Search

The cooling techniques of photovoltaic (PV) panels captured special attention due to positive impact on PV panels efficiency as continuous elevation of temperature degraded its performance. A number of studies have suggested the better prospects of air, water and phase change material (PCM) for thermal management of PV modules. The present work studies three different nanoparticle-based nano-PCMs for acceleration in performance of PV panel in terms of temperature reduction and increment of electrical efficiency. The experimental methodology was tested in the outdoor conditions of Taxila, Pakistan during winter seasons by using different concentrations (0.25 wt % and 0.5 wt %) of multiwall carbon nanotubes nanoparticles, graphene nanoplatelets and magnesium oxide nanoparticles in phase change material (PT-58). The topmost performance of PV panel is found at 0.5 wt % nanomaterial concentration in graphene nanoplatelets/PT-58 nano-PCM. The experimental results indicate that maximum temperature reduction is observed to be 9.94 °C , 6.53 °C for PV/nano-PCM at 0.5 wt % of graphene nanoplatelets/PT-58 nano-PCM and 0.25 wt % of graphene nanoplatelets/PT-58 nano-PCM respectively while it was 5.01 °C for PV/PCM with highest observation in electrical efficiency of 12.10 % , 11.97 % and 11.74 % respectively as compared to conventional PV panel. The maximum percentage increase of electrical power was 33.07 % in case of GNPs/PT-58 nano-PCM at 0.5 wt % of nanomaterial in base PCM. The graphene nanoplatelets based nano-PCM exhibited best results in terms of temperature reduction as well as electrical efficiency and higher concentration of nanoparticles indicated good results compared to low concentration in nano-PCM. Image 1 • Discussion on cooling techniques of photovoltaic panels. • Concise summary of previous studies on cooling of photovoltaic panels by various authors. • Discussion on nanoparticles-based phase change materials used for experimental work. • Comparison of different properties of nano doped and simple phase change materials in photovoltaic. [ABSTRACT FROM AUTHOR]

In this study, a series of experimental runs performed under different conditions in order to evaluate the effectiveness of a household refrigerator. Two eutectic phase change materials (PCMs) arranged in a cascade configuration have been tested on the performance of the system. The PCMs were placed on the back-side of the wire-and-tube condenser in a decreasing order of their melting temperatures along the refrigerant flow direction to achieve a high heat transfer rate and to reduce energy consumption. The operating characteristics of the novel refrigerator were studied and compared with the results of a refrigerator equipped with a single PCM and two ordinary refrigerators with and without measurement packages (M-packs). All the tests have been performed in standard condition in Philver Company in Tehran, Iran. For the novel refrigerator, the temperature of the condenser surface significantly decreased, which led to a lower condensing temperature during the refrigeration cycle and improved the coefficient of performance (COP). Also, the ratio of the on-time to the total experiment time was considerably shorter compared to the refrigerator equipped with a single PCM and two ordinary refrigerators. According to the results, integration of two different PCMs on the condenser surface in a cascade arrangement decreases the compressor work time percentage from 32.7 to 27.6, while this parameter was decreased to 29.6 with a single PCM. Finally, the energy consumption was reduced by 13% in the novel refrigerator whereas it was only reduced by 8% in the refrigerator equipped with a single PCM. • Efficiency enhancement of a household refrigerator has been studied. • Eutectic phase change materials with cascade configuration have been used in the system. • The compressor off-time of the novel system lowered significantly. • Energy consumption of the refrigerator with single PCM was reduced by 8%. • Further energy consumption reduction up to 13% has been achieved in cascade configuration. [ABSTRACT FROM AUTHOR]

The phase change material (PCM) based cooling systems have gained recent popularity with PV module temperature (T PV) reduction and enhanced performance. The technology is confined with the spacious demerits like physical contact, conductivity and PCM melting temperature (T melt) loss. It is found that PCM T melt loss is higher than other losses and in most of the cases examining single PCM is not effective throughout the year. In this study, two different tropical and one sub-tropical conditions are selected to analyze the variations in T PV with respect to extremely varying climatic conditions. Pearson's correlation method is adopted and analyzed to determine the dependence of T PV on the ambient temperature (T amb) for summer and winter. It is noted that for the selected tropical climate in Thailand, 33 °C of T amb in winter causes the T PV to rise to 60 °C emphasizing the need for cooling system even in winter. So cascaded PCM is selected for Thailand. The first layer of the PCM (PCM-A) has a lower T melt within the range 36–39 °C and the second layer is a higher T melt (PCM-B) within the range 44–47 °C. During winter, PCM-A turns active, following which PCM-B assists in maintaining a lower PCM-A temperature, and for summer both PCM layers will be effective in operation. Based on the proposed PCM T melt optimization, the tropical climate in India and sub-tropical climate in France do not require PCM for cooling in winter, but for summer it is necessary within the ranges 44–47 °C and 31–34 °C, respectively. The study highlights the need for adopting different PCM-based systems depending on the location/climatic conditions. • PCM type and classification used for PV cooling are reviewed. • Proper type of PCM must be selected to suite a climate condition. • Novel cascaded PCM is proposed for tropical climate. • Range of PCM melting point is suggested for tropical and sub-tropical climates. • Climatic conditions play crucial role in choosing PCM for PV cooling. [ABSTRACT FROM AUTHOR]