Najiba Hasan Hamad^1,*, Ranj Sirwan Abdullah², Ahmed Mohammed Adham²

Energy Engineering, Vol.123, No.1, 2026, DOI:10.32604/ee.2025.073377 - 27 December 2025

Abstract Coiled tube heat exchangers are widely preferred in shell structures due to their superior heat transfer performance, driven by favorable flow characteristics. This study investigates the effect of modifying coil and shell configurations on heat transfer efficiency. Two key enhancements were examined: adding fins to the outer coil surface and integrating longitudinal slots within a hollowed shell. These modifications promote turbulence and extend heat transfer duration, thereby improving performance. However, they also introduce challenges, including increased pressure loss and manufacturing complexity. Numerical simulations were conducted using ANSYS Fluent 2024R1 under identical boundary conditions. With a… More > Graphic Abstract

Marija Macenić, Tomislav Kurevija^*, Tin Herbst

Energy Engineering, Vol.123, No.1, 2026, DOI:10.32604/ee.2025.067067 - 27 December 2025

Abstract The increased interest in geothermal energy is evident, along with the exploitation of traditional hydrothermal systems, in the growing research and projects developing around the reuse of already-drilled oil, gas, and exploration wells. The Republic of Croatia has around 4000 wells, however, due to a long period since most of these wells were drilled and completed, there is uncertainty about how many are available for retrofitting as deep-borehole heat exchangers. Nevertheless, as hydrocarbon production decreases, it is expected that the number of wells available for the revitalization and exploitation of geothermal energy will increase. The… More >

Noor Moneer Basher¹, Omar Rafae Alomar^1,*, Omar Mohammed Ali², Diyar Abdullah Ahmed³

Frontiers in Heat and Mass Transfer, Vol.23, No.6, pp. 2001-2024, 2025, DOI:10.32604/fhmt.2025.066997 - 31 December 2025

Abstract The energy consumption of a Split air conditioning unit (ACU) inside a building is extremely large, and efforts to decrease this issue are ongoing. The current work aims to experimentally investigate the thermal performance of ACU using an external cooling-water loop for pre-cooling the condenser to improve the efficiency and to reduce energy consumption by reducing refrigerant temperature before entering the condenser, thereby reducing the coefficient of performance. The experiments are performed on ACU with and without using an external cooling-water loop under different climate conditions. By using the experimental data, the systems’ performances for… More >

S. Srinivasa senthil, K. Vijayakumar^*

Energy Engineering, Vol.122, No.12, pp. 5149-5173, 2025, DOI:10.32604/ee.2025.070889 - 27 November 2025

Abstract Heating, ventilation, and air conditioning (HVAC) systems contribute substantially to global energy consumption, while rejecting significant amounts of low-grade heat into the environment. This paper presents a non-intrusive spiral-coil heat exchanger designed to recover waste heat from the outdoor condenser of a split-type air conditioner. The system operates externally without altering the existing HVAC configuration, thereby rendering it suitable for retrofitting. Water was circulated as the working fluid at flow rates of 0.028–0.052 kg/s to assess thermal performance. Performance indicators, including the outlet water temperature, heat transfer rate, convective coefficient, and efficiency, were systematically evaluated.… More >

Kashif Ahmed Soomro^1,2,3,*, Rahool Rai^1,3,4, S. R. Qureshi², Sudhakar Kumarasamy^4,5,6, Abdul Hameed Memon¹, Rabiya Jamil¹

Energy Engineering, Vol.122, No.12, pp. 4857-4872, 2025, DOI:10.32604/ee.2025.069847 - 27 November 2025

Abstract Plate heat exchangers suffer from significant energy losses, which adversely affect the overall efficiency of thermal systems. To address this challenge, various heat transfer enhancement techniques have been investigated. Notably, the incorporation of surface corrugations is widely recognized as both effective and practical. Chevron corrugation is the most employed design. However, there remains a need to investigate alternative geometries that may offer superior performance. This study aims to find a novel corrugation design by conducting a comparative CFD analysis of flat, square, chevron, and cylindrical corrugated surfaces, assessing their impact on heat transfer enhancement within… More > Graphic Abstract

J. E. López-Gil¹, J. F. Ituna-Yudonago^1,*, V. Pérez-García², V. Martínez-Calzada³, J. L. Rodríguez-Muñoz⁴, J. Serrano-Arellano⁵

Frontiers in Heat and Mass Transfer, Vol.23, No.5, pp. 1365-1393, 2025, DOI:10.32604/fhmt.2025.068100 - 31 October 2025

Abstract This paper presents a thermophysical study approach for a pure environmental control system (ECS), incorporating the geometric dimensions of heat exchangers, ram air duct, and air cycle machine (ACM) blades of the Sabreliner’s environmental control system. Real flight scenarios are simulated by considering flight input variables such as altitude, aircraft speed, compression ratio of the air cycle machine, and the mass flow rate of bleed air. The study evaluates the coefficient of performance (COP) of the environmental control system, the heat exchanger efficiencies, and the work distribution of the air cycle machine based on five… More >

Yijin Zhang, Panding Wang^*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.33, No.2, pp. 1-1, 2025, DOI:10.32604/icces.2025.011144

Abstract As a type of porous material with high porosity and a large surface-area-to-volume ratio, triply periodic minimal surface (TPMS) structures divide space into two non-interconnected parts. This increases the contact area while maintaining full connectivity and smoothness, which helps reduce flow resistance, making it naturally suited for applications in heat exchange designs. The advancement of additive manufacturing (AM) technology has contributed to the development of TPMS-based heat exchangers. However, due to the complexity of fluid heat exchanger designs, developing effective representations, models, and optimization schemes for TPMS structures in multi-fluid heat exchange problems is very… More >

Chen Zhu¹, Xiao Ma¹, Lumin Chen², Qi Ma¹, Yi Sun¹, Fuping Qian^1,*

FDMP-Fluid Dynamics & Materials Processing, Vol.21, No.8, pp. 1895-1915, 2025, DOI:10.32604/fdmp.2025.067899 - 12 September 2025

Abstract The rotary gas-gas heat exchanger (GGH) is a vital component in waste heat recovery systems, particularly for Selective Catalytic Reduction (SCR) processes employed in cement kiln operations. This study investigates the thermal performance of a rotary GGH in medium- and low-temperature denitrification systems, using a simplified porous medium model based on its actual internal structure. A porous medium representation is developed from the structural characteristics of the most efficient heat transfer element, and a local thermal non-equilibrium (LTNE) model is employed to capture the distinct thermal behaviors of the solid matrix and gas phase. To… More >

Ans Ahmed Memon¹, Laveet Kumar^1,2,*, Abdul Ghafoor Memon¹, Khanji Harijan¹, Ahmad K. Sleiti²

Frontiers in Heat and Mass Transfer, Vol.23, No.3, pp. 833-856, 2025, DOI:10.32604/fhmt.2025.064805 - 30 June 2025

Abstract Climate change, rising fuel prices, and fuel security are some challenges that have emerged and have grown worldwide. Therefore, to overcome these obstacles, highly efficient thermodynamic devices and heat recovery systems must be introduced. According to reports, much industrial waste heat is lost as flue gas from boilers, heating plants, etc. The primary objective of this study is to investigate and compare unary (Al₂O₃) thermodynamically, binary with three different combinations of nanoparticles namely (Al₂O₃ + TiO₂, TiO₂ + ZnO, Al₂O₃ + ZnO) and ternary (Al₂O₃ + TiO₂ + ZnO) as a heat transfer fluid. Initially, three different types of… More > Graphic Abstract

Roasi A. Flayh^*, Ayser Muneer Flayh

Energy Engineering, Vol.122, No.7, pp. 2801-2818, 2025, DOI:10.32604/ee.2025.062916 - 27 June 2025

Abstract Double pipe heat exchangers (DPHEs) are normally utilized in various manufacturing uses owing to their simple design and low maintenance requirements. For that, performance enhancement by improved heat transfer is ongoing. Air injections are a good strategy for enhancing the thermal performance of the DPHE. In the present work, the influence of air bubble injection in a DPHE was experimentally investigated, and the system’s hydrothermal performance improvement parameters were evaluated. Two modes were designed, manufactured, and used to conduct the experiments. The first mode was conducted with no air injection, named a single phase mode,… More >