International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 13 Issue: 06 | Jun 2026
p-ISSN: 2395-0072
www.irjet.net
Experimental Heat Transfer and Thermal Performance Analysis of a Direct Absorption Solar Collector Using CuO–Water Nanofluid Shubham Pandey1, Ajeet Kumar2 1M.Tech. Scholar, Deaprtment of Mechanical Engineering, Sagar Institute of Technology and Management,
Barabanki
2 Assistant Professor, Deaprtment of Mechanical Engineering, Sagar Institute of Technology and Management,
Barabanki ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - The increasing demand for energy due to
Earth in a single day is nearly equal to the total global energy demand for an entire year. However, efficiently capturing and utilizing this enormous amount of energy remains a major challenge due to significant energy losses during conversion and storage processes[1].
industrialization, population growth, and technological advancement has intensified the depletion of conventional fossil fuels and raised serious environmental concerns. As a result, renewable energy sources have gained significant importance for sustainable development. Among them, solar energy is considered one of the most abundant and ecofriendly resources. Solar collectors are commonly used to convert solar radiation into useful thermal energy. However, conventional heat transfer fluids used in these collectors possess low thermal conductivity, which limits overall thermal performance. To address this issue, nanofluids have emerged as an effective alternative. Nanofluids are produced by dispersing nanoparticles into base fluids, improving thermal conductivity, heat transfer capability, and solar energy absorption. In this study, the thermal performance of a Direct Absorption Solar Collector (DASC) using CuO–H₂O nanofluid was experimentally investigated. Unlike conventional collectors, DASCs absorb solar radiation directly within the fluid, leading to improved volumetric heat absorption and enhanced efficiency. Experimental results showed that the use of CuO–H₂O nanofluid increased collector efficiency by approximately 4–6% compared to water at mass flow rates of 60–100 mL/hr. The study also found that nanoparticle concentration significantly affects performance. Lower nanoparticle volume fractions provided better stability and heat absorption, while higher concentrations caused agglomeration and sedimentation, reducing efficiency. Further improvement of 10–15% may be achieved through enhanced nanofluid stabilization and mixing techniques.
When solar radiation reaches the Earth’s surface, a part of it is absorbed, leading to an increase in surface temperature. As the temperature of the system rises, the surrounding atmosphere absorbs a considerable amount of heat, which is gradually lost from the surface at a higher rate. A steadystate condition is achieved when the rate of heat loss to the atmosphere becomes equal to the rate of solar heat absorbed by the system [2]. Extraterrestrial solar radiation refers to the solar energy received outside the Earth’s atmosphere on a surface placed perpendicular to the incoming rays of the sun. The average intensity of this radiation at the mean distance between the Earth and the Sun is known as the solar constant. As solar radiation travels through the atmosphere, a part of it is reflected back into space, while another portion is absorbed by air molecules, dust particles, and water vapour present in the atmosphere. The remaining radiation is scattered in various directions before reaching the Earth’s surface. The radiation that reaches the surface directly from the sun is called beam radiation, whereas the scattered radiation received from the sky is known as diffuse radiation [3] 1.1 Solar Energy Collector Solar collectors are devices that are specifically designed to capture solar radiation and convert it into useful thermal energy. They operate by absorbing the sun’s rays either directly or by concentrating them onto a particular surface. The absorbed solar energy is then transferred to a working fluid, such as water or air, which flows through the collector. The efficiency and overall performance of a solar collector mainly depend on its ability to effectively absorb solar radiation and transfer the generated heat energy.
Key Words: Heat Transfer, Direct Absorption Solar Collector, Nanofluid Heat Transfer, CuO–Water Nanofluid, Solar Energy, Thermal Performance Analysis
1. INTRODUCTION Solar energy has been available in immense quantities since ancient times and remains one of the most important energy resources for humanity. It serves as the primary source of energy for the entire solar system and forms the foundation of nearly all other energy sources, whether conventional or non-conventional, renewable or non-renewable. Sources such as wind energy and tidal energy are indirectly derived from the sun. One of the most remarkable facts about solar energy is that the amount of solar radiation received by the
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Solar collectors are broadly classified into two major categories: non-concentrating or flat plate solar collectors, and concentrating solar collectors. Non-concentrating or flat plate collectors absorb solar radiation over a wide surface area without focusing the sunlight. These collectors are generally used for low and moderate temperature applications. On the other hand, concentrating solar
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