发电技术，2020，41(3)：220-230．
	ZHANG Z Y， JU X， PAN X Y，et al. Photovoltaic/concentrated solar power hybrid technology and its commercial application[J]．Power Generation Technology，2020，41(3)：220-230．
2	张晓东，牛海明．槽式光热电站镜场效率计算模型与仿真分析[J]．分布式能源，2020，5(5)：56-63． doi:10.16513/j.2096-2185.DE.2006010
	ZHANG X D， NIU H M ．Calculation model and simulation analysis of mirror field efficiency of through CSP station[J]．Distributed Energy，2020，5(5)：56-63． doi:10.16513/j.2096-2185.DE.2006010
3	王泽众，黄平瑞，魏高升，等．太阳能热发电固‒气两相化学储热技术研究进展[J]．发电技术，2021，42(2)：238-246．
	WANG Z Z， HUANG P R， WEI G S，et al ．Research progress of solid-gas two-phase chemical heat storage technology for solar thermal power generation[J]．Power Generation Technology，2021，42(2)：238-246．
4	梁政，魏震波，孙舟倍，等．光热发电商参与下的电力现货市场均衡分析[J]．电力建设，2022，43(1)：122-131．
	LIANG Z， WEI Z B， SUN Z B，et al ．Analysis of the equilibrium of electricity spot market with the participation of CSP[J]．Electric Power Construction，2022，43(1)：122-131．
5	XU C， LI X， WANG Z，et al ．Effects of solid particle properties on the thermal performance of a packed-bed molten-salt thermocline thermal storage system[J]．Applied Thermal Engineering，2013，57(1/2)：69-80． doi:10.1016/j.applthermaleng.2013.03.052
6	DU B C， HE Y L， ZHENG Z J，et al ．Analysis of thermal stress and fatigue fracture for the solar tower molten salt receiver[J]．Applied Thermal Engineering，2016，99：741-750． doi:10.1016/j.applthermaleng.2016.01.101
7	Sandia National Lab ．A final report on the Phase 1 testing of a molten-salt cavity receiver[R]．Albuquerque：Sandia National Lab，1992． doi:10.2172/5042358
8	WANG K， HE Y L， QIU Y，et al ．A novel integrated simulation approach couples MCRT and Gebhart methods to simulate solar radiation transfer in a solar power tower system with a cavity receiver[J]．Renewable Energy，2016，89：93-107． doi:10.1016/j.renene.2015.11.069
9	TEHRANI S S M， TAYLOR R A ．Off-design simulation and performance of molten salt cavity receivers in solar tower plants under realistic operational modes and control strategies[J]．Applied Energy，2016，179：698-715． doi:10.1016/j.apenergy.2016.07.032
10	LI X， KONG W， WANG Z，et al ．Thermal model and thermodynamic performance of molten salt cavity receiver[J]．Renewable Energy，2010，35(5)：981-988． doi:10.1016/j.renene.2009.11.017
11	RODRÍGUEZ-SÁNCHEZ M R， SÁNCHEZ- GONZÁLEZ A， MARUGÁN-CRUZ C，et al ．New designs of molten-salt tubular-receiver for solar power tower[J]．Energy Procedia，2014，49：504-513． doi:10.1016/j.egypro.2014.03.054
12	RODRÍGUEZ-SÁNCHEZ M R， MARUGAN-CRUZ C， ACOSTA-IBORRA A，et al ．Comparison of simplified heat transfer models and CFD simulations for molten salt external receiver[J]．Applied Thermal Engineering，2014，73(1)：993-1005． doi:10.1016/j.applthermaleng.2014.08.072
13	FANG J， TU N， WEI J ．Effects of absorber emissivity on thermal performance of a solar cavity receiver [J]．Advances in Condensed Matter Physics，2014，2014：1-10． doi:10.1155/2014/564639
14	FANG J B， TU N， WEI J J ．Numerical investigation of start-up performance of a solar cavity receiver[J]．Renewable Energy，2013，53：35-42． doi:10.1016/j.renene.2012.10.053
15	CHANG Z， LI X， XU C，et al ．Numerical simulation on the thermal performance of a solar molten salt cavity receiver[J]．Renewable Energy，2014，69：324-335． doi:10.1016/j.renene.2014.03.044
16	TEICHEL S H， FEIERABEND L， KLEIN S A，et al ．An alternative method for calculation of semi-gray radiation heat transfer in solar central cavity receivers [J]．Sol Energy，2012，86(6)：1899-1909． doi:10.1016/j.solener.2012.02.035
17	GONZALEZ M M， PALAFOX J H， ESTRADA C A ．Numerical study of heat transfer by natural convection and surface thermal radiation in an open cavity receiver[J]．Sol Energy，2012，86(4)：1118-1128． doi:10.1016/j.solener.2012.01.005
18	WAGNER M J ．Simulation and predictive performance modeling of utility-scale central receiver system power plants[D]．Wisconsin：University of Wisconsin Madison，2008． doi:10.1115/es2009-90132
19	ZHANG Q， LI X， WANG Z，et al ．Cavity receiver thermal performance analysis based on total heat loss coefficient and efficiency factor[J]．International Journal of Energy Research，2018，42(6)：2284-2289． doi:10.1002/er.3999
20	YANG Z， GARIMELLA S V ．Thermal analysis of solar thermal energy storage in a molten-salt thermocline [J]．Solar Energy，2010，84(6)：974-985． doi:10.1016/j.solener.2010.03.007
21	ZHANG Q， LI X， CHANG C，et al ．An experimental study：thermal performance of molten salt cavity receivers[J]．Applied Thermal Engineering，2013，50 (1)：334-341． doi:10.1016/j.applthermaleng.2012.07.028
22	ZHANG Q， LI X， WANG Z，et al ．Experimental and theoretical analysis of a dynamic test method for molten salt cavity receiver[J]．Renewable Energy，2013，50：214-221． doi:10.1016/j.renene.2012.06.054
23	LIAO Z， LI X， XU C，et al ．Allowable flux density on a solar central receiver[J]．Renewable Energy，2014，62：747-753． doi:10.1016/j.renene.2013.08.044

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