The Thermal Effect of Variate Cross-Sectional Profile on Conformal Cooling Channels in Plastic Injection Moulding

Cooling system is an important role in designing a productive plastic injection moulding (PIM). The selection of geometry and layout for plastic injection moulding cooling channels strongly influences the cooling performance such as cooling time and thermal distribution that leads to shrinkage and warpage. This paper presents the study to determine the best cooling channel layout and cross-sectional profile which include circular straight drilled cooling channels, circular conformal cooling channels, square shape conformal cooling channels, elliptical conformal cooling channels and diamond conformal cooling channels. The cooling time and thermal distribution were simulated by Moldflow Insight (MFI) software. Results are presented based on ejection time and temperature variation by using transient analysis in MFI. The results found the best cross-sectional of cooling channels indicated by square shape conformal cooling channels, compare to others due to the shortest cooling time that recorded from simulation. The conformal cooling channel layout also resulted greater thermal distribution compared to straight drilled cooling channel design. Â

A rocket engine design expert system

The overall structure and capabilities of an expert system designed to evaluate rocket engine performance are described. The expert system incorporates a JANNAF standard reference computer code to determine rocket engine performance and a state-of-the-art finite element computer code to calculate the interactions between propellant injection, energy release in the combustion chamber, and regenerative cooling heat transfer. Rule-of-thumb heuristics were incorporated for the hydrogen-oxygen coaxial injector design, including a minimum gap size constraint on the total number of injector elements. One-dimensional equilibrium chemistry was employed in the energy release analysis of the combustion chamber and three-dimensional finite-difference analysis of the regenerative cooling channels was used to calculate the pressure drop along the channels and the coolant temperature as it exits the coolant circuit. Inputting values to describe the geometry and state properties of the entire system is done directly from the computer keyboard. Graphical display of all output results from the computer code analyses is facilitated by menu selection of up to five dependent variables per plot

Investigation of Selective Laser Melting Fabricated Internal Cooling Channels

Channels where coolant is run to cool a system are common in injection mold tooling. Conventionally, these channels are machined into the mold. This has limited the design of mold cooling systems to the constraints of traditional machining processes, where straight circular channels machined from cast material are typical. The transfer of heat away from the part cavity into these cooling channels has a large effect on the cooling time of the injection mold cycle. In this investigation, laser powder bed fusion processes were used to create non-circular cooling channels. To compare cooling performance, elliptical and circular channels of equal crosssectional area were investigated for mass flow rate and rate of heat transfer. Between conventionally machined and additively manufactured channels, surface roughness of the channel wall and condition of the parent material were investigated as potential factors as well. Through simulation, analysis of channel surface roughness, and experimentation, the results indicated that: the channel machined from cast 316L stainless steel had higher flow rate and rate of heat transfer compared to the machined channel fabricated from selective laser melting 316L metal powder, the machined channel had higher flow rate and rate of heat transfer compared to the as-fabricated additively manufactured sample, and the circular additively manufactured channel had higher flow rate and rate of heat transfer compared to the elliptical channel. Overall, the traditionally machined circular channels had superior cooling performance than the additively manufactured elliptical channels. However, the results demonstrate that changing the length-to-width ratio of elliptical cross channels can be used to locally control cooling on regions of the part to reduce hot-spots in the mold and part defects

Analysis of cooling plate designs for fuel cell applications.

In this thesis, theoretical and computational analyses of the heat exchange in a polymer electrolyte membrane fuel cell (PEMFC) cooling plate are described. Thermal management of the fuels cells is essential to ensure high efficiency, durability, and safety of their applications. PEMFC are generally used as a power supply for vehicles in transportation, but can be extended as a back-up power system for household or corporate needs. Analysis of convective heat transfer of PEMFC cooling plates is considerably important in future optimizations techniques to develop new cooling plate designs. Cooling plates are investigated with a method using entropy generation as a numerical analysis alternative to evaluate the performance of the cooling plate designs in addition to temperature variation, pressure drop and velocity profile. The results obtained for the entropy generation in each designs gave effects of the frictional and thermal components of the entropy on heat transfer of cooling channels, confirmation of previous findings, and thermal and hydrodynamic fully developed regions in cooling plates. Benefits and constraints of each design are discussed followed by possible upgrades on designing cooling plates for better PEMFC performance

Optimization of a die insert produced through metal powder bed fusion

The study described in this paper is a reference application of HPDC and AM simulation coupling the benefits of the two manufacturing processes. The thermo-mechanical performance of traditional diecasting insert is improved by conformal cooling channels. The SLM simulation validate the 3D printing of steel material and conformal channels. The cost-benefits analysis supports the decision to maximize the benefits and reducing costs

Modelling and simulation techniques for forced convection heat transfer in heat sinks with rectangular fins

The official published version of this article can be found at the link below.This paper provides a comprehensive description of the thermal conditions within a heat sink with rectangular fins under conditions of cooling by laminar forced convection. The analysis, in which increasing complexity is progressively introduced, uses both classical heat transfer theory and a computational approach to model the increase in air temperature through the channels formed by adjacent fins and the results agree well with published experimental data. The calculations show how key heat transfer parameters vary with axial distance, in particular the rapid changes in heat transfer coefficient and fin efficiency near the leading edges of the cooling fins. Despite these rapid changes and the somewhat ill-defined flow conditions which would exist in practice at the entry to the heat sink, the results clearly show that, compared with the most complex case of a full numerical simulation, accurate predictions of heat sink performance are attainable using analytical methods which incorporate average values of heat transfer coefficient and fin efficiency. The mathematical modelling and solution techniques for each method are described in detail.This work was part of a project funded by Solas Technology Limited, Ireland

Effect of Rib Turbulators on Heat Transfer Performance in Stationary Ribbed Channels

The thermal performance was examined computationally for the stationary channels with rib turbulators oriented at 90 degrees. Ribs were placed on opposite walls and the heat transfer coefficients and frictional loss were calculated. Three stationary channels with aspect ratios (W/H) 1, 2 and 4 were considered for the analysis. The thermal performance was measured by calculating the Nusselt number and frictional losses. Square ribs (w/e = 1) were considered as the baseline configuration. The rib width and rib spacing varies while the rib height is maintained constant. Rib spacing (P/e) of 10 and 20 and rib width to rib height ratios (w/e) ranging from 1/8 to 14 were considered. The heat transfer performance for all the channels were calculated for Reynolds numbers 10,000, 30,000 and 60,000. The code was validated by comparing the results for channels with square ribs (w/e =1) with the experimental results. The results obtained for all the channels with different rib configuration proved that the increase in rib width reduced the thermal performance of the channels. By combined effect of rib width, rib spacing and flow parameters, the optimal cooling configuration was obtaine

Effect of Rib Turbulators on Heat Transfer Performance in Stationary Ribbed Channels

The thermal performance was examined computationally for the stationary channels with rib turbulators oriented at 90 degrees. Ribs were placed on opposite walls and the heat transfer coefficients and frictional loss were calculated. Three stationary channels with aspect ratios (W/H) 1, 2 and 4 were considered for the analysis. The thermal performance was measured by calculating the Nusselt number and frictional losses. Square ribs (w/e = 1) were considered as the baseline configuration. The rib width and rib spacing varies while the rib height is maintained constant. Rib spacing (P/e) of 10 and 20 and rib width to rib height ratios (w/e) ranging from 1/8 to 14 were considered. The heat transfer performance for all the channels were calculated for Reynolds numbers 10,000, 30,000 and 60,000. The code was validated by comparing the results for channels with square ribs (w/e =1) with the experimental results. The results obtained for all the channels with different rib configuration proved that the increase in rib width reduced the thermal performance of the channels. By combined effect of rib width, rib spacing and flow parameters, the optimal cooling configuration was obtaine

Numerical investigation of micro-channel based active module cooling for solar CPV system

PublishedConference Proceeding4th International Conference on Advances in Energy Research 2013, ICAER 2013Concentrating photovoltaic (CPV) technology is one of the fastest growing solar energy technologies achieving higher electrical conversion efficiencies. The increase in temperature of solar CPV cell significantly reduces the performance; the efficiency of a CPV system can be improved by introducing effective thermal management or cooling system. This paper presents the design and numerical analysis of a heat sink based on micro-channels for efficient cooling of a commercial high concentration photovoltaic (HCPV) cell. A combinatory model of an array of micro-channels enclosed in a wide parallel flow channel design is developed. The optimized geometry of the micro-channel heat sink was found by using commercial CFD software ANSYS 13. Based on numerical simulations, it is found that the optimum configuration of micro-channel with 0.5mm width and aspect ratio of 8. The micro-channels provided high heat transfer over heat generations spots and parallel flow channels resulted in lower pressure drop. The temperature rise across the micro-channel is estimated as10K in CPV module of 120 × 120 mm2 and with a pressure drop of 8.5 kPa along a single channel with six such channels in each modules at a flow rate of 0.105 liter/s. © 2014 The Authors

Design and optimization of a micro heat sink for concentrating photovoltaic/thermal (CPVT) systems

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.An optimization methodology for a microchannel heat sink suitable for the cooling of a parabolic trough CPVT system is presented in this study. Two different microchannel configurations are considered, Fixed (FWμ) and stepwise Variable-Width (VWμ) microchannels respectively. The performance evaluation criteria comprise the thermal resistance of the heat sink and the cooling medium pressure drop through the heat sink. Initially, the effect of the geometric parameters on the heat sink thermal and hydrodynamic performance is investigated using a thermal resistance model in order to save computational time. The results of the 1-D model enable the construction of surrogate functions for the thermal resistance and the pressure drop of the heat sink, which are considered as the objective functions for the multiobjective optimization process that leads to the optimal geometric parameters. In a second step, a 3-D numerical model of fluid flow and conjugate heat transfer in the optimized FWμ heat sink is developed in order to investigate in detail the flow and thermal phenomena. The overall analysis demonstrates that microchannel heat sinks achieve very low values of thermal resistance and that the use of variable-width channels can significantly reduce the pressure drop of the cooling fluid. Furthermore, it is proven that the 1-D model is capable of providing a good estimate of the behavior of the heat sink