Novel techniques to enhance thermal performance using a helical coil receiver tube and nano-fluid materials are presented in this paper. Two different applied techniques to enhance thermal performance are used as a new application on parabolic trough solar collector (PTSC). Lots of researches are going on to enhance the heat transfer rate using the helical coil tube and nano-fluid for heat exchanger and dish solar concentrated. So that these combining techniques together combined with the PTSC can be considered as a new application. Novel techniques to enhance thermal performance using a helical coil receiver tube and Nano-fluid materials are presented in this paper. Two different applied techniques to enhance thermal performance are used as a new application on parabolic trough solar collector (PTSC). In the present work, PTSC has been fabricated using Dioxide Silicon SiO2 with an average particle size of 40nm by taking volume fraction of SiO2 0.1, 0.2 and 0.3%. Distilled water based Nano-fluid as a working fluid and a helical coil receiver tube were used in this paper. Varying the flow rate of Nano-fluids 100,150 and 200l/h are used, respectively. A solar tracking mechanism experimentally has been used with the PTSC. As per ASHRAE standard, the experimental results showed that at volume fraction 0.3 % and flow rate of 200 l/h, the highest increase in the energy absorbed factor FR(τα) was 14.6 %  and energy removal factor FRUL was 29.4 % compared with distilled water...

The present work presents design and implementation of an automated two-axis solar tracking system using local materials with minimum cost, light weight and reliable structure. The tracking system consists of two parts, mechanical units (fixed and moving parts) and control units (four LDR sensors and Arduino UNO microcontroller to control two DC servomotors). The tracking system was fitted and assembled together with a parabolic trough solar concentrator (PTSC) system to move it according to information come from the sensors so as to keep the PTSC always perpendicular to sun rays. The experimental tests have been done on the PTSC system to investigate its thermal performance in two cases, with tracking system (case 1) and without tracking system (case 2). The experimental results showed that the average solar radiation falling on the PTSC prototype in the two cases during the same time was 854 and 701 watt/m2, respectively, which means an increase in the solar radiation about 21.8 % when using tracking system. It was found that the average useful heat gain output of solar collector was equal to (376.2, 252.6 watt) for the two cases, respectively, so there was an increase of about 48.9 % when using the tracking system. Also, the average thermal efficiency of the PTSC was found to be (20.7, 26.5 %) for the two cases, respectively, which means an increase in the average efficiency by 28% with use of tracking system compared to the fixed case.

In this paper, the experimental thermal performance for a parabolic trough solar concentrator (PTSC) combined with helical tube receiver and directed by two axes solar tracking system at different amount of water flow rates has been analyzed. The experimental test results of thermal performance with regard to temperature rise of water, useful heat gain and collector thermal efficiency for the PTSC prototype at controlled water flow rates (2.3, 22.5 and 29.4 L/h) are collected. The results show that the increase of water mass flow rates causes decrease in the average water output temperature as (120.8, 63.82 and 46.08oC), respectively, the maximum outlet temperature becomes (160.5, 76, 47) oC, respectively, and thus, the average useful heat gain will be (1249.4, 732, 732.5W), respectively and the average thermal efficiency decreases as (73.021, 49.51 and 44.31 %), respectively. The experimental results show that decrease the water mass flow rate by 74.4%, causes an increase in the thermal efficiency of the PTSC by 64.7%.

Solar concentrators are an important facility to utilize the solar energy. There are many kinds of solar concentrators. In this work an experimental has been implemented to improve the thermal performance of Parabolic Trough Solar Collector (PTSC) using three different fluids as a working fluid (water, nanoparticles of CuO mixed with distilled water nanoparticles of Al 2 O 3 mixed with distilled water) with concentration ratio 0.01% and mass flow rate 20Lt/hr without tracking system. The experimental tests have been carried out in electro-mechanical engineering department at university of technology in Baghdad city during October 2017 and daytime between (9am -15pm) hours. The obtained results for three different fluids are as follows:-Using (CuO + distilled water) as a working fluid increases the average of the output temperatures by 10.4%, the average of useful heat gains increases by 11% and the average of the collector efficiencies increases by15%.-Using (Al 2 O 3 +distilled water) as a working fluid increased the average of output temperatures by 4%, the average of useful heat gains is increased by 6.5% and the average of collector efficiencies is increased by 8.2%.

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