Title: Thermodynamic analysis of an air solar collector

Authors: Ioan Luminosu, Laurentiu Fara

Addresses: Department of Physics, Universitatea 'Politehnica' Timisoara, Piata Regina Maria No. 1, RO 300004 Timisoara, Romania. ' Department of Physics, Universitatea 'Politehnica' Bucuresti, Splaiul Independentei No. 313, RO 060032 Bucuresti, Romania

Abstract: The paper presents the experimental study of an air solar installation with a collecting area A_C = 4.2m² and variable working fluid flow rate in the range 0.02÷0.06 kg/s. The experimental data are processed statistically through thermodynamic analysis, using energy (semi-empirical) and exergy methods. The aim of the paper is to establish the optimal air flow rate through this solar thermal system in order to ensure minimum irreversibility of the collecting-heating-cooling process under Romania|s insolation conditions. The paper is also a demonstrative example of cost-effective and efficient use of solar energy for heating in Romania. It is experimentally proven that for this solar installation, the optimum air flow rate is of 0.04 kg/s. At a flow rate of 0.04 kg/s, irreversibility has the lowest values for all daytime hours with a maximum at noon (2640 W). For this flow rate the exergy efficiency reaches the highest value, η_ex:max = 0:197.

Keywords: energy analysis; entropy; exergy analysis; exergy efficiency; irreversibility; solar installation; air solar collectors; thermodynamics; fluid flow rate; air flow rate; Romania; solar energy; solar power; heating; exergy efficiency.

DOI: 10.1504/IJEX.2005.007788

International Journal of Exergy, 2005 Vol.2 No.4, pp.385 - 408

Published online: 16 Sep 2005 *

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