Geothermal energy, derived from the Earth’s internal heat, is a renewable and sustainable source that can provide continuous electricity and heating. While successfully developed in countries such as the United States, Iceland, and Italy, its use in Pakistan is still negligible despite favorable geothermal conditions. This review aims to assess the potential of geothermal energy in Pakistan globally, finding technological opportunities, barriers, and policy needs. A literature-based method was applied, analyzing published research on geothermal resources, extraction techniques, and international case studies to prove benchmarks for Pakistan’s energy sector. Findings show that Pakistan exhibits geothermal gradients ranging from 1.5°C/100m to 4.1°C/100m, with wellhead temperatures reaching up to 180°C, making it suitable for binary and flash steam power systems. Furthermore, more than six hundred abandoned oil and gas wells in the Indus Basin offer opportunities for cost-effective geothermal retrofitting and integration with carbon capture technologies. However, high drilling costs, lack of supportive policies, and limited awareness constrain progress. Global advancements, including Enhanced Geothermal Systems, binary cycle plants, and the use of supercritical CO 2 as a working fluid, prove improved efficiency and reduced environmental risks. The review concludes that, with strategic investment, policy reform, and the adaptation of proven technologies, geothermal energy can strengthen Pakistan’s energy security, reduce its dependence on fossil fuels, and contribute to the global transition toward sustainable energy.

Ensuring accurate modulation of momentum, thermal, and mass transport in micro/nanoscale lubrication is vital for high-performance microelectromechanical systems (MEMS), lab-on-chip devices, and modern industrial technologies. These configurations frequently involve intricate interactions between stretching surfaces, unsteady film geometry, electromagnetic fields, and nanofluid properties. The challenge lies in enhancing energy performance amidst localized irreversibilities and nonuniform transport. This research explores how a three-dimensional electroconductive hybrid nanofluid film develops over time when enclosed between a laterally moving membrane and an oscillating upper compressor, both influenced by applied electric and magnetic fields. A mathematical model accounting for Joule heating, electroosmosis, thermo-diffusion, and reactive mass transfer is solved using a numerical finite difference method to analyze flow, thermal, mass, and irreversibility characteristics. Key findings disclose that entropy is localized: high in ’troughs’ (frictional/EM dissipation), low in ’crests’ (heat transfer dominant). Joule heating helps in reducing external energy needs, but it contributes to entropy generation which mandates the optimal electric field control and an improved channel geometry for energy-efficient operation. Additionally, Brownian motion and thermophoresis ensure uniform nanoparticle dispersion, providing stable, thin-film lubrication and reducing dry patches. For sustainable nanoscale fluidics, these insights are crucial, leading to energy-efficient design and control by optimizing transport and managing entropy.

Thermoelectric devices (TEDs) intrinsic electrical resistance is fundamental to its operation. This internal electrical resistance value negatively affects a TED’s performance when it is operated as a thermoelectric cooler (TEC), and positively affects a TED when operated as a thermoelectric heater (TEH). TEDs inherent electrical resistance value is temperature dependent, making it difficult to measure / know the exact value. As a result, it is hardly published / discussed in details in most technical / scholarly works. This study practically researched and present in detailed, TEDs electrical resistance from a Peltier effect (TEC / TEH) perspective. Sixteen similar TEDs were in turns operated as TECs (until maximum cooling) and TEHs (at 0, 5 and 10 minutes of operation) with 4 V, 6 V, 8 V, 10 V and 12 V direct current (DC) power supply. A total of 320 observations were made to practically and accurately determine the TEDs electrical resistance to be mostly between 3 and 4 Ω and furthermore, a novel analytical framework based on power regression analysis was introduced as the study highlight, to validate it. It was employed to easily and accurately compute the x16 TEDs electrical resistance mean at 12 V, 10 V, 8 V, 6 V and 4 V to be respectively 3.43 Ω, 3.38 Ω, 3.34 Ω, 3.33 Ω and 3.34 Ω, as well as their combined final mean to be 3.39 Ω.

Saving energy or converting it to different forms requires a continuous technique to improve the applications’ thermal performance. The present investigation analyzed the thermal performance and temperature distribution of the Phase Change Material (PCM) discharging method numerically and experimentally inside an annulus of concentric tube. The inlet temperature of heat transfer fluid flow in the inner tube of the annulus was maintained to be lower than the solidification points of the PCM. The computational domain has been simulated as a 3D model for the coupled system. Under various flow rates, the local temperature is measured and computed. It is found that the computational predictions in a good matching with the acquired experimental data. Different mass flow rates have been considered varying in range of (0.0134-0.0952) kg/s. The experimental results showed that there is an inverse proportional relationship between the amount of mass flow rates and the time required for the solidification of paraffin wax. The optimum times (275, 220, 165, and 75) minutes are reached to obtain hot water for domestic use compared to the previously mentioned mass flow rates during the discharge process.

Various numerous tools, techniques, and surveys have been proposed on free convection, related heat transfer from solo single obstacle with circular cylinder cross section in free space at High Rayleigh number (Ra). For fluid heat exchangers in [refrigeration systems](https://www.sciencedirect.com/topics/engineering/refrigeration-system) more efficient and compact, passive methods for [heat transfer enhancement](https://www.sciencedirect.com/topics/engineering/heat-transfer-enhancement) produced by tubes in various positions and temperature must be surveyed and assessed. Furthermore, the case of an array of cylinders in natural convection correlations were scarily developed and reviewed for high Ra. The paper mainly studies the feasibility and convenience of Lattice Boltzmann Method (LBM) in numerical treatment of free convection with cold and hot column obstacles. The current numerical study deals with natural convection between hot solid cylindrical-shaped obstacles and a cold cavity. In this paper, the LBM is proposed and implemented to calculate the free convection which is the result of a difference of temperature between the external (cold) enclosure and six solid cylindrical obstacles, and expounds the dynamic and thermal transformation behavior from Ra=10 6 to Ra=10 7 and its influence on hydrothermal treatment. After simulating energy, mass and momentum equations, the effects of High Ra are critically investigated on the Newtonian fluid dynamic and thermal transfer behaviors inside the enclosure with length H. Two numerical tests are well-thought-out. First one deals with two columns containing circular bodies at a constant temperature T H. The first column is located on the Vertical Centerline (VC) at x/H=1/4 of the cavity and the other on the Vertical Centerline (VC) at x/H=3/4. While in case 1 and 2, two opposite columns of hot and cold bodies placed at x/H=1/4 and x/H=3/4 is considered. Besides, the effect of magnetic field is high-lighted. This article sheds light on the workability and LBM facilitates in numerical treatment of a free convection with hot and cold array of cylindrical obstacles. The dynamic and thermal transition behaviors from Ra=10 6 to Ra=10 7 and their effect on hydrothermal treatment of the Newtonian fluid have been illustrated via isotherms, horizontal and vertical velocity, the streamlines, square mean velocity and pressure fields. The obtained results provide strong numerical basis database for nuclear power plant containment with passive residual heat removal structure performance.

The “ Analyzing Laminar and Turbulent Flow Performance in Finned Heat Transfer Systems” is a study or research project that focuses on assessing the effectiveness and efficiency of heat transfer systems equipped with finned surfaces. Optimizing thermal management in passive cooling pin fin devices is the focus of this research. The Reynolds number is a key parameter in its study of heat transfer efficiency and flow dynamics, distinguishing laminar and turbulent flows. The Shear Stress Transport (SST) k-omega model is used to simulate laminar and turbulent flows in finer heat transfer systems. Comparing the two flow regimes, it measures velocity, temperature, pressure, Reynolds number, and skin friction coefficient. The author wants to find the best fin design for heat transmission. Both flow types visually display streamlined patterns. The cooled heat transfer system is laminar, and turbulent flow is covered in ”Results and Discussion”. In laminar flow, velocities ranged from 0 to 0.129 m/s, static temperature varied from 305 to 320 K, static pressure ranged from -0.02 to 0.064 Pa, Reynolds number ranged from 128 to 243, and skin friction coefficient varied from 0.0048 to 0.01. In turbulent flow, velocities ranged from 0 to 0.235 m/s, static temperature varied from 300 to 320 K, static pressure ranged from -0.02 to 0.064 Pa, Reynolds number ranged from 2658 to 3736, and skin friction coefficient varied from 0.00487 to 0.012. Streamline patterns were also illustrated for both flows.

An experimental study was conducted to investigate how the arrangement of conical fins enhances the performance of a heat sink under forced convection conditions. Two types of heat sinks were manufactured: a staggered heat sink and an inline heat sink. The heat sink was manufactured from AL383 alloy, and the dimensions of the fins are 50 mm in height, 12 mm in diameter, with a distance of 30 mm between them. The heat sink is positioned within a horizontal channel. Five different speeds, ranging from 1.5 to 4 m/s, were utilized with a constant heat source. A variety of variables were examined, including heat dissipation, heat transfer coefficient, temperature distribution along the fin, Reynolds number (Re), Nusselt number (Nu), and heat sink efficiency. It’s evident from the results that the staggered heat sinks disperse heat more effectively than the inline heat sink, exhibiting an 8.78% increase in heat dissipation at Re 15000. Furthermore, the staggered heat sink demonstrates a significant improvement in the heat transfer coefficient (h), with a 35% enhancement at Re 15000 compared to the inline heat sink. The Nusselt number of staggered heat sinks increases with an increase in Reynolds number. The ANSYS program was utilized to determine the optimal height-to-diameter (B/d) ratio for the conical fin. While the diameter could vary from 8 mm to 16 mm, the height remained constant at 50 mm. Consequently, the ratio was tested at (6.2, 5, 4, 3.5, 3.1). The staggered heat sink dissipated 8.78% more heat than the linear heat sink at Re 15000. The heat transfer coefficient (h) value increases by 35% at Re 15000 for the staggered heat sink compared with the linear heat sink. Additionally, the Nusselt number increases with the rise in the Reynolds number (Re) and is higher for the staggered then the inline heat sink by 45% at Re 15000. Also, the results clearly convey the finding that the efficiency at Re 15000, the staggered heat sink outperforms the inline heat sink by 7.24%. Additionally, the optimal ratio for dispersing heats throughout the fin’s length was (B/d=4).

This study is motivated by the challenges of global warming and energy issues, as well as the need to overcome the difficulties in injection and combustion that lead to high NOx emissions, to encourage research on improving the physicochemical properties of biodiesel as an alternative diesel fuel. In this context, the effects of adding acetone and magnesium oxide (MgO) as additives to the fuel obtained by blending biodiesel, produced from Pistacia terebinthus oil - a naturally occurring oil in Turkey notable for its high content of free fatty acids, renewable but non-edible, with diesel fuel, on engine performance, combustion, and emissions have been examined. Nanoparticles and acetone were used as additives in a blend of 80% diesel and 20% biodiesel (B20), and their effects on combustion parameters were evaluated. The fuels obtained by adding acetone and acetone + MgO resulted in decreases in the rate of pressure rise, instantaneous energy release rate, cylinder pressure, average gas temperature, and cumulative heat release rate. Regarding performance parameters, a general trend of increase in specific fuel consumption was observed, while a general trend of decrease was noted in brake thermal efficiency. CO emissions showed a reduction of 6.65% in the B20 fuel mixture with added acetone and 2.10% in the fuel mixture with added acetone + MgO compared to diesel fuel. Additionally, the inclusion of only acetone to the B20 fuel resulted in a 41.64% decrease in NOx emissions, while the addition of acetone + MgO resulted in a 46.03% decrease, but led to a 26.48% increase in HC emissions. These results demonstrate that improved biodiesel formulations have the potential to offer a viable alternative to traditional diesel fuel while addressing energy and environmental challenges.

The study aims to quantify the effect of Dufour number, on flow patterns and heat transfer rates in the exponentially accelerated vertical plate with MHD flow and chemical reaction. The unsteadiness of the flow suggests that time-dependent changes in velocity, temperature, and other relevant parameters are considered. MHD further complicates analysis with the electromagnetic interactions between the fluid and the field. The fluid, be characterized as a gray, absorbing/emitting radiation medium, indicating that it absorbs and emits thermal radiation but does not exhibit scattering behavior. Set of partial differential equations are then resolve using FEM. Graphical results are then discussed. Profiles vary with different, Dufour number, radiation, or temperature-dependent heat source/sink parameter. By varying the values of these governing parameters, on the skin-friction coefficient, Nusselt number, and Sherwood number are also analyzed.

This study examines turbulent convective heat transfer performance (CHTP) and entropy production rate (EPR) of distilled water flowing in outwardly corrugated converging pipes (CCPs) of various diameter ratios (DR). The SST k - ω turbulence models were used to simulate the flow of H 2O inside the pipe. The effects of Reynolds number ( 5 . 0 × 10 3 ≤ Re  ≤ 5 . 0 × 10 4 ), and DR ( 1 ≤ DR  ≤ 2 ) on average Nusselt number ( Nu ), Poiseuille number (fRe) thermal performance evaluation criterion (PEC), EPR, and thermal effectiveness number ( I ) Nu were investigated parametrically. The findings revealed a significant improvement in Nu in the modified pipe compared with the straight pipe. This improvement is attributed to flow acceleration and increases in the mixing rate of hot fluid near the wall with cold fluid at the core fluid zone. Also, Nu , fRe , and EPR increase with increasing Re and DR. However, the opposite is the case for PEC and   I . Finally, the values of PEC, and I revealed that the modified pipe is advantageous compared with a straight pipe at ( 5 × 10 3 ≤ Re ≤ 1 . 0 × 10 4 ) .

The study aims to find the optimal fin length distribution for improved heat transfer during melting and solidification in a tubular PCM heat exchanger designed for heat storage. Three types of horizontal PCM tabular heat exchangers, all with five longitudinal fins, were studied numerically. While maintaining a constant heat transfer area, each model depicts a unique fin length distribution design. The first model, which serves as the reference design, has a homogeneous fin length distribution and each fin is 30 mm long. The second model has shorter upper and side fins and longer lower fins (20 mm for the upper fin, 25 mm for the side fins, and 40 mm for the lower fins). The third model has long lower fins but shorter than that of second model, short side fins and no change in upper fin length with reference design (30 mm for upper fin, 25 mm for side fins and 35 mm for lower fins). The findings indicate that the second model exhibits the best heat transfer performance for the melting process, while the first model is most effective for solidification. Interestingly, the third design emerges as the optimum choice for both melting and solidification processes.

While a variety of solar concentrators have been studied for decades, the study of the spherical glass concentrator has never been reported, to the best of our knowledge. For that, this paper examines the optical characteristics of the novel solar spherical glass concentrator and identifies its performance and features. In addition, the thermal and exergetic performance of the concentrator are studied with three cavity receiver designs under various operating temperatures and different mass flow rates. More specifically, the examined receiver shapes: spiral, conical, and cylindrical. All the cavities are analyzed in order to determine the best design which maximizes the thermal efficiency of the solar collector. According to the results, the spherical collector can concentrate the heat flux up to 25 times the incident flux value. Also, the study is defined the best receiver dimensions that achieve optimum optical performance. Then, the optical analysis is conducted with an optical simulation in COMSOL Ray Optics to validate this work’s findings. Moreover, the best design is found to be the one with a spiral shape, while the conical is the next choice. The cylindrical is the third design in the performance sequence.