Journal articles on the topic 'Heat-exchanging surface'

At present, recuperative burners are becoming more extended in the gas-heated facilities, thanks to their significant advantages comparing with conventional gas-burning devices. However, the wide application of the recuperative burners is restricted by their high price. Therefore, studies for perfection recuperative burner designs and technologies of aggregates heating with the burners application are very actual. Results of analysis of modern ways of the burners designs and methods of their application presented, including diagnostics of the recuperative burner heat-exchanging surface state, optimization of the heat-exchanging surface and others. Items of ribbing rational parameters selection for imbedded recuperative devices considered. Perfection of the preliminary combustion chambers and air distribution by combustion stages are important ways of the recuperative burner perfection. It was noted, that in addition to traditional two-stage combustion systems, three-stage combustion systems are appeared lately. It was showed, that under unfavorable conditions of a furnace running, a significant contamination of the recuperative device surface can take place earlier comparing with the set regulation time of periodical cleaning, resulting in losses related to increase of fuel consumption. From the other side, unjustified decrease of the furnace operation period between the recuperative device surfaces cleaning is inconvenient in organization. A methodology of operative diagnostic of a recuperative device state elaborated, due to which the estimation of the imbedded recuperative device heat-exchanging surface state can be done by the identification of the current values of recuperation coefficient and their comparing with the standard values. The methodology enables regulating the periods of cleaning of the surfaces of both the central recuperative devices and recuperative burners.

Tubular parts with an external finned heat-exchanging surface are usually produced by the laborious method of cutting on lathes. Besides, there is a method for the high-performance manufacturing of fins by cold knurling with ring-cut knurls, which, compared with cutting, reduces labor intensity by two to six times with a significant increase in the operational properties of the product. The disadvantage of the cold knurling method with ring-cut knurls can be unwanted surface defects and deformations of the entire product. Obtaining finned surfaces on ring blanks with high surface quality during knurling requires accurate calculation of the ratio of longitudinal and transverse strains. The most important factors determining the ratio of longitudinal and transverse strains (rolling-out and rolling-off) are the length and width of the contact surface. The need for a quantitative assessment of the parameters of longitudinal and transverse strains determined the purpose of this manuscript. This study aimed to develop a methodology for calculating the contact surface of a knurl with a ring blank (pipe) when knurling with ring-cut knurls. The proposed method for calculating the knurl's contact surface with a tube when knurling with ring-cut knurls allows for estimating the recommended range of pipe sizes for knurling. Based on the dependencies mentioned in the manuscript, the limiting sizes for blank pipes were calculated to ensure high-quality finning. Experiments on cold rolling of ribbing on pipes with different lengths and diameter ratios were carried out, confirming the possibility of using the proposed methodology for calculating the knurl's contact surface with a pipe when knurling heat-exchanging finning with ring-cut knurls.

This paper focuses on the problems of ash deposition and corrosion caused by alkali metal chloride in biomass boiler. Kaolin, pulverized coal ash, silica fume, dolomite, limestone and bauxite are used as additives in this study, to investigate the degree of corrosion of four metal materials on biomass boiler. The results show that the corrosion rate of metal samples is significantly reduced after adding additives. Kaolin, pulverized coal ash, silica fume and bauxite show much obvious effect on corrosion inhibition. Corrosion resistance of four pipe metals: T91>15CrMoG>12CrMoVG>20G, in which the corrosion resistance of T91 is much better than the other three metals.

The article discusses the features of the creation and use of efficient heat exchanger. Designs of pipes with a developed heat exchange is presented. The procedure for determining the degree of development of the heat exchanging surface, the heat transfer coefficient, and the calculation of the heat transfer equation are given. As a result of creating efficient heat exchangers, three main parameters are used: the pipe outside diameter; the estimated flow rate; the Prandtl number.

Empirical studies on the heat exchange characteristic of the span borderline CO2 of the parallel flow gas cooler in the hol-aluminium microchannel and the surface temperature distribution of the gas cooler during heat exchanging of the span borderline CO2. Through experiments we got the surface temperature distribution of the cooler in the wind. These studies provide evidences for the design of the hol-aluminium mirochannel parallel flow gas cooler in the carbon dioxide automobile air conditioning system.

Vacuum is an important economic indicator of influencing turbine load and thermal efficiency. And heat transfer efficiency affects the level of vacuum directly. From the point of heat transfer analysis, combining with the production practice in a power plant, this paper proposes a method of improving heat transfer effectiveness and the condenser exchanging condition. Through the method of reducing the heat load of condenser, improving the tightness of the vacuum system, cleaning the heat surface and reducing the cooling water temperature, we improve the vacuum and reach the aim of energy saving.

Changing "high consumption energy, low temperature heat to the indoor, waste heat to the environment", and turning the HVAC harmoniously into the natural ecological cycle, conform to the trend of the development of ecological architecture. Heat pump technology is a way of HVAC energy saving the most practical. Although low heat and cold source of the city sewage is ideal, but the quality is very unstable, can not meet the operation requirements of heat exchange equipment. This paper analyzes the key problems of the sewage side in sewage source heat pump technology application in the present: hair dirt clog sewage heat exchanger; fouling in heat surface reduces the heat transfer performance, and results in large heat-transfer equipment in the practical application. According to the key problems of sewage side, this paper prevents hair clogged with large tube heat exchanger; reduces the fouling thermal resistance, and enhances heat transfer process using the heat exchanging technology of circulating fluidized bed.

Abstract. Crop growth and agricultural management can affect climate at various spatial and temporal scales through the exchange of heat, water, and gases between land and atmosphere. Therefore, simulation of fluxes for heat, water, and gases from agricultural land is important for climate simulations. A land surface model (LSM) combined with a crop growth model (CGM), called an LSM-CGM combined model, is a useful tool for simulating these fluxes from agricultural land. Therefore, we developed a new LSM-CGM combined model for paddy rice fields, the MATCRO-Rice model. The main objective of this paper is to present the full description of MATCRO-Rice. The most important feature of MATCRO-Rice is that it can consistently simulate latent and sensible heat fluxes, net carbon uptake by crop, and crop yield by exchanging variables between the LSM and CGM. This feature enables us to apply the model to a wide range of integrated issues.

Aerogel has its advantages of light density of 0.003-0.35 g/cm3 and its high specific surface area, 600-1000m2/g, mean pore diameter ~20nm. However, aerogel has its disadvantages of fragility and high cost. To overcome the mechanical fragility, we synthesized aerogel composite blankets with glass wools by drying at ambient atmosphere. Colloidal silica sol was first prepared by ion exchanging sodium silicate through amberlite column. Then, glass wool was soaked into the pH-controlled silica aerogel and then gelated. Ageing of silica aerogel composite was conducted in purified water and solvent exchange/surface modification was simultaneously processed in hexane and TMCS solution. After drying at 60oC and heat-treatment at 230oC, we evaluated the properties of aerogel composite, its apparent density and specific surface area.

Purpose The purpose of this study is to address one-dimensional, unsteady heat conduction in a large plane wall exchanging heat convection with a nearby fluid under “small time” conditions. Design/methodology/approach The Transversal Method of Lines (TMOL) was used to reformulate the unsteady, one-dimensional heat conduction equation in the space coordinate and time into a transformed “quasi-steady”, one-dimensional heat conduction equation in the space coordinate housing the time as an embedded parameter. The resulting ordinary differential equation of second order with heat convection boundary conditions is solved analytically with the method of undetermined coefficients. Findings Semi-analytical TMOL dimensionless temperature profiles of compact form with/without regressed terms are obtained for the whole spectrum of Biot number (0 < Bi < ∞) in the “small time” sub-domain. In addition, a new “large time” sub-domain is redefined, that is, setting a smaller critical dimensionless time or critical Fourier number τcr = 0.18. Originality/value The computed dimensionless center, surface and mean temperature profiles in the large plane wall accounting for all Biot number (0 < Bi < ∞) in the “small time” sub-domain τ < τcr = 0.18 exhibit excellent quality while carrying reasonable relative errors for engineering applications. The exemplary level of accuracy indicates that the traditional evaluation of the center, surface and mean temperatures with the standard infinite series retaining a large number of terms is no longer necessary.

Climate change inevitably leads to changes in hydrothermal circulation. However, thermal-hydrologic exchanging caused by land cover change has also undergone ineligible changes. Therefore, studying the comprehensive effects of climate and land cover changes on land surface water and heat exchanges enables us to well understand the formation mechanism of regional climate and predict climate change with fewer uncertainties. This study investigated the land surface thermal-hydrologic exchange across southern China for the next 40 years using a land surface model (ecosystem-atmosphere simulation scheme (EASS)). Our findings are summarized as follows. (i) Spatiotemporal variation patterns of sensible heat flux (H) and evapotranspiration (ET) under the land cover scenarios (A2a or B2a) and climate change scenario (A1B) are unanimous. (ii) BothHand ET take on a single peak pattern, and the peak occurs in June or July. (iii) Based on the regional interannual variability analysis,Hdisplays a downward trend (10%) and ET presents an increasing trend (15%). (iv) The annual averageHand ET would, respectively, increase and decrease by about 10% when woodland converts to the cultivated land. Through this study, we recognize that land surface water and heat exchanges are affected greatly by the future climate change as well as land cover change.

This study represents the results of numerical simulation of fluid motion and free-convective heat transfer in a square cavity with partitions mounted on the lower (heated) and upper (cooled) walls. The height of partitions and their heat conductivity were varied Kr = 2 ? 8000 together with Rayleigh number Ra = 103 ? 106, which corresponded to the laminar flow. It is assumed that vertical walls of the cavity are adiabatic, and its horizontal walls are kept at constant, but different temperatures. The numerical solution based on transformation of determining equations by the method of finite differences was achieved. The obtained results show that the surface-average heat transfer coefficient decreases with a rise of partition height due to the suppression of convection. Also the results show that with an increase in heat conductivity coefficient of partitions, the Nusselt number increases significantly. In addition, it was found that when the value of relative heat conductivity coefficient changes by four orders, Nu number for the highest partitions changes by the factor of 1.5 - 2 only and integral heat transfer through the whole interlayer increases with development of the heat exchanging area.

<p>The paper describes a mathematical model of the cooling process of a highly concentrated sugar solution in an exchanger with a specifically shaped heat exchanging surface of the cooling panels. An analysis of the individual parts of the stum cooling line is made, dealing with the cooling performance of the cooling panels located in the stum tanks, whose volume is 3230 litres or 1430 litres. One of the monitored parameters is the cooling performance of the JN30 aggregate. The article also deals with an appropriateness of the aggregate for cooling the stum of the total volume 78.21 m³, from the real operation temperature to 0 °C during 48 hours.</p>

The aim of the research is to probate the improved vacuum-evaporative apparatus with a changed heating system and increased heat exchanging surface, designed for producing high-quality concentrated blended fruit-berry compositions. Such constructive solution allows to realize an even stabilizing temperature effect, achieved at the expanse of eliminating a steam heating tunic by using a mixer of the apparatus itself. This approach provides simplification of exploitation conditions of such apparatuses, increases the heat exchanging surface that results in decreasing the thermal processing duration at concentrating natural raw materials with a possibility to create original blended compositions of the high readiness degree on its base. For providing production of concentrated semi-products, it is offered to blend fruit-berry raw materials in integral compositions of the high readiness degree. Food semi-products, obtained by this way, differ by original organoleptic properties and increased structural-mechanical indices that give a possibility of their wide use in different branches of food industry and restaurant economy. There is used a method of determining changes of the obtained structure of blended fruit-berry paste with different ratios of components, using the differential function for distribution of pores by radius that provides determination of an influence of each raw material on the obtained dispersion. It is established, that a composition, based on apple, cranberry and blackberry demonstrates a dispersion decrease at introducing cranberry within 25–35 % and its growth at a concentration increase up to 45 % ( = 1.8 nm). At the apparatus probation there is established the evenness provision of a heat flow from a flexible film resistant electric heater of the radiating type, used for heating. Thus, at the given temperature on the heater surface as 146 °С, a difference of temperature values in control points is within error. The result of the gustatory examination proved an advantage of the obtained blended fruit-berry concentrated semi-product, characterized by the homogenous structure with a peasant color and original taste qualities. The offered innovative construction-technological idea allows to produce high-quality concentrated products at using the improved equipment with the even stabilizing temperature effect, decreased metal consumption and increased exploitation indices

The use of foundation structures (piles) coupled to a heat pump system, commonly referred to as geothermal energy pile (GEP) system, provides a renewable energy solution of achieving space heating and cooling in buildings; whilst also being utilised for the structural stability of the overlying structures. The system operates by exchanging the low-grade heat energy within the shallow earth surface with the building, via the circulation of heat carrier fluid enclosed in a high-density polyethylene plastic pipes. In summer, heat energy is extracted from the building and transferred into the ground to achieve space cooling. While in winter, the ground heat energy is harnessed and transferred to the building to achieve sustainable space heating. This paper investigates the thermal performance of group of GEP system under the effects of different initial soil pore water content. Through the five-year simulation’s period, it was found that the increase in soil pore water content decreases the possibility of thermal interaction between the GEPs in the group. Also, it was observed that the trend in maximum temperature witnessed within the soil domain decreases nonlinearly during the five years period.

In the wake of energy crises, the researchers are encouraged to explore new ways of enhancement in the thermal performance of heat exchanging equipment. In the current research, the SST k-? model and finite volume method were employed to augment heat transfer into the separation flow of TiO2 nanofluid in the annular space of two concentric cylinders. In the present investigation TiO2 nanoparticles of volume fractions, 0.5%-2% at Reynolds number range of 10000-40000, and contraction ratios from 1 to 2 were considered at constant heat flux boundary condition. Simulation results reveal that the highest enhancement in the heat transfer coefficient is corresponding to the annular pipe with a contraction ratio of 2 due to the generated re-circulation flow zone that begins after the separation point on the wall. Further, the surface heat transfer coefficient enhances with the increase of nanoparticles volume fraction and Reynolds number. The velocity distribution profile before and after the steps reveals that increasing the height of the step and Reynolds number, re-circulation regions also increases. Numerical results indicate that the highest pressure drop occurs at the Re = 40000 and contraction ratio of 2.

For many years traditional injection moulding has been the norm for obtaining polymer based products, and yet this cycle still shows potential for improvement. This paper will encompass the potential in the thermal part of the cycle, by introducing a novel approach to conventional tubular cooling designs, empowered by additive technologies this reiterates what’s being known as conformal cooling. Different geometries and techniques are compared to determine the optimal cross section layout of the fluid channels and inner surface of the moulding parts. If the cooling achieved is sufficiently fast the crystallographic growth of the material can be manipulated to obtain specific properties observable in the mesoscale. This however can be transversely applied in other heat exchanging structures in future studies.

This paper presents a numerical analysis of natural convection dominated melting inside a rectangular enclosure coupled with forced convection heat transfer in a transport fluid via a finite conductance heat exchanging surface. A computational methodology based on a stream function-vorticity-temperature formulation is adopted and the irregular shape of the moving solid-liquid interface is treated with body-fitted coordinates. The model is then employed to investigate the interaction between natural convection in the PCM filled cavity and forced convection in the HTF. Numerical experiments were carried out for Rayleigh numbers, Ra, between 2.08‧108 and 4.60‧109, modified Reynolds numbers, Re between 4.23 and 423.0, wall-PCM thermal diffusivity ratios, α, between 5.0 and 10.0 and dimensionless wall thickness, w, between 0.005 and 0.05. Results show that the melting process is increasingly delayed by heat conduction across a wall of decreasing thermal conductivity and/or increasing thickness. This effect is accentuated for low HTF flow rates (Re ~ 4.23). On the other hand, for a wail of given thickness and thermal conductivity, the effect of increasing the HTF flow rate on the melting process becomes imperceptible for Re ≥ 4.23.

The aim was to optimize the dependence between fuel consumption and heat loading of regional consumers varied due to climatic conditions, taking into account the determination of structural characteristics of heat exchanging equipment for grid water heating in a heat gas turbine. A heat gas turbine comprising two fuel combustion chambers, a waste-heat boiler and a contact heat exchanger to heat makeup grid water was investigated. Scheme and parametric optimization studies were carried out using a mathematic model of a gas turbine created using a software and hardware system developed at the Department of Heat Power Systems of the Melentiev Energy Systems Institute, Siberian Branch of the Russian Academy of Sciences. Th turbine operating conditions differing in heat loads in four suggested operating regions were studied. It was found that an increase in fuel consumption in the second combustion chamber was 29%– 84% compared to that in the first combustion chamber. This rise was recorded when the turbine heat loading was increasing in the considered regions. Data analysis of the scheme and parametric optimization studies showed that, for operating conditions with a higher heat loading, it seems reasonable to ensure the maximum possible heating of makeup grid water as the loading rises. It is also recommended to slightly increase the heat surface area of the makeup grid water heater whose structural materials are less expensive than in a waste-heat boiler. It was shown that the suggested technical solution slightly increases specific capital investments while fully providing electrical and heat power to consumers. The obtained results can be used to select optimal technical solutions ensuring competitiveness in the operation of a heat gas turbine in regions with various climatic characteristics.

Black bears (Ursus americanus) can spend half of their lives in a severe winter climate using only internal sources of energy and exchanging energy only as heat with their external environment. This paper presents the energy requirement to maintain a bear, and the magnitude of the heat transfer pathways to the bear's surroundings. Flux rate densities of the heat budget were measured for two denning black bears. It was found that the surface area of an oblate spheroid simulating the shape of the curled-up bears balanced the budgets. From these data a simulated bear–den system was constructed for a 75-kg animal: a fur-covered spheroid that was electrically heated and maintained at 36 °C. The energy requirement and heat transport were measured through the skin and in the den over winter, as was the oxygen consumption of a live bear in a similar den nearby. Over a 145-day denning period, mass loss due to fat catabolism would have ranged between 24 and 28% for the simulated bear with the entrance sealed or open, respectively. Using the amount of oxygen consumed and holding body water constant, the mass loss of the live bear over the same period would have been 19% if just fat had been catabolized. However, additional protein catabolism near the end of the denning period caused the loss to increase to 31%, primarily through urination. Once net protein catabolism began, dehydration and not starvation became life threatening.

No unified electromagnetic anti-fouling mechanism is currently available. Most research has focused on the effects of structural parameters and water quality parameters on electromagnetic fields; variations in water quality parameters under the influence of electromagnetic fields have not been reported. A variable-frequency vertical electromagnetic field is proposed in this study. Relationships between conductivity, pH value, dissolved oxygen, turbidity, fouling resistance, and magnetic acting time were carefully analyzed using statistical analysis. Results show that the conductivity difference was the most explanatory predictive variable on magnetic acting time in the multiple stepwise regression model. Magnetic acting time has a greater impact on conductivity than pH value and dissolved oxygen. Conductivity is used as an adaptive feedback control parameter for the optimum anti-fouling state. Fouling resistance on the heat-exchanging surface of the magnetic experiment was smaller than that of the contrast experiment. The anti-fouling efficiency in 1 kHz and 5 kHz magnetic and contrast experiments was 91.23% and 46.97%, respectively. Better anti-fouling performance was realized under the influence of low-frequency electromagnetic fields, confirming that physical water treatment is an effective and environmentally friendly method to eliminate heat exchanger fouling. This research serves as a reference for the development of an electromagnetic-adaptive closed-loop water treatment device.

AbstractSea spray exchanging momentum, heat, and moisture is one of the major uncertainties in modeling air–sea surface heat fluxes under high wind speeds. As a result of several untested assumptions in existing models and low fidelity in the measurements, questions regarding the appropriate method for modeling the effects of spray on air–sea fluxes still exist. In this study, we implement idealized direct numerical simulations (DNS) via an Eulerian–Lagrangian model to simulate spray droplets in turbulent flows. Then, we verify the bulk spray models of Fairall et al. and Andreas et al. with the detailed physics from DNS. We find that the quality of the underlying assumptions of bulk models is sensitive to the time scales governing spray microphysics and lifetime. While both models assume that spray experiences a uniform and steady ambient condition, our results show that this assumption only works well for droplets with long thermodynamic time scales and relatively short lifetime. When the thermodynamic time scales are short, the models fail to predict the correct temperature and radius change of spray (e.g., condensation), thus spray-mediated heat fluxes, which in turn overestimates the total heat fluxes. Moreover, using our two-way coupled simulations, we find a negative feedback induced by the spray evaporation that may be missing in the bulk models, which could lead to further overestimates of the total heat flux when the spray-mediated flux is treated as an add-on to the corresponding interfacial flux. We further illustrate that the feedback effects are consistent under different flow Reynolds numbers, which suggests that the findings are relevant at practical scales.

An OMMT (organic montmorillonite) was prepared by ion exchanging between Na-montmorillonite and cetyl trimethyl ammonium bromide (CTAB) and was applied to modify Dicyclopentadiene Dioxide Epoxy(R-122). FT-IR spectra showed that the organic molecules had intercalated into the layers of MMT successfully, X-ray diffraction illustrated that the spacing of layers of MMT increased from 1.43 nm to 3.85 nm. R-122 composite was prepared with this nano-organic montmorillonite. When the content of OMMT was 4.0% (wt%), the impact strenth of the composite reached to the highest(21.2 J/m), which is 92.7% higher than the pure R-122 . Morphology of the fracture checked by SEM, reveals a depth depended distribution which generated more new surface, thus can absorb more impact energy. Differential scanning calorimetry(DSC) showed that the thermal stability of the composite had improved compared with the pure resin. And what’s more, the improvement of toughness doesn’t hurt the resin’s heat resistance, it may provid a new way to prepare high performance R-122 composites.

In the present study the oxidation behaviour of a number of candidate alloys for heat exchanging components was investigated in model gas mixtures containing high amounts of CO2 and/or water vapour in the temperature range 550-700°C up to exposure times of 1000 h. During exposure in Ar/CO2 and Ar/CO2/H2O base gas mixtures at 550-650°C the oxidation rates and scale compositions of martensitic 9-12%Cr steels were similar to those previously observed in steam environments. Thin and protective Cr-rich oxide scales which are commonly found during air oxidation was observed locally on the specimens surfaces after oxidation in Ar-(1-3%)O2-CO2. The tendency for protective chromia base scale formation increased when 3% oxygen was added, especially for the 12%Cr steel. When iron base oxide scales were formed on the metal surface, the martensitic steels tended to exhibit carburisation whereby the extent was reduced by increasing the water vapour and oxygen contents. All three studied austenitic alloys exhibited very slow scale growth rates at 550°C, however, at and above 600°C the steels with lower Cr content started to form two-layered iron rich surface oxide scales whereby the outer oxide was prone to spallation upon thermal cycling. The high-Cr austenitic steel 310N and the nickel base alloy 617 formed very thin, Cr-rich oxide scales at all used test temperatures and atmospheres. For those two materials the oxidation behaviour in gases containing water vapour in combination with intentionally added oxygen was affected by formation of volatile chromium oxyhydroxide.

A novel approach of treating near-compact heat exchangers (NCHX) (surface to volume ratio, α=100-300m2∕m3 with hydraulic diameter DM∼6mm) as a “global” porous media, whose thermohydraulic performance is being influenced by the presence of “local” tube-to-tube porous medium interconnectors, connecting the in-line arrangement of tubes (D=2mm) having square pitch of XT=XL=2.25, is investigated in this study using numerical methods. The thermohydraulics of the global porous media (NCHX) are characterized by studying the effect of transverse thickness (δ) and permeability (represented by Dai) of the local metal foam type porous medium interconnectors on the global heat transfer coefficient (Nu) and nondimensional pressure drop (ξ). The fluid transport in the porous medium interconnectors is governed by the Brinkman–Darcy flow model while the volume averaged energy equation is used to model energy transport, with the tube walls kept at constant temperature and exchanging heat with the cooling fluid having Pr=0.7 under laminar flow (10<Re<100). For the chosen NCHX configuration, ξ and Nu increases for an increase in Re and also with an increase in the thickness (δ) of the interconnecting porous medium. However, as the local Darcy number (Dai) of the interconnecting porous medium increases, the ξ decreases but the Nu increases. Treating the heat exchanger as a global porous media this result translates to an increase in the ξ and Nu as the global permeability (represented by Dag) decreases, where the decrease in Dag is because of either an increase in δ or a decrease in Dai. Separate correlations predicting ξ and Nu as a function of Re and Dag (which in turn is correlated to δ and Dai) have been developed for the chosen NCHX configuration, both of which predict the numerical data with ±20% accuracy.

Abstract The Southern Ocean (SO) is vital to Earth’s climate system due to its dominant role in exchanging carbon and heat between the ocean and atmosphere and transforming water masses. Evaluating the ability of fully coupled climate models to accurately simulate SO circulation and properties is crucial for building confidence in model projections and advancing model fidelity. By analyzing multiple biases collectively across large model ensembles, physical mechanisms governing the diverse mean-state SO circulation found across models can be identified. This analysis 1) assesses the ability of a large ensemble of models contributed to phase 5 of the Coupled Model Intercomparison Project (CMIP5) to simulate observationally based metrics associated with an accurate representation of the Antarctic Circumpolar Current (ACC), and 2) presents a framework by which the quality of the simulation can be categorized and mechanisms governing the resulting circulation can be deduced. Different combinations of biases in critical metrics including the magnitude and position of the zonally averaged westerly wind stress maximum, wind-driven surface divergence, surface buoyancy fluxes, and properties and transport of North Atlantic Deep Water entering the SO produce distinct mean-state ACC transports. Relative to CMIP3, the quality of the CMIP5 SO simulations has improved. Eight of the thirty-one models simulate an ACC within observational uncertainty (2σ) for approximately the right reasons; that is, the models achieve accuracy in the surface wind stress forcing and the representation of the difference in the meridional density across the current. Improved observations allow for a better assessment of the SO circulation and its properties.

Arctic sea ice plays a vital role in modulating the global climate. In the most recent decades, the rapid decline of the Arctic summer sea ice cover has exposed increasing areas of ice-free ocean, with sufficient fetch for waves to develop. This has highlighted the complex and not well-understood nature of wave-ice interactions, requiring modeling effort. Here, we introduce two independent parameterizations in a high-resolution coupled ice-ocean model to investigate the effects of wave-induced sea ice break-up (through albedo change) and mixing on the Arctic sea ice simulation. Our results show that wave-induced sea ice break-up leads to increases in sea ice concentration and thickness in the Bering Sea, the Baffin Sea and the Barents Sea during the ice growth season, but accelerates the sea ice melt in the Chukchi Sea and the East Siberian Sea in summer. Further, wave-induced mixing can decelerate the sea ice formation in winter and the sea ice melt in summer by exchanging the heat fluxes between the surface and subsurface layer. As our baseline model underestimates sea ice cover in winter and produces more sea ice in summer, wave-induced sea ice break-up plays a positive role in improving the sea ice simulation. This study provides two independent parameterizations to directly include the wave effects into the sea ice models, with important implications for the future sea ice model development.

The article contains the results of a research in constructing of modern heat exchangers form of heat exchanging surfaces and modes of heat media flux, providing minimum area (size) of heat exchanging apparatus. Decreasing of heat-transferring area is achieved by using different techniques of intensification of convective heat exchange. Intensification of the heat exchange is accompanied by increasing of energy consumption for pumping the coolant. It is concluded that under the conditions of turbulent flow, the transport mechanism does not strongly depend on the shape of the perturbations introduced into the flow, while the tendency to approach the dependences is common to the curves for the considered surfaces, and the experimental data obtained on pipes with a periodic section of the flow cross-section along the length. Using surfaces creating channels with a greater coefficient of hydraulic resistance when creating a compact heat exchangers, which corresponds to surfaces for which the principle of trans-verse flow is realized.

Neste trabalho foram investigadas as tendências anuais de temperatura absoluta do ar máxima e mínima de seis estações meteorológicas convencionais do Instituto Nacional de Meteorologia – INMET, localizadas no estado do Tocantins, para o período de 1961 a 2017. A análise de tendência foi realizada aplicando o teste não paramétrico de Mann-Kendall. Os resultados indicam tendência significativa de aumento da temperatura máxima anual em todas as estações. A temperatura mínima anual também apresentou tendência positiva, porém com significância estatística apenas para as estações de Porto Nacional, Palmas e Taguatinga. Embora haja diferenças nas tendências entre as estações, verificou-se um aumento sistemático da temperatura máxima e mínima, especialmente a partir da década de 90. A maior taxa de crescimento da temperatura foi registrada na estação de Palmas, de 4,14 °C para a mínima e de 3,68 °C para a máxima, em um período de 23 anos. O aumento da temperatura mínima encontrados nesse trabalho evidencia que essas cidades estão passando por um processo de maior retenção de energia na forma de calor sensível durante a noite, possivelmente devido a substituição da cobertura da superfície terrestre, devido a maior dificuldade da troca de energia entre a superfície e a atmosfera. Palavras-chave: Mann-Kendall; detecção de tendências; mudanças climáticas. ANNUAL TEMPERATURE TRENDS IN THE STATE OF TOCANTINS ABSTRACT: In this work, the annual trends in absolute and maximum air temperature of six conventional meteorological stations of the National Institute of Meteorology - INMET, located in the state of Tocantins, for the period from 1961 to 2017 were investigated. The trend analysis was performed using the Mann-Kendall non-parametric test. The results indicate a significant trend of increasing the maximum annual temperature in all seasons. The annual minimum temperature also showed a positive trend, but with statistical significance only for the Porto Nacional, Palmas and Taguatinga stations. Although there are differences in trends between seasons, there was a systematic increase in maximum and minimum temperature, especially from the 90s. The highest rate of temperature growth was registered at Palmas station, from 4.14° C to the minimum and 3.68° C for the maximum, over a period of 23 years. The increase in the minimum temperature found in this work shows that these cities are going through a process of greater energy retention in the form of sensitive heat during the night, possibly due to the replacement of the Earth's surface coverage, due to the greater difficulty in exchanging energy between the surface and the atmosphere. Keywords: Mann-Kendall; trend detection; climate changes.

Global energy consumption is increasing every year, and, despite their many negative impacts, fossil fuels are a major source of energy, but their reserves are gradually depleting. One of the promising but underutilized resources is plant biomass (phytomass). The main problem of plant biomass combustion is the low melting temperature of ash, but there are also problems with corrosion of heat exchangers and clogging of heat-exchanging surfaces. This work is concerned with the production of straw pellets in order to increase the melting temperature of ash by adding an additive. The paper sludge contains substances that can increase the melting point of ash and was therefore added to the pellet samples. This additive was mixed with straw in ratios from 90:10, 80:20 and 70:30 (straw/paper sludge). The use of paper sludge showed positive effects on increasing the melting temperature of the ash samples. The deformation temperature of the ash has already risen from 1020 to 1260 °C after the addition of 10% sludge, which is comparable to wood pellets.

The operation of steam generators and thermal power plants is commonly evaluated on a basis of energy analysis. However, the real useful energy loss cannot be completely justified only by the First law of thermodynamics, since it does not differentiate between the quality and amount of energy. The present work aims to give a contribution towards identification of the sources and magnitude of thermodynamic inefficiencies in utility steam generators. The work deals with a parallel analysis of the energy and exergy balances of a coal-fired steam generator that belongs to a 315 MWe power generation unit. The steam generator is de-signed for operation on low grade coal - lignite with net calorific value 6280 to 9211 kJ/kg, in a cycle at 545?C/177.4 bar, with feed water temperature 251?C, combustion air preheated to 272?C and outlet flue gas temperature 160?C. Since the largest exergy dissipation in the thermal power plant cycle occurs in the steam generator, energy, and exergy balances of the furnace and heat exchanging surfaces are established in order to identify the main sources of inefficiency. On a basis of the analysis, optimization of the combustion and heat transfer processes can be achieved through a set of measures, including retrofitting option of lignite pre-drying with flue gas and air preheating with dryer exhaust gases.

This publication discusses the task of developing an induction heating system for billets made of aluminum alloy with a given limit on the permissible temperature deviation. The purpose of the work is to determine the parameters of the inductor sections and the settings of the control system to achieve a given distribution of the billet before being fed under the press. The complexity of the problem is associated with the presence of several heater sections that differ in length from the workpieces, which leads to an additional factor leading to an increase in the unevenness in the distribution of temperature in the load. The model of the electromagnetic process is built taking into account the change in resistivity in the workpieces. When searching for a more efficient calculation algorithm, a joint solution to the thermal and electromagnetic problems is considered, which allows to simplify the procedure for exchanging data between applications. This approach is very convenient for solving problems that are not connected with harsh conditions with the achievement of the final state. When modeling thermal processes, the formulation of the problem takes into account all the features associated with radiant heat transfer between extended surfaces having different temperatures, temperature dependences of the workpiece parameters, a varying heat release region due to displacement. As options for a heating system, software control and a multichannel system with control correction for temperature control at one point are considered. When simulating a multi-channel heating control system, built-in software functions were used that made it possible to form control actions for each channel and recommend the location of temperature sensors providing high-quality control of heating.

t A heat flow and fluid flow investigation of double tube heat exchanger by means of warped tape insert under the mixing water based nano fluids. In this article Aluminium oxide and Titanium oxide was used to get better performance heat exchanging device. A different mass flow rate of fluids used to conduct the experiment and gathered various surface temperature for analyses the heat flow augmentation. A heat flow rate Nano fluids 10 to 12% was enhanced compare with the plain base water. A heat flow with liquid flow Aluminum oxide was enhanced with +8% compare with the plain base water. A heat transfer characteristics titanium oxide were augment with raise of Re and 12% was augmented compare with the plain water. However heat flow and liquid flow heat exchanging device was increasing with volume of Nano fluids increased and leading to friction facto

Heat exchanging devices produce an outstanding part in numerous engineering applications. Because of this, a varied sort of researches are undertaking to decrease the size and cost of the heat transfer equipment with high performance by indulging in diverse invaluable works similar to changing its design, incorporating corrugated structures with different dimension with different flow configurations. In this work, the design of double pipe heat exchanger had been modified similar to the plate type model with the incorporation of a corrugated copper plate which separates the hot and cold fluid inside the SS304 material tube. Three baffles at the top and two baffles at the bottom of the plate have been placed to reduce the velocity and heat interaction timing of the fluids. This could enhance the surface area of the plate and point of contact between the plate surface and fluid particle flowing over the plate surface. The experiment had been undergone with the parameters like engendering the flow arrangements of hot and cold fluid in counter current direction, hot fluid in the three sided baffle at the top and cold fluid at the two sided baffle at the bottom. This allowed liquids of differing thermodynamic equilibrium to interact, bringing about thermal transfer to calculate its maximum efficiency. In addition to these factors, the heat exchanging performance has been estimated with the heat transfer coefficient using LMTD method gave 8-10% enhancement in the overall heat transfer coefficient with respect to the mass flow rate.

This work is devoted to the numerical investigation of heat and fluid flow past a sphere with a centric, cylindrical bore. Such spherical rings are of interest in many technological processes. In chemical reactors, for example, spherical rings are used as a catalyst with an increased reacting surface. Motivated by this fact, we considered spherical rings with different bores and different orientations in flow regimes corresponding to Reynolds numbers from 10 up to 300. The results show a significant influence of the bore diameter on the symmetry and hence the steadiness of the flow field. The Nusselt number can be increased, which leads to a moderate rise in the drag coefficient. Thereby, the effect of the borehole depends on the Reynolds number, the bore diameter, and the angle of attack. For that reason, drag forces and total heat transfers do not simply follow the heat exchanging surface area. Based on the presented results, new correlations are given for both the drag coefficient and the Nusselt number; correlations which incorporate the bore geometry and the bore orientation in the flow field.

Buildings account for a significant portion of the total energy consumption in the U.S., especially the energy-inefficient commercial building sector. As part of the future path toward realizing net zero energy buildings, innovative energy-efficient technologies must be developed. In this study, the potential of phase-change material (PCM)-enhanced constructions to lower heating, ventilating, and air conditioning (HVAC) energy consumption in a commercial restaurant building was investigated. A commercially available fatty acid based PCM product was selected due to their promising thermal and chemical properties. Differential scanning calorimetry (DSC) was used in isothermal step mode to accurately measure the latent heat energy storage of the PCM. A U.S. Department of Energy (DOE) commercial reference building model with a PCM-enhanced ceiling was simulated using a finite-difference conduction heat transfer algorithm in EnergyPlus to determine the effects of the PCM on the building energy performance. It was found that, although the PCM-enhanced ceiling had a beneficial stabilizing effect on the interior surface temperature of the ceiling, the zone mean air temperatures were not significantly altered. As such, minimal HVAC energy savings were seen. Future work should focus on active PCM systems, which utilize heat exchanging fluids to discharge the PCM to remove the stored thermal energy of the PCM during the night in summer, overcoming the fundamental issue of the passive PCM system returning stored thermal energy back into the building.

Through Andy Warhol, much important thinking about the meanings of celebrity for a capitalist, schizoid world takes place — by Andy, by his significant others (Pat Hackett, Bob Colacello, Brigid Berlin), and by the consumers and contemplators of his works. Both a source of his own observations and a screen on which philosophies are projected, Warhol presents an unparalleled critique of celebrity. Other horizontalities, such as Madonna’s, do not generate half the heat as Warhol’s own tendril-like intrusion into so many aspects of the media machine (music, publishing, modeling, painting, film-making, writing). Exchanging competence for breadth, Warhol follows Michel de Certeau’s critique of Freud in Heterologies: Discourse on the Other perfectly: he, too, makes a “conquista” of disciplines and practices outside his sphere of competence. Warhol’s comments with respect to actress Janet Gaynor’s paintings after her May 1976 opening at Manhattan’s Wally Findlay Gallery refer both to Gaynor and himself: “‘The paintings are so bad…but I bet they go up. Look how big she signs her name. It’s like buying an autograph and then you get the flowers thrown in, right?’” (Colacello 289). Comprehending the power of branding, Warhol grants autograph primacy over “autographed.” Factoring the art market into his aesthetics, Warhol founds his definition about what counts as art upon what counts as economics. Through him, business art truly comes into its own. Contemplating art suddenly means comprehending art’s social and financial contexts as well — as when, for example, Warhol ponders the absence of a black audience for his work: “Some blacks recognized me a few times this weekend, and I’m trying to figure out what they recognize so I can somehow sell it to them, whatever it is” (Diaries, Sunday 3 July 1977). Setting his own life up as a philosophical object, Warhol exemplifies astrophysics’ great question of how nothing can produce something. Fashion philosophe himself, he also answers fellow thinker Quentin Crisp’s important question about how “zero” becomes “one.” For both Warhol and Crisp, celebrity is founded upon the algebraic exchange of a positive quantity (fame) for a placeholding nonquantity (nonentity). In How to Have a Life-Style, Crisp traces his interest in the proliferative zero to the educative childhood lunchtime acquisition which first taught him the importance of spontaneous generation: One day, when I was lying as naked as the Greater London Council would allow on a few planks in the “life” room of Walthamstowe College of Art, a student came and sat beside me. It did not befit my station in life to begin a conversation with her. My supposition was that she wished less to be with me than in front of the only electric heater in the place. I was amazed when she asked me if I would like some of the chocolate that formed the “afters” of her instant lunch. I sat up at once. My limbs were galvanized, as though insulin had been pumped into my muscles, by the thought of getting something for nothing. The girl broke her slab of chocolate in two and handed me half. (3) For Crisp, the production of celebrity from nonentity echoes other unbalanced nonexchanges; concerned with similar economic aberrances, Warhol takes a related pleasure in the freak appearance of fame. Like Crisp, he also finds himself “galvanized” by the prospect of converting the null set into the productive series. Setting himself up as a “stargazer” (Stephen Koch’s epithet), Warhol makes it his project to reflect the fame of others, while using those reflections to garner fame for himself. Becoming a surface, Warhol makes fame a question of optics. Throughout the Diaries, we witness Warhol’s constant attention to his own appearance: “Got my live-in contacts but I can’t read or draw in them. Do they have bifocals you can wear with contacts? It’s so scary to wake up in the middle of the night and be able to see” (Tuesday 11 Aug. 1981). Normality is consistently painted in the fauve colors of the bizarre — in this quote, vision becomes a source of disorientation. Sight and unsight cross wires. Rather than facilitate the production of his art, ocular prostheses impede it — implying that he is a better artist when blind or half-sighted. Even odder is the fact that Warhol’s new contacts boost his performance as a model. That someone with so “off” an appearance should ever qualify as model material seems almost like a cruel insider joke (as in John Waters’ 1972 film Female Trouble, the repulsive is given new life as the gorgeous). Warhol had always been interested in modeling, though, as a 1968 photo shoot, “The Status Shirt Put On,” demonstrates. The caption reads: “Andy Warhol, right, garnishes velvet pants ($40, from Stone the Crows) with chains, belts and a lace-trimmed dinner shirt from Turnbull & Asser ($40, Bonwit Teller).” Situated at the confluence of status, fashion and chicanery, Warhol as putter-on emerges from his chrysalis as a model — someone meant to be looked at and emulated, a body meant to be run through the media machine and copied. As the Diaries draw to a close, Warhol’s modeling career provides him with his final cultural act: “In the morning I was preparing myself for my appearance in the fashion show Benjamin coordinated at the Tunnel. They’d sent the clothes over and I look like Liberace in them. Should I just go all the way and be the new Liberace? Snakeskin and rabbit fur. Julian Schnabel (laughs) would be so impressed he would start wearing them” (Tuesday 17 Feb. 1987). Bob Colacello is less than kind in his analysis of Warhol as model: Zoli did get him a couple of runway jobs and Daniela Morela put him in a L’Uomo Vogue spread jumping up and down with some other cute guys, but it was obvious that he was being used for his joke value. That October, Halston asked him to model in a Martha Graham charity fashion show as Bloomingdale’s. He didn’t appear until the end of the show, accompanied by Victor Hugo. His face was caked with makeup and he wore a voluminous royal blue taffeta smock with a big red bow around his neck. He looked like a cross between a clown and a Christmas present. Victor wore the same outfit in emerald green. As Andy minced down the runway, I could hear the ladies around me buzz. The words they used were weirdo, creep, and sissy. (442-3) Bursting Warhol’s balloon, and probably paying him back for countless episodes of personal humiliation, Colacello points out the strangeness of Warhol’s new career choice. Like so many other classes of people (old bags, debs), models pique Andy’s curiosity by virtue of their ontological freshness. In his Diaries, Warhol expresses a keen interest in model anthropology: how this new breed of human beings and these new workers comport themselves commands attention. Their language bemuses him: “Jerry Hall came by with a Halston model named Carol, and models just all talk that baby talk, the girls and the boys — you always know you’re talking to a model” (Wednesday 8 July 1981). Like all other industry-bound jargons, model talk emerges from a concrete set of practices and concerns. All creatures from the modeling industry seem to partake of its linguistic possibilities: “Went into the kitchen for coffee in the main house. Pat Cleveland was reading her Latin books and her mind-control books…She was after Jon, showing him how to walk like you have a dime up your ass and they did that well. She talks model talk. And she plays the flute. And she does yoga. All those things” (Saturday 11 July 1981). Generically distinct from other public creatures, models have their own enunciative staples and rules for structuring an utterance. Like Martians, they have their own unique mode of communicating. Ever interested in specificity, Warhol cannot help but be intrigued by the novelty of their speech; in its simplicity and in its constant juvenilization, their language mirrors his own. Saturated with Hollywoodisms, like “up-there” or “the kids,” Warhol’s vocabulary and syntax point to the existence of other linguistic subsystems and idioms. What matters most is the existence of what de Certeau refers to as a “way of operating,” a mode of getting around. Warhol’s fascination with celebrity species informs his own attention to his development over time. Reflecting important fashion debates of the decades he inhabits, Warhol makes his body a living record of all that transpires around it. As in Richard Avedon’s famous photograph of Warhol’s torso (Andy Warhol, Artist, New York City, 8/20/69), his body tells a story — in this instance, about Valerie Solanas’ rage and its traces. Warhol gets to know Warhol, recording his own oscillations in image: “Everyone tells me they like my hair this new way. I cut it every day. It’s almost a crewcut. Fred said I dress like the kids I hang around with now, he likes it. I guess the preppie look really is big because of the Preppie Handbook. I’m wearing all of Jed’s leftover clothes, the ones he left behind. I’m so skinny they fit me now” (Wednesday 8 July 1981). Warhol monitors his appearance with precision, never failing to provide his readers with the details of his transformation from one type to another. With almost an evolutionary sensibility, Warhol traces the development of new styles while also showing the effect they have on his own aesthetic of dressing. Inextricably immersed in time, Warhol gives in to its flows, which wash over him, carrying his body along with their currents. Similarly, he keeps meticulous track of styles of locomotion, as when, after a Twyla Tharp show, he comments: “The dancing, it’s a funny new kind of dancing, falling and tripping, and it looks like disco dancing. It looks like if you had a creative person on the disco floor, that they would do this (intermission drinks $10)” (Thursday, February 15, 1979). Using his early films, like Vinyl, to document dance styles, such as the frug, Warhol records different ways of posturing. He also documents the emergence of new social diseases: “The Donahue Show was on the flasher problem. This is a big important new problem, right? Men who flash. A wife and her husband who flashed were on, they were in the dark, and businessmen and lawyers who flashed” (Monday 28 July 1980). Within the hypermediated universe of capitalism, everything has its fifteen moments of fame, including problems. Ever the voyeur, Warhol makes note of new trends in exhibitionism, well aware that the job of the talk show is to fabricate and disseminate new fears (What do I do if my neighbor flashes me?, etc.). Fears, too, are commodities, as discussed by Barry Glossner in his The Culture of Fear. Alongside locomotionary styles and fashion creature Feynmann sums, anxieties wax and wane in popularity, produced, dissolved and eventually recycled by the media as products-of-the-week. Recognizing the new status of the media in everyday life, Warhol dedicates himself to recording its fluctuations for the purposes of fashion documentary, biography and contemplation. Positing glamour as a breakdown in the fashion system, Warhol offers a worldview in which the faux pas, the leftover and the mismatched forge an aesthetics of desperation. Warhol is the vehicle for fame. Through him, this abstract entity comes to know itself as such, realizing its possibilities through sensual and material objectification. References Books Colacello, Bob. Holy Terror: Andy Warhol Close Up. New York: Cooper Square Press, 1990. Crisp, Quentin. How to Have a Life-Style. Los Angeles: Alyson Books, 1998. De Certeau, Michel. Heterologies: Discourse on the Other. Minneapolis: University of Minnesota Press, 1986. Glossner, Barry. The Culture of Fear. New York: Basic Books, 1999. Warhol, Andy. The Warhol Diaries. New York: Warner Books, 1989. ——— and Hackett, Pat. POPism: The Warhol Sixties. New York: Harcourt Brace Jovanovich, 1980. Articles “The Status Shirt Put On.” Look. 12 Nov. 1968. Time Capsule –12. Films Warhol, Andy. Vinyl, 1965. Waters, John. Female Trouble. New Line Cinema, 1972. Citation reference for this article MLA Style Tata, Michael Angelo. "Beyond the Stars: Warholian Meta-Celebrity." M/C Journal 7.5 (2004). echo date('d M. Y'); ?> <http://journal.media-culture.org.au/0411/11-tata.php>. APA Style Tata, M. (Nov. 2004) "Beyond the Stars: Warholian Meta-Celebrity," M/C Journal, 7(5). Retrieved echo date('d M. Y'); ?> from <http://journal.media-culture.org.au/0411/11-tata.php>.