International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 01 | Jan 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 151 Performance Analysis of the Solar Linear Fresnel Reflector Mohamed H. Ahmed 1 1 Solar Energy Dept., National Research Centre, Giza, Egypt ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract - In recent decades, The Linear Fresnel Reflector (LFR) has attracted considerable attention from the researcher, engineers, and the stakeholders. This attention can be attributed to the characterization of this type of condenser with several advantages that can overcome the problems of other types of solar concentrators. A numerical simulation for the thermal performance of the LFR has been carried out through one year for a certain design under Cairo climate. The effects of the operating parameters (the inlet temperature and flow rate) on the thermal performance of the Solar LFR were investigated. The variation of the incidence angle modifier (IAM) through one year was also studied. The results show an important effect of the daily and seasonal changes in the incidence angle of direct radiation on the IAM and thus thermal performance and concentrator efficiency. At solar noon, the best values for the IAM ranged from 0.9 to 0.98 in June. While the maximum rate of energy gained was about 41 kW and 96 kW for Dec. and June respectively. This numerical model can be used for design optimization to get the maximum efficiency of the solar LRF. Key Words: Linear Fresnel Reflector, simulation model, receiver tube, incident angle modifier, concentrator efficiency 1. INTRODUCTION Solar reflectors are significant tools to concentrate the solar irradiance in a small area to get thermal energy at a high temperature. Despite the widespread deployment and operation of a solar power plant that uses the parabolic trough concentrator (PTC) compare to the Linear Fresnel Reflector (LRC), there are many efforts and attempts to make the LFR a strong competitor in the solar concentrator market. This is because linear Fresnel concentrates have significant technical and economic advantages when compared to the parabolic trough concentrator. The linear Fresnel concentrators have less thermal efficiency compared to other types of solar concentrators, but the low cost of the LFR may compensate that, providing a solution to the cost problems of solar energy collectors on a large scale [1]. The advantages of Fresnel Linear Concentrations include relatively simple installation and low wind load. It also includes the non-movement of the receiving tube and optimal utilization of available land area [2]. In some stations using Fresnel concentrators, the shaded area under mirrors can be used (e.g. for parking lots) and supply basic needs to rural remote communities. The previous features of the LFR and the low cost of the operation and maintenance (O & m) results in a significant reduction in the levelized energy cost by about 12 % compared to the parabolic trough concentrator. The idea on which Fresnel concentrator is based in the use of a series of flat, long and parallel mirrors that focus solar radiation in a linear focus on a receiver tube where the reflected radiation is absorbed by a receiving tube [3] and the non-falling radiation re-reflected again through a secondary compounded parabolic reflector [4]. The outlet temperature and the solar energy to heat energy gained for the linear Fresnel concentrator were investigated at different numbers of mirror elements by Singh et al. [5]. The main drawback of the LFC concentrator is that the concentration ratio is significantly lower than the PTC and changes significantly during the day. However, Muñoz et al. proved that the concentration efficiency achieved by the LRF was very close to the PTC concentration efficiency [6]. Most concentration plants using Fresnel concentrators were used to generate heat at low or medium temperature [7]. For example, small plants that produce thermal energy with temperature ranges from 150 to 300 ºC which are suitable for cooling and heating processes of the buildings [8], domestic heating water [9], steam generation for mining, textile and chemical industries, agriculture and timber and food applications [4]-[10]. The linear Fresnel concentrators differ from each other in terms of reflective mirror width, design of the tracking system and the curvature of the mirror (flat, parabolic, circular), the ratio of the mirror area to the available area, the height of the receiver tube above the primary mirrors, and the details of the receiver: multiple tube receiver or single-tube receiver. Several studies have been conducted on the use of multiple pipes in the receiver tube of the LFC [11], [12]. The multi-pipe receiver tube consists of a group of parallel pipes located inside a cavity and often in the shape of a trapezoid placed in a horizontal plane and thus without a second reflective mirror. Some of the designs for the receiver tube lay a flat glass cover below the cavity to cover the receiver tube and protect the selective surface, which reduces the rate of heat loss. An additional benefit for the glass cover is to make a greenhouse effect that improves the receiver performance. It also minimizes convection losses, due to the vacuum between the steel tube and the glass cover. The main reason for the low of the concentration ratio is the drift and uncertainty in the direction of the reflected radiation with the increase of the length between the mirrors and the receiver.