FREEZE PROFILE AND HEAT BALANCE CALCULATION OF THE 160kA DRAINED CELL

A 2D full cell thermo-electric model of 160kA drained cell was set up using finiteelement code to calculate its freeze profile, then the drained cell model was modifiedaccording to the freeze profile computed and its heat balance was calculated. Comparedwith that of a 160kA conventional Hall-Heroult cell (H-H cell), though the melts vol-ume of the drained cell reduced greatly, the whole heat loss from it didn't drop downapparently, and an analysis was presented in the paper. On the other hand, the anode-cathode distance (ACD) of a drained cell was much less than that of a H-H cell, sothe voltage drop on it and heat produced decreased too, steps should be taken to keepa workable heat balance on a drained cell.

Role of heat balance on the microstructure evolution of cold spray coated AZ31B with AA7075

A promising solid-state coating mechanism based on the cold spray technique provides highly advantageous conditions on thermal-sensitive magnesium alloys.To study the effect of heat balance in cold spray coating on microstructure,experiments were designed to successfully coat AA7075 on AZ31B with two different heat balance conditions to yield a coated sample with tensile residual stress and a sample with compressive residual stress in both coating and substrate.The effects of coating temperature on the microstructure of magnesium alloy and the interfaces of coated samples were then analyzed by SEM,EBSD,TEM in high-and low-heat input coating conditions.The interface of the AA7075 coating and magnesium alloy substrate under both conditions consists of a narrow-band layer with very fine grains,followed by columnar grains of magnesium that have grown perpendicular to the interface.At higher temperatures,this layer became wider.No intermetallic phase was detected at the interface under either condition.It is shown that the microstructure of the substrate was affected by coating temperature,leading to stress relief,dynamic recrystallization and even dynamic grain growth of magnesium under high temperature.Reducing the heat input and increasing the heat transfer decreased microstructural changes in the substrate.

Study on the Influence of Piloti on Mean Radiant Temperature in Residential Blocks by 3-D Unsteady State Heat Balance Radiation Calculation

Piloti is commonly used in tropical and subtropical climate zones to get high wind velocity and create shadowed areas in order to optimize the living environment of residential blocks,but there are few studies to reveal the influence of piloti on the radiant environment of residential blocks systematically. Taking the city of Guangzhou as an example,using 3-D Unsteady State Heat Balance Radiation Calculation Method,this paper shows that the mean radiant temperature( MRT) under piloti area increases with the increase of piloti ratio,and especially when piloti ratio is equal to 100%,the MRT increase trend becomes sharp. The MRT of exposed area decreases with the increase of piloti ratio,especially when piloti ratio reaches 100%,the decrease trend of MRT becomes sharp,which offers the reference for the study on piloti design in subtropical climate zones and further research on living environment by CFD simulation in residential blocks.

Effect of the Lower Boundary Position of the Fourier Equation on the Soil Energy Balance

In this study, the e?ect of the lower boundary position selection for the Fourier equation on heat transfer and energy balance in soil is evaluated. A detailed numerical study shows that the proper position of the lower boundary is critical when solving the Fourier equation by using zero heat ?ux as the lower boundary condition. Since the position de?nes the capacity of soil as a heat sink or source, which absorbs and stores radiation energy from the sky in summer and then releases the energy to the atmosphere in winter, and regulates the deep soil temperature distribution, the depth of the position greatly in?uences the heat balance within the soil as well as the interaction between the soil and the atmosphere. Based on physical reasoning and the results of numerical simulation, the proper depth of the position should be equal to approximately 3 times of the annual heat wave damping depth. For most soils, the proper lower boundary depth for the Fourier equation should be around 8 m to 15 m, depending on soil texture.

The heat balance on the sea surface in the mature phase of 1982/83 El Nino event

Using the air-sea data set of January, 1983 (the mature phase of the 1982/83 El Nino event), the net radiation on the sea surface, the fluxes of the latent and the sensible heat from ocean to the atmosphere and the net heat gain of the sea surface are calculated over the Indian and the Pacific Oceans for the domain of 35°N-35°S and 45°E-75°W. The results indicate that the upward transfer of the latent and the sensible heat fluxes over the winter hemisphere is larger than that over the summer hemisphere. The sensible heat over the tropical mid Pacific in the Southern Hemisphere is transported from the atmosphere to the ocean, though its magnitude is rather small. The latent heat flux gained by the air over the eastern Pacific is less than the mean value of the normal year. The net radiation, on which the cloud amount has considerable impact, is essentially zonally distributed. Moreover, the sea surface temperature (SST) has a very good correlation with the net radiation, the region of warm SST coinciding with that of the low net radiation. The net radiation obtained by the mid Pacific Ocean is reduced by the SST anomaly during the El Nino event, whereas the atmosphere over there get more latent heat flux, and this results in the diminution of the net heat gain of the ocean. The overview of the heat budget is that the ocean over the winter hemisphere is the energy source of the atmosphere, and that over the summer hemisphere its energy sink.

Parallel Correlative Study of the Heat Balance Test Process for Testing the Efficiency of Turbo-Generators

In order to prolong the life span of a turbo-generator plant and sustain its performance at high efficiency, it is subjected periodically to regular test to monitor the operational profile and efficiency of power conversion from mechanical energy to electrical energy. Analysis of these test data serves as a measure to indicate deviation from normal operation profile and deterioration of plant performance. This present work implemented the heat balance tests process to three turb- generator units in order to assess the harmony, consistency, and accuracy of results to establish parallel correlation for the test process. The test process involves carrying out a heat balance for the turbo-generators at 50%, 75% and 100% load respectively through the determination of the heat losses through the hydrogen coolers, bearing oil, seal oil and radiation and convention to the atmosphere. Some important results were presented in the paper.

Numerical Experiments for the influence of the Transition Zone Migration on Summer Climate in North China

As the position of the transition zone changes obviously, that is, as the transition zone migrates to the north or the south from present position, it affects water or heat balance between the land and the atmosphere in a considerable degree and has a profound influence on climate in North China. The experiment results in this paper indicate whether in the dry case or in the wet case of the large-scale climatological background field, the surface air temperature in a wide range of the transition zone migration and its surrounding decreases as the transition zone migrates northward. Moreover, the net upward fluxes of the surface long wave radiation and the sensible heat decrease, and the evaporation to the atmosphere increases. As the transition zone migrates southward, the results are opposite. This kind of significant thermal forcing between the land and the atmosphere can excite secondary circulation or circulation cells, which interact with the large-scale circulation systems, changing the atmospheric motion, affecting the water vapor transportation and consequently having an effect on the precipitation.

OAKS(QUERCUS SPP.)IN NORTHEAST CHINA

There arc eight species and four varieties of oak in northeast China. This paper reports and describes the distribution and phylocoenogenesis of the Korean pine-broadleaved mixed forest and the mongolian oak formation. The close relationship between the flora of Ussuli—Amur region and Japan is discussed. Analyses of heat and energy balance, and biomass of mongolian oak forests arc provided. Many measurements indicate that, in a nonclosed stand, the wood production of a stand is positively correlated with leaf area index (LAI).

Water use measurement by non-irrigated Tamarix ramosissima in arid regions of Northwest China

Tamarix ramosissima Ledeb. is a typical hardy desert plant growing in arid regions of Northwest China. Sap flow in stems of Z ramosissima plants were measured continuously to determine the diurnal and seasonal variations of sap flow and to understand the water requirements of this species and the response of sap flow to meteorological factors. This article compared the sap flow rate measured by the heat balance method with the transpiration rate measured by rapid weighing, and validated that heat balance sap flow gauges were reliable for monitoring transpiration. The influence of meteorological factors on stem sap flow during the growing season was： solar radiation 〉 vapor pressure deficit 〉 air temperature 〉 rela- tive humidity 〉 wind speed. Bidirectional sap flows occurred at night, and negative sap flow generally corresponded to high atmospheric humidity. The average error in predicted sap flow rate ranged from -0.78% to 14.00% from June to September and for transpiration the average error was 8.19%. Therefore, based on the functional equations between sap flow and meteorological factors as well as sapwood area, transpiration of an individual plant, and even the stand-level transpiration, can be estimated accurately through extrapolation.

Lift Force at Equatorial Sea Level Due to Compressed Air Dynamics of the Trade Wind’s Boundary Layer

Starting with a recent unconventional explanation of the lift force on a wing, featuring compressibility of the air, an application of the same concept is made to the lift force on the equatorial sea surface due to the Trade Winds, by greatly increasing the spatial scales. If the equatorial sea level does rise up, the northward slope to the sea level should facilitate the poleward flux of summer heat in both the North Pacific and North Atlantic Oceans, as two examples, in accordance with the heat budget requirements of these oceans. Compressed air dynamics consists of Bernoulli’s law applied to the streamlines of the Trade Winds, the force balance between the upward centrifugal force of the curved streamlines at the earth’s surface and a downward pressure force, and the perfect gas law for air.

Northwest Atlantic Ocean’s SSTs

In the southwestern North Atlantic Ocean, the area between the 80F isotherm and the equator, and between 30W longitude and the western most land boundary, is compiled for each month from a world atlas of sea surface temperatures. Between February and March, the area starts to increase from 100 units until a maximum of over 1000 units is reached in August, after which the area decreases. One unit equals one latitude/longitude square. While increasing by swelling to the north, the temperature inside the area essentially does not increase, in spite of the self-evident fact that absorption of solar heat increases the whole time in the top 100 m of the water column. It is proposed that sea level rises by thermal expansion, starting at the equator, producing a northward slope in sea level which in turn drives warm water in the surface layer northward. This proposition is consistent with the heat balance required of the North Atlantic.

Comparison of Temperature Field Distribution between Cement Preclinkering Technology and Cement Precalcining Technology

Through the comparison of calcination conditions between cement preclinkering technology and cement precalcining technology,we studied the characteristics of temperature field distribution of cement preclinkering technology systems including cyclone preheater,preclinkering furnace,and rotary kiln.We used numericalsimulation method to obtain data of temperature field distribution.Some results are found by system study.The ratio of tailcoalof cement preclinkering technology is about 70%,and raw mealtemperature can reach 1070 ℃.Shorter L/D kiln type of preclinkering technology can obtain more stable calcining zone temperature.The highest solid temperature of cement preclinkering technology is higher than 80 ℃,and high temperature region（〉1450 ℃）length is 2 times,which is beneficialfor calcining clinker and higher clinker quality.So cement preclinkering technology can obtain more performance temperature filed,which improves both the solid-phase reaction and liquid-phase reaction.

General heat balance for oxygen steelmaking

Energy balances are a general fundamental approach for analyzing the heat requirements for metallurgical processes.The formulation of heat balance equations was involved by computing the various components of heat going in and coming out of the oxygen steelmaking furnace.The developed model was validated against the calculations of Healy and McBride.The overall heat losses that have not been analyzed in previous studies were quantified by back-calculating heat loss from 35 industrial data provided by Tata Steel.The results from the model infer that the heat losses range from 1.3%to 5.9%of the total heat input and it can be controlled by optimizing the silicon in hot metal,the amount of scrap added and the postcombustion ratio.The model prediction shows that sensible heat available from the hot metal accounts for around 66%of total heat input and the rest from the exothermic oxidation reactions.Out of 34%of the heat from exothermic reactions,between 20%and 25%of heat is evolved from the oxidation of carbon to carbon monoxide and carbon dioxide.This model can be applied to predict the heat balance of any top blown oxygen steelmaking technology but needs further validation for a range of oxygen steelmaking operations and conditions.

Mass and heat balance calculations and economic evaluation of an innovative biomass pyrolysis project

Biomass can be converted intoflammable gas,charcoal,wood vinegar,wood tar oil and noncombustible materials with thermo-chemical pyrolysis reactions.Many factors influence these processes,such as the properties of the raw materials,and temperature control and these will affect the products that are produced.Based on the data from a straw pyrolysis demonstration project,the mass and heat balance of the biomass pyrolysis process were analyzed.The statistical product and service solutions(SPSS)statistical method was used to analyze the data which were monitored on-site.A cost-benefit analysis was then used to study the viability of commercializing the project.The analysis included net present value,internal rate of return and investment payback period.These results showed that the straw pyrolysis project has little risk,and will produce remarkable economic benefits.

Applicability and comparison of solar-air source heat pump systems between cold and warm regions of plateau by transient simulation and experiment

Solar-air source heat pump(solar-ASHP)system has a potential application in the field of hot water and space heating in residential buildings.Such system features the complementary advantages to solve the discontinuous operation of the single solar system and the frosting issue of the single ASHP system.This paper built the solar-ASHP systems in Kunming and Shangri-La,and tested the system performance under different weather conditions in these two regions of plateau.Meanwhile,the transient heat balance models of the system were established under the sunlight time and non-sunlight time and were verified by the experimental results.Moreover,the verified model was applied to reveal the energy balance performance between the energy supply and building heat demand.The law of the system performance affected by the ambient temperature,effective heat collecting area,and cumulative heating capacity of collector was explored by the validated model.The results indicate that when the ambient temperature decreases by 1℃during non-sunlight time,the energy efficiency ratio decreases by about 0.07.A square meter decline in the effective heat collecting area pushes an increase in the heating capacity of 5.75 MJ.Meanwhile,the cumulative heating capacity of collector increases by 5 MJ,and the ASHP energy consumption decreases by 0.54 kWh.The dynamic changes of the ambient temperature and instantaneous solar radiation are the main reasons of the heat balance errors.Therefore,both the developed system and model are feasible and reliable in different climate regions.

A novel model for predicting the temperature profile in gas lift wells

One of the most common methods for calculating the production oil rate in a gas lift well is nodal analysis.This manner is an accurate one,but unfortunately it is very time consuming and slow.In some modern studies in petroleum engineering such as close loop control of the wells this slowness makes it impossible to have an online optimization.In fact,before the end of the optimization the input parameters have changed.Thus having a faster model is necessary specially in some of the new studies.One of the sources of slowness of the nodal analysis is the temperature profile estimation of the wells.There are two general approaches for temperature profile estimation,some like heat balance are accurate but slow.Others,similar to linear profile assumption are fast but inaccurate and usually are not used commonly.Here,as a new approach,a combination model of heat balance and linear temperature profile estimation has represented which makes the nodal analysis three times faster and it is as accurate as heat balance calculations.To create this,two points(gas injection point and end of tubing)are selected,then using heat balance equations the temperature of those two points are calculated.In normal nodal analysis the temperature of each wanted point in the well is estimated by heat balance and it is the source of slowness but here just two points are calculated using those complex equations.It seems that between these points assuming a linear temperature profile is reasonable because the parameters of the well and production such as physical tubing,and casing shape and properties and gas oil ratio are constants.But of course,it still has some deviation from the complete method of heat balance which using regression and assigning a coefficient to the model even this much of the deviation could be overcame.Finally,the model was tested in various wells and it was compared with the normal nodal analysis with complete heat balance models.Results showed that the new model is as accurate as normal heat balance but three times faster.

An ignored key link in greenhouse effect:Soil and soil CO_(2) slow heat loss

The ever-increasing atmospheric CO_(2) concentration is a key driver of modern global warming.However,the low heat capacity of atmosphere and strong convection processes in the troposphere both limit heat retention.Given the higher heat capacity and CO_(2) concentration in soil compared to the atmosphere,the direct contributions of soil to the greenhouse effect may be significant.By experimentally manipulating CO_(2) concentrations both in the soil and the atmosphere,we demonstrated that the soil-retained heat and the slower soil heat transmission decrease the amount of heat energy leaking from the earth.Furthermore,the soil air temperature was affected by soil CO_(2) concentration,with the highest value recorded at 7500 ppm CO_(2).This study indicates that soil and soil CO_(2),together with atmospheric CO_(2),play a crucial role in the greenhouse effect.The spatial and temporal heterogeneity of soils and soil CO_(2) should be further investigated,given their potentially significant influence on global climate change.

Energy recovery of solid waste disposal in Russia,State of the Art and operation experience

For Russia,there is no alternative way of a civilized solution to the problem of municipal solid wastes(MSW):through combustion(energy utilization)to complex processing.The government of the Russian Federation in 2017 adopted some decisions aimed at thermal processing of MSW.The order defines the construction of renewable energy facilities on the basis of MSW with a total electric capacity of 280 MW in Moscow region and one object with an electric capacity of 55 MW in the Republic of Tatarstan.In Russia,only three plants where the energy potential of MSW is converted into electricity were built.The results of the operation experience of fluidized bed furnaces for MSW incineration at Rudnevo plant in Russia are done.The main problems were connected with ash properties,deposit formation,and corrosion of superheater tubes.Also,the data of mathematical modeling of dynamic behavior near gas burners,chemical composition and material balance of solids,and the influence of secondary air injection on NOx formation are given.A special test rig was designed for the investigation of the corrosion mechanism.Also,the main corrosion factors(temperature of the tube surface,rates of O_(2),HCl,SO_(2),and H_(2)O in flue gas,contains chloride and alkali metals in deposits)were found during the tests.Experience of energy recovery from waste incineration of pulp and paper mill plants is presented.Considerable attention is paid to improv-ing the efficiency of waste incineration and bed particle agglomeration.Special experiments were carried out to optimize the bed drain flow rate.The influence of secondary air supply improvement on mixing with the main flow and boiler efficiency is given.Semi-empirical three-zone method of engineering heat calculations for fluidized bed furnaces of biomass boilers was proposed to predict both the value of outlet furnace temperature and the value of fluidized bed temperature.The method based on empirical values and relationships of the share of heat release in fluidized bed zone.