In this paper, a novel design including cooling media for packing the rechargeable Lithium (Li)-ion batteries used in hybrid and electric vehicles is proposed. The proposed battery pack satisfies all ...thermal and physical issues relating to the battery packs used in vehicles such as operating temperature range and volume, and furthermore it increases the battery life cycle and charge and discharge performances. The temperature and voltage distributions of the proposed battery pack are calculated using the characteristics of a sample Li-ion battery and heat transfer principles. The proposed battery pack uses several distributed thin ducts for cooling which is based on distributed natural convection. Ultra uniform voltage and temperature distributions, minimum temperature dispersion in each battery unit, minimum increase in the battery pack volume, natural convection (no extra energy consumption for cooling), the maximum observed temperature less than that in other proposed battery packs and high thermal performance for different ambient temperatures until 48 degree C are some advantages of the proposed Li-ion battery pack including proposed distributed cooling media. Simulation results and a comparison between the parameters of the proposed cooling media and other related work are presented to validate the theoretical results and to prove the superiority of the proposed battery pack design.
In this paper, the thermo-optical performance using novel cooling strategy improvements for a hybrid photovoltaic/parabolic dish concentrator with a conical thermal receiver using a beam splitter ...filter (PV/PDC-CTR-BSF) is investigated. The study’s main goal is to improve the cooling effectiveness of the serpentine-shaped cooling duct by investigating the effect of the cross-section shape and positioning of the cooling duct under the PV panel. Typical cooling pipes have either a rectangular or circular cross-section and are usually attached to the back sheet of the PV panel using off-the-shelf adhesives that have very low thermal conductivity. With the advent of 3D printing technology, the back sheets could be 3D-printed with integral cooling ducts of different cross-sections at different locations and orientations within the back sheet that allow for increased heat transfer from the back sheet and thus improve PV/PDC-CTR-BSF’s thermos-optical performance. For this purpose, the study investigates and compares the thermal performance of four different cooling duct cross-sections that include: rectangular, semi-circular, semi-elliptical and triangular. For each of the cooling duct cross-sections, several positions and orientations, which include flush below the back sheet layer and embedded inside the back sheet but positioned at the bottom, middle and top of the back sheet, are examined. Numerical simulations using the commercial software ANSYS FLUENT(R2019) are performed to assess the performance of the cooling ducts and, in turn, the thermo-optical performance of the PV/PDC-CTR-BSF system. The semi-elliptical cross-section duct embedded in the middle of the back sheet was found to yield the best cooling performance since its rate of heat removal from the PV back sheet was found to be the highest.
Shrinking transformer size increases thermal challenges due to reduced cooling surface area and higher loss per unit volume. Furthermore, increased thermal stress results in larger cooling system ...size volume, voiding power density gains from moving to a higher operating frequency. This paper proposes a novel cooling duct structure that was designed using computational fluid dynamics to cool parallel 500 kHz planar transformers. The two transformer windings are potted in thermal epoxy to improve lateral heat conduction and cooling surface area. The potted transformer is tested at 18 kW and peak winding temperature is 126 °C. To reduce cooling system size while maintaining a high heat transfer coefficient a converging duct with turbulators is proposed. The designed converging duct with turbulators achieves a peak winding temperature of 106 °C at 15 kW load. The cooling system and transformers combined have a total power density of 562 W/in 3 , 44 mm height, 99.5% efficiency at full load, and the cooling system only consumes 5W. The transformers and cooling duct are implemented in an 18 kW CLLC resonant converter and total power density is 120 W/in 3 .
An effective one-dimensional model is presented that describes the temperature profile of a winding of an oil-filled distribution transformer with an arbitrary number of partial cooling ducts. An ...analytical solution of the model is applied to a specific example — a low voltage winding of a 400 kVA distribution transformer with one or two partial cooling ducts. Starting from the exact solution, a simple and practical formula for the temperature rise of similar windings has been derived that is suitable for transformer designers.
This paper discusses a radar structure with multi-cavity coupling sealed cooling ducts. These ducts can achieve independent cooling with various power dissipation systems, thus improving the working ...ability of the complete machine at high temperatures. The seal structure increases the ability of the radar to operate under harsh circumstances and guarantees its round-the-clock working mode. The thorny problem of heat dissipation of the radar components, such as the TR module, wave-controlled power supply board, signal processing and microwave module, is solved. The adaptability of the complete machine to high-low temperature, dampness and hotness, salt mist, sand and dust, EMC, etc. is also improved.
Zusammenfassung
Bei luftgekühlten, gekapselten und thermisch hoch beanspruchten Traktionsasynchronmaschinen spielen die Kühllochgeometrie sowie Strahlung und Konvektion an der Maschinenoberfläche ...eine essentielle Rolle bei der Kühlung der Maschine. Die Relevanz dieser Thematik wird bei verschiedenen Kühlungsarten und den dazugehörigen Blechschnitten erörtert sowie eine Berechnungsmethode vorgestellt. Ferner werden Messungen zur Verifikation präsentiert.
Correct finite-element method (FEM) computations of end-winding leakage inductances of MVA-range machines are discussed. This is shown through validations against total stator reactance measurements ...of 11 air-suspended stators and a reasonable agreement of FEM computations with the International Electrotechnical Commission 60034-4 standard. To achieve this goal, the need to have several 2-D and 3-D FEM models, including those representing the cooling ducts, is emphasized. Steps to utilize the validated stator FEM models for direct computation of end-winding leakage inductances are also listed. It is also shown that measurements of zero-sequence reactances cannot help the FEM validations and do not provide a reliable estimation of the leakage inductances.
As an innovative process of manufacturing ultra high strength steel (UHSS), hot stamping or press hardening is a multi-physical coupling process with complex changes in thermal, mechanical and phase ...transformation. In this work, in order to study heat transfer from workpiece to upper & lower die and cooling water, a new approach, named Bulk Flow, is adopted to model the cooling ducts and to simulate heat transfer in hot stamping die. Not only can tool design, cooling duct layout and process parameters be studied and optimized to increase the cooling rate and to homogenize temperature distribution in workpiece, but also, the precision of hot stamping simulation be improved. The experimental results of boron steel components formed by the designed die show that the martensite is homogenous. It indicates the feasibility of the bulk flow method．
This paper undertakes an investigation into thermal modelling of Totally Enclosed Fan-Cooled (TEFC) motors used in traction applications. In the process, a 3D Computational Fluid Dynamics (CFD)-based ...Conjugate Heat Transfer (CHT) model is utilized, including the realistic stator geometry with cooling channels and considering the rotor rotation through the multiple reference frame approach. Extended air flow measurement data are used to determine the modelled air speed through the cooling channels and account for the impact of partial duct blockage. Loss distributions obtained via a transient electromagnetic Finite Element (FE) model are used in the process of heat source definition. Additionally, a simplified net radiation model is integrated in the boundary definitions along with natural convection. The main purpose of this paper is to highlight how different modelling approaches affect the obtained temperature distribution. The particular focus of this work is on the stator side and can be extended to various rotor structures. The methodology developed is applied for the thermal characterization of a prototype Interior Permanent Magnet (IPM) motor.
In this paper the influence of the cooling ducts on the leakage inductances, and therefore on the breakdown torque, in induction machines is discussed. This effect is typically a three-dimensional ...one, and one has to analyse numerous geometrical variants. A simplified 3D finite element model of the induction machine is hence used, whose equivalent inductances are calculated. Due to the transversal orientation of cooling ducts, with respect to the main flow paths, the simplified model is able to deliver accurate qualitative results concerning the real machine.
PDF
