Heat flow balance and control strategies for a large GSHP

The possibility of underground imbalance between heat emission and absorption has a negative impact on the performance of ground-source heat pump systems （GSHPs）. Numerical and experimental researches were made in a residential building, which is supplied with a GSHP system and a ceiling radiation system combined with a replacement fresh air system. EnergyPlus simulations were used to estimate heating and cooling loads, and to assess the heat generated from the water pump, the fan and the heat pump unit. Then, Fluent simulations were used to compare three different control strategies of handling the underground heat exchange. These simulations were strongly based on an experimentally verified model. It is obtained that a ratio between cooling and heating loads is 5.08 ： 1 in a case study in Nanjing. Moreover, the control strategy based on the starting time is more efficient and reliable than the temperature and temperature difference strategies to control the underground heat exchange.

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.

Heat balance of solar-soil source heat pump compound system

Based on the state-of-the-art studies of solar-soil source heat pump compound system, operation patterns of solar-soil compound system were analyzed, particularly the advantages of parallel operation pattern. It is found that parallel operation pattern is better for solar-soil compound system. Furthermore, the heat balance issue of solar-soil compound system was emphatically analyzed from four aspects, which were annual analysis of heating and cooling load, the heat exchange of ground heat exchanger, capacity determination of solar-assisted heat sottrce and heat balance calculation of solar-soil compound system. Moreover, annual rate of heat balance in a solar-soil source heat pump compound system was calculated with a case study. It is shown that the annual heat unbalance ratio is 19%, which is less than 20%. As a result, the practical solar-soil compound system can basically maintain the heat balance of soil.

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.

Modeling of the Earth’s Planetary Heat Balance with Electrical Circuit Analogy

The integral heat model for the system of the Earth’s surface—the atmosphere—the open space based on the electrical circuit analogy is presented. Mathematical models of the heat balance for this system are proposed. Heat circuit which is analog of the electrical circuit for investigating the temperature dependencies on the key parameters in the clear form is presented.

The Heat Balance in the Western Equatorial Pacific Warm Pool during the Westerly Wind Bursts: A Case Study

The responses of sea surface temperature (SST) in the western equatorial Pacific warm pool to the westerly wind bursts (WWBs) play an important role in the relationship between WWB and ENSO. By using data collected from eight buoys of TOGA (Tropical Ocean-Global Atmosphere)- COARE (Coupled Ocean-Atmosphere Response Experiment), the heat balances of the upper ocean in the western equatorial Pacific around 0 degrees, 156 degreesE during two WWB events were calculated according to Stevenson and Niiler's (1983) method. In both events, SST increased before and after the WWBs, while decreased within the WWBs. The SST amplitudes approximated to 1 degreesC. Although sometimes the horizontal heat advections may become the biggest term in the heat balance, the variation of SST was dominated by the surface heat flux. On the other aspect, some different features of the two events are also revealed. The two cases have different variation of mixed layer depth. The depth of mixed layer is almost double in the first case (35 in to 70 m), which is caused by Ekman convergence, while only 10m increments due to entrainment in the second one, There are also differences in the currents structure. The different variations of thermal and currents structure in the mixing layers accounted for the different variation of the heat balance during the two events, especially the advection and residue terms. The seasonal variation of SST in this area is also investigated simply. The first WWB event happened just during the seasonal transition. So we considered that it is a normal season transition rather than a so-called anomaly. That also suggested that the seasonal distinction of the WWB is worthy of more attention in the researches of its relationship to ENSO.

Heat balance simulation of drained aluminum reduction cell

Compared with a conventional Hall Heroult cell(H H cell), the interpolar distance of a drained cell can be reduced significantly and the cell voltage and heat produced in the electrolysis will decrease greatly as well, which makes it crucial to achieve a new heat balance in the drained cell. A half anode cathode slice model of a hypothetical drained cell retrofitted from a 160 kA currently used in H H cell was developed for the thermo electric calculation and simulation. The results were presented and analyzed and possible approaches for setting up a new heat balance in a drained cell were discussed.

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.

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.

Conflict between Population and Urbanization Factors： Impact of Urban Heat Island on Energy Consumption Balance

High density of buildings and population in urban areas increases urban temperature, generally known as the urban heat island. Raised temperature, especially in SUlIuner, alms city centers into unwelcome hot areas, with direct effects on electricity demand and energy consttrnption for cooling buildings and increases the production of carbon dioxide and other pollutants. Therefore, by considering that the energy consumption in the world has been faced with intense crisis, it becomes increasingly important to study the effects of urban heat island on energy constunption in order to improve people＇s environment and decrease energy use in cities. This paper, therefore, is focused on urbanization and population size factors to understand tile influence way of these factors on formation of UHI and energy consumption balance. To achieve this aim, this paper explores literally the conceptual framework of confliction between population and urban structure, which produce UHI intensity and affected energy consumption balance. It is then discussed how these two factors can be affected and give implication to the city, and then, focuses on whether actions should be taken for balancing adaptation and mitigation UHI effects. It will be concluded by making the recommendations for preventive action and provide quality of life.

Application of Energy Balance Snowmelt Model on Sunny Slope in Western Tianshan Mountains

[Objective] The study aimed to apply energy balance snowmelt model for estimating the snowmelt runoff generated by seasonal snow in Tianshan Mountains. [Method] Three snow water collecting sites were set on a sunny slope in western Tianshan Mountains to measure the snowmelt rates at hourly interval. The positive sensible heat and negative latent heat fluxes were calculated by the energy balance snowmelt model; the snowmelt rate was also estimated by the model. Finally, the ac- curacy for the model was investigated in detail. [Result] The results indicated that sensible heat fluxes and latent heat fluxes accounted for 13.4% of total energy input and 15.1% of energy output, respectively. A good agreement between observed and estimated SWE was proved by low volume difference and the high Nash-Sutcliff coef- ficients（R2） which were 0.86, 0.92 and 0.91, respectively. [Conclusion] The energy balance snowmelt model has been proved to be a powerful tool for snowmelt estimation.

Effects of working parameters on gasoline engine exergy balance

To improve the energy utilization efficiency of internal combustion （IC） engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exergy balance model was built. The working processes of gasoline engine were simulated by using the GT-power. In this way, the required parameters were calculated and then gasoline engine exergy balance was obtained by programming on computer. On this basis, the influences of various parameters on exergy balance were analyzed. Results show that, the proportions of various forms of exergy in gasoline engine from high to low are irreversible loss, effective work, exhaust gas exergy and heat transfer exergy. Effective exergy proportion fluctuates with cylinder volumetric efficiency at full load, while it always increases with break mean effective pressure （BMEP） at part load. Exhaust gas exergy proportion is more sensitive to speed, and it increases with speed increasing except at the highest speed. The lower proportion of heat transfer exergy appears at high speed and high load. Irreversible loss is mainly influenced by load. At part load, higher BMEP results in lower proportion of irreversible loss; at full load, the proportion of irreversible loss changes little except at the highest speed.

Recent Energy Balance of Earth

A recently published estimate of Earth’s global warming trend is 0.63 ± 0.28 W/m2, as calculated from ocean heat content anomaly data spanning 1993-2008. This value is not representative of the recent (2003-2008) warming/cooling rate because of a “flattening” that occurred around 2001-2002. Using only 2003-2008 data from Argo floats, we find by four different algorithms that the recent trend ranges from –0.010 to –0.161 W/m2 with a typical error bar of ±0.2 W/m2. These results fail to support the existence of a frequently-cited large positive computed radiative imbalance.

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.

RADIATION BALANCE AND MICROCLIMATIC FEATURES OF MARSH IN THE SANJIANG PLAIN

Radiation balance, soil temperature and the temperature and humidity of air were measured in marshes and reclaimed farmlands of the Sanjing Plain. Soil-heat flux was calculated with two different methods. Through the analysis of a lot of data, the daily variations and the law of vertical distribution of microclimate factors on marsh surface was obtained. It is found that after marshes are reclaimed, radiation balance increases, both soil temperature at different depths and air temperature of various height near ground layer rise, and air humidity decreases obviously. Therefore, one should take the establishment of artificial ecosystem of growing paddy and reed and breeding fish as the main development direction of marshes, at the same time, protect some marshes in order to prevent the environment from getting dry, and maintain regional ecological balance.

Load-Balance Policy in Two Level-Cluster File System

In this paper, we explored a load-balancing algorithm in a cluster file system contains two levels of metadata-server, primary-level server quickly distributestasks to second-level servers depending on the closest load-balancing information. At the same time, we explored a method which accurately reflect I/O traffic and storage of storage-node： computing the heat-value of file, according to which we realized a more logical storage allocation. According to the experiment result, we conclude that this new algorithm shortens the executing time of tasks and improves the system performance compared with other load algorithm.

考虑主从博弈的电热能源系统优化调度

针对多主体利益纷争导致电热能源系统运行经济性欠优的问题,提出一种基于主从博弈理论的电热能源系统优化调度方法。首先,分析博弈过程中的信息交互机理,建立电热能源系统调度框架;其次,制定上网电价和供能商出力约束,构建旨在实现环境成本和购电成本之和最小化的主体模型,同时构建以自身经济性最优为目标的从体模型;最后,采用差分进化法求解各主体的出力分配和利益分配问题。仿真结果验证了所提模型的优越性。

不同含水率下的生活垃圾气化特性模拟

我国不同地区的垃圾含水率有很大差异,为了探究垃圾含水率对气化特性的影响,更进一步地实现生活垃圾资源化利用,本文基于Aspen Plus建立了垃圾气化的工艺流程模型,分析了不同含水率下的温度对气化合成气组分、碳转化率(CCE)、低位热值(LHV)、气体产率的影响,气化温度提高促进CCE、LHV先降低后升高。结果表明升温和增加含水率可提高CCE、降低LHV,温度小于650℃时,增加含水率可促进气体产率,温度大于650℃时,增加含水率会降低气体产率;通过诸多气化指标得出垃圾含水率为25%、气化温度为850℃时为最优工况,在此基础上,40.63%的产气燃烧比例放热可以为干燥、热解、气化阶段提供热量,实现系统的热量自给。当气化温度和产气燃烧比例不变时,随着垃圾含水率的提高,气化系统对外界放出的热量先增加后减小。

离子液脱硫技术中热平衡的研究与实践

介绍了离子液脱硫系统的工艺流程,分析了系统运行中的热交换过程,主要换热设备采用板式换热器,针对换热过程中出现的热平衡被破坏的情况及影响进行探讨,提出了保持离子液脱硫系统稳定运行的措施。