Study on Heat Loss Factors of Parabolic Trough Solar Collectors

doi:10.12096/j.2096-4528.pgt.21070

Abstract

Abstract:

Combining solar thermal electricity technology with distributed energy system is conducive to increasing the proportion of renewable energy in the energy consumption structure. Parabolic trough solar collectors are currently the most widely used solar-thermal energy conversion equipment in solar thermal electricity. Their operational characteristics determine whether solar thermal electricity technology and other energy technologies in distributed energy systems can cooperate with each other. Aiming at the heat loss affecting the operation characteristics of the trough collectors, this paper carried out the on-site utility-scale experimental system test, then verified the established mathematical model of the trough collectors, and further applied the model to analyze the parameters of the residual gas volume in the vacuum zone, the wind speed, and the emissivity of the absorber.

Key words: solar thermal electricity (STE), distributed energy system, solar collector, heat loss

CLC Number:

TK 513.1

Li XU, Feihu SUN, Jun LI, Qiangqiang ZHANG. Study on Heat Loss Factors of Parabolic Trough Solar Collectors[J]. Power Generation Technology, 2023, 44(2): 229-234.

Figures/Tables 10

Fig. 1 Thermal analysis on HCE of parabolic trough solar collectors

Fig. 2 Parabolic trough solar collectors used in the experiment

Fig. 3 Measured HTF temperatures at the inlet, and measured and simulated HTF temperatures at the outlet

Fig. 4 Distribution of HTF temperature along distance from collector inlet under different H2 pressures

Tab. 1 Energy analysis for different H2 pressures

H₂压力/Pa	q_b，c/kW	q_b，r/kW	$η$ _HTF/%
0.01	1.3	126.0	94.5
10	238.8	114.2	84.9
1 000	293.1	111.4	82.7
100 000	393.6	106.0	78.5

Tab. 1 Energy analysis for different H2 pressures

H₂压力/Pa	q_b，c/kW	q_b，r/kW	$η$ _HTF/%
0.01	1.3	126.0	94.5
10	238.8	114.2	84.9
1 000	293.1	111.4	82.7
100 000	393.6	106.0	78.5

Fig. 5 Distribution of HTF temperature along distance from collector inlet under different wind speeds

Tab. 2 Energy analysis for different wind speeds

风速/(m⋅s^-1)	q_g，c/kW	q_g，r/kW	$η$ _HTF/%
2	121.9	54.8	94.61
4	139.4	38.7	94.55
6	148.3	30.5	94.52
12	161.7	18.0	94.47

Tab. 2 Energy analysis for different wind speeds

风速/(m⋅s^-1)	q_g，c/kW	q_g，r/kW	$η$ _HTF/%
2	121.9	54.8	94.61
4	139.4	38.7	94.55
6	148.3	30.5	94.52
12	161.7	18.0	94.47

Fig. 6 Variation in the absorber emissivity with the absorber temperature under different emissivity multipliers

Fig. 7 HTF temperature distribution along the length from the collector inlet under different emissivity multipliers

Tab. 3 Energy analysis for different emissivity multipliers

F_emi	q_g，c/kW	q_g，r/kW	q_b，r/kW	$η$ _HTF/%
0.5	92.6	24.3	64.9	97.2
1	139.4	38.7	126.0	94.5
4	353.1	125.5	426.9	81.7

Tab. 3 Energy analysis for different emissivity multipliers

F_emi	q_g，c/kW	q_g，r/kW	q_b，r/kW	$η$ _HTF/%
0.5	92.6	24.3	64.9	97.2
1	139.4	38.7	126.0	94.5
4	353.1	125.5	426.9	81.7

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