bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparing the Enhancement of Heat Transfer Caused by Sliding Gas Bubbles and by Sliding Vapor Bubbles in Subcooled Flow in a Minichannel
Authors: Albahloul Khaled E. , Hollingsworth D. Keith , Witte Larry C. , Ozer Arif B. 
Published: December 2013

Studies published over the past decade have established the importance of sliding bubbles in enhancing the heat transfer in subcooled two-phase flow in channels small enough to confine the bubbles. Recent work in this laboratory (Ozer et al., 2011, 2012) proposed that the primary enhancement mechanism is a single-phase convective mechanism: the transport of cold fluid nearer the wall due to the mixing behind the bubble. This is in contrast to two phase-change mechanisms: distributed bubble nucleation and the evaporation of the liquid microlayer between a sliding bubble and the surface.
The work reported here explores this hypothesis by comparing the heat transfer enhancement produced by injected air bubbles to Ozer’s measurements obtained with naturally nucleated vapor bubbles. Data were collected under similar conditions in a highly subcooled laminar flow of Novec 649 in a horizontal rectangular minichannel of 1.21 to 1.484 mm channel spacing. The channel was formed by an electrically heated metallic upper wall and an unheated transparent lower wall. For the air/liquid flow, bubbles were injected at either a single point on the lower wall or through a sintered metal plug. The latter system produced a more channel-filling distribution of bubbles. A high-speed imaging system recorded the bubble motion and liquid crystal thermography recorded time-averaged surface temperature data. The comparison is presented in the form of the streamwise evolution of surface temperatures and the enhancement in time-averaged Nusselt number. Also, results for the passage of a single air bubble are presented.
The air/liquid flow produced a Nu enhancement of between 120–350% compared to a single-phase flow at the same conditions. The passage of the single gas bubble produced a decrease in the wall temperature directly behind the bubble of 2–5 °C.
The Nu enhancement produced by the air/liquid data and the nucleated vapor data is well correlated to appropriate dimensionless groups involving bubble diameter and frequency. The results from both data sets support the contention that a transient transport/mixing model developed previously for the vapor/liquid case captures the dominant single-phase convective mechanism in sliding bubble flows in highly confined channels.
The Impact of Fin Deformation on Condensation Heat Transfer Coefficients in Internally Grooved Tubes
Authors: Mehendale Sunil 
Published: December 2013

In HVACR equipment, internally enhanced round tube (microfin) designs such as axial, cross-grooved, helical, and herringbone are commonly used to enhance the boiling and condensing performance of evaporators, condensers, and heat pumps. Typically, such tubes are mechanically expanded by a mandrel into a fin pack to create an interference fit between the tube outside surface and the fin collar to minimize the thermal contact resistance between tube and fin. However, during this expansion process, the internal enhancements undergo varying amounts of deformation, which degrades the in-tube thermal performance.
Extensive data on condensing heat transfer coefficients in microfin tubes have been reported in the open literature. However, researchers have seldom used expanded tubes to acquire and report such data. Hence, it is always questionable to use such pristine tube data for designing heat exchangers and HVACR systems. Furthermore, the HVACR industry has been experiencing steeply rising copper costs, and this trend is expected to continue in coming years. So, many equipment manufacturers and suppliers are actively converting tubes from copper to aluminum. However, because of appreciable differences between the material properties of aluminum and copper, as well as other manufacturing variables, such as mandrel dimensions, lubricant used, etc., tube expansion typically deforms aluminum fins more than copper fins.
Based on an analysis of the surface area changes arising from tube expansion, and an assessment of the best extant in-tube condensation heat transfer correlations, this work proposes a method of estimating the impact of tube expansion on in-tube condensation heat transfer. The analysis leads to certain interesting and useful findings correlating fin geometry and in-tube condensation thermal resistance. This method can then be applied to more realistically design HVACR heat exchangers and systems.
Experimental Investigation on Mixed Convection in Horizontal Channels Heated Below and Partially Filled With Aluminum Foam
Authors: Buonomo Bernardo , Ferraro Giuseppe , Manca Oronzio , Marinelli Lorenzo , Nardini Sergio 
Published: December 2013

In this paper an experimental investigation on mixed convection in air in a heated channel partially filled with an aluminum foam is carried out. The aluminum foam layer is sets on the lower heated wall of the channel. The channel upper plate has a heat transfer toward the external ambient. The investigation allows to evaluate the effect of the aluminum foam on the mixed convection in the heated channel by wall temperature measurements and flow visualization. Results are given for heated channel without and with foam in terms of wall temperature profiles for different Reynolds number value, form 10 to 300, wall heat flux and for aluminum foam with 10 and 20 pore per inch.
Lower wall temperature values are detected for the channel with foam with respect to the channel clean without foam. Foams with higher pore per inch shows lower average wall temperature values whereas the local wall temperatures showed different behaviors for the different pore per inch values. The presence of foam in heated channel determined weaker secondary motions with respect to the clean cases. The effect of the foams seems more significant for the high Reynolds number values and average Nusselt number increases with the foam presence in the heated channel.
Numerical Solution of a Ground Source Heat Pump System Using Foundation Piles
Authors: Oguma Masahito , Matsumoto Takeshi , Funabiki Ayako , Miyaoka Futoshi , Ito Kosuke , Kakizaki Takao 
Published: December 2013

A ground source heat pump (GSHP) system has higher cooling and heating performances than an air source heat pump system, so the GSHP system has attracted attention in the cold regions. Particularly after the 2011 earthquake off the Pacific coast of Tohoku, which damaged nuclear power plants, the GSHP utilizing renewable energy, has become attractive in heating system in the Tohoku region. However, it is necessary to install wells to collect ground source heat, and so, together with the cost of the heat pump itself, the installation cost is a barrier to widespread adoption of this technology in Japan.
On the other hand, due to poor subsoil, foundation piles are often required in the construction of buildings in Japan. By using foundation piles as heat exchangers, which are commonly used in residential construction, the cost of using GSHP systems in houses may be reduced. However, since the placement of the piles depends on the floor layout of the residence, that is arbitrary sequence. Moreover, an arbitrary floor layout requires a complicated multi-dimensional numerical analysis to design the GSHP, and the analysis is burdensome for general designers. Therefore, the use of the model unit of the two-dimensional cylindrical heat exchange well is proposed. The use of this model, which includes an unused volume of soil, reduces the analysis burden for general design tools.
On experience, the arrangement rate is 4 m2 per pile, and the well separation is narrow. And the foundation piles will form a group. So thermal interference between heat exchanger wells might be working hard. In addition, the foundation piles are very short, compared to the traditional borehole depth of 50 to 100 m. Therefore, the thermal performance of the well may degrade compared to that of the traditional GSHP system, although the initial costs are less. Therefore, we examined a GSHP system with heat exchanger piles by using the heat exchange well unit model for residences in the Tohoku region.
As a result, the two-dimensional analysis and more is needed to predict the thermal performances of the heat exchanger piles so that the effect of the pitch of the heat exchange wells on the heat transfer in the axial direction will be large. In cold climates, the heating demand is large and, in the summer, the amount of waste heat to the ground is small, so a large amount of heat penetration into the ground from the atmospheric air is important for continuous GSHP operation in the Tohoku region, and in Fukushima Prefecture in particular.
Development of Heat Transfer in a Two-Dimensional Wavy Falling Film of Water and its Influence on Wave Stability
Authors: Haustein Herman D. , Rohlfs Wilko , Al-Sibai Faruk , Kneer Reinhold 
Published: December 2013

Heat exchangers employing falling films are relevant to a multitude of industrial applications using water-based liquids. In the present study, periodic, two-dimensional waves are imposed by excitation on a vertically falling film of water, which is then heated by a uniform heat flux, within the laminar and transitional flow range (39<Re<200). Liquid-film thickness is measured by confocal chromatic imaging and surface temperature is measured by high-speed IR thermography. As the 2D waves travel downstream they destabilize in the spanwise direction and evolve 3D structures (bumps). Further wave destabilization, under relatively low heating, was observed to coincide with the appearance of local thermal flows (“hot streaks”), though no deformation of the liquid surface could be measured. These flows are understood to be induced by thermo-capillary forces, which in extreme cases are known to lead to the formation of rivulets, film rupture and heater burnout. Understanding these initial stages of thermo-capillary flow is crucial to its suppression.
Analysis of the thermal images reveals several significant streamwise length scales: a thermal inlet length based on the emergence of the thermal boundary layer (Lt), a thermal inlet length based on reaching thermally developed conditions (Lh), and the length at which “hot-streaks” first appear (Ls). In addition the dominant (most unstable) spanwise wavelength of the hot streaks, Lz, was identified through FFT analysis of the thermal profile beyond Ls. First the independence of the thermal inlet lengths from the heat-flux was established. Next, the influence of the nominal flow conditions (Reynolds number and excitation frequency) on Lt, Lh and Lz was examined — thereby extending the range of previous studies to higher Reynolds numbers. The thermal inlet lengths Lt and Lh were found to increase with flow rate, whereas they had opposing trends with regard to frequency. Lz consistently decreased with an increase of the flow rate, as smaller (turbulent) scales became more dominant, and it was found to be indifferent to excitation frequency over a wide range. Some future directions and methods of hot streak suppression are discussed, as well.
Design of an Interrupted-Plate Heat Exchanger Used in a Liquid-Piston Compression Chamber for Compressed Air Energy Storage
Authors: Zhang Chao , Shirazi Farzad A. , Yan Bo , Simon Terrence W. , Li Perry Y. , Van de Ven James 
Published: December 2013

In the Compressed Air Energy Storage (CAES) approach, air is compressed to high pressure, stored, and expanded to output work when needed. The temperature of air tends to rise during compression, and the rise in the air internal energy is wasted during the later storage period as the compressed air cools back to ambient temperature.
The present study focuses on designing an interrupted-plate heat exchanger used in a liquid-piston compression chamber for CAES. The exchanger features layers of thin plates stacked in an interrupted pattern. Twenty-seven exchangers featuring different combinations of shape parameters are analyzed. The exchangers are modeled as porous media. As such, for each exchanger shape, a Representative Elementary Volume (REV), which represents a unit cell of the exchanger, is developed. The flow through the REV is simulated with periodic velocity and thermal boundary conditions, using the commercial CFD software ANSYS FLUENT. Simulations of the REVs for the various exchangers characterize the various shape parameter effects on values of pressure drop and heat transfer coefficient between solid surfaces and fluid. For an experimental validation of the numerical solution, two different exchanger models made by rapid prototyping, are tested for pressure drop and heat transfer. Good agreement is found between numerical and experimental results. Nusselt number vs. Reynolds number relations are developed on the basis of pore size and on hydraulic diameter.
To analyze performance of exchangers with different shapes, a simplified zero-dimensional thermodynamic model for the compression chamber with the inserted heat exchange elements is developed. This model, valuable for system optimization and control simulations, is a set of ordinary differential equations. They are solved numerically for each exchanger insert shape to determine the geometries of best compression efficiency.
Energy Performance of Sustainable Roofing Systems
Authors: Sailor David J. , Vuppuluri Prem 
Published: December 2013

This study presents efforts to analyze how sustainable roofing technologies can contribute to the energy budget of buildings, and the resulting implications for heating and cooling energy use. The data analyzed in this study were obtained from a field experiment performed on a four story warehouse/office building in Portland, Oregon USA. The building’s roof includes a 216 panel, 45.6 kW solar photovoltaic array in combination with 576 m2 of vegetated green roofing. While most of the surface consists of green roof shaded by photovoltaic panels, the roof also has test patches of dark membrane, white membrane and un-shaded green-roofing. Interior and exterior surface temperatures were monitored over a period of two years and heat flux into the building is estimated using a finite difference conduction model.
On average, the black roof membrane was the only roof that caused a net heat gain into the building in the summer. In the winter, all four roofing technologies resulted in net heat losses out of the building. Both the PV-shaded and un-shaded green-roofs indicated a net heat loss out of the interior of the building during both the summer and winter. This latter effect is largely a result of green-roof evaporative cooling — which can benefit air conditioning demand in summer but may be undesirable during heating-dominated seasons.
Prediction of Non-Uniform Frost Distribution on a Fin Tube Heat Exchanger
Authors: Hwang Jieun , Cho Keumnam 
Published: December 2013

Heat exchanger experiences frost on its surface when it operates below 0°C under heating condition of the heat pump. Since frost blocks air flow through the fin tube heat exchanger, it increases air-side pressure drop and deteriorates heat transfer rate of the heat exchanger. Prediction of the frost profiles on the heat exchanger is needed to minimize the unfavorable effect on the heat exchanger by frost. The present study predicts non-uniform frost distribution on the surface of fin-tube heat exchanger and shows its accuracy by comparing with measured profiles.
Fin and tube heat exchanger for heat pump was considered for the frost prediction under practical refrigerant and air conditions. Non-uniform frost pattern was predicted by using segment by segment method of the heat exchanger. Heat transfer rate and exit temperature of air and refrigerant for each segment were calculated by applying ε-NTU method. Air volume flow rate in the front of the heat exchanger was decreased as frost goes on. It was utilized for the prediction of the frost formation. Numerically predicted results were compared with measured local data. They agreed within ±10.4% under the ISO 5151 condition.
Hybrid Cooling for Thermal-Electric Power Generation
Authors: Maulbetsch John S. 
Published: December 2013

Water use by power plant cooling systems has become a critical siting issue for new plants and the object of increasing pressure for modification or retrofit at existing plants. Wet cooling typically costs less and results in more efficient plant performance. Dry cooling, while costing more and imposing heat rate and capacity penalties on the plant, conserves significant amounts of water and eliminates any concerns regarding thermal discharge to or intake losses on local water bodies.
Hybrid cooling systems have the potential of combining the advantages of both systems by reducing, although not eliminating, water requirements while incurring performance penalties that are less than those from all-dry systems. The costs, while greater than those for wet cooling, can be less than those for dry.
This paper addresses parallel wet/dry systems combining direct dry cooling using a forced-draft air-cooled condenser (ACC) with closed-cycle wet cooling using a surface (shell-and-tube) steam condenser and a mechanical-draft, counterflow wet cooling tower as applied to coal-fired steam plants, gas-fired combined-cycle plants and nuclear plants.
A brief summary of criteria used to identify situations where hybrid systems should be considered is given. A methodology for specifying and selecting a hybrid system is described along with the information and data requirements for sizing and estimating the capital costs and water requirements a specified plant at a specified site.
The methodology incorporates critical plant and operating parameters into the analysis, such as plant monthly load profile, plant equipment design parameters for equipment related to the cooling system, e.g. steam turbine, condenser, wet or dry cooling system, wastewater treatment system. Site characteristics include a water budget or constraints, e.g. acre feet of water available for cooling on an annual basis as well as any monthly or seasonal “draw rate” constraints and meteorological data. The effect of economic parameters including cost of capital, power, water and chemicals for wastewater treating are reviewed. Finally some examples of selected systems at sites of varying meteorological characteristics are presented.
Draft Genome Sequence of
Pseudozyma brasiliensis
sp. nov. Strain GHG001, a High Producer of Endo-1,4-Xylanase Isolated from an Insect Pest of Sugarcane
Authors: Oliveira Juliana Velasco de Castro , dos Santos Renato Augusto Corrêa , Borges Thuanny A. , Riaño-Pachón Diego Mauricio , Goldman Gustavo Henrique 
Published: December 2013

ABSTRACT

Here, we present the nuclear and mitochondrial genome sequences of
Pseudozyma brasiliensis
sp. nov. strain GHG001.
P. brasiliensis
sp. nov. is the closest relative of
Pseudozyma vetiver
.
P. brasiliensis
sp. nov. is capable of growing on xylose or xylan as a sole carbon source and has great biotechnological potential.
Draft Genome Sequences for Oil-Degrading Bacterial Strains from Beach Sands Impacted by the Deepwater Horizon Oil Spill
Authors: Overholt Will A. , Green Stefan J. , Marks Kala P. , Venkatraman Raghavee , Prakash Om , Kostka Joel E. 
Published: December 2013

ABSTRACT
We report the draft genome sequences of 10 proteobacterial strains isolated from beach sands contaminated with crude oil discharged from the Deepwater Horizon spill, which were cultivated under aerobic and anaerobic conditions with crude oil as the sole carbon source. All strains contain multiple putative genes belonging to hydrocarbon degradation pathways.
Draft Genome Sequence of Sodium-Independent Alkaliphilic
Microbacterium
sp. Strain TS-1
Authors: Fujinami Shun , Takeda Kiyoko , Onodera Takefumi , Satoh Katsuya , Sano Motohiko , Narumi Issay , Ito Masahiro 
Published: December 2013

ABSTRACT

Alkaliphilic
Microbacterium
sp. strain TS-1, newly isolated from the jumping spider, showed Na
+
-independent growth and motility. Here, we report the draft genome sequence of this bacterium, which may provide beneficial information for Na
+
-independent alkaline adaptation mechanisms.
Full-Length Genome Sequence of a Plaque-Cloned Virulent Porcine Epidemic Diarrhea Virus Isolate (USA/Iowa/18984/2013) from a Midwestern U.S. Swine Herd
Authors: Hoang Hai , Killian Mary L. , Madson Darin M. , Arruda Paulo H. E. , Sun Dong , Schwartz Kent J. , Yoon Kyoungjin J. 
Published: December 2013

ABSTRACT
Porcine epidemic diarrhea (PED) was recognized in U.S. swine for the first time in early 2013. A plaque-purified PED virus (PEDV) isolate (USA/Iowa/18984/2013) was obtained from a diarrheic piglet. The isolate is genetically close to other previously reported U.S. PEDVs and recent Chinese PEDVs and was virulent when inoculated into neonatal pigs.
Complete Genome Sequence of
Bacteroidales
Strain CF from a Chloroform-Dechlorinating Enrichment Culture
Authors: Tang Shuiquan , Edwards Elizabeth A. 
Published: December 2013

ABSTRACT

Bacteroidales
strain CF is the most abundant nondechlorinating organism in a
Dehalobacter
-containing enrichment culture that consistently reductively dechlorinates >50 mg/liter chloroform or 1,1,1-trichloroethane (methyl chloroform). We assembled and closed the complete genome sequence of this organism from the metagenomic sequencing data for enrichment cultures. This organism is predicted to ferment
l
-lactate and ethanol.
Genome Sequences of 28 Bordetella pertussis U.S. Outbreak Strains Dating from 2010 to 2012
Authors: Harvill Eric T. , Goodfield Laura L. , Ivanov Yury , Meyer Jessica A. , Newth Christopher , Cassiday Pamela , Tondella Maria Lucia , Liao Patty , Zimmerman Jerry , Meert Kathleen , Wessel David , Berger John , Dean J. Michael , Holubkov Richard , Burr Jeri , Liu Teresa , Brinkac Lauren , Kim Maria , Losada Liliana 
Published: December 2013

ABSTRACT

Despite the availability of highly effective vaccines,
Bordetella pertussis
incidence has been rapidly rising in highly vaccinated populations. Recent outbreaks have received media attention, feeding concerns about the emergence of dangerous new strains with increased virulence or that escape vaccine-induced immunity. To accelerate the study of this reemerging pathogen, we sequenced the genomes of 28
B. pertussis
strains isolated during outbreaks from 2010 through 2012, making both strains and sequence data available to the scientific community.
High-Quality Draft Genome Sequence of Bifidobacterium longum E18, Isolated from a Healthy Adult
Authors: Zhurina Daria , Dudnik Alexey , Waidmann Mark S. , Grimm Verena , Westermann Christina , Breitinger Katrin J. , Yuan Jing , van Sinderen Douwe , Riedel Christian U. 
Published: December 2013

ABSTRACT

Bifidobacteria are important gastrointestinal commensals of a number of animals, including humans, and various beneficial effects on host health have been attributed to them. Here, we announce the noncontiguous finished genome sequence of
Bifidobacterium longum
E18, isolated from a healthy adult, which reveals traits involved in its interaction with the host.
Draft Genome Sequence of Strain X47-2AL, a Feline Helicobacter pylori Isolate
Authors: Veyrier Frédéric J. , Ecobichon Chantal , Boneca Ivo G. 
Published: December 2013

ABSTRACT

Helicobacter pylori
is a human-specific pathogen that exclusively inhabits the human gastric mucosa. However, occasionally, humans transmit
H. pylori
to susceptible animal hosts bred in colonies. Here, we report the genome sequence of strain X47-2AL, isolated from a domestic cat and used in anti-
H. pylori
immunization studies.