Research paper Optimization of channel geometry in a mini-cooling system: A study of triangular, square, and semicircular sections Samaneh Amini Ahour * , Moharram Jafari , Seyyed Faramarz Ranjbar , Reza Hassannejhad Heat transfer Laboratory, Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran A R T I C L E INFO Keywords: Mini-cooling system High heat rate Turbulence ﬂow Solar collector Photovoltaic systems Heat transfer Thermal management Experimental investigation ABSTRACT This work examines both experimental and numerical methodologies for a cooling system applied to a copper ﬂat plate under steady-state conditions. The primary factors examined are different inlet ﬂuid temperatures, high applied heat rates, and the various geometries of the channel cross-sections. the effect of the Reynolds number on wall temperature, pressure drop inside the channels, and heat transfer coefﬁcient. The subsequent analysis ex- amines the inﬂuence of pump power on the wall temperature and the temperature of the cooling ﬂuid at the outlet. Ultimately, pressure reductions, heat transfer coefﬁcients, and the thermal absorption of the cooling ﬂuid at varying ﬂow rates are compared throughout the three channel geometries. The ideal ﬂow rate for the system has been determined. The ﬁndings indicate that the square channel geometry signiﬁcantly outperforms earlier designs, with a maximum heat removal rate of 339 W at an optimal ﬂow rate of 0.019 L/s. Research on pressure drops indicates that the square channel results in minimum pressure loss for the cooling ﬂuid. Furthermore, numerical simulations conducted using COMSOL software demonstrate a signiﬁcant coincidence with experi- mental data, with a maximum deviation of around 4 %. Such evidence indicates that the numerical results are accurate and dependable. 1. Introduction Heating and electricity are the most necessary energies in the world. Nowadays, approximately 80 % of the world’s energy is produced by fossil fuels [1]. The most available and achievable energy is solar. The sun is used for providing heat, electricity, and light for industrial uses by solar technologies [2]. A photovoltaic (PV) cell is one of the solar technologies. The widely applicable heat collection system is a ﬂat module collector and solar cell for thermal and electrical applications. Generally, temperature increment leads to a decrease in the efﬁciency of the solar cells [3]. The working temperature increases due to the fact that large parts of the solar radiation do not convert to electricity but are absorbed by the plates as heat. So, the PV module should be cooled. Solar cells’ cooling can be achieved by water or air [3–5]. PV cell is arranged in a series or parallel circuit to generate higher current, voltage, and power values. There are several cooling methods, including forced air, water spraying, circulation forced water, heat sink, a phase-change material, immersion in water, transparent coating, ther- moelectric cooling, and heat pipe cooling [6]. Many researchers inves- tigated the cooling methods of solar collectors and ﬂat plates. Najafpour et al. [7] examined the impact of geometric designs and nanoﬂuids on enhancing the thermal performance of multi-branch channel heat sinks in solar collector applications. Simultaneously, progress has been ach- ieved in solar-powered air conditioning systems and evacuated tube collectors that diminish air humidity, with heat transfer from solar ra- diation serving as a critical performance determinant. Several re- searchers are investigating the domain of convective heat transfer. Haq et al. [8] conducted a numerical investigation on the thermal conduction within a partially heated trapezoidal cavity containing a single-walled carbon nanotube nanoﬂuid. Their research indicated that conduction was predominant at low Rayleigh numbers, but convection gained sig- niﬁcance at high Rayleigh numbers. Additionally, ﬂuids with reduced viscosities impede heat transfer, resulting in enhanced ﬂuid circulation. Mohamed ElAmine Slimani et al. [9] Study and modeling of energy performance of a hybrid photovoltaic/thermal solar collector: Conﬁg- uration Suitable for an indirect solar dryer. The results illustrated the electrical, thermal, and overall efﬁciency at 0.015 kg/s were 10.5 %, 70 %, and 90 % respectively. Poorya et al. [10] analyzed the Performance of four air-based photovoltaic thermal collectors’ conﬁgurations with bifacial solar cells. It was observed that the double-pass in parallel ﬂow type has the highest energy efﬁciency of 51 %  67 %, and the single-pass has the lowest energy efﬁciency of 28–49 %, then the packing parameter was 0.7. Shyam et al. [11] examined * Corresponding author. E-mail address: s.aminiahour@tabrizu.ac.ir (S.A. Ahour). Contents lists available at ScienceDirect Results in Engineering journal homepage: www.sciencedirect.com/journal/results-in-engineering https://doi.org/10.1016/j.rineng.2025.106424 Received 27 April 2025; Received in revised form 29 June 2025; Accepted 21 July 2025 Results in Engineering 27 (2025) 106424 Available online 25 July 2025 2590-1230/© 2025 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by- nc-nd/4.0/).