Optimization of the flow resistance characteristics of the direct return flat plate solar collector field

Dengjia Wang; Ruichao Zhang; Yanfeng Liu; Xinyu Zhang; Jianhua Fan

doi:10.1016/j.solener.2020.12.054

Optimization of the flow resistance characteristics of the direct return flat plate solar collector field

Dengjia Wang^*, Ruichao Zhang, Yanfeng Liu, Xinyu Zhang, Jianhua Fan

^*Corresponding author for this work

Research output: Contribution to journal › Journal article › Research › peer-review

Abstract

The uneven (flow) resistance of branched pipes commonly causes local overheating and freezing in solar collector fields. In this paper, the resistance characteristics of the direct return flat plate solar collector field are studied using a numerical model. The accuracy of the model is verified with experimental data, and the maximum relative error is below 10%. A new evaluation index, the ratio of resistance imbalance rate to efficiency (R_RIRE), is introduced. In this way, it is possible to comprehensively evaluate the effect of different factors (configuration, flow rate per unit heat collection area, inlet temperature, working medium) on both the resistance characteristics and efficiency of the solar collector field. The results show that, when the number of rows (N_row) exceeds the number of collectors in each row (N_col), the inlet temperature is below 40 °C. In addition, the flow rate per unit heat collection area is below 0.06 m³/(h m²). Hence, the R_RIRE is smaller and the system has better resistance efficiency. Considering the viscosity change due to the temperature change in the fluid of the solar collector field, a new temperature difference correction method is proposed. This makes it possible to calculate the frictional drag for a fluid in the collector field, which allows a more realistic calculation of flow resistance. This study lays the foundation for improved layout design and parameter optimization in solar collector fields.

Original language	English
Journal	Solar Energy
Volume	215
Pages (from-to)	388-402
ISSN	0038-092X
DOIs	https://doi.org/10.1016/j.solener.2020.12.054
Publication status	Published - 2021

Bibliographical note

Funding Information:
The research was supported by the National Natural Science Foundation of China (No. 51678468 ), the Science Foundation for Outstanding Youth of Shaanxi Province (2020JC-43), and the Key Research and Development Program of Shananxi Province (Project No. 2018ZDCXL-SF-03-01).

Keywords

Flow-resistance characteristics
Influence factors
Resistance calculate method
Solar collector fields

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10.1016/j.solener.2020.12.054

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IEA Task 55: IEA SHC Task 55 - Integration of Large SHC Systems into District Heating and Cooling (DHC) Networks (II)
Fan, J. (Project Participant), Furbo, S. (Project Participant), Perers, B. O. (Project Participant), Kong, W. (Project Participant), Dragsted, J. (Project Participant), Nielsen, E. N. N. (Project Participant) & Jensen, A. R. (Project Participant)
01/01/2019 → 31/12/2020
Project: Research
Follow up on large scale storage in Denmark, Gram
Fan, J. (Project Participant), Furbo, S. (Project Participant), Perers, B. O. (Project Participant), Kong, W. (Project Participant) & Nielsen, E. N. N. (Project Participant)
Energiteknologisk Udviklings- og Demonstrationsprogram
01/01/2016 → 31/12/2018
Project: Research

Cite this

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title = "Optimization of the flow resistance characteristics of the direct return flat plate solar collector field",

abstract = "The uneven (flow) resistance of branched pipes commonly causes local overheating and freezing in solar collector fields. In this paper, the resistance characteristics of the direct return flat plate solar collector field are studied using a numerical model. The accuracy of the model is verified with experimental data, and the maximum relative error is below 10%. A new evaluation index, the ratio of resistance imbalance rate to efficiency (RRIRE), is introduced. In this way, it is possible to comprehensively evaluate the effect of different factors (configuration, flow rate per unit heat collection area, inlet temperature, working medium) on both the resistance characteristics and efficiency of the solar collector field. The results show that, when the number of rows (Nrow) exceeds the number of collectors in each row (Ncol), the inlet temperature is below 40 °C. In addition, the flow rate per unit heat collection area is below 0.06 m3/(h m2). Hence, the RRIRE is smaller and the system has better resistance efficiency. Considering the viscosity change due to the temperature change in the fluid of the solar collector field, a new temperature difference correction method is proposed. This makes it possible to calculate the frictional drag for a fluid in the collector field, which allows a more realistic calculation of flow resistance. This study lays the foundation for improved layout design and parameter optimization in solar collector fields.",

keywords = "Flow-resistance characteristics, Influence factors, Resistance calculate method, Solar collector fields",

author = "Dengjia Wang and Ruichao Zhang and Yanfeng Liu and Xinyu Zhang and Jianhua Fan",

note = "Funding Information: The research was supported by the National Natural Science Foundation of China (No. 51678468 ), the Science Foundation for Outstanding Youth of Shaanxi Province (2020JC-43), and the Key Research and Development Program of Shananxi Province (Project No. 2018ZDCXL-SF-03-01). ",

year = "2021",

doi = "10.1016/j.solener.2020.12.054",

language = "English",

volume = "215",

pages = "388--402",

journal = "Solar Energy",

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AU - Wang, Dengjia

AU - Zhang, Ruichao

AU - Liu, Yanfeng

AU - Zhang, Xinyu

AU - Fan, Jianhua

N1 - Funding Information: The research was supported by the National Natural Science Foundation of China (No. 51678468 ), the Science Foundation for Outstanding Youth of Shaanxi Province (2020JC-43), and the Key Research and Development Program of Shananxi Province (Project No. 2018ZDCXL-SF-03-01).

PY - 2021

Y1 - 2021

N2 - The uneven (flow) resistance of branched pipes commonly causes local overheating and freezing in solar collector fields. In this paper, the resistance characteristics of the direct return flat plate solar collector field are studied using a numerical model. The accuracy of the model is verified with experimental data, and the maximum relative error is below 10%. A new evaluation index, the ratio of resistance imbalance rate to efficiency (RRIRE), is introduced. In this way, it is possible to comprehensively evaluate the effect of different factors (configuration, flow rate per unit heat collection area, inlet temperature, working medium) on both the resistance characteristics and efficiency of the solar collector field. The results show that, when the number of rows (Nrow) exceeds the number of collectors in each row (Ncol), the inlet temperature is below 40 °C. In addition, the flow rate per unit heat collection area is below 0.06 m3/(h m2). Hence, the RRIRE is smaller and the system has better resistance efficiency. Considering the viscosity change due to the temperature change in the fluid of the solar collector field, a new temperature difference correction method is proposed. This makes it possible to calculate the frictional drag for a fluid in the collector field, which allows a more realistic calculation of flow resistance. This study lays the foundation for improved layout design and parameter optimization in solar collector fields.

AB - The uneven (flow) resistance of branched pipes commonly causes local overheating and freezing in solar collector fields. In this paper, the resistance characteristics of the direct return flat plate solar collector field are studied using a numerical model. The accuracy of the model is verified with experimental data, and the maximum relative error is below 10%. A new evaluation index, the ratio of resistance imbalance rate to efficiency (RRIRE), is introduced. In this way, it is possible to comprehensively evaluate the effect of different factors (configuration, flow rate per unit heat collection area, inlet temperature, working medium) on both the resistance characteristics and efficiency of the solar collector field. The results show that, when the number of rows (Nrow) exceeds the number of collectors in each row (Ncol), the inlet temperature is below 40 °C. In addition, the flow rate per unit heat collection area is below 0.06 m3/(h m2). Hence, the RRIRE is smaller and the system has better resistance efficiency. Considering the viscosity change due to the temperature change in the fluid of the solar collector field, a new temperature difference correction method is proposed. This makes it possible to calculate the frictional drag for a fluid in the collector field, which allows a more realistic calculation of flow resistance. This study lays the foundation for improved layout design and parameter optimization in solar collector fields.

KW - Flow-resistance characteristics

KW - Influence factors

KW - Resistance calculate method

KW - Solar collector fields

U2 - 10.1016/j.solener.2020.12.054

DO - 10.1016/j.solener.2020.12.054

M3 - Journal article

AN - SCOPUS:85099613578

SN - 0038-092X

VL - 215

SP - 388

EP - 402

JO - Solar Energy

JF - Solar Energy

ER -

Optimization of the flow resistance characteristics of the direct return flat plate solar collector field

Abstract

Bibliographical note

Keywords

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Projects

IEA Task 55: IEA SHC Task 55 - Integration of Large SHC Systems into District Heating and Cooling (DHC) Networks (II)

Follow up on large scale storage in Denmark, Gram

Cite this