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Abstract In this study, the effect of fin number and size on the solidification output of a double‐tube container filled with phase change material (PCM) was analyzed numerically. By altering the fins' dimensions, the PCM's heat transfer performance is examined and compared to finless scenarios. To attain optimal performance, multiple inline configurations are explored. In addition, the initial conditions of the heat transfer fluid (HTF), including temperature and Reynolds number, are considered in the analysis. The research results show a significant impact of longer fins with higher numbers on improving the solidification rate of PCM. The solidification rate increases by 67%, 170%, 308%, and 370% for cases with 4, 9, 15, and 19 fins, respectively, all with the same fin length and initial HTF boundary condition. The best case results in a solidification time that is 4.45 times shorter compared to other fin number and dimension scenarios. The study also found that moving from Reynolds numbers 500 to 1000 and 2000 reduced discharging times by 12.9% and 22%, respectively, and increased heat recovery rates by 14.4% and 27.9%. When the HTF entrance temperature was 10°C and 15°C, the coolant temperature showed that the entire discharging time decreased by 37.5% and 23.1% relative to the solidification time when the initial temperature was 20°C. Generally, this work highlights that increasing the length and number of fins enhances thermal efficiency and the phase change process.

In this study, the effect of fin number and size on the solidification output of a double‐tube container filled with phase change material (PCM) was analyzed numerically. By altering the fins' dimensions, the PCM's heat transfer performance is examined and compared to finless scenarios. To attain optimal performance, multiple inline configurations are explored. In addition, the initial conditions of the heat transfer fluid (HTF), including temperature and Reynolds number, are considered in the analysis. The research results show a significant impact of longer fins with higher numbers on improving the solidification rate of PCM. The solidification rate increases by 67%, 170%, 308%, and 370% for cases with 4, 9, 15, and 19 fins, respectively, all with the same fin length and initial HTF boundary condition. The best case results in a solidification time that is 4.45 times shorter compared to other fin number and dimension scenarios. The study also found that moving from Reynolds numbers 500 to 1000 and 2000 reduced discharging times by 12.9% and 22%, respectively, and increased heat recovery rates by 14.4% and 27.9%. When the HTF entrance temperature was 10°C and 15°C, the coolant temperature showed that the entire discharging time decreased by 37.5% and 23.1% relative to the solidification time when the initial temperature was 20°C. Generally, this work highlights that increasing the length and number of fins enhances thermal efficiency and the phase change process. [ABSTRACT FROM AUTHOR]

Highlights • Adsorption cooling system driven by the exhaust gas for A/C application is modeled. • Optimum fin spacing of longitudinal and annular finned tube adsorber beds is determined. • Heat exchangers with annular fins provide higher cooling power than longitudinal fins. • Adsorption cooling system can decrease fuel consumption and greenhouse emissions. • Heat and mass transport in porous beds of adsorbent particles is investigated. Abstract Adsorption cooling systems (ACS) are considered as potential alternatives to traditional vapor compression air conditioning systems in heavy-duty vehicles. In ACS, adsorber bed heat exchangers (ABHEx) replace compressors and their appropriate design directly impacts the ACS performance. During operation, ABHEx undergo a large temperature swing to derive a refrigerant in ACS and their response time affects the dynamic behavior of ACS. In this study, a detailed three dimensional non-equilibrium model is developed to study the effects of heat and mass transfer in annular and longitudinal finned tube adsorber beds filled with zeolite-13x particles. The effects of fin height and spacing are studied on the system operating parameters to identify an optimum fin geometry. The simulation results show that a decrease in fin spacing leads to a decrease in the coefficient of performance (COP) and an increase in the specific cooling power (SCP), and no optimum value is observed for them in a specific fin spacing. However, variations of the total cooling power (TCP) maximize at a certain fin spacing. For longitudinal finned tube ABHEx, the optimum averaged fin spacing shifts from 5.4 to 6.8 mm for the adsorber beds with 10, 15, and 20 mm fin heights, while the optimum fin spacing of annular finned tube ABHEx changes from 5.0 to 6.4 mm. Furthermore, the results show that under similar dimensions and operating conditions, an ACS with annular finned tube ABHEx provides a 10% higher total cooling power than that with a longitudinal finned tube ABHEx at the optimum fin spacing. Using the ACS with optimized ABHEx in a truck would annually save about 370 L of fuel consumption and decreases greenhouse emissions by up to 738 kg CO 2e. [ABSTRACT FROM AUTHOR]

Abstract: A parametric study on the dynamic natural convection from long horizontal fin arrays (L =128, 254 and 380mm) is made using a 3-D unsteady numerical analysis. The investigated range of height H is 6.4–38mm and that of spacing S is 6.4–20mm. Increasing L tends to enhance the oscillating sliding-chimney flow, whereas increasing S weakens it. The time-averaged overall convection heat transfer coefficients are larger for high and short fin arrays, due to the stronger buoyancy and thinner boundary layers. The –S relation exhibits a steep drop when S is narrowed below a threshold, which is larger for lower and longer fins. The optimum fin spacing S opt occurs near the threshold S, below which the benefit of increasing heat transfer area surrenders to the decrease of caused by excessive viscous drag. The heat transfer rate per unit base area Q/A b decreases with increasing L and decreasing H. The predicted dependence of S opt on H and L agrees well with experimental results and is explained based on numerical results of flow and heat transfer characteristics. The present predictions of Nu agree well with the correlations in the literature which use S as the characteristic length. [Copyright &y& Elsevier]