电动汽车热泵系统中易燃制冷剂R290的燃烧特性

研究了制冷剂R290在电动汽车热泵空调系统潜在泄漏过程中的燃烧特性,通过实验得到了不同泄漏温度和体积流量下R290的燃烧特性,并与制冷剂R134a进行对比。实验表明:R290在低温下更难点燃,而在高泄漏体积流量下和高泄漏温度下会发生喷射火焰的吹灭现象,且当泄漏温度在30~60℃之间时,泄漏体积流量的增大会提高其燃烧强度。R290制冷剂气体温度越高,其火焰燃烧强度越大,燃烧火焰越细,火焰心高度越低;R290制冷剂气体的体积流量越大,火焰燃烧区域越大,火焰高度越低,热辐射通量越大。     

超临界水中钾对甲醛降解过程影响的研究

为掌握生物质中钾对生物质超临界水降解过程的影响,选择生物质气化转化过程中生成的重要小分子中间产物甲醛作为研究对象,研究不同工艺条件下(反应温度400～650℃、压力23～29 MPa、停留时间4～12 s),单一钾成分(KHCO₃/K₂CO₃/KCl)或混合钾成分(KHCO₃、K₂CO₃、KCl)对甲醛超临界水降解气体产物的影响。结果表明,KHCO₃、K₂CO₃、KCl、混合钾均降低了气体产物中CO的体积分数,提高了CO₂的体积分数,但KCl的影响程度弱于其他三种钾成分。此外,由于不同钾成分均不利于气体产物中CO和H₂体积分数的提高,从而使得气体产物的热值降低。KHCO₃、K₂CO₃、KCl、混合钾均降低了H₂、CO、CO₂的产率以及气化率,其对H₂产率以及气化率的抑制程度从大到小依次为:混合钾、KHCO₃、K₂CO₃、KCl,且提高反应温度、延长反应停留时间时抑制气体生成的作用相对越明显。而当反应压力改变时,钾成分对H₂产率及气化率的影响程度变化较小。较高反应温度、较高反应压力、较长停留时间时,混合钾中各成分出现协同作用,明显抑制了气体产物的生成。     

R245fa和其他四种工质在高温热泵中的理论对比

把R245fa和R134a、R11、R1336mzz(Z)和R1233zd(E)四种工质的热物理性质对比,在相同的工况下理论分析了五种工质在中高温热泵中的COP、压缩机排气温度、单位容积制热量、压缩比等性能参数。结果表明,在高温热泵70～100℃的运行区间内,R245fa冷凝压力较低、制热COP高、排气温度相对较低等特性,具有良好的循环性能。R245fa拥有应用于更高冷凝温度工况下的潜质,为今后更为深入的研究提供借鉴。     

不同制备条件对TiO2/beads光催化活性的影响

以空心玻璃微球为载体,采用浸涂法制备TiO₂/beads光催化剂;利用X射线衍射、扫描电镜、热分析对TiO₂/beads进行了表征。研究了不同制备条件对TiO₂/beads光催化活性的影响。结果表明,热处理600℃,5h,A/R为81/19时,TiO₂/beads光催化活性最高;样品由非晶向锐钛矿型转变的温度为429℃,当锐钛矿型TiO₂与金红石型TiO₂以一定的比例共存时,TiO₂/beads的光催化活性较好.     

17R4/F127混合水溶液的凝胶结构

结合流变学频率扫描和同步辐射小角X射线散射(SAXS), 研究了17R4(PO₁₄-EO₂₄-PO₁₄)含量和温度对17R4/F127(EO₉₉-PO₆₅-EO₉₉)混合水溶液凝胶结构的影响. 结果表明, 溶胶、 软凝胶和硬凝胶分别对应无序结构、 无序与立方相共存结构以及立方相结构. 对于F127水溶液体系, 可以将F127形成的胶束看作硬球, 随着温度的升高, 胶束的硬球半径和胶束中F127链的聚集数随之减小, 这是因为17R4在较低温度下很难形成胶束, 当温度升高时, 17R4链参与胶束的形成, 从而使胶束数目增加, 因此每个胶束中的F127链数也随之减小. 当17R4含量较高时, 胶束外壳中F127部分的PEO链段数随着温度升高而减小, 胶束外壳变得更软, 因此, 当17R4/F127摩尔比为2: 1时, 混合溶液在高温下呈现面心立方(fcc)到体心立方(bcc)的结构转变.     

低阶煤半焦利用热重在O2/CO2、O2/N2和O2/Ar气氛下燃烧特性研究

利用热重研究了两种中国西北典型低阶煤半焦的燃烧特性。探究了不同气氛（O₂/CO₂、O₂/N₂和O₂/Ar）和不同氧气浓度对其燃烧特性的影响。实验结果表明,无论是反应气氛还是氧气浓度都会对低阶煤半焦的燃烧产生影响。相比于N₂和Ar,CO₂明显有利于燃烧反应进行：当反应气氛由O₂/CO₂变为O₂/Ar时,两种不同低阶煤半焦的燃尽温度分别升高了63.7和68.8℃;而当反应气氛由O₂/CO₂变为O₂/N₂时,两种不同低阶煤半焦的燃尽温度分别升高了135.9和129.6℃。在研究范围内,氧气浓度的提高也能明显提高半焦的燃烧性能。与此同时,半焦燃烧特性的动力学分析表明,随着氧气浓度提高,两种半焦燃烧反应的表观活化能E和指前因子A均呈增大趋势。通过对E和A两者关系的分析结果表明,半焦富氧燃烧的活化能和指前因子存在动力学补偿效应。     

四-对磺酸基-苯基卟啉铁(Ⅲ)的轴向配位快速反应动力学研究

用UnionGikenRA-410温度跃变紫外可见分光光度计研究了二聚的四-对磺酸基-苯基卟啉铁[Fe(Ⅲ)TPPS₄)_D]与咪唑(Im)、2-甲基咪唑(MeIm)、2-乙基-4-甲基咪唑(EMIm)轴向配位快速反应动力学。提出了反应机理,研究了轴向配体和温度对反应的影响,应用Gauss-Newton-Marquardt方法求得基元反应的速率常数及活化参数。     

十二烷基氯化吡啶合成工艺的热危险性研究

利用全自动反应量热仪(RC1mx)、差示扫描量热仪(DSC)和绝热加速量热仪(ARC)检测十二烷基氯化吡啶合成反应的反应热、最大反应温度及热稳定性，依据绝热温升(ΔT_ad)、最大反应速率到达时间为24 h的温度(T_D24)和失控体系可能达到的最高温度(MTSR)等温度参数对工艺危险性进行评估。结果显示，ΔT_ad为276.2 K,T_D24为290℃，MTSR为165.6℃。经过研究反应温度和吡啶滴加时间，确认了145℃是合理的反应温度。如果缩短吡啶滴加时间会导致物料累积，影响反应转化率，增加危险性。     

LaFe1-xNixO3甲烷燃烧催化剂的制备及其性能研究

采用共沉淀法制备单钙钛矿型催化剂LaFe_1-xNi_xO₃（x=0, 0.2, 0.4, 0.6, 0.8, 1.0）系列催化剂,其结构和性能经XRD、 BET、 H₂-TPR和TG-DSC。以催化甲烷燃烧为目标反应,考察不同Ni₂₊掺杂量对催化活性的影响。结果表明：不同掺杂量的Ni₂₊对该系列催化剂性能影响较大,催化活性均呈现先变大后变小的趋势,其中LaFe_0.6Ni_0.4O₃催化剂的比表面积为13.4 m₂·g^-1,催化活性最好,起燃温度T_10%为402 ℃,完全转化温度T_90%为542 ℃。     

POP-290阻燃剂对丙烯酸酯光固化涂料的影响

制备了双酚A环氧丙烯酸酯(EA)/阻燃剂(POP-290,聚合物聚醚多元醇)/活性单体阻燃UV涂料,主要考察了不同用量的阻燃剂对丙烯酸酯UV涂料的阻燃性能和光固化的影响.研究结果表明,阻燃剂的使用提高了UV涂料体系的固化速度、凝胶含量及玻璃化转变温度(T_g).当m(EA):m(活性单体)=4:1,POP-290含量为7%(质量分数)时,水平燃烧等级达到FH-1,LOI从原来的21提高到26.     

Thermodynamic analysis of a direct expansion solar-assisted heat pump system working with R290 as a drop-in substitute for R22

The thermodynamic analysis of direct expansion solar-assisted heat pump system working with R290 as a drop-in substitute for R22 was carried out under the metrological conditions of Calicut, India. A prototype of a DXSAHP system consists of a compressor, an air-cooled condenser with evaporator–collector and thermostatic expansion valve. The experiments were carried during the winter months of 2016. The artificial intelligence technique artificial neural network integrated with genetic algorithm model was presented to predict energy and exergy performance of a system. The energy performance ratio of a system was found to be 5.75% higher and reduced heating capacity of about 6.8% when compared to R22. Similarly, the second law analysis (exergy analysis) of a total system working with R290 was found to be better when compared to baseline refrigerant. The selected alternative working fluid is a hydrocarbon and has zero ozone depletion and negligible global warming potential. Hence, R290 can be used as a drop-in substitute for R22 in DXSAHP systems.

     

全无霜空气源热泵系统及吸附式除湿方法

总结了多种全无霜空气源热泵的系统原理和实现无霜化的吸附式除湿技术。介绍了液体吸附式和固体吸附式全无霜空气源热泵系统,并比较其优缺点,前者具有大量处理湿空气的优点,后者具有能效比高等优点。对吸附式除湿的吸附材料和吸附装置进行综述,介绍了能低温再生和吸附量较大的吸附材料。最后指出,吸附材料和除湿装置需要进一步研究从而提高除湿和再生效率,而系统需要进一步优化,以降低其初始成本和运行成本,从而提高市场应用潜力。     

Solar-Gas Solid Sorption Refrigerator

The general goal of this paper is to present the results of an investigation of a new environmentally friendly refrigerator. In this design a physical adsorption and chemical reactions are used simultaneously for a heat and cold generation. A solar refrigerator is made of a solar collector, adsorbed natural gas vessel (ANG), and compact, portable refrigeration system, which consists of two small adsorbers with heat pipe heat recovery system. An active carbon fiber Busofit saturated with different salts (CaCl₂, BaCl₂, NiCl₂) is used as a sorbent bed and ammonia is used as a working fluid. The main particularity of this refrigerator is consumption of solar energy with methane gas burner as a back-up. The system management consists only in actuating the special type valves to change the direction of the heating circuit and water valves to change the water cooling circuit. The goal of this work is the experimental determination of the main refrigerator parameters using solar/gas high temperature source of energy and air/water as a low temperature source of energy to cool and heat air/water.     

Performance analysis of an integrated cooling system consisted of earth-to-air heat exchanger (EAHE) and water spray channel

This study evaluates the cooling performance of a new hybrid system composing of an earth-to-air heat exchanger (EAHE) and a water spray channel to provide thermal comfort in Tehran, Iran. The inlet air temperature passing through the EAHE dissipates its heat to the surrounding soil and become slightly colder. To reach thermal comfort, the pre-cooled air flows upward through a channel spraying water downward and enters the living space. Considering the evaporative thermal comfort zone, the results showed that this system can meet comfort conditions for summer season Tehran. Moreover, according to the results, the cooling effectiveness of the proposed hybrid system is more than 100%, which means that the integrated system is capable of decreasing the air dry-bulb temperature below the inlet ambient wet-bulb temperature. Employing ground as a reliable source of alternative energy, the proposed cooling system can be considered an eco-friendly and energy-efficient system. Therefore, the introduced cooling system can be utilized as an alternative to conventional evaporative coolers or mechanical vapor compression systems while it can be considered an eco-friendly and energy-efficient system.

     

Vapor compression CuCl heat pump integrated with a thermochemical water splitting cycle

In this paper, the feasibility of using cuprous chloride (CuCl) as a working fluid in a new high temperature heat pump with vapor compression is analyzed. The heat pump is integrated with a copper–chlorine (Cu–Cl) thermochemical water splitting cycle for internal heat recovery, temperature upgrades and hydrogen production. The minimum temperature of heat supply necessary for driving the water splitting cycle can be lowered because the heat pump increases the working fluid temperature from 755 K up to ～950 K, at a high COP of ～6.5. Based on measured data available in past literature, the authors have determined the T–s diagram of CuCl, which is then used for the thermodynamic modeling of the cycle. In the heat pump cycle, molten CuCl is flashed in a vacuum where the vapor quality reaches ～2.5%, and then it is boiled to produce saturated vapor. The vapor is then compressed in stages (with inter-cooling and heat recovery), and condensed in a direct contact heat exchanger to transfer heat at a higher temperature. The heat pump is then integrated with a copper–chlorine water splitting plant. The heat pump evaporator is connected thermally with the hydrogen production reactor of the water splitting plant, which performs an exothermic reaction that generates heat at 760 K. Additional source heat is obtained from heat recovery from the hot reaction products of the oxy-decomposer. The heat pump transfers heat at ～950 K to the oxy-decomposer to drive its endothermic chemical reaction. It is shown that the heat required at the heat pump source can be obtained completely from internal heat recovery within the plant. First and second law analyses and a parametric study are performed for the proposed system to study the influence of the compressor's isentropic efficiency and temperature levels on the heat pump's COP. Two new indicators are presented: one represents the heat recovery ratio (the ratio between the thermal energy obtained by internal heat recovery, and the energy needed at the heat pump evaporator), and the other is the specific heat pump work per mole of hydrogen produced. This new heat pump with CuCl as a working fluid can be attractive in other industrial contexts where high temperature heat is needed. One may replace a common heating technology (combustion or electric heating) with the present sustainable method that uses heat recovery and high efficiency temperature upgrading for heating applications.     

Waste heat driven solid sorption coolers containing heat pipes for thermo control

This paper provides a focus on the R&D of solid sorption coolers and heat pumps made in the Luikov Heat & Mass Transfer Institute (CIS Countries Association Heat Pipes) under Thermacore, Inc. Agreement.Commercial and space applications of sorbent systems offer an attractive alternative to compression systems and liquid sorption systems for cooling, heating and air conditioning.MgA zeolites solid sorption systems are analyzed. Some new results are presented.Solid sorption heat pump technology utilizing heat pipe heat recovery with a condensing/evaporating refrigerant holds considerable promise for bivariant (space and domestic) applications due to the variable temperature and variable load capabilities of such machines.     

Porous glass electroosmotic pumps: design and experiments

An analytical model for electroosmotic flow rate, total pump current, and thermodynamic efficiency reported in a previous paper has been applied as a design guideline to fabricate porous-structure EO pumps. We have fabricated sintered-glass EO pumps that provide maximum flow rates and pressure capacities of 33 ml/min and 1.3 atm, respectively, at applied potential 100 V. These pumps are designed to be integrated with two-phase microchannel heat exchangers with load capacities of order 100 W and greater. Experiments were conducted with pumps of various geometries and using a relevant, practical range of working electrolyte ionic concentration. Characterization of the pumping performance are discussed in the terms of porosity, tortuosity, pore size, and the dependence of zeta potential on bulk ion density of the working solution. The effects of pressure and flow rate on pump current and thermodynamic efficiency are analyzed and compared to the model prediction. In particular, we explore the important tradeoff between increasing flow rate capacity and obtaining adequate thermodynamic efficiency. This research aims to demonstrate the performance of EOF pump systems and to investigate optimal and practical pump designs. We also present a gas recombination device that makes possible the implementation of this pumping technology into a closed-flow loop where electrolytic gases are converted into water and reclaimed by the system.     

Exergy analysis of a domestic refrigerator using eco-friendly R290/R600a refrigerant mixture as an alternative to R134a

The aim of the present work is to bring out an exergy analysis of the hydrocarbon refrigerant mixture of R290/R600a as an alternative to R134a on the performance of a domestic refrigerator which is originally designed to work with R134a. The performance of both refrigerants was evaluated using an exergy analysis. The effects of evaporator temperature on the coefficient of performance (COP), exergy loss, exergic efficiency, and efficiency defect in the four major components of the system for R134a and R290/R600a mixture were experimentally investigated. The results obtained showed that the COP of R290/R600a mixture was improved up to 28.5 % than that of R134a. The highest average exergic efficiency of the system (42.1 %) was obtained using R290/R600a mixture at an evaporator temperature of 263 K (?10 °C). The overall efficiency defect in the refrigeration cycle working with R290/R600a mixture was consistently better than R134a.     

热分析法研究超高分子量聚乙烯的热熔性质

本文采用差热分析(DTA)、差示扫描量热法(DSC)研究了一系列以高效催化聚合而得的初生态超高分子量(M_w=70-315×10⁴)聚乙烯粉的热熔行为,还研究了在接近熔化或部分熔化的温度下恒温热处理对晶体性质的影响.