水源热泵热水器实验研究

水源热泵技术利用少量电能将地表水或地下水的低品位能量转移至高品位,目前正成为节能领域的研究热点.针对水源热泵变冷凝参数的相关研究缺乏的现状,通过搭建水源热泵热水器实验台进行了相应实验研究.在水流量Q为0.7~1.3 m~3·h~(-1),进水温度t为15~30℃范围内,对系统功耗、制热量、制冷量、热泵性能系数COP等参数进行了测量.实验结果表明,在水流量为1.1 m~3·h~(-1),进水温度为20℃时,COP达到最大值,系统平均热泵性能系数COP_(ave)为3.23,此时系统处于最佳运行工况.由此可知,寻找系统的最佳运行工况对热泵系统设计和实际工程应用具有重要的意义.     

太阳能/空气源热泵复合热水系统的串、并联式性能研究

提出自行设计一套太阳能/空气源热泵复合热水系统方案,明确系统全年运行模式满足全天候热水供应。统计分析了福州地区典型年气象资料,得出全年各月运行工况,确定热泵最佳开启时间为15:00。在此基础上,建立串、并联式数学模型进行供热性能计算,比较分析在各月工况下,两种方式系统为制备热水(55~60℃)时热泵运行性能和耗电量的变化关系。     

直膨式太阳能热泵集热/蒸发器性能优化及其低温适应性研究

对直膨式太阳能热泵系统的集热/蒸发器结构进行优化,设计由六边形与四边形单元组合的流道结构,并进行仿真与实验研究。在上海地区,冬季工况下,将水温从10℃加热到50℃,系统COP可达到4.5;夏季工况下,将水温从30℃加热到55℃,系统COP可达到6.60。在此基础上,针对严寒地区冬季运行,研究了与喷气增焓循环耦合的低温型直膨式太阳能热泵系统。在环境温度为-10℃时,系统COP可达到3.79;环境温度为-20℃时,系统COP可达到3.69。依据实验与仿真数据,运用全生命周期经济性分析方法,以当量热价(LCoH)为评价指标,为太阳能热泵采暖经济性分析提供计算方法和理论依据。     

EXPERIMENTAL RESEARCH ON TWO NATURAL WORKING FLUIDS OF MODERATELY HIGH TEMPERATURE HEAT PUMP

以筛选适合中高温热泵工况,环境性能优良的自然工质为目标,在理论循环分析基础上,采用指定工质侧参数的循环性能对比实验评价研究方法,在水-水蒸气压缩式热泵实验台上,对理论循环性能优良、样品可得的自然工质HC600(丁烷)、HC600a(异丁烷),在蒸发温度为30 ～ 50℃,冷凝温度为60 ～95℃范围进行实验研究.研究结果表明,两种自然工质中高温热泵循环性能优良,两者在较低温度工况循环性能差别不大,在较高温度工况HC600的循环性能优于HC600a,在蒸发温度为44℃,冷凝温度为90℃时,丁烷和异丁烷COP分别为3.84和3.33,但两种工质的可燃性应引起足够重视.     

天然气脱硫节能应用研究

为了节约天然气脱硫中MDEA再生过程能源的消耗,利用热泵节能的原理设计并制作了一台制冷功率为23 kW、蒸发温度为5℃、冷凝温度为85℃和系统最大压力为2 MPa的热泵实验装置,通过调节水系统和热泵系统工况使之与MDEA溶液的再生过程相似。并根据实验数据绘制了水系统温度、流量与热泵系统COP和PBP之间的关系,从理论上确定了系统运行最经济参数。最后将确定的系统运行最经济参数进行验证分析,得出在此参数范围内热泵经济运行的可行性。     

HFC245fa用于高温热泵系统的循环性能评价

以寻求冷凝温度为80～110℃的高温热泵工况范围内的适用工质为目的,对臭氧破坏势COP为零、温室效应势GWP较低的工质HFC245fa进行了循环性能理论和实验研究。结果表明,HFC245fa的理论循环性能优于传统工质CFC114;在实验工况范围内,HFC245fa系统的实际循环性能随运行工况温度的提高而提高。实验中,系统的热输出温度达到了102℃。     

基于水蒸气工质新型压缩-吸收式热泵循环性能分析

针对常规热泵在工业余热利用领域应用温度范围受限的技术难题,该文对一种压缩-吸收式耦合热泵系统在大温升工况下制取约130 ℃热水或蒸汽开展研究。首先介绍耦合热泵循环的运行原理,构建耦合热泵的完整热力学模型,通过EES软件最优化函数计算发现吸收侧压力越低,循环性能系数（COP）越好,同时在溶液热交换器出口浓溶液温度高于结晶温度10 ℃及溶液放汽范围为5.0%~5.5%的约束条件下,以某工业余热回收工况为设计工况,其中余热热水进/出口温度为90/75 ℃,余热水流量为30 kg/s,高温热水进/出口温度为100/125 ℃,吸收与发生侧最优压力值分别为40和2.2 kPa,对应耦合热泵的COP为9.8。同理分析了不同余热热水出口温度及高温热水出口温度变化工况下系统的循环性能,验证了该循环在高制热温度下仍具有较好的性能系数。     

基于有机朗肯循环的低温地热制冷系统热力学分析

为有效利用低温地热资源,本文以有机朗肯–蒸汽压缩制冷系统为研究对象,建立了系统的热力学模型,分析比较了分别以R290、R600、R600a、R601、R601a和R1270为工质时的系统性能,并以系统整体COP和每千瓦制冷量所对应的工质流量为关键指标对工质进行了优选。分析结果表明：当地热水温度为60 ~ 90℃,冷凝温度为30 ~ 55℃,蒸发温度为 –15 ~15℃时,R601是系统的最佳工质。当地热水温度为90℃,其余参数为典型工况值时,工质R601所对应的系统性能系数COP为0.49。     

R290直膨式太阳能热泵供暖系统实验研究

为分析直膨式太阳能热泵耦合地板辐射供暖系统在北方寒冷地区的实际运行特性,设计并搭建以丙烷(R290)为工质的直膨式太阳能热泵供暖实验平台,分析冬季不同运行工况下环境参数对系统热力性能的影响。实验结果表明：系统可实现室内供暖的稳定性,实验测试期间平均室温保持在16.1～20.8℃之间,热泵系统性能系数(COP)保持在2.57～4.30之间,供暖系统COP保持在2.24～3.98之间。太阳辐照度每增加50 W/m²,热泵系统COP提升4.9%;环境温度每升高1℃,热泵系统COP提升2.4%。太阳辐照度对热泵系统的电子膨胀阀开度和工质质量流量影响较为显著。当终止水温从45℃提升至55℃时,热泵系统COP降低12.2%;而在终止水温为50℃时,供暖系统COP达到最大值3.37。     

光伏直驱PV/T双源热泵热水系统性能研究

针对传统太阳能光伏光热PV/T双源热泵存在的热力性能差、能量损耗大等问题,提出一种光伏直驱PV/T双源热泵制热水系统(太阳能+空气源),并对系统进行实验研究。结果表明,在室外平均环境温度27.9℃、平均太阳辐射强度691.1 W/m²的夏天户外实验工况下,系统运行约4 h,将250 L 26.5℃的水加热到目标温度55℃,热泵平均COP为8.83。实验期间,PV/T光伏组件的平均温度比同样工况下的纯参比光伏组件温度降低9.8℃,光电性能相对提高17.53%。     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

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Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.