Thermal Efficiency Of Solar Collector Research Articles

Evaluation of thermal efficiency of double-pass solar collector with porous–nonporous media

The double-pass solar collector with porous media in the lower channel provides a higher outlet temperature compared to the conventional single-pass collector. Therefore, the thermal efficiency of the solar collector is higher. A theoretical model has been developed for the double-pass solar collector. An experimental setup has been designed and constructed. The porous media has been arranged in different porosities to increase heat transfer, area density and the total heat transfer rate. Comparisons of the theoretical and the experimental results have been conducted. Such comparisons include the outlet temperatures and thermal efficiencies of the solar collector for various design and operating conditions. The relationships include the effect of changes in upper and lower channel depth on the thermal efficiency with and without porous media. Moreover, the effects of mass flow rate, solar radiation, and temperature rises on the thermal efficiency of the double-pass solar collector have been studied. In addition, heat transfer and pressure drop relationships have been developed for airflow through the porous media. Close agreement has been obtained between the theoretical and experimental results. The study concluded that the presence of porous media in the second channel increases the outlet temperature, therefore increases the thermal efficiency of the systems.

China: Dezhou Hongqiao — aniline

In this paper, one novel heat pipe solar adsorption chiller with mass-heat recovery was designed. 65 kg of micro-porous silica gel was used as adsorbent in each adsorbent bed. The influence of operating conditions on the chiller was investigated. The chiller was applied in Green Building in Dezhou city (north latitude of 36°41′) in China. Under the typical summer weather conditions, the average thermal efficiency of solar collector, the average COP (coefficient of performance) of the adsorption refrigerator and the average solar COP of the system are 0.36, 0.44 and 0.16, respectively. The results show that the adsorption cooling performance rises as the hot water inlet temperature, chilled water outlet temperature rise, and it declines as the cooling water inlet temperature rises. The performance can be improved by mass-heat recovery significantly. When the hot water inlet temperature, cooling water inlet temperature, chilled water outlet temperature are 79.0 °C, 25.4 °C, 13.7 °C, respectively, the cooling capacity and COP are 17.9 kW and 0.63, respectively.

97/04833 Modelling, optimisation and performance evaluation of a parabolic trough solar collector steam generation system: Kalogirou, S. et al. Solar Energy, 1997, 60, (11), 49–59

Chapter 4 deals with the methods to determine experimentally the performance of solar collectors. It outlines the various tests required to determine the thermal efficiency of solar collectors. Initially collector thermal efficiency measurement is presented and the effect of flow rate, collectors connected in series, and the standard requirements of the test are analyzed. Subsequently, the methods to determine the collector incidence angle modifier for flat-plate and concentrating collectors are presented followed by the acceptance angle for concentrating collectors and the collector time constant. The dynamic test method is also presented followed by the efficiency parameter conversion and assessment of the uncertainty in solar collector testing. This is followed by the way the collector test results can be used for the preliminary collector selection. Subsequently, the quality test methods are presented followed by a review of European standards used for this purpose as well as details of the Solar Keymark certification scheme. Finally, the chapter describes the characteristics of data acquisition systems including portable data loggers.