Coolant Media Research Articles

Effects of Different Mold Materials and Coolant Media on the Cooling Performance of Epoxy-Based Injection Molds.

Metal additive manufacturing techniques are frequently applied to the manufacturing of injection molds with a conformal cooling channel (CCC) in order to shorten the cooling time in the injection molding process. Reducing the cooling time in the cooling stage is essential to reducing the energy consumption in mass production. However, the distinct disadvantages include higher manufacturing costs and longer processing time in the fabrication of injection mold with CCC. Rapid tooling technology (RTT) is a widely utilized technology to shorten mold development time in the mold industry. In principle, the cooling time of injection molded products is affected by both injection mold material and coolant medium. However, little work has been carried out to investigate the effects of different mold materials and coolant media on the cooling performance of epoxy-based injection molds quantitatively. In this study, the effects of four different coolant media on the cooling performance of ten sets of injection molds fabricated with different mixtures were investigated experimentally. It was found that cooling water with ultrafine bubble is the best cooling medium based on the cooling efficiency of the injection molded parts (since the cooling efficiency is increased further by about 12.4% compared to the conventional cooling water). Mold material has a greater influence on the cooling efficiency than the cooling medium, since cooling time range of different mold materials is 99 s while the cooling time range for different cooling media is 92 s. Based on the total production cost of injection mold and cooling efficiency, the epoxy resin filled with 41 vol.% aluminum powder is the optimal formula for making an injection mold since saving in the total production cost about 24% is obtained compared to injection mold made with commercially available materials.

THE UK NATIONAL THERMAL-HYDRAULICS FACILITY: MOTIVATIONS, DESIGN AND PLANNING STATUS

A UK National Thermal-Hydraulics Facility (NTHF) dedicated to supporting new reactor and other relevant business is being developed, one of the purposes being to deliver on the government’s carbon emission reduction commitments. The facility site is foreseen to be at Menai Science Park on the isle of Anglesey in North Wales, a region expected to see significant low carbon energy deployment in coming years. The UK NTHF is envisioned to cater for the needs of emerging nuclear in the UK – but also to serve as a hardware platform for international thermal-hydraulics research collaboration. Plans are to construct a platform capable of maintaining several test loops including support for the UK’s on-going, conventional nuclear new build programme as well as Gen-IV systems and associated materials like molten salt and liquid metal coolant media. Motivations are given for NTHF expected capabilities and requirements, which form the basis for its current design and planning state.

The Effect of Cooling Media on Tensile Strength of Medium Carbon Steel in Post Welding Process Using Electric Welding (SMAW) with E7018 Electrodes

The use of cooling media in post welding process will affect the tensile strength of a material. This study aims to determine how much the influence of using cooling media in post welding and which cooling media is appropriate to use. The process is done by comparing the tensile strength of each cooling media, namely the cooling media of water, air, and coolant. The use of cooling media is carried out after the welding process, until the material that is ready to be welded reaches room temperature. Based on the experiments that have been conducted, the use of post-welding cooling media affects the tensile strength of medium carbon steel with the highest effect on the water cooling media, then the coolant media, and the lowest is the air cooling media. Therefore, the choice of the use of cooling media significantly affects the tensile strength of medium carbon steel in the post-welding process.

The Effect of Surface Roughness of Low Carbon Steel by Heat Treatment in Turning Operation

This research focuses on enhancing the surface roughness of low carbon steel by heat treatment of low carbon steel in turning operation. Heat treatment is mainly used to improve the mechanical properties of materials. Two sets of specimens used during the experiment where each has 5 pieces of mild steel that heat-treated of two-level of temperatures of 650 oC and 900oC. After the heating process of all specimens, it will be exposed to different coolant media which are quenching, normalizing and annealing. A carbide single-point tool, one level of cutting parameters selected as one level of cutting speed and depth of cut and two levels of feed rate used during this research. The results show that specimen quenched by oil bath measures the highest value of the surface roughness of 8.26 µm at 900oC and machined with a feed rate of 0.113 mm. While quenched water specimens show less surface roughness of 4.91µm at 650oC in the same feed rate.

Comparison of thermo-hydraulic performance of nanofluids and mixing vanes in a triangular fuel rod bundle

In this paper, two approaches are investigated to enhance the heat transfer coefficient in VVER-440 fuel rod bundle. The first approach is the use of nanofluids as the coolant media and the second approach is putting mixer vanes on the spacer grids. The fuel rod bundle contains 60 fuel rods with length of 960 mm and 4 spacer grids. To perform correct calculation the grid quality of fuel rod bundle is studied and the results are compared with the reference data. Two-phase mixture model has been used to investigate the thermo-hydraulic behavior of the nanofluid in fuel rod bundle. In order to investigate the effect of mixing vanes on the thermo-hydraulic parameters four angles were defined (7°,10°, 13°and 15°). The results show that utilization of nanofluid has increased the heat transfer coefficient up to 58 %, while putting mixer vanes on the spacer grids has enhanced the heat transfer coefficient only about 8 %. So, from the viewpoint of thermal performance the use of nanofluids as the coolant media is more effective than putting mixer vanes on the spacer grids.

Experimental study of transient forced convection heat transfer from simulated electronic chips

Experiments are performed to study the single-phase transient forced convection heat transfer on an array of four in-line, flush-mounted simulated electronic chips in a vertical rectangular channel. Water is the coolant media and the flow covers the wide range of laminar flow regime with Reynolds number, based on heat source length, from 800 to 2,625. The heat flux ranges from 1 W/cm2 to 7 W/cm2. The heat transfer characteristics are studied and correlations are presented. The transient correlation for overall data recommended is Nul= 0.945(Pel1/3) Fo−1/2.

Effect of protrusion on thermal transient behavior of chips in a liquid channel during loss of pumping power

Experiments are performed to study the single-phase transient heat transfer at different protrusion heights of the electronic chips during an accidental stoppage of coolant flow due to loss of pumping power. Water is the coolant media and the flow covers the wide range of laminar flow regime with Reynolds number, based on heat source length, from 800 to 2625 and the heat flux ranging from 1 W/cm 2 to 7 W/cm 2. The general impacts of heat source protrusions ( B=1, 2 mm) on heat transfer behavior of four chips are investigated by comparing the results obtained from flush-mounted ( B=0) heat sources. Finally the correlation equations are obtained by modifying the correlations of flush-mounted heater, employing the chips' protrusion height ( B) in the dimensionless ( B/ℓ) form.

Surface Waviness Controlled Grinding of Thin Mold Inserts Using Chilled Air as Coolant

The ongoing trend of miniaturization in electronic related parts, which is an average of two times every 5 to 7 years, introduces machining challenges. Surface grinding of thin miniature parts is an ardent task due to its warpage, induced by high specific grinding energy (10–100 J/mm3). Therefore, coolant is used to avoid thermal damage, improve surface integrity, and prolong wheel life. However, coolant, the incompressibility media, introduces high forces at the grinding zone, that create dimensional and shape instability. This article presents the results of a new grinding method when using chilled air as coolant media for thin mold insert, two-stage vapor compression refrigeration cycle was adopted for production of chilled air of temperature, −35°C; pressure, 0.2–0.3 MPa; and flow rate, 0.4 m3/min. Along with chilled air, traces of vegetable oil mist was also impinged to the grinding zone. Both chilled air and vegetable oil mist were applied through two independent paths of a specially designed twin compartment nozzle for maximizing the penetration.

Experimental and Numerical Thermal Transient Behavior of Chips in a Liquid Channel During Loss of Pumping Power

Both transient and steady-state experiments are performed to study the single-phase heat transfer characteristics on an array of four in-line, flush-mounted simulated chips in a vertical rectangular channel. Water is the coolant media, and the flow covers the wide range of laminar regimes with the Reynolds number, based on heat source length, from 800 to 2625. The effect of heat fluxes, coolant flow rates, and geometric parameters (such as chip configuration number) are investigated. The operation is extended to study the transient natural convection during an accidental stoppage of coolant flow due to loss of pumping power. Results compare favorably with those obtained from three-dimensional numerical calculations. The transient correlation recommended is Nul=0.3Fo−0.2Ral*1/4.

An Experimental Study of Transient Heat Transfer From Discrete Heat Sources in Water Cooled Vertical Rectangular Channel

Experiments are performed to study the single-phase transient forced convection heat transfer on an array of 4×1 flush-mounted discrete heat sources in a vertical rectangular channel during the pump-on transient operation. Water is the coolant media and the flow covers the wide range of laminar flow regime with Reynolds number, based on heat source length, from 800 to 2625. The applied uniform heat flux ranges from 1 to 7W∕cm2. For flush-mounted heaters the heat transfer characteristics are studied and correlations are presented for four chips as well as for overall data in the transient regime. The experimental results indicate that the heat transfer coefficient is affected strongly by the number of chips and the Reynolds number. Finally the general impacts of heat source protrusions (B=1, 2 mm) on heat transfer behavior of four chips are investigated by comparing the results obtained from flush-mounted (B=0) heaters.