一种有潜力的吸附式制冷工作对——活性炭纤维—甲醇

吸附式制冷具有无ＣＦＣｓ问题、可利用低品位热能驱动、价格效用比高等一系列优点。由于一般吸附剂吸附／解吸时间长和单位质量制冷功率小使吸附式制冷的产品化受阻。活性炭纤维是一般吸附剂活性炭的较好替代物，其对甲醇的吸附容量为活性炭的２－３倍，而吸附／解吸时间仅为活性炭的１／１０左右。对紧凑式吸附式冰箱，活性炭纤维－甲醇是一种好的工作对。     

氯化锶-氨吸附制冷性能的实验研究

建立了化学吸附式制冷实验单元，对氯化锶－氨工质对的制冷性能进行实验研究，得出不同热源温度下的制冷量，吸附速率、解吸速率等数据，并与活性炭－甲醇工质对进行了比较。     

活性炭－乙醇吸附式制冷系统的实验研究

采用液体置换法再活化活性炭，成功地实现了制冷循环。同时进行了以乙醇取代甲醇的可行性研究。实验表明，乙醇的最大吸附量与循环特性均与甲醇十分接近，这一发现推翻了以往活性炭－乙醇不适于吸附式制冷的观点。     

连续稳定循环的三效吸附式热泵在两种工况下的COP值计算

设计了连续而又稳定循环的三效吸附式热泵单元－三效冷环，由于各吸附床的吸附循环之间具有先后连贯性，因此既避免了吸附床的过热，又消除了热泵输出端的不稳定工作状态，使得热泵系统ＣＯＰ值，Ｙｏｎｇ效率以及各吸附循环的效率比双效和单效系统有显著提高，重点分析了回收和不回收降温，吸附热时三效吸附式热泵比之与其它系统所存在的优越性。     

固体吸附式制冷的关键技术研究

描述吸附容量的Ｄ－Ａ方程、吸附床内的传热传质、新型热力循环的潜力与可行性、吸附系统的技术经济性和优化控制、实际吸附循环理论以及双效／多效吸附式制冷等是吸附式制冷尚需进行研究的基础课题。本文对固体吸附式制冷机的关键技术进行了探讨。     

连续稳定循的三效吸附式热泵单元——三效冷环的设计和原理分析

设计了连续而又稳定循环的三效吸附式热泵单元－－三效冷环，使各吸附床的吸附循环之间具有先后连贯性，既可避免吸附床的过热，又能消除热泵输出端的不稳定工作状态，使得热泵系统的ＣＯＰ值、ｙｏｎｇ效率以及各级附循环的效率均有显著提高。此外，单元化使三效冷环易于长期维持真空度，便于根据余热量的大小进行并联组合成较大的热泵系统。     

连续稳定循环的三效吸附式热泵单元──三效冷环的设计和原理分析

设计了连续而又稳定循环的三效吸附式热泵单元─－三效冷环，使各吸附床的吸附循环之间具有先后连贯性，既可避免吸附床的过热，又能消除热泵输出端的不稳定工作状态，使得热泵系统的ＣＯＰ值、效率以及各吸附循环的效率均有显著提高。此外，单元化使三效冷环易于长期维持真空度，便于根据余热量的大小进行并联组合成较大的热泵系统。     

基本循环吸附式制冷的计算机模拟

在以甲醇-活性炭为工质的基本型吸附式制冷循环中的热量分析中,采用数学软件Matlab模拟计算和理论分析,得出了循环工况对制冷性能和制冷量的影响。     

连续稳定循环的三效吸附式热泵在两种工况下的COP值针算

设计了连续而又稳定循环的三效吸附式热泵单元——三效冷环，由于各吸附床的吸附循环之间具有先后连贯性，因此既避免了吸附床的过热，又消除了热泵输出端的不稳定工作状态，使得热泵系统的ＣＯＰ值、■效率以及各吸附循环的效率比双效和单效系统有显著提高。重点分析了回收和不回收降温、吸附热时三效吸附式热泵比之与其它系统所存在的优越性。     

吸附式制冷机及空调/热泵的运行实验和性能改进

研制了一台采用螺旋板式吸附器的连续回热型吸附式制冷机和一台采用板翅式吸附器的空调／热泵,给出了实验数据。吸附式制冷系统采用活性炭－甲醇吸附工质对,以９０－１００℃絷不作为热源,实验得到单位质量活性炭的制冷能量密度为：制冰机每ｋｇ吸附剂日制冰２．６ｋｇ,空调／热泵组在空调工况下每ｋｇ吸附剂制冷功率为１５０Ｗ。     

碳质吸附剂吸附储氢的研究现状

论述了活性炭、碳纳米纤维、碳纳米管吸附储氢的研究历程，从实验、理论研究两个方面总结了前人的研究成果：活性炭在低温下有好的吸附储氢特性，但在室温条件下的结果却不令人满意；碳纳米管和碳纳米纤维的实验结果令人振奋，但众多的实验结果并不一致；碳纳米材料的制备技术和净化技术还仅处在实验规模的阶段；蒙特卡罗、密度泛函等方法是常用的计算机模拟技术，但目前它们只是考虑了理想的物理模型，没有考虑碳纳米管表面的一些不规则现象；碳质吸附剂吸附储氢从理论到应用还有一段距离。     

The pyrolysis process of biomass by two-stage chemical activation with different methodology and iodine adsorption

Current concerns with the high energy/cost nature of activated carbon production have encouraged research into alternative activated carbon production methods to reduce the environmental impact. The purpose of this study is to produce the activated carbon from biomass (carob bean seed husk, CBSH) by chemical activation with a different methodology using zinc chloride. Two different activation temperature methodologies for the preparation of activated carbons were applied at the ranges of 30–80 and 200–350°C. The effects of the pre-activation and activation temperatures, duration time, and the impregnation ratio on the surface and chemical properties of activated carbon were investigated. Studies were conducted on the adsorption of iodine from the prepared activated carbon. The highest iodine adsorption number was achieved as 874 mg/g. Langmuir surface area was 1544 m²/g. The structural morphology of activated carbons was evaluated with a scanning electron microscope. The surface chemical characteristics of activated carbons were determined by the Fourier transform infrared (FTIR) spectroscopic method.     

High-Pressure Adsorption Isotherms of Carbon Dioxide and Methane on Activated Carbon From Low-Grade Coal of Indonesia

ABSTRACT

Adsorption isotherms data of methane and carbon dioxide gases on the activated carbons were measured experimentally using a volumetric method with pressure and temperatures ranging from 0 to 3.5 MPa and 27 to 65°C, respectively. Two types of activated carbons, namely, (1) Kalimantan Timur type activated carbon, which is lab-produced from Indonesian low-grade coal and (2) a commercial (Carbotech) activated carbon were used. The adsorption isotherms obtained were found to belong to type 1 of the International Union of Pure and Applied Chemistry classification. The adsorption uptakes for both carbon dioxide and methane on commercial activated carbon are higher than for the Kalimantan Timur activated carbon. This is due to higher Brunauer–Emmet–Teller surface area and pore volume of the former. Langmuir and Tóth isotherm models are correlated to predict the experimental data with acceptable accuracy.     

Method for the control of NOx emissions in long-range space travel

The wheat straw, an inedible biomass that can be continuously produced in a space vehicle has been used to produce activated carbon for effective control of NOx emissions from the incineration of wastes. The optimal carbonization temperature of wheat straw was found to be around 600 degrees C when a burnoff of 67% was observed. The BET surface area of the activated carbon produced from the wheat straw reached as high as 300 m2/g. The presence of oxygen in flue gas is essential for effective adsorption of NO by activated carbon. On the contrary, water vapor inhibits the adsorption efficiency of NO. Consequently, water vapor in flue gas should be removed by drying agents before adsorption to ensure high NO adsorption efficiency. All of the NO in the flue gas was removed for more than 2 h by the activated carbons when 10% oxygen was present and the ratio of carbon weight to the flue gas flow rate (W/F) was 30 g min/L, with a contact time of 10.2 s. All of NO was reduced to N2 by the activated carbon at 450 degrees C with a W/F ratio of 15 g min/L and a contact time of 5.1 s. Reduction of the adsorbed NO also regenerated the activated carbon, and the regenerated activated carbon exhibited an improved NO adsorption efficiency. However, the reduction of the adsorbed NO resulted in a loss of carbon which was determined to be about 0.99% of the activated carbon per cycle of regeneration. The sufficiency of the amount of wheat straw in providing the activated carbon based on a six-person crew, such as the mission planned for Mars, has been determined. This novel approach for the control of NOx emissions is sustainable in a closed system such as the case in space travel. It is simple to operate and is functional under microgravity environment.     

活性炭吸附储存H2的研究

通过几种储氢方式的对比,论证了以活性炭作为吸附剂储存H_2的可行性;着重阐述了影响H_2吸附储存的因素,即活性炭的比表面积、活性炭的微孔容积和活性炭表面含氧官能团对H_2吸附储存量的重要影响。综述了活性炭吸附储存H_2的研究,同时概括了H_2吸附储存的理论研究并展望今后发展及研究的方向。     

Methane catalytic decomposition over ordered mesoporous carbons: A promising route for hydrogen production

Methane decomposition offers an interesting route for the CO₂-free hydrogen production. The use of carbon catalysts, in addition to lowering the reaction temperature, presents a number of advantages, such as low cost, possibility of operating under autocatalytic conditions and feasibility of using the produced carbons in non-energy applications. In this work, a novel class of carbonaceous materials, having an ordered mesoporous structure (CMK-3 and CMK-5), has been checked as catalysts for methane decomposition, the results obtained being compared to those corresponding to a carbon black sample (CB-bp) and two activated carbons, presenting micro- (AC-mic) and mesoporosity (AC-mes), respectively. Ordered mesoporous carbons, and especially CMK-5, possess a remarkable activity and stability for the hydrogen production through that reaction. Under both temperature programmed and isothermal experiments, CMK-5 has shown to be a superior catalyst for methane decomposition than the AC-mic and CB-bp materials. Likewise, the catalytic activity of CMK-5 is superior to that of AC-mes in spite of the presence of mesoporosity and a high surface area in the latter. The remarkable stability of the CMK-5 catalyst is demonstrated by the high amount of carbon deposits that can be formed on this sample. This result has been assigned to the growth of the carbon deposits from methane decomposition towards the outer part of the catalyst particles, avoiding the blockage of the uniform mesopores present in CMK-5. Thus, up to 25 g of carbon deposits have been formed per gram of CMK-5, while the latter still retains a significant catalytic activity.     

Copper-doped activated carbon from amorphous cellulose for hydrogen,methane and carbon dioxide storage

The transition away from fossil fuel and ultimately to a carbon-neutral energy sector requires new storage materials for hydrogen and methane as well as new solutions for carbon capture and storage. Among the investigated adsorbents, activated carbons are considered especially promising because they have a high specific surface area, are lightweight, thermally and chemically stable, and easy to produce. Moreover, their porosity can be tuned and they can be produced from inexpensive and environmentally friendly raw materials. This study reports on the development and characterization of activated carbons synthesized starting from amorphous cellulose with and without the inclusion of copper nanoparticles. The aim was to investigate how the presence of different concentrations of metal nanoparticles affects porosity and gas storage properties. Therefore, the research work focused on synthesis and characterization of physical and chemical properties of pristine and metal-doped activated carbons materials and on further investigation to analyze their hydrogen, methane and carbon dioxide adsorption capacity. For an optimized Cu content the microporosity is improved, resulting in a specific surface area increase of 25%, which leads to a H₂ uptake (at 77 K) higher than the theoretical value predicted by the Chahine Rule. For CH₄, the storage capacity is improved by the addition of Cu but less importantly because the size of the molecule hampers easy access of the smaller pores. For CO₂ a 26% increase in adsorption capacity compared to pure activated carbon was achieved, which translated with an absolute value of over 48 wt% at 298 K and 15 bar of pressure.     

Modification of single wall carbon nanotubes (SWNT) for hydrogen storage

Due to unique structural, mechanical and electrical properties of single wall carbon nanotubes, SWNTs, they have been proposed as promising hydrogen storage materials especially in automotive industries. This research deals with investing of CNT’s and some activated carbons hydrogen storage capacity. The CNT’s were prepared through natural gas decomposition at a temperature of 900?C over cobalt-molybdenum nanoparticles supported by nanoporous magnesium oxide (Co–Mo/MgO) during a chemical vapor deposition (CVD) process. The effects of purity of CNT (80–95%wt.) on hydrogen storage were investigated here. The results showed an improvement in the hydrogen adsorption capacity with increasing the purity of CNT’s. Maximum adsorption capacity was 0.8%wt. in case of CNT’s with 95% purity and it may be raised up with some purification to 1%wt. which was far less than the target specified by DOE (6.5%wt.). Also some activated carbons were manufactured and the results compared to CNTs. There were no considerable H₂-storage for carbon nanotubes and activated carbons at room-temperature due to insufficient binding between H₂ molecules carbon nanostructures. Therefore, hydrogen must be adsorbed via interaction of atomic hydrogen with the storage environment in order to achieve DOE target, because the H atoms have a very stronger interaction with carbon nanostructures.     

Environmentally benign working pairs for adsorption refrigeration

This paper begins from adsorption working pairs: water and ethanol were selected as refrigerants; 13x molecular sieve, silica gel, activated carbon, adsorbent NA and NB, proposed by authors, were selected as adsorbents, and the performance of adsorption working pairs in adsorption refrigeration cycle was studied. The adsorption isotherms of adsorbents (NA and NB) were obtained by high-vacuum gravimetric method. Desorption properties of adsorbents were analyzed and compared by thermal analysis method. The performance of adsorption refrigeration was studied on simulation device of adsorption refrigeration cycle. After presentation of adsorption isotherms, the thermodynamic performance for their use in adsorption refrigeration system was calculated. The results show: (1) the maximum adsorption capacity of water on adsorbent NA reaches 0.7 kg/kg, and the maximum adsorption capacity of ethanol on adsorbent NB is 0.68 kg/kg, which is three times that of ethanol on activated carbon, (2) the refrigeration capacity of NA–water working pair is 922 kJ/kg, the refrigeration capacity of NB–ethanol is 2.4 times that of activated carbon–methanol, (3) as environmental friendly and no public hazard adsorption working pair, NA–H₂O and NB–ethanol can substitute activated carbon–methanol in adsorption refrigeration system using low-grade heat source.     

The comparison of two activation techniques to prepare activated carbon from corn cob

We report on the preparation of biomass-based activated carbons by the steam physical activation and KOH chemical activation methods. In addition, we also investigate their adsorption performance. By adjusting the reaction parameters, different carbon materials are prepared from corn residues and characterized using instrumental analyses such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Brunauer–Emmett–Teller (BET). It is found that the synthesized activated carbons exhibit high surface area (1600 m² g⁻¹) and large pore volume (2.01 cm³ g⁻¹). Furthermore, the high methylene blue and iodine adsorption value and a considerable CO₂ uptake (exceeding 1.5 mmol g⁻¹) are attained with the activated carbons, showing their potential usage for the CO₂ adsorbent.