Numerical investigation on the thermal performance of perforated and non-perforated twisted fins at different twisting angles

The present study numerically investigated the effect of variations in the twisting angle and perimeter of diamond-shaped perforation on the heat transfer of twisted fin heat sinks. The study showed a possible configuration of a heat sink design, aiming to improve heat transfer and the hydrothermal performance factor (HTPF). ANSYS/FLUENT computational fluid dynamics software was used to perform the simulations, and the Reynolds-averaged Navier–Stokes-based k−ε turbulence model was used. Results revealed that a maximum of 46 % enhancement in the Nusselt number and a 25 % increase in (HTPF) could be attained with a twisting angle of 540° in comparison with conventional cylindrical fins. Furthermore, the variation in perforation perimeter at a twisting angle of 540° resulted in a maximum of 28 % enhancement in the Nusselt value and a 36 % enhancement in HTPF in comparison with the twisted fins with no perforations. Therefore, this configuration is recommended as the optimal heat sink configuration

Numerical Investigation of the Effect of Square and Sinusoidal Waves Vibration Parameters on Heat Sink Forced Convective Heat Transfer Enhancement

Among numerous electronic cooling methods, a vibrating heat sink using sinusoidal wave vibration effectively enhances the heat transfer by disturbing the thermal boundary layer. However, sinusoidal wave vibration has reached its limits in enhancing heat transfer. The present study utilizes a new square wave-shaped vibration and numerically investigates the thermal performance of a heat sink subjected to sinusoidal and square waves vibration. It is found that using the square wave vibration is more beneficial to the thermal performance of the heat sink than the sinusoidal wave. The sudden impulsive motion of square wave vibration induces a higher randomness of the airflow profile and recirculation zones than the sinusoidal wave, causing the air flow to impinge directly into the fin surfaces, and further enhances the heat transfer. Furthermore, increasing the frequency and amplitude leads to a higher heat transfer enhancement. Moreover, square wave vibration achieves a 25% increase in Nusselt values compared to the nonvibrating fins and it is 11% higher than the Nusselt number recorded by the sinusoidal vibration. Consequently, Reynolds number values can be reduced by 42.2% to achieve the Nusselt number values of nonvibrating fins, potentially reducing the cooling system or fin size. This reduction may contribute to solving the challenges of electronic systems compactness

Numerical Investigation of the Effect of Square and Sinusoidal Waves Vibration Parameters on Heat Sink Forced Convective Heat Transfer Enhancement

Among numerous electronic cooling methods, a vibrating heat sink using sinusoidal wave vibration effectively enhances the heat transfer by disturbing the thermal boundary layer. However, sinusoidal wave vibration has reached its limits in enhancing heat transfer. The present study utilizes a new square wave-shaped vibration and numerically investigates the thermal performance of a heat sink subjected to sinusoidal and square waves vibration. It is found that using the square wave vibration is more beneficial to the thermal performance of the heat sink than the sinusoidal wave. The sudden impulsive motion of square wave vibration induces a higher randomness of the airflow profile and recirculation zones than the sinusoidal wave, causing the air flow to impinge directly into the fin surfaces, and further enhances the heat transfer. Furthermore, increasing the frequency and amplitude leads to a higher heat transfer enhancement. Moreover, square wave vibration achieves a 25% increase in Nusselt values compared to the nonvibrating fins and it is 11% higher than the Nusselt number recorded by the sinusoidal vibration. Consequently, Reynolds number values can be reduced by 42.2% to achieve the Nusselt number values of nonvibrating fins, potentially reducing the cooling system or fin size. This reduction may contribute to solving the challenges of electronic systems compactness

Life cycle cost analysis of an electric centrifugal chiller integrated with a district cooling plant

Electric Centrifugal Chillers (ECC) are mostly incorporated into District Cooling (DC) systems for charging the Thermal Energy Storage (TES) tank or/and to supply Chilled Water (CW) directly to the DC network for Air Conditioning (AC). ECC accounts for the highest percentage of the total electrical energy consumption, making it the most energy-intensive system in the DC setup. The high positive correlation between energy consumption and cost, and its influence on the decision-making process, necessitate the requirement to conduct an economic performance evaluation of the ECC plants. To achieve this objective, a Life Cycle Cost (LCC) analysis is performed to quantify the economic implication resulting from the ECC system's acquisition, operation, and maintenance. In this analysis, four (4) ECC systems installed in a large DC plant in Malaysia are considered the case study. The result obtained from the analysis of the study year revealed that April and June accounted for the maximum and minimum cost implication per outcome, respectively. It is also observed from the results that the climatic temperature conditions had a significant influence on the monthly cooling demand, energy consumed, and cost incurred. The operational phase of the system's life cycle accounted for the highest cost implication from the overall LCC result. A significant reduction in the operating cost is recorded as the indirect energy source used for driving the chiller plant is switched from the electricity supplied from the National Electricity Grid (NEG) and supplied from the Natural Gas Plant (NGP). The LCC per refrigeration ton of the ECC system is estimated to be MYR 1.44/RTh. The impact of system degradation (i.e. decrease in Coefficient of Performance (COP) value) over time on the overall cost per output refrigeration was also investigated. The study also revealed that operating an actual ECC system on electricity from NGP led to a 31% cost savings compared to an ideal system running on electricity from NEG. A sensitivity analysis is also conducted at the end of the study to determine the influence of the input variable on the output result