数码涡旋多联式空调系统制冷运行部分负荷特性实验

以数码涡旋多联式空调系统为研究对象,通过研究其在夏热冬冷地区制冷运行时部分负荷条件下的运行特性,分析小时能效比、小时耗功随部分负荷率、室外温度的变化规律。研究结果表明:不论室内机开启台数和室外温度如何变化,小时耗功和小时能效比在室内外工况一定时随部分负荷率分别呈下凹和上凸曲线分布,数码涡旋多联式空调机组在部分负荷时具有很好的节能特性;室内机全开、部分负荷率在0.52～1.08范围内,室外温度较高时,小时耗功随部分负荷率增加而增加的趋势更显著,不利于系统节能运行,而室外温度较低时,小时能效比随部分负荷率增加而增加的趋势更显著,有利于系统节能运行;室内外温度一定、部分负荷率相同时,小时耗功随室内机开启台数的增加而减小,小时能效比随室内机开启台数的增加而增加。     

可实现快速制热和除霜的蓄能型空气源热泵系统的实验研究

提出一种可快速制热和除霜的蓄能型空气源热泵系统,并在室外温度约-0.7℃,相对湿度约95%的雨雪天气条件下进行实验测试,结果表明,结霜过程中蓄热器可有效阻止室内机出风温度的下降,除霜过程中新系统的压缩机出力大,效率高。除霜用时比常规除霜缩短68%,除霜能耗比常规除霜减少51.4%,除霜末期室内机出风温度为28℃,比常规系统高22℃,几乎没有吹冷风感;新系统开机快速制热效果十分显著,其6 min的制热量相当于常规开机制热10 min的制热量,新系统显著提高了空气源热泵的供热效果。     

冬季极端天气状况下空气源热泵运行实验研究

对夏热冬冷地区某住宅的空气源热泵空调器在降雪天气状况下的运行性能进行了实测研究。结果表明:制热量平均值较额定值下降约15%,瞬时值最大下降约30%;制热工况平均COP值为2.66,较额定值下降11.3%,包含除霜在内的运行周期平均COP值为2.37,较额定值下降20.9%,除霜耗电量为总耗电量的9.2%;不受结霜影响的瞬时制热量最大值达到额定值的94%～98%;室内机风速变化引起的制热量变化幅度约为4%。分析表明,室外机在结霜状况下工作是导致制热量及COP值下降的主要原因,先进的除霜方式是降低结霜对制热量的影响与提高运行能效的关键。     

空气源热泵热水系统结霜和除霜研究现状与进展

空气侧换热器结霜和除霜是影响空气源热泵热水系统冬季运行的一个重要因素。目前国内外对结霜和除霜问题的研究主要集中在以下几个方面:霜层形成机理的研究、换热器结霜特性的模拟和除霜控制方法的研究。在能源和环保压力日益加大的今天,进一步提高空气源热泵热水系统的运行效率,改善冬季低温天气下系统的运行状况,研究结霜的机理以寻求更优的除霜方案具有重要的现实意义。     

气候环境实验室换热器除霜技术的研究

气候环境实验室在进行低温、高湿工况试验时,换热器表面会结霜。换热器结霜将增加换热空气的流动阻力、导致换热效率下降。为保证空气处理系统正常运行需要对换热器进行除霜。文中通过建立换热器模型对换热器结霜和除霜过程进行仿真分析,计算了结霜和除霜过程中霜层厚度、滞留水量的变化过程,提出了除霜开始判据和结束判据。以此为理论依据对实验室换热器除霜方案和除霜流程进行了优化,并在实验室调试过程中得到应用,取得了良好效果。     

不同相变蓄能器对多联机空气源热泵蓄热特性影响

以多联机空气源热泵相变蓄能除霜系统为研究对象,采用实验研究的方法对采用翅片管型和螺旋盘管型相变蓄能器的多联机空气源热泵除霜系统的蓄能过程进行实验分析。研究结果显示:室内机全负荷状态下,相变蓄能器在供热过程中蓄热,螺旋盘管型蓄能器与翅片型蓄能器完成蓄热分别需要6.00和33.00 min。从整个供热周期来看,翅片型蓄能器对供热过程的影响更小,蓄热过程会引起室内平均进出风温差降低4℃、平均供热量降低6 kW,系统结霜时间缩短8 min。     

数码涡旋空调系统节能分析

目前变制冷剂流量空调系统越来越受到广泛的关注，而数码涡旋空调系统是变制冷剂流量空调系统中的一种新兴技术。介绍了数码涡旋压缩机技术，分析了数码涡旋空调系统的特点和节能因素，并将其与VAV(Variable Air Volume)空调系统进行对比，指出了数码涡旋空调系统是目前中央空调尤其是小型的中央空调系统的一个发展方向。     

三星应用数码涡旋技术 领跑高效节能空调

数码涡旋空调系统是先进的数码技术和涡旋缩机结合的产物,它是三星公司将自己强大的数码控制技术与涡旋压缩机相结合,其节能原理主要在于实现了“无级调节”。在三星主导下,数码涡旋技术在商用空调领域得到深入应用。     

剑指高效节能，三星凭技术领跑

数码涡旋空洞系统是先进的数码技术和涡旋压缩机结合的产物，它是三星公司将自己强大的数码控制技术与涡旋压缩机相结合，其节能原理主要在于实现了“无级调节”。在三星主导下，数码涡旋技术在商用空调领域得到深入应用。     

直膨式太阳能热泵制热性能的对比研究

直膨式太阳能热泵(direct expansion solar assisted heat pump,DX-SAHP)可直接吸收利用太阳能,进而提高热泵的蒸发温度和性能系数(COP),有利于改善热泵的热性能和结霜。本文在带有太阳模拟发射器的焓差实验室中建立直膨式太阳能热泵和常规直彭热泵的对比实验,对不同条件下的热泵系统参数进行测量并进行性能对比和分析。实验结果显示,直膨式太阳能热泵能够吸收太阳能,在辐照度分别为100和200 W/m~2的工况下,系统制热功率比无辐照时的制热功率分别提高9.8%和21.8%,COP分别提高11.7%和23.7%,且除霜启动延迟23 min;辐照度为200 W/m~2时,直膨式太阳能热泵在环境温度5℃下的制热功率比1℃下的制热功率提高16.92%;在室外温度为1℃,相对湿度为95%的工况下,提高太阳辐照度,可有效减小涂层蒸发器进出口温度的波动,提高蒸发器运行的稳定性。此外,直膨式太阳能热泵在运行过程中吸收的太阳辐射被用来蒸发液态制冷剂工质,导致压缩机进气量增加,系统的制热功率和COP提高。     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

液压系统常见的故障诊断及处理

任何工程机械式液压设备使用时出现故障是不可避免的。但是怎样确定故障的原因及找到好的解决方法，这是使用者最关心的问题。讲述了液压系统常见的故障及其排除方法。     

Economie d'énergie en trigénération

Trigeneration is defined as the production of three useful forms of energy—heat, cold and power—from a primary source of energy such as natural gas or oil. For instance, trigeneration systems typically produce electrical power via a reciprocating engine or gas turbine and recover a large percentage of the heat energy retained in the lubricating oil, exhaust gas and coolant water systems to maximize the utilization of the primary fuel. The heat produced can be totally or partially used to fuel absorption refrigerators. Therefore, trigeneration systems enjoy an inherently high efficiency and have the potential to significantly reduce the energy-related operation costs of facilities. In this paper, we describe a model of characterization of trigeneration systems trough the condition of primary energy saving and the quality index, compared to the separate production of heat, cold and power. The study highlights the importance of the choice of the separate production reference system on the level of primary energy saving and emissions reduction.     

Mineralogical characterization of the intraseam layers of Lofoi lignite deposits in Florina basin (western Makedonia,northwest Greece)

The mineralogical composition of intraseam layers from Lofoi lignite deposits (northwest Greece) is the subject of the present study. The samples were examined by means of X-ray diffraction (XRD), thermo-gravimetric (TG/DTG) and differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectrometry. The clay minerals prevail in most samples, with illite-muscovite being the dominant phase, and kaolinite and chlorite being the other major clay components. No smectite was found. Quartz and feldspars, dominate in two cases. The studied materials are characterized as clays to clayey sands, showing significant similarities with the intraseam layers of the adjacent Achlada lignite deposits.     

Innovative methodologies in renewable energy: A review

This paper is concerned with innovative approaches to renewable energy sources computation methodologies, which provide more refined results than the classical alternatives. Such refinements provide additional improvements especially for replacement of fossil energy usages that emit greenhouse gas (GHG) into the atmosphere leading to climate change impact. Current knowledge gap among each renewable energy source calculation is rather missing fundamentals of plausible, rational, and logical explanations for the interpretation of results. In the literature, there are rather complicated and mechanically applicable methodologies, which require input and output measurement data match with missing physical explanations. The view taken in this review paper is to concentrate on quite plausible, logical, rational, and effectively applicable innovative energy calculation methodologies with simplistic fundamentals. For this purpose, a set of renewable energy methodological approaches is revisited with their innovative structures concerning solar, wind, hydro, current, and geothermal energy resources. With the increase in the renewable energy utilizations to combat the undesirable impacts of global warming and climate change, there is a need for better models that will include physical environmental conditions and data properties in the probabilistic, statistical, stochastic, logical, and rational senses leading to refined and more reliable estimations with application examples in the text. Finally, new research directions are also recommended for more refined innovative energy system calculations.     

Constrained Optimization of Heat Transfer from an Extended Surface

Two different zero‐order optimization techniques are used to maximize the rates of heat transfer from a fin assembly of a specified cost and in the shape of several annular fins that are mounted on a central stem. The problem is formulated to account for two‐dimensional steady‐state heat transfer that is limited by several inequality constraints. The dimensionless governing equations are used to identify the relevant decision variables. The number of fins making up the assembly is treated as an input parameter. A digital computer is used to determine the required temperature distributions and to implement the optimization search algorithms. Three different fin materials are assessed—aluminum, copper and carbon steel. Design optimizations of the extended surface assembly were made over a range of operating conditions, encompassing several different convection heat transfer coefficients that are representative of free and forced convection in air, and several different overall temperature differences between the substrate surface and air. A few recommendations based on trends in the predicted results are given. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(6): 504–521, 2014; Published online 3 October 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21093     

CY6D78Ti型柴油机的开发研制

本文介绍了CY6D78Ti型柴油机的开发研制过程及现状,CY6D78Ti型柴油机能满足国内中、重型卡车和豪华客车市场对柴油机动力性、经济性、可靠性的需求。由于该机型的高档配置,保证了其排放达到欧Ⅱ标准,同时为进一步提高性能、降低排放,采用电控及高压共轨等技术手段搭建了平台。     

我国车用柴油机的技术现状及发展趋势

本文根据国内外信息和资料，分析了我国目前车用柴油机制造技术方面与国际水平所存在的差距，预测今后若千年内车用柴油机要向节能降耗、应用增压技术、提高可靠性、降低排放、采用电控技术方面发展，以尽快接近和赶上国际先进水平．