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 72 for “"superheat"”.
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Conceptual design of an annular-fueled superheat boiling water reactor
The conceptual design of an annular-fueled superheat boiling water reactor (ASBWR) is outlined. The proposed design, ASBWR, combines the boiler and superheater regions into one fuel assembly. This ensures good neutron moderation throughout the reactor core. A single fuel design is used in the core. …
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Superheat control for air conditioning and refrigeration systems: Simulation and experiments
… (PID) controller. Evaporator superheat is a key parameter considered in this research since precise control optimizes evaporator efficiency while protecting the system from component damage. The controllers developed in this thesis ultimately provide better transient and steady …
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Design of an experiment to investigate superheat effect on gate velocities
… was to design an experiment to investigate superheat effect on gate velocities pressurized and unpressurized gating system each having two gates, and to analyze statistically any interrelationship between these variables in CO₂ molds. A discussion on metal flow through different parts of a …
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Aluminium smelting cell control and optimisation
… cell should operate at a fixed temperature and superheat. However, spatial and temporal operating strategies cause changes in temperature, which usually result in variations in superheat as well. Contrasting, in the long term, for mature cells the aluminium fluoride consumption is fairly …
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Evaporation-induced non-wetting droplets on superhydrophilic surfaces
… that this wetting behavior can be altered by superheating the substrate such that droplets can reside in a non-wetting state due to evaporation. Photolithography and deep reactive ion etching were used to fabricate well-defined silicon micropillar arrays with a square pattern with varying …
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Two phase flow distribution in parallel flow heat exchangers -- experimentally verified model
… effectiveness, especially when controlled by superheat. This paper describes modeling and numerical simulation of two phase mass flow distribution in a microchannel evaporator, on the basis of the pseudo 2-D finite volume method. Emphasis is placed on refrigerant-side heat transfer and …
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Coupling electrolysis and surface patterning to improve onset of nucleate boiling and bubble departure in pool boiling heat transfer
… increase nucleation site density at low superheat, while patterned gold thin-strip surfaces facilitate coalescence-induced bubble departure, thereby further enhancing boiling performance. To verify this hypothesis, a pool boiling setup was designed and developed. The system employs an …
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Evaporation from nanoporous membranes
… up to one order of magnitude larger for a given superheat in comparison to the flooding regime. An improved experimental setup for investigating thin film evaporation from nanopores was developed, where a biphilic membrane, i.e., a membrane with two wetting behaviors, was used for enhanced …
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Experimental investigation of subcooled flow boiling using synchronized high speed video, infrared thermography, and particle image velocimetry
… IR thermography allowed measurement of wall superheat (local distribution and surface-averaged values), heat transfer coefficient, nucleation site density, and bubble frequency. Particle image velocimetry allowed for the measurement of velocity profiles in the liquid phase for single bubble …
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Conceptual design of a lead-bismuth cooled fast reactor with in-vessel direct-contact steam generation
… for the reactor power, chimney height and steam superheat. A 1260MWth power is found possible for 10m chimney height and 25°C superheat. The temperature of the low-nickel steel clad is maintained below 600°C, which results in limited corrosion if tight control of the coolant oxygen concentration …
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Investigation of the effects of surfactant concentration on the boiling curve of water
… specific heat fluxes showed the lowering of the superheat that improves heat transfer when surfactants were added, resulting in an overall left shift of the boiling curve. The shifting that occurs at low concentrations of surfactant seem correlated with the diffusion coefficients of the different …
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A study of the supercooling behavior of high purity liquid bismuth
… by the melting atmosphere, the amount of superheat, and the intentional addition of metallic and non-metallic foreign materials to the melt. It was found that the amount of oxide on the melt surface is a controlling factor in the degree of supercooling obtainable in bismuth. In the …
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Effect of conical distributors on evaporator and system performance
… and orientation in gravity and the resulting superheat profiles of the evaporator circuit outlets are recorded. To examine possible effect of cone misalignment feeder tubes are switched in several steps and the data shows that there is imbalance in both the evaporator and distributor. It is …
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Experimental Study of Meniscus Thin-Film Evaporation in a Horizontal-Tube, Falling-Film Heat Exchanger, Focusing on Dynamic Contact Angle Variation of an Advancing Meniscus
… effects of solution subcooling, evaporator wall superheat, and porous-layer coating on the portions of sensible and evaporation heat transfer in a falling-film system. The porous layer was found to enhance both sensible and evaporation heat transfer by exploiting the capillary pumping of the …
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Fundamental research regarding the ultrasonic stirring effects on the microstructure of A356 castings
… frequency of 18 kHz, and then at relatively high superheat, the melt was cast into a permanent metal mold which complies with ASTM B108-02. The UST processing system was custom built to perform the present UST study. The relatively high superheat condition is similar to the one used in the …
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INVESTIGATION OF PERFORMANCE DEGRADATION OF EVAPORATOR FOR LOW TEMPERATURE REFRIGERATION APPLICATIONS
… frosting cycle, which resulted in the loss of superheat towards the end of each cycle. The defrost operation could not restore the full capacity of the evaporator. The defrost cycle consists out of two phases, melting the ice and re-cooling the coil. The first phase melts all the ice of the …
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Experimental design for study of nucleate boiling in porous structures
The superheat required to initiate nucleate boiling inside porous wicks is not well understood in practice. This thesis reports the design of an experimental setup for investigating the onset of vapor nucleation in sintered porous structures. Pressure sensing was evaluated as an effective means of …
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Potential of controlling subcooling in residential air conditioning system
… controlling subcooling. Instead of conventional superheat control at evaporator outlet, condenser subcooling is monitored and controlled and the corresponding effects on vapor-compression system performance as well as the sensitivity of subcooling control to different operating conditions and …
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A study on the characteristics of the flow inside a thermostatic expansion valve
… the response time of the valve to the change of superheat in the evaporator, or the relationship between the location of the valve and the system efficiency, etc. However, few studies have looked into the valve and fundamentally studied the physical process of the refrigerant taking place near …
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Modeling of Multicomponent Fuel Vaporization in Internal Combustion Engines
… in the injector nozzle, and the effect of superheat degree on spray atomization was captured.
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