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The purpose of this paper is to present the results of performance analysis of a heat driven continuous vapor adsorption refrigerator with activated carbon as the adsorbent and 1,1,1,2-tetrafluoroethane (HFC-134a) as the refrigerant. A set of four adsorption cells takes on the role of the mechanical compressor in the conventional vapor compression refrigeration (VCR) system. Three specimens of activated charcoal under various packing densities were investigated. A parametric analysis was carried out with several evaporating, condensing/adsorbing and desorbing temperatures which are typical operating conditions catered to by HFC-134a. A new integrated relative performance evaluation scheme is proposed. It uses the maximum cycle uptake difference as a factor against which the coefficient of performance (COP) and exergetic efficiency are evaluated. It is shown that there is an optimal set of operating conditions wherein the exergetic efficiency is the maximum. A major part of the thermal energy input is for sensible heating of the compressor body. 相似文献
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The available adsorption working pairs applied to adsorption refrigeration system, which utilize activated carbon as adsorbent, are mainly activated carbon-methanol, activated carbon-ammonia, and composite adsorbent-ammonia. The adsorption properties and refrigeration application of these three types of adsorption working pairs are investigated. For the physical adsorbents, consolidated activated carbon showed best heat transfer performance, and activated carbon-methanol showed the best adsorption property because of the large refrigerant amount that can be adsorbed. For the composite adsorbents, the consolidated composite adsorbent with mass ratio of 4:1 between CaCl2 and activated carbon, showed the highest cooling density when compared to the granular composite adsorbent and to the merely chemical adsorbent. The physical adsorption icemaker that employs consolidated activated carbon-methanol as working pair had the optimum coefficient of refrigeration performance (COP), volume cooling power density (SCPv) and specific cooling power per kilogram adsorbent (SCP) of 0.125, 9.25 kW/m3 and 32.6 W/kg, respectively. The composite adsorption system that employs the consolidated composite adsorbent had a maximum COP, SCPv and SCP of 0.35, 52.68 kW/m3 and 493.2 W/kg, respectively, for ice making mode. These results are improved by 1.8, 4.7 and 14 times, respectively, when compared to the results of the physical adsorption icemaker. 相似文献
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An activated carbon monolith (ACM) with a high helium adsorption/desorption capacity, high density, low pressure drop, low thermal expansion and good mechanical properties was prepared and applied successfully in a helium adsorption compressor as a part of a 4.5 K sorption cooler. The activated carbon (AC) used in the monolith preparation was selected from a series of ACs prepared from an anthracite and bituminous coals activated using KOH, NaOH and CO2, and having a variety of surface areas, micropore size distributions and packing densities. The selected AC was combined with a binder to prepare an ACM with suitable mechanical properties for machining. The results of this study, related to an helium sorption compressor includes: packing density, mechanical properties (compression strength, vibration tests), thermal expansion, pressure-drop measurements and also helium adsorption isotherms measured at high pressure (up to 35 bar) and low temperatures (from 20 K up to 150 K). 相似文献
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针对以硅胶-水为工质对的太阳能吸附式制冷系统,实验研究了不同粒径的硅胶材料对吸附床传热传质特性及系统制冷能力的影响。三组对比实验的硅胶材料平均粒径分别为1mm、3mm和5mm,在太阳辐射接近的条件下完成实验测试,结果表明粒径中等的硅胶材料表现最优,其制冷系数COP和按照循环周期定义的比制冷功率SCP2均最高。小粒径材料虽然使吸附剂填充量有所增加,但是会导致吸附床轴向传质阻力增加,影响其末端吸附能力的发挥。而材料的粒径过大,则会降低吸附床的吸附剂填充量及其传热性能,从而导致预热脱附和冷却过程的时间延长,不利于系统的制冷性能改善。实验结果表明,吸附剂粒径是影响太阳能吸附式制冷系统工作性能的一个重要因素,在系统设计中需要给予重视。 相似文献
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Zhipeng Qie Lijie Wang Fei Sun Huan Xiang Hua Wang Jihui Gao Guangbo Zhao Xiaolei Fan 《Frontiers of Chemical Science and Engineering》2022,16(9):1345
A simple method was developed to tune the porosity of coal-derived activated carbons, which provided a model adsorbent system to investigate the volumetric CO2 adsorption performance. Specifically, the method involved the variation of the activation temperature in a K2CO3 induced chemical activation process which could yield activated carbons with defined microporous (< 2 nm, including ultra-microporous < 1 nm) and meso-micro-porous structures. CO2 adsorption isotherms revealed that the microporous activated carbon has the highest measured CO2 adsorption capacity (6.0 mmol∙g–1 at 0 °C and 4.1 mmol∙g–1 at 25 °C), whilst ultra-microporous activated carbon with a high packing density exhibited the highest normalized capacity with respect to packing volume (1.8 mmol∙cm−3 at 0 °C and 1.3 mmol∙cm–3 at 25 °C), which is significant. Both experimental correlation analysis and molecular dynamics simulation demonstrated that (i) volumetric CO2 adsorption capacity is directly proportional to the ultra-micropore volume, and (ii) an increase in micropore sizes is beneficial to improve the volumetric capacity, but may lead a low CO2 adsorption density and thus low pore space utilization efficiency. The adsorption experiments on the activated carbons established the criterion for designing CO2 adsorbents with high volumetric adsorption capacity. 相似文献
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Adsorption characteristics of cationic dyes and surfactants onto clay and sandstone from a single component system were studied using toluidine blue (TB) and cetyl trimethylammonium bromide (CTAB). Equilibrium data of TB and CTAB in the single solute systems fit well to the Langmuir and the Freundlich adsorption isotherms. Competitive adsorption was observed between dye and surfactant cations. The effect of sodium chloride on dye and surfactant adsorption was studied in TB–NaCl and CTAB–NaCl binary systems. Equilibrium adsorption for binary systems was analyzed by using the extended Langmuir and the extended Freundlich models. Adsorption results for the TB–CTAB system onto both adsorbents were also well described by the Sheindorf–Rebuhn–Sheintuch (SRS) model for multi-component systems. Free energy changes for adsorption systems were calculated using thermodynamic equilibrium constants evaluated from selectivity coefficients of the binary systems. The site distribution functions estimated using Freundlich model parameters gave valuable information about the ratio of the adsorption sites on adsorbent surface having different affinity for competing cations. 相似文献
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Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can af-fect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters. 相似文献
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配制溶质为Al2O3纳米粒子、黄原胶为分散剂,经超声波振荡后分散均匀稳定的Al2O3-H2O纳米流体。利用真空动态喷射制冰实验装置,设定初始压力300 Pa,研究在有无固体吸附作用、不同纳米流体浓度、不同纳米颗粒粒径和不同供液流量下的真空闪蒸制冰特性。结果表明,吸附作用对真空制冰系统稳压效果显著且有助于捕捉实验中的水蒸气;当冷却介质温度低于吸附剂初始温度时,吸附剂有更好的吸附能力但冷却温度不宜过低;纳米流体浓度越大、纳米粒子粒径越小,更利于制取高含冰率的冰浆;对于同一浓度的纳米流体,合理控制供液流量可以获得不同含冰率的冰浆;在2%(质量)NaCl下,各粒径的纳米流体浓度不宜超过0.05%(质量)。 相似文献
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采用化学聚合法强化吸附剂——沸石颗粒的热传导性能,利用苯胺单体在沸石颗粒表面氧化聚合,使少量的聚苯胺形成均匀连续的导热性能好的高分子材料网,在实验条件下可使该种吸附剂的有效导热系数提高到原来的4倍多。同时,将强化后的吸附剂挤压成型,进行强化吸附床层的传热研究,结果表明堆积密度为原来的1.5倍的成型块,其有效导热系数比原来提高30%,对比混合法的实验和数据分析表明,化学聚合法较物理混合法效果更明显,是一种适宜吸附剂热传导强化的新途径。 相似文献
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To improve the performance of the adsorption refrigeration of CaCl2-ammonia adsorption system, activated carbon has been distributed uniformly in the mass of CaCl2, thereby helping to enhance mass transfer and uplift the cooling power density. A multifunctional heat pipe adsorption refrigerator, in which activated carbon-CaCl2 is used as compound adsorbent and ammonia as refrigerant, is designed. Water and acetone are used as working liquids for the heat pipe. This paper presents a study on the adsorption refrigeration performances of this adsorption refrigerator under two different working conditions, ice-maker for fishing boat driven by the waste heat from exhaust gases, and solar ice-maker driven by solar water heating. The obtained average SCP (specific cooling power) and the COP (coefficient of performance) of the refrigerator were measured to be 770.4 W/kg and 0.39 at about −20 °C of evaporating temperature for the former working condition, and they were 161.2 W/kg and 0.12 at about −15 °C of evaporating temperature for the later working condition. 相似文献
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对以SrCl2、活性炭为吸附剂,NH3为制冷剂所组成的吸附式制冷工质对的吸附性能进行了研究。拟解决SrCl2吸附剂颗粒强度不高、长期使用后易出现膨胀粉化、吸附床传热传质性能下降等问题,将SrCl2分别与活性炭、CaSO4按质量比4∶1复配,进行吸附制冷性能实验。并对SrCl2的吸附机理及CaSO4的胶凝作用进行了探讨。实验结果表明:温度是过程的控制因素,在100℃时,SrCl2/活性炭、SrCl2/CaSO4复合吸附剂的单位脱胶凝剂基吸附剂制冷量分别是SrCl2的2.1倍和1.4倍。对吸附剂比表面积及孔结构进行表征,结果显示:SrCl2/CaSO4复合吸附剂的比表面积和孔结构保持良好;SrCl2/活性炭复合吸附剂的比表面积和孔容明显增大,孔结构得到了改善。 相似文献
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A new metal-organic framework of MIL-101 was synthesized by hydrothermal method and the powder prepared was pressed into a desired shape. The effects of molding on specific surface area and pore structure were investigated using a nitrogen adsorption method. The water adsorption isotherms were obtained by high vacuum gravimetric method, the desorption temperature of water on shaped MIL-101 was measured by thermo gravimetric analyzer, and the adsorption refrigeration performance of shaped MIL-101-water working pair was studied on the simulation device of adsorption refrigeration cycle system. The results indicate that an apparent hysteresis loop ap-pears in the nitrogen adsorption/desorption isotherms when the forming pressure is 10 MPa. The equilibrium ad-sorption capacity of water is up to 0.95 kg·kg^-1 at the forming pressure of 3 MPa (MIL-101-3). The desorption peak temperature of water on MIL-101-3 is 82℃, which is 7 ℃ lower than that of silica gel, and the desorption temperature is no more than 100 ℃. At the evaporation temperature of 10 ℃, the refrigeration capacity of MIL-101-3-water is 1059 kJ·kg^-1, which is 2.24 times higher than that of silica gel-water working pair. Thus MIL-101-water working pair presents an excellent adsorption refrigeration performance. 相似文献
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Alexander M. Puziy Olga I. Poddubnaya James A. Ritter Armin D. Ebner Charles E. Holland 《Carbon》2001,39(15)
A two-stage analysis of the mechanism of metal ion binding by a heterogeneous adsorbent was developed. In the first stage, a continuous proton affinity distribution was calculated from potentiometric titration data using the CONTIN method with a Langmuir kernel. Electrostatic effects were accounted for using a diffuse layer model. In the second stage, the parameters obtained from the continuous distribution function (i.e. the number of different types of surface sites, site densities and their protonation constants) were utilized in a discrete distribution to represent the adsorbent in surface complexation and double layer models using the GRFIT speciation code. This information on the surface groups was applied to metal ion potentiometric titration experiments to calculate the surface complexation equilibrium constants of the metal ions and hence elucidate the mechanism of ion binding to these sites. The proposed method was applied successfully to the adsorption of Sr and Cu ions on carbon-composite adsorbents, KAU-mod and SCN-mod. The continuous distribution method (CONTIN) revealed three types of surface sites within these carbon-composite adsorbents with pK values ranging between 3.5–4.1, 5.3–6.3 and 7.7–8.2. The analysis of the metal ion adsorption data using the GRFIT speciation code showed that only the first two surface sites were capable of forming surface complexes with the Sr ions, and that only the first site governed the adsorption of the Cu ions. 相似文献
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A. V. Galakhov E. V. Tsibailo G. A. Fomina B. S. Mitin 《Refractories and Industrial Ceramics》1995,36(4):116-120
Results of computer simulation of the packing of particles in compacts from agglomerated powders are presented. The effect of the characteristics of agglomerated powders, such as the number of particles in the agglomerates, the size distribution of agglomerates, and the volume share of the fine fraction (individual particles) on the factors that determine the sinterability of compacts, i.e., the density, the mean number of contacts per particle, and the mean size and the mean coordination number of the pores, is investigated. It is established that compared to compacts from individual particles the presence of agglomerates sharply worsens the packing characteristics. The worst effect is due to agglomerates containing less that 30 – 40 particles. The packing characteristics can be improved by using powders with a wide size distribution of agglomerates or by adding unagglomerated particles. It is interesting that computer models of powder compacts can be used for predicting the strength properties of the materials sintered from these powders. Data on the influence of the packing characteristics on the mean strength and the Weibull modulus are presented.Translated from Ogneupory, No. 4, pp. 14–17, April, 1995. 相似文献