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Sādhanā

, 44:23 | Cite as

Performance assessment of evacuated U-tube solar collector: a numerical study

  • B Kiran Naik
  • P MuthukumarEmail author
Article
  • 81 Downloads

Abstract

This paper presents a finite element method based three-dimensional thermal model for predicting the performance of evacuated U-tube solar collector. Numerically predicted working fluid outlet temperature is compared with the experimental data available in the literature and a good agreement is observed between them. The influence of average solar irradiance on efficiency and useful heat gain rate of the solar collector is studied for two different evacuated tube configurations. Employing water and air as working fluid, copper, aluminium and brass as U-tube material, and graphite, magnesium oxide and aluminium oxide as filler material and the performance of the evacuated tube solar collector is investigated in detail.

Keywords

Numerical model evacuated tube solar collector useful heat gain rate filler material U-tube material working fluid 

Nomenclature

Ac

area of the collector (m2)

cp

specific heat at constant pressure (kJ/kgK)

kg

thermal conductivity of the glass tube (W/mK)

kfr

thermal conductivity of the filler material (W/mK)

ka

thermal conductivity of the inner glass tube/absorber tube (W/mK)

kf

thermal conductivity of the fin material (W/m-K)

ku

thermal conductivity of the U-tube (W/mK)

LHS

latent heat storage

\( \dot{\hbox{m}} \)

mass flow rate (kg/s)

P

pressure (Pa)

Quseful

useful heat gained by the working fluid (W)

T

temperature (°C)

\( \vec{v} \)

velocity (m/s)

Greek letters

α

absorptivity of the inner glass tube/absorber tube

λ

average solar irradiance (W/m2)

ρ

density (kg/m3)

μ

dynamic viscosity of working fluid (Pas)

ε

emissivity of the outer glass tube

η

solar collector efficiency (%)

σ

Stephen Boltzmann constant (W/m2K4)

τ

transmissivity of the inner glass tube/absorber tube

Subscript

amb

ambient air

ini

initial

i

inner

o

outer

w,o

working fluid outlet

w,i

working fluid inlet

wf

working fluid

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Copyright information

© Indian Academy of Sciences 2019

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringIndian Institute of Technology GuwahatiGuwahatiIndia

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