土壤源--水环式热泵空调系统的设计

本文简要阐述了土壤源———水环式热泵空调系统的工作原理,以及该系统不同于常规水环热泵空调系统的特点,接着介绍了某应用土壤源———水环式热泵空调系统所具有的设计特点。     

热泵热水装置的应用与分析

从提高能源利用效率的角度出发，对利用热泵进行家庭热水供给的太阳能与热泵热水结合装置、空调与热泵一体装置做了总结。介绍了正在进行试验研究的太阳能热泵热水空调一体装置，分析了该装置的运行能耗以及费用。太阳能热泵热水空调一体装置节能效果突出，实用价值明显。     

某矿坑水源热泵空调系统设计及节能分析

介绍平顶山地区某住宅建筑的空调系统工程,该空调系统充分利用废弃矿坑的水资源作为水源热泵空调机组的水源。对水源热泵空调系统的设计要点:冷热源系统、水源侧水系统、空调水系统、空调末端及机房的设计及布置进行了全面介绍,并对矿坑水源热泵系统的节能原理进行了分析。因矿坑水源较低的水温,空调机组的性能更加高效、稳定,进一步说明了矿坑水源热泵在节能环保方面的优势。对类似建筑物空调系统的设计提供了参考。     

水环热泵空调系统应用性分析

水环热泵空调系统是小型水／空气热泵机组的一种应用。通过连通建筑物周边区和内区的水循环环路将小型水／空气热泵机组并联在一起,形成一个封闭环路,将建筑物内区制冷产生的冷凝热转移到周边区,作为周边区热泵的低温热源。水环热泵空调系统在对建筑物内区供冷的同时实现对周边区供热,使建筑物空调的内、外区冷热相抵,建筑物内部余热得到充分利用,节约了能源。本文比较了水环热泵系统相对于常规空调系统在系统结构、节省能源等方面的优势和应用中遇到的问题,并结合工程应用实例,分析了水环热泵空调系统的经济性。     

低温热泵空调和配套锅炉的研发及应用

介绍了低温气源热泵空调及配套锅炉利用空调废热制热水的研发情况及应用工程实例,分析了低温热泵空调的应用效益和锅炉利用空调废热后,空调的性能变化情况,以及减少环境污染和利用空调废热节能所带来的效益。     

低温热泵空调和配套锅炉研发及应用

介绍了低温气源热泵空调及配套锅炉利用空调废热制热水的研发情况及应用工程实例,分析了低温热泵空调的应用效益和锅炉利用空调废热后,空调的性能变化情况,以及减少环境污染和利用空调废热节能所带来的效益.     

水环热泵空调系统的应用研究

介绍水环热泵的应用背景与意义,阐述水环热泵空调系统的概念和原理,相对于常规空调系统分析其适用性和经济性,最后提出水环热泵空调系统今后的研究发展方向.     

某洗浴中心水源热泵空调系统设计及节能分析

介绍了某娱乐性洗浴中心空调设计的特点,探讨了其暖通空调系统形式与水源水系统、冷热源、空调自控及噪声控制的方法,并分析了系统热泵工况下的运行经济性,结果表明水源热泵系统节能效果明显。     

住宅空调方案选择研究

本文以上海某一高层建筑住宅为例,分析三种典型住宅空调方案的特点,采用BIN法计算了各方案的全年能耗,研究了各方案的初投资和运行费用。研究表明:变制冷剂流量热泵空调年耗电量在三个方案中最小,具有显著的节能效果;但在初投资上却是最高,与分体空调器和风冷热泵空调系统相比没有竞争优势;但是在运行费用上,变制冷剂流量热泵空调的年运行费用最低,与风冷热泵空调系统、分体空调器相比分别节省了10.9%、11.7%的电费。     

一种更经济的绿色空调系统--中产地温水环热泵空调系统

一、地温水环热泵空调系统 水环热泵空调20世纪60年代在美国加州开始应用,至今已有了很大的发展.中产地温水环热泵空调系统节能及环保效益显著,安装简便,对新旧建筑物供暖、空调及卫生用水系统的建设及改造有着极大的优势,有广阔的应用前景.     

Heat transfer performance of wet porous solar collectors under periodic conditions

Fourier's law was often used to study the heat transfer of collector plates. However, some scholars have found that under time-varying periodic boundary conditions, using Fourier's law for research will produce certain deviations. In the current work, periodic boundary conditions are used, so the effect of non-Fourier efficiency on the heat transfer of the collector plate needs to be considered. Based on the Cattaneo–Vernotte equation, a heat transfer model of the solar collector plate with a limited heat transfer rate is constructed, and the problem is solved by the lattice Boltzmann method. On this basis, the influence of radiation, porous media, humidity, and relaxation time on solar collectors is considered. And the average efficiency, tip temperature, and exergy loss of the collectors are quantitatively analyzed. The results show that when the non-Fourier effect is considered, the tip temperature of the collector plate decreases, the average efficiency and the exergy loss increase. Moreover, with the increase of relaxation time, the tip temperature is lower, the efficiency and the exergy loss are greater. As the humidity and radiation increase, the tip temperature decreases, and the exergy loss and average efficiency increase. When other factors remain unchanged, the average efficiency, tip temperature, and exergy loss increased with an increase in porosity.     

Research progress on hydrate plugging in multiphase mixed rich-liquid transportation pipelines

The plugging mechanism of multiphase mixed rich-liquid transportation in submarine pipeline is a prerequisite for maintaining the fluid flow in the pipeline and ensuring safe fluid flow. This paper introduced the common experimental devices used to study multiphase flow, and summarized the plugging progress and mechanism in the liquid-rich system. Besides, it divided the rich-liquid phase system into an oil-based system, a partially dispersed system, and a water-based system according to the different water cuts, and discussed the mechanism of hydrate plugging. Moreover, it summarized the mechanism and the use of anti-agglomerates in different systems. Furthermore, it proposed some suggestions for future research on hydrate plugging. First, in the oil-based system, the effect factors of hydrates are combined with the mechanical properties of hydrate deposit layer, and the hydrate plugging mechanism models at inclined and elbow pipes should be established. Second, the mechanism of oil-water emulsion breaking in partially dispersed system and the reason for the migration of the oil-water interface should be analyzed, and the property of the free water layer on the hydrate plugging process should be quantified. Third, a complete model of the effect of the synergy of liquid bridge force and van der Waals force in the water-based system on the hydrate particle coalescence frequency model is needed, and the coalescence frequency model should be summarized. Next, the dynamic analysis of a multiphase mixed rich-liquid transportation pipeline should be coupled with the process of hydrate coalescence, deposition, and blockage decomposition. Finally, the effects of anti-agglomerates on the morphological evolution of hydrate under different systems and pipeline plugging conditions in different media should be further explored.     

烘焙对生物质热化学转化特性影响的研究进展

生物质是可再生能源的重要组成部分,储量巨大,但其含水量高、能量密度和热值低等缺点致使其研磨难度大、存储运输不便,难以资源化利用。本文对烘焙预处理技术的过程及特点、能耗分析和较为理想的烘焙标准进行了简述;并重点阐述了烘焙对生物质燃烧、热解和气化特性影响的研究进展。经烘焙处理后的生物质在炉膛内可快速、稳定燃烧,炉内温度迅速升高,产生的烟气量减少;热解产生的生物质焦油中水和乙酸含量明显减少,苯酚含量增加,热值总体升高;气化合成气品质明显提升,能量密度增大,总气化效率显著提高。此外,对烘焙预处理技术在城市固体废弃物处理的应用进行了简要的概述,并对其在生物质和城市固体废弃物研究方向上进行了展望。     

Exergetic sustainability evaluation and optimization of an irreversible Brayton cycle performance

Owing to the energy demands and global warming issue, employing more effective power cycles has become a responsibility. This paper presents a thermodynamical study of an irreversible Brayton cycle with the aim of optimizing the performance of the Brayton cycle. Moreover, four different schemes in the process of multi-objective optimization were suggested, and the outcomes of each scheme are assessed separately. The power output, the concepts of entropy generation, the energy, the exergy output, and the exergy efficiencies for the irreversible Brayton cycle are considered in the analysis. In the first scheme, in order to maximize the exergy output, the ecological function and the ecological coefficient of performance, a multi-objective optimization algorithm (MOEA) is used. In the second scheme, three objective functions including the exergetic performance criteria, the ecological coefficient of performance, and the ecological function are maximized at the same time by employing MOEA. In the third scenario, in order to maximize the exergy output, the exergetic performance criteria and the ecological coefficient of performance, a MOEA is performed. In the last scheme, three objective functions containing the exergetic performance criteria, the ecological coefficient of performance, and the exergy-based ecological function are maximized at the same time by employing multi-objective optimization algorithms. All the strategies are implemented via multi-objective evolutionary algorithms based on the NSGAII method. Finally, to govern the final outcome in each scheme, three well-known decision makers were employed.     

Spectral local linearisation method for MHD Casson fluid on stratified bioconvective porous medium flow due to gyrotactic microorganisms

In this paper, the effect of hall parameter on the flow of Casson nanofluid containing gyrotactic microorganisms over a stretching boundary in a porous medium is studied. The stratification, porosity, and Casson fluid parameters are also examined. Using suitable similarity transformations, the basic equations describing the flow are converted to nonlinear differential equations, which are then solved computationally using the spectral local linearisation method. The effects of key parameters such as the Hall parameter, the thermophoresis parameter, the porosity parameter, and Casson fluid parameters are analyzed. The results obtained suggest that the Hall parameter has the effect of decreasing the secondary flow, the heat and mass transfer rate, and density of the motile microorganisms. A decrease in the the Hall parameter is found to cause an increase in the transfer rate, the mass transfer rate, and the density of the motile microorganisms. An increase in the porosity parameter leads to a decline in the skin friction, heat transfer rate, mass transfer rate, and density of the motile microorganisms. The applications of this study arise in industrial areas, including Hall current accelerators, planetary dynamics, Hall current sensors, and magnetohydrodynamic power generators.     

Heat transfer enhancement and drag reduction of a flat plate normal to the airstream (flow control using a rod)

To control the flow around a flat plate, a small rod was set upstream of the plate. The chord length of the plate, D, was 50 mm. The diameter of the rod, d, and the distance between the axes of the rod and plate, L, were varied. The Reynolds number ranged from 1.3 × 10⁴ to 7.7 × 10⁴. For the cases without vortex shedding from the rod, the shear layer from the rod reattaches to the front face of the plate. Consequently, quasi-stationary vortices are formed between the rod and the plate. In this case, at d/D = 0.4 and L/D = 1.4 to 2.0, the maximum reduction of total drag coefficient is 20 to 30%. The average heat transfer on each face increases and the overall heat transfer increases by about 40 to 50% compared with values obtained without the rod in place. © 1998 Scripta Technica, Heat Trans Jpn Res, 27(2): 99–113, 1998     

A chemical mechanism for low to high temperature oxidation of n-dodecane as a component of transportation fuel surrogates

Using surrogate fuels in lieu of real fuels is an appealing concept for combustion studies. A major limitation however, is the capability to design compact and reliable kinetic models that capture all the specificities of the simpler, but still multi-component surrogates. This task is further complicated by the fairly large nature of the hydrocarbons commonly considered as potential surrogate components, since they typically result in large detailed reaction schemes. Towards addressing this challenge, the present work proposes a single, compact, and reliable chemical mechanism, that can accurately describe the oxidation of a wide range of fuels, which are important components of surrogate fuels. A well-characterized mechanism appropriate for the oxidation of smaller hydrocarbon species [G. Blanquart, P. Pepiot-Desjardins, H. Pitsch, Chemical mechanism for high temperature combustion of engine relevant fuels with emphasis on soot precursors, Combust. Flame 156 (2009) 588–607], and several substituted aromatic species [K. Narayanaswamy, G. Blanquart, H. Pitsch, A consistent chemical mechanism for the oxidation of substituted aromatic species, Combust. Flame 157 (10) (2010) 1879–1898], ideally suited as a base to model surrogates, has now been extended to describe the oxidation of n-dodecane, a representative of the paraffin class, which is often used in diesel and jet fuel surrogates. To ensure compactness of the kinetic scheme, a short mechanism for the low to high temperature oxidation of n-dodecane is extracted from the detailed scheme of Sarathy et al. [S. M. Sarathy, C. K.Westbrook, M. Mehl, W. J. Pitz, C. Togbe, P. Dagaut, H. Wang, M. A. Oehlschlaeger, U. Niemann, K. Seshadri, Comprehensive chemical kinetic modeling of the oxidation of 2-methylalkanes from C₇ to C₂₀, Combust. Flame 158 (12) (2011) 2338–2357] and integrated in a systematic way into the base model. Rate changes based on recent rate recommendations from literature are introduced to the resulting chemical mechanism in a consistent manner, which improve the model predictions. Extensive validation of the revised kinetic model is performed using a wide range of experimental conditions and data sets.     

Combustion characteristics and flame stability of linear esters of palmitic acid based on OH-PLIF technology

Experimental study on combustion characteristics and method for evaluating flame stability was carried out. Methyl palmitate, ethyl palmitate, propyl palmitate, butyl palmitate, and amyl palmitate were prepared using pyridine n-butyl bisulfate ionic liquid as catalyst in a self-designed reactor to catalyze esterification reaction of palmitic acid with methanol, ethanol, propanol, butanol, and pentanol, respectively. Combustion characteristics including the flame height, flame front area, and flame speed were analyzed; and OH-PLIF time-average total signal strength by the OH-PLIF technique and cold flow properties of linear-chain alkyl esters of palmitic acid were also studied. Image diagnosis was applied to the study of flame stability, and an image segmentation method using three color feature matrices of flame corresponding to the red, green, and blue components was proposed. A color was selected as the evaluation color and the iterative method was used to obtain the optimal threshold for the area where the flame was located. Each pixel in the matrix was compared with an optimal threshold, and the flame stability was evaluated by calculating the ratio variance under continuous conditions. The method is simple in operation, accurate in repeatability, less interfered, and provides some guidance for analysis and optimization of biodiesel combustion process.     

Energy use in Indian household sector – An actor-oriented approach

Over the years, significant changes have taken place with regard to the type as well the quantity of energy used in Indian households. Many factors have contributed in bringing these changes. These include availability of energy, security of supplies, efficiency of use, cost of device, price of energy carriers, ease of use, and external factors like technological development, introduction of subsidies, and environmental considerations. The present paper presents the pattern of energy consumption in the household sector and analyses the causalities underlying the present usage patterns. It identifies specific (groups of) actors, study their specific situations, analyse the constraints and discusses opportunities for improvement. This can be referred to “actor-oriented” analysis in which we understand how various actors of the energy system are making the system work, and what incentives and constraints each of these actors is experiencing. It analyses actor linkages and their impact on the fuel choice mechanism. The study shows that the role of actors in household fuel choice is significant and depends on the level of factors – micro, meso and macro. It is recommended that the development interventions should include actor-oriented tools in energy planning, implementation, monitoring and evaluation. The analysis is based on the data from the national sample survey (NSS), India. This approach provides a spatial viewpoint which permits a clear assessment of the energy carrier choice by the households and the influence of various actors. The scope of the paper is motivated and limited by suggesting and formulating a powerful analytical technique to analyse the problem involving the role of actors in the Indian household sector.     

Heat transfer in ash deposits: A modelling tool-box

The objective of this paper is to review the present state-of-the-art knowledge on heat transfer to the surface of and inside ash deposits formed in solid fuel-fired utility boilers, and-based on the review-to propose models for calculation of heat transfer, e.g. in deposition models. Heat transfer will control the surface temperature of the deposit, thereby influencing the physical conditions at the deposit surface, e.g. if the surface is molten. The deposit surface conditions will affect the deposit build-up rate as well as the removal/shedding of deposits: molten deposit may lead to a more efficient particle capturing, but may also flow down the heat transfer surfaces.

The heat transfer parameters of prime interest are the convective heat transfer coefficient h, the effective thermal conductivity of the deposit k_eff, and the surface emissivity ε of the deposit. The convective heat transfer coefficient is a function of flow characteristics, and can be calculated using different correlation equations, while the other two parameters depend on the deposit properties, and can be calculated using different structure-based models.

The thermal conductivity of porous ash deposits can be modelled using different models for packed beds. These models can be divided into two major groups, depending on the way they treat the radiation heat transfer, i.e. the unit cell models and the pseudo homogeneous models. Which model will be suitable for a particular application depends primarily on the deposit structure, i.e. whether deposit is particulate, partly sintered or completely fused.

Simple calculations of heat transfer resistances for deposits have been performed, showing that major resistances are in the heat transfer to the deposit (by convection), and the heat transfer through the deposit (by conduction). Very few experimental data on the thermal conductivity of ash deposits, especially at high temperatures where radiation is important, are found in the literature. Although the structure of the deposit is essential for its thermal conductivity, most of the measurements were done on crushed samples. The results obtained using different models were compared with the experimental data published in Rezaei et al. [Rezaei, Gupta, Bryant, Hart, Liu, Bailey, et al. Thermal conductivity of coal ash and slags and models used. Fuel 2000;79:1697–1710.], measured on crushed coal ash samples. Although errors of the predictions were very high in most cases, two models were proposed as suitable for heat conductivity calculations, i.e. the Yagi and Kunii model for particulate deposits, and the Hadley model for sintered and fused deposits.

This literature study showed the need for a wide range of experimental data, which would help in evaluating and improving the existing thermal conductivity models. Also, it is necessary to formulate a more accurate model for the thermal conductivity of solid mixtures, in which potentially important sources of errors can be identified.