Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 35 for “"Heat Transfer And Pressure Drop"”.
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Flow, Heat Transfer, and Pressure Drop Interactions in Louvered-Fin Arrays
In many compact heat exchangers, interrupted-fin surfaces are used to enhance air-side heat transfer performance. One of the most common interrupted surfaces is the louvered fin. The goal of this work is to develop a better understanding of the flow and its influence on heat transfer and pressure …
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Heat transfer and pressure drop for evaporation of water in a vertical tube
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1953.
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Heat transfer and pressure drop in the condensing superheated region with visualization and film thickness measurement
… by division into three zones: desuperheating, two-phase, and subcooled regions. According to this characterization, heat transfer and pressure drop in condensers are modeled separately for the single-phase and two-phase regions. When plotted as a function of enthalpy, the correlations …
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The effect of surface roughness and surface finish on two-phase and single-phase heat transfer and pressure drop characteristics
… thermal systems where compact, high-performance heat exchangers needs to dissipate large heat loads. With rising power densities and the demand for energy-efficient systems, research has focused on enhancing boiling performance through surface structuring while simultaneously improving air-side …
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Experimental Investigation of the Effect of Copper Nanowires On Heat Transfer and Pressure Drop For A Single Phase Microchannel Heat Sink
<p>This thesis experimentally investigates the heat transfer and pressure drop characteristics of a shallow rectangular single phase microchannel heat sink with hydraulic diameter of 0.672 mm and whose bottom wall is coated with Cu nanowires (CuNWs) of 200 nm in diameter and 0.050 mm in length. …
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Investigation of the condensing and expansion behaviors of alternative refrigerants
This study examines the heat transfer and pressure drop performance of R22 and R502 alternatives while condensing in an enhanced tube with 0% to 3% oil and while expanding in a capillary tube. The capillary tube study examined the mass flow rate of refrigerants while expanding, with an emphasis on …
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Longitudinal Vortex Generation to Enhance the Performance of Compact Heat Exchangers: Flow and Heat Transfer Behavior for Plain and Interrupted Fins
… implementation of a VG-enhanced multi-louver heat exchanger. The heat transfer and pressure drop performance under both dry- and wet-surface conditions were determined through wind-tunnel experiments. Average heat transfer enhancements of 21% for dry conditions and 23% for wet conditions are …
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Computational fluid dynamics modeling and comparison of advanced techniques for heat transfer augmentation for nuclear applications
… reactor designs. Twist tape is one passive heat enhance heat technique. The present research investigated thermo-hydraulic characteristics of natural and forced convection of water under different configurations of twisted tape inserted in tube as well as NuScale rod bundles for uniform wall …
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Role of internal heat exchanger in air conditioning systems
Internal heat exchangers (IHX) has been implemented into refrigeration and air-conditioning industry for a long time because of its ability to improve the efficiency of refrigeration cycles for several commonly used and potential substitution of refrigerants (R134a, R744 and R1234yf among them). It …
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Heat transfer enhancement phenomena and pressure drop characteristics in two-phase pulsating flow using R-134A
The heat transfer and pressure drop aspect of a saturated two-phase flow imposed to periodic inlet mass flow rate were studied using both experimental and modeling approaches. The two-phase flow of R-134 was tested in a single pass, horizontal smooth copper tube coil with a 6.2 mm (0.244-in.) inner …
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Convection and Flow Boiling in Microgaps and Porous Foam Coolers
An open and foam-filled microgap cooler, providing direct liquid cooling for a simulated electronic/photonic component and which eliminates the problematic thermal resistance of the commonly-used thermal interface material (TIM), is examined. The single phase heat transfer and pressure drop results …
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Thermohydraulic Performance of Supercritical Carbon Dioxide (sCO2) in Horizontal Enhanced Surface Tubes
… a promising working fluid for power generation and refrigeration systems due to its favorable thermophysical behavior near the pseudocritical region (Lemmon et al., 2018). However, in this region abrupt variations in density, viscosity, and specific heat introduce strong buoyancy and …
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Laminar-flow Liquid-to-air Heat Exchangers - Energy-efficient Display Cabinet Applications
Provisions are stored and displayed in supermarkets and grocery stores, at a temperature lower than the ambient, in display cabinets, which are responsible for a significant amount of the energy use in this sector. During the 1990s, major changes in the regulations governing the use of synthetic …
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Condensation in horizontal smooth round tube
From thermodynamic point of view, first droplet of liquid during condensation appears at quality one and the last vapor disappears at quality zero. This is because thermodynamic assumes equilibrium and temperature to be uniform. Therefore, conventional modeling of condensation typically contains …
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Convective boiling of refrigerants near the micro-macroscale transition inside plate heat exchangers
… work focuses on the refrigerant flow morphology and its impact on evaporative heat transfer and pressure drop during plate heat exchanger (PHE) operation at low mass flux conditions. While there is interest in this operating regime in the heating, ventilating, air conditioning, and refrigeration …
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Effect of oil in circulation on automotive A/C component and system performance
… system, oil is mixed with refrigerant and runs in the system. Although some amount of oil is beneficial to compressor to reduce compressor wear and prevent leakage, the existence of oil in circulation influences the performance of the air-conditioning system and components. In this …
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Design and modeling of a high flux cooling device based on thin film evaporation from thin nanoporous membranes
Heat dissipation is a limiting factor in the performance of integrated circuits, power electronics and laser diodes. State-of-the-art solutions typically use air-cooled heat sinks, which have limited performance owing to the use of air. One of the promising approaches to address these thermal …
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Design And Manufacture Of An Oil Cooler By Additive Manufacturing
The objective of this study is to design and fabricate an oil cooler (oil to air heat exchanger) by metal additive manufacturing as a swap-in replacement for an existing aluminum oil cooler in a Case New Holland model CX55B excavator. The oil cooler must provide a heat duty of 15 kW with pressure …
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Projeto térmico de trocadores de calor resfriados a ar
The scarcity and the treatment costs of the water cooling, in the petroleum and petrochemical industries, are increasing the use of the air cooled heat exchangers. Exchangers designing usualy utilize the estimate and global methods. This paper shows these methods and presents a new approach for …
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