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An experimental study on optimum spacing between grooved tubes is reported in this paper. Two grooved tubes having pitch of 10 mm and 15 mm and a plain tube were considered for the heat transfer analysis. The spacing between two tubes with same pitch was varied from 10 mm to 35 mm with a step size of 5 mm. Velocity of air flowing over the tube surfaces was changed from 0.4 m/s to 1 m/s using a blower fan. Based on Nusselt number (Nu) the optimum spacing between the tubes was decided. The optimum spacing between grooved tubes of pitch 10 mm and 15 mm was compared with that of plain tubes. From the experimental analysis it was noticed that with increase in air velocity (increase in Reynolds number) the tube surface temperature reduced irrespective of any tube considered. Nu increased with increase in air velocity for all the tubes. The important conclusion drawn from the present study was that, there exists a limiting spacing (optimum) between the tubes above which no change in Nu was observed. Spacing of 30 mm was found to be the optimum spacing between the tubes irrespective of its surface geometry modifications.

The prime objective of this investigation is to address the problem of optimum spacing of channels formed by parallel plates having volumetric heat generation, subjected to conjugate forced convection-conduction cooling. Assuming non uniform volumetric heat generation in the plate, the two dimensional equation governing the temperature distribution in the solid domain are solved simultaneously with stream function, vorticity transport, and energy equation for the flow and thermal fields of the fluid domain, using appropriate finite difference method. Keeping aspect ratio ( A r ) of the plate constant, results are presented in the form of effect of conduction-convection parameter ( N c c ), total heat generation parameter ( Q t ), Reynolds number ( R e H ) on the optimum spacing of the plates, for various Prandtl number ( P r ) representing the coolants liquid Sodium, Sodium Potassium, Lead and Helium. It is concluded that the optimum spacing between the plates ( B o p t ) is independent of Q t and N c c , whereas decreases with increase in R e H , and P r . It is also concluded that, Helium acts as the best among all the coolants considered in this study, whereas Lead serves to be the best among all liquid metal coolants.

The major goal of this research is to identify optimal arrangement of forced cooling enhancements such as baffles and fins. This research focuses to determine the effect of the different configurations for achieving higher thermal efficiency of the 150 W solar photovoltaic thermal collectors (PV/T). The air-cooling enhancements evaluated in this PV/T system are free duct without fins, ducts with fully transverse fins, partially transverse fins, longitudinal fins with straight baffles and inclined baffles. The experiments are done on hot days of summer in May 2018, India and achieved diverse flow rates of air mass ranging from 0.012 to 0.016 kg/s. The Reynolds number obtained in the flow experiments are in the range of 900–1300 and Nusselt number 35–130.A Computational fluid dynamics study was established to achieve a parametric research to determine surface and outside profiles to study the cooling effectiveness. The impacts on flow rate of air mass on the outlet T, Reynolds Number, coefficient of heat transfer and Nusselt number were studied. The maximum irreversibility occurred at the free type fins whereas minimum irreversibility obtained at longitudinal type with inclined baffles and detected that PV/T system have a prodigious impact on the energy efficacy as well as energy losses increased with increasing surface T. This research displayed that the coefficient of heat transfer of solar panel upsurges by means of growing Reynolds number. Additionally, the PV module thermal efficacy by growing flow rate and reduced with increasing friction factor. An increase by 6–8% in exergy efficiency and 5% to 7% in energy efficiency was recorded while using these forced air-cooling enhancements. A reasonable agreement was reached between experimental and computational model. The exergy performance was increased from 20% to 28 % while using air cooling duct with longitudinal fins and inclined baffles. The thermal energy performance was increased from 12 to 18 % while using air cooling duct with longitudinal fins and inclined baffles. This is the maximum energy efficiency achieved in this PV/T system with the Nusselt number ranging from 30 to 130 and Reynolds number 900–1300. This study showed that Nusselt number of PV/T system upsurges with growing Reynolds number of air flow. The PV module thermal efficacy upsurges by means of growing flow rate as the friction factor increases. The longitudinal fins with inclined baffles provided higher friction factor, thereby ensured higher heat transfer rate. The fins and baffles employed in our research are economical and relaxed to manufacture and install. They bid a fairly lower friction lack in movement of air and henceforth do not necessitate higher fan power. This set up can be used for green and smart cities as it helped to reduce the energy consumption considerably.

In this article, effect of spacing between the battery cells ($$\bar{W}_{\text{f}}$$) on thermal performance of Li-ion battery cells is investigated in detail. Developing a finite volume method-based numerical code for the present analysis, conjugate boundary condition at the cell and coolant interface is considered. SIMPLE algorithm employed for solving the Navier–Stokes equation is validated with famous benchmark lid-driven cavity problem. The heat generation inside the modern battery cell is uniform in accordance with cell zone. Air being the coolant flows between the channel spacing of the battery cells. Forced laminar flow of coolant and steady-state analysis with operating parameters like heat generation term ($$\bar{S}_{\text{q}}$$), Reynolds number (Re), conduction–convection parameter (ζcc), and aspect ratio (Ar) is analyzed with main focus of $$\bar{W}_{\text{f}}$$. The range of $$\bar{W}_{\text{f}}$$ is from 0.02 to 0.14 varied in steps of 0.02 and Re from 250 to 2000 in step of 250. Coupled heat transfer behavior in terms of maximum temperature and average Nusselt number for these parameters is provided. From the numerical analysis, it is observed that for most of the range of operating parameters, at $$\bar{W}_{\text{f}} = 0.02$$, causes a sudden increase in temperature distribution and rise in maximum temperature above critical limits. Average Nusselt number increased with decrease in $$\bar{W}_{\text{f}}$$ up to 0.04 and below this, it dropped. Spacing of $$\bar{W}_{\text{f}} = 0.04$$ and $$\bar{W}_{\text{f}} = 0.06$$ proved to be an optimal spacing at which average Nusselt number is the highest and the maximum temperature is within the safe limit for parameters considered.

The thermal enhancement characteristics of a solar thermal collector (STC) roughened with single arc protrusion ribs are investigated. Out of various techniques used for enhancing the performance of STC, jet impingement and artificial roughness (AR) have a dominant role in heat transfer augmentation. The impinging air jets STC is roughened with single arc protrusion ribs of different parametric values. The combined impact of artificial roughness and jet impingement on the thermo-hydraulic performance of STC is experimentally investigated. Reynolds number is varied from 4000 to 18,000 during experimentation. The AR parameters; relative height ratio of the rib is varied from 0.8 to 1.7, relative pitch ratio of the rib is varied from 9 to12, angle of arc protrusion rib from 40° to 80°, streamwise variation to d hy ratio (hydraulic diameter) is from 0.39 to 0.56 and spanwise variation to d hy ratio from 0.82 to 0.99 during experimentation. The parametric values of artificial roughness for the optimum thermo-hydraulic performance of 1.5, are found out to be relative height ratio of rib = 1.1, relative pitch ratio of rib = 10, angle of arc protrusion rib = 60°, streamwise variation to d hy ratio = 0.43 and Span wise variation to d hy ratio = 0.86. Artificial neural network modeling of Nurs – Nusselt number and f f – friction factor is also performed which accurately predicts these factors easily.

This paper investigates the heat transfer and fluid flow characteristics of liquid metal coolants (such as Sodium, Sodium potassium, Bismuth, Lead, and Lead–bismuth) flowing over a nuclear fuel element having non-uniform internal energy generation numerically using finite difference method. The Full Navier Stokes Equations governing the flow were converted into stream function-Vorticity form and solved simultaneously along with energy equation using central finite difference scheme. For the two dimensional steady state heat conduction and Stream-Function Equation, the discretization was done in the form suitable to solve using ‘Line-by-Line Gauss-Seidel ’ solution technique whereas the discretization of Vorticity transport and energy equations were done using Alternating Direction Implicit (ADI) scheme. After discretization the systems of equations were solved using ‘Thomas Algorithm’. The complete task was done by writing a computer code. The results were obtained in the form of variation of Maximum temperature in the fuel element (hot spots) and its location, mean coolant temperature at the exit .The parameters considered for the study were aspect ratio of fuel element, A r , conduction-convection parameter N cc , total energy generation parameter Q t , and flow Reynolds number Re H . The results obtained can be used to minimize the Maximum temperature in the fuel element (hot spots).