Numerical Analysis of Concentrated Beam Solar Circular Receivers Kaustubh G. Kulkarni * , Sanjay N. Havaldar, Harsh V. Malapur School of Mech. Eng., Dr. Vishwanath Karad MIT World Peace University, Pune 411038, India Corresponding Author Email: Kaustubh.Kulkarni@mitwpu.edu.in https://doi.org/10.18280/ijht.400203 ABSTRACT Received: 1 February 2022 Accepted: 23 February 2022 The solar central receiver is the most crucial part of a solar tower power plant (CSP). In this study, a computational fluid dynamics (CFD) framework was used for analysing four circular designs (with same surface area and mass flow rate of heat transfer fluid) of the central tower receiver. In this study, a computational fluid dynamics (CFD) framework was developed for analyzing four circular (stain steel) designs of the central tower receiver, namely, a circular constant tube diameter (CCD), a circular vertical constant tube diameter solar receiver (CUTD), a circular variable tube diameter (CVTD) receiver and a leaf type circular solar receiver (LTSR). This analysis studied the solar radiation heat transfer efficiency, temperature distribution, and fluid outlet temperature; pressure and velocity distributions for the designs using CFD. It was found that the LTSR design helped achieve a higher rise in temperature of the heat transfer fluid (HTF) when the mass flow rate was in the range of 0.1 to 0.2 liter per minute. The LSTR model of circular receiver was more efficient in heat transfer circular receiver designs compared with other circular designs for same surface area and strength of solar beam irradiations. Keywords: circular solar receiver, spiral solar receiver, leaf type solar receiver, solar concentrator 1. INTRODUCTION For millions of years, solar energy has been a natural vital force for all geomorphological changes on Earth [1]. Conventional energy sources (coal, oil, and natural gas) have higher power densities. If conventional energy sources are utilized, the toxic gases emitted into the atmosphere pollute the environment [2]. In a CSP system, a specific arrangement of mirrors (heliostats) reflects and concentrates solar radiation on a receiver atop a tower. This concentrated solar beam is then utilised as a heating source to heat a heat transfer fluid (HTF) circulating in the piping of the central solar receiver. Solar energy is a clean and alternative energy source [3] that needs to be explored. Because it is a dilute source of energy, it may not be directly utilised to generate power [4], but if this dilute source is utilised as input to systems, a concentrated high- energy solar beam could then be utilised for domestic, industrial, or power generation [5]. 2. LITERATURE REVIEW Concentrated solar radiation is a high-temperature, high- energy source [6]. This radiation is utilised as thermal energy when it is directed at a receiver or concentrating device [7]. Several authors have looked into incorporating solar thermal power into high-temperature production processes, using Computational Fluid Dynamics (CFD) to analyze high- temperature solar devices for improving prototype designs and the high-temperature process' performance [8]. Intense sunlight irradiates the tubes of the receiver in a concentrated solar thermal power plant, converting solar power into heat. The heat flux density on the receiver surface may be approximately 2.5 MW/m 2 . The heat flux density distribution on the receiver surface is determined by the aiming method [9]. This heat flux is transferred from the receiver tube walls to the heat transfer fluid (HTF), which is circulated in the receiver (heat exchanger) system [10]. A greater HTF temperature is achieved with an increased receiver concentrated solar beam temperature [11]. Solar receivers are heat exchangers that transfer solar energy to heat energy through the use of water. Then the fluid transfers the thermal energy to steam that will then be passed through a turbine to generate electricity [12]. The amount of solar irradiance reflected by the heliostats on the receiver determines the amount of heat input to the receiver [13]. An analytical framework that could be employed for "n" no. of mirrors is utilised for selecting a tiny central receiver system, and an empirical investigation of temperature readings of working fluid in a spiral receiver was performed for variable heat flux and mass flow rate [14]. Figure 1. CST layout with a receiver, heliostat, support structure system, etc. International Journal of Heat and Technology Vol. 40, No. 2, April, 2022, pp. 375-382 Journal homepage: http://iieta.org/journals/ijht 375