International Journal of Advanced Technology and Engineering Exploration ISSN (Print): 2394-5443    ISSN (Online): 2394-7454 Volume-13 Issue-135 February-2026
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Experimental validation of a two-pipe one-dimensional optical–thermal model for an Acurex-based parabolic trough collector using Therminol VP-1

Kiran Beldar1 and Rajesh Kale2

Assistant Professor, Department of Mechanical Engineering,St. John College of Engineering and Management, Palghar,Maharashtra,India1
Professor, Department of Mechanical Engineering,Rajiv Gandhi Institute of Technology, Mumbai,Maharashtra,India2
Corresponding Author : Kiran Beldar

Recieved : 18-April-2025; Revised : 15-February-2026; Accepted : 17-February-2026

Abstract

This study presents a detailed experimental and numerical analysis of a solar parabolic trough collector (PTC) designed and fabricated based on the ACUREX solar field geometry. Its thermal performance was evaluated under real operating conditions. The experimental setup employed Therminol VP-1 as the heat transfer fluid (HTF) at a steady flow rate of 12 L/min to validate a one-dimensional (1D) two-pipe mathematical model. The model incorporated energy balance equations for the absorber and glass envelopes, integrating principles of conduction, convection and radiation. The results indicated a maximum variation of 0.79% only between measured and predicted outlet temperatures, confirming the high predictive accuracy of the developed model. The collector exhibited stable operation over the medium-temperature range (100°C–320°C), with peak outlet temperatures occurring between 12:00 PM and 2:00 PM, corresponding to maximum direct normal irradiation (DNI). Statistical validation yielded a root mean square error (RMSE) of 1.39 K and a mean absolute error (MAE) of 1.22 K, both of which fell within the combined experimental uncertainty of ±1.4 K. Moreover, convective losses accounted for approximately 58% of total heat losses, followed by radiative (22%) and conductive losses (1%). These findings assert that the proposed 1D model accurately represents the collector’s thermo–hydraulic behaviour while offering a computationally efficient alternative to complex computational fluid dynamics (CFD)–based approaches. These observations highlight the importance of optical–thermal coupling including incident angle modifier (IAM), proper system insulation and optimal mass flow management for improving energy conversion efficiency in solar PTC systems.

Keywords

Parabolic trough collector (PTC), Therminol VP-1, One-dimensional thermal modelling, Thermo–hydraulic performance, Solar thermal energy systems.

Cite this article

Beldar K, Kale R. Experimental validation of a two-pipe one-dimensional optical–thermal model for an Acurex-based parabolic trough collector using Therminol VP-1. International Journal of Advanced Technology and Engineering Exploration. 2026;13(135):189-208. DOI : 10.19101/IJATEE.2025.121220506

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