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Performance analysis of cogeneration systems based on micro gas turbine (MGT), organic Rankine cycleand ejector refrigeration cycle

Zemin BO, Kai ZHANG, Peijie SUN, Xiaojing LV, Yiwu WENG

《能源前沿（英文）》 2019年第13卷第1期页码 54-63 doi: 10.1007/s11708-018-0606-7

摘要： In this paper, the operation performance of three novel kinds of cogeneration systems under design and off-design condition was investigated. The systems are MGT (micro gas turbine) + ORC (organic Rankine cycle) for electricity demand, MGT+ ERC (ejector refrigeration cycle) for electricity and cooling demand, and MGT+ ORC+ ERC for electricity and cooling demand. The effect of 5 different working fluids on cogeneration systems was studied. The results show that under the design condition, when using R600 in the bottoming cycle, the MGT+ ORC system has the lowest total output of 117.1 kW with a thermal efficiency of 0.334, and the MGT+ ERC system has the largest total output of 142.6 kW with a thermal efficiency of 0.408. For the MGT+ ORC+ ERC system, the total output is between the other two systems, which is 129.3 kW with a thermal efficiency of 0.370. For the effect of different working fluids, R123 is the most suitable working fluid for MGT+ ORC with the maximum electricity output power and R600 is the most suitable working fluid for MGT+ ERC with the maximum cooling capacity, while both R600 and R123 can make MGT+ ORC+ ERC achieve a good comprehensive performance of refrigeration and electricity. The thermal efficiency of three cogeneration systems can be effectively improved under off-design condition because the bottoming cycle can compensate for the power decrease of MGT. The results obtained in this paper can provide a reference for the design and operation of the cogeneration system for distributed energy systems (DES).

关键词： cogeneration system different working fluids micro gas turbine (MGT) organic Rankine cycle (ORC) ejector refrigeration cycle (ERC)

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Refrigeration cycle for cryogenic separation of hydrogen from coke oven gas

CHANG Kun, LI Qiang

《能源前沿（英文）》 2008年第2卷第4期页码 484-488 doi: 10.1007/s11708-008-0096-0

摘要： Ten billion cubic meters of hydrogen are dissipated to the environment along with the emission of coke-oven gas every year in China. A novel cryogenic separation of hydrogen from coke oven gas is proposed to separate the hydrogen and liquefy it simultaneously, and the cooling capacity is supplied by two refrigeration cycles. The performance of the ideal vapor refrigeration cycle is analyzed with methane and nitrogen as refrigerant respectively. The results show that the coefficient of performance (COP) of methane refrigeration cycle is 2.7 times that of nitrogen refrigeration cycle, and the figure of merit (FOM) of methane refrigeration cycle is 1.6 times that of nitrogen refrigeration cycle. The performance of ideal gas refrigeration cycle is also analyzed with neon, hydrogen and helium as refrigerant respectively. The results show that both the coefficient of performance and figure of merit of neon refrigeration cycle is the highest. It is thermodynamically possible to arrange the refrigeration cycle with methane and neon as refrigerant, respectively.

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of 1,3-dimethylimidazolylium dimethylphosphate-water binary mixture for a single effect absorption refrigeration

Gorakshnath TAKALKAR, Ahmad K. SLEITI

《能源前沿（英文）》 2022年第16卷第3期页码 521-535 doi: 10.1007/s11708-021-0720-9

摘要： The energy and exergy analyses of the absorption refrigeration system (ARS) using H O-[mmim][DMP] mixture were investigated for a wide range of temperature. The equilibrium Dühring ( - - ) and enthalpy ( - - ) of mixture were assessed using the excess Gibbs free non-random two liquid (NRTL) model for a temperature range of 20°C to 140°C and from 0.1 to 0.9. The performance validation of the ARS cycle showed a better coefficient of performance (COP) of 0.834 for H O-[mmim][DMP] in comparison to NH -H O, H O-LiBr, H O-[emim][DMP], and H O-[emim][BF4]. Further, ARS performances with various operating temperatures of the absorber ( ), condenser ( ), generator ( ), and evaporator ( ) were simulated and optimized for a maximum COP and exergetic COP (ECOP). The effects of from 50°C to 150°C and and from 30°C to 50°C on COP and ECOP, the , , and circulation ratio (CR) of the ARS were evaluated and optimized for from 5°C to 15°C. The optimization revealed that needed to achieve a maximum COP which was more than that for a maximum ECOP. Therefore, this investigation provides criteria to select low grade heat source temperature. Most of the series flow of the cases of cooling water from the condenser to the absorber was found to be better than the absorber to the condenser.

关键词： ionic liquid driven absorption cycle H₂O-[mmim][DMP] coefficient of performance (COP) exergy analysis thermodynamics mixture property

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Polymeric nanocomposites for electrocaloric refrigeration

《能源前沿（英文）》 2023年第17卷第4期页码 450-462 doi: 10.1007/s11708-022-0858-0

摘要： Electrocaloric refrigeration represents an alternative solid-state cooling technology that has the potential to reach the ultimate goal of achieving zero-global-warming potential, highly efficient refrigeration, and heat pumps. To date, both polymeric and inorganic oxides have demonstrated giant electrocaloric effect as well as respective cooling devices. Although both polymeric and inorganic oxides have been identified as promising cooling methods that are distinguishable from the traditional ones, they still pose many challenges to more practical applications. From an electrocaloric material point of view, electrocaloric nanocomposites may provide a solution to combine the beneficial effects of both organic and inorganic electrocaloric materials. This article reviews the recent advancements in polymer-based electrocaloric composites and the state-of-the-art cooling devices operating these nanocomposites. From a device point of view, it discusses the existing challenges and potential opportunities of electrocaloric nanocomposites.

关键词： nanocomposites electrocaloric refrigeration polymer

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New refrigeration system using CO vapor-solid as refrigerant

HUANG Dongping, DING Guoliang, QUACK Hans

《能源前沿（英文）》 2008年第2卷第4期页码 494-498 doi: 10.1007/s11708-008-0070-x

摘要： A refrigerant must be in the vapor-liquid phase in a vapor-compression refrigeration system, therefore, CO cannot be used as a refrigerant for temperatures lower than -56°C because solid CO will form under the triple point temperature of -56°C. A refrigeration system with CO vapor-solid particles as refrigerant is put forward, by which a temperature lower than the triple point is achieved. An adjustable nozzle, a sublimator, a high-pressure regulating valve and a low-pressure regulating valve are used to replace the conventional evaporator. Theoretical cycle analysis of the refrigeration system shows that its COP can be 50% higher than that of the conventional one.

关键词： refrigerant adjustable temperature vapor-compression refrigeration sublimator

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Available energy analysis of new tandem double-capillary tube refrigeration system for refrigerator-freezers

HE Maogang, ZHANG Ying, SONG Xinzhou, ZHANG Jiantao

《能源前沿（英文）》 2008年第2卷第1期页码 36-42 doi: 10.1007/s11708-008-0013-6

摘要： A new tandem double-capillary tube refrigeration system for refrigerator-freezers is proposed. A capillary tube was added between the two evaporators in the fresh and frozen food storage chests to raise the evaporation temperature of the refrigerating chamber, and reduce the heat exchange temperature difference and the available energy loss. Peng-Robinson (P-R) equation of state was adopted to calculate the thermodynamic properties of the refrigerants, and the available energy analysis of the vapor compression refrigeration cycle was programmed to calculate the thermodynamic performances of the new and the conventional refrigeration cycle of the refrigerator-freezer. The calculation results show that the available energy efficiency of the conventional refrigeration cycle of the refrigerator-freezer is 21.20% and 20.57%, respectively when the refrigerant is R12 and R134a, while that of the double-capillary tube refrigeration cycle of the refrigerator-freezer is 23.97% and 23.44%, respectively. By comparison, the available energy efficiency of the new refrigeration system increases by 13.07% and 13.95%, respectively.

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Performance analysis of solar absorption-subcooled compression hybrid refrigeration system in subtropical

Xiangyang YE,Liming LIU,Zeyu LI

《能源前沿（英文）》 2019年第13卷第1期页码 185-192 doi: 10.1007/s11708-017-0452-z

摘要： Solar absorption-subcooled compression hybrid refrigeration system is a new type of efficient and economical solar refrigeration device which always meets the demand of cooling load with the change of solar irradiance. The performance of the hybrid system is higher due to the improvement of evaporator temperature of absorption subsystem. But simultaneously, the variation of working process as well as performance is complicated since the absorption and compression subsystems are coupled strongly. Based on the measured meteorological data of Guangzhou, a subtropical city in south China, a corresponding parametric model has been developed for the hybrid refrigeration system, and a program written by Fortran has been used to analyze the performance of the hybrid system under different external conditions. As the condensation temperature ranges from 38°C to 50°C, the working time fraction of the absorption subsystem increases from 75% to 85%. Besides, the energy saving fraction also increases from 5.31% to 6.02%. The average COP of the absorption subsystem is improved from 0.366 to 0.407. However, when the temperature of the absorption increases from 36°C to 48°C, the average COP of hybrid system decreases from 2.703 to 2.312. Moreover, the working time fraction of the absorption subsystem decreases from 80% to 71.7%. The energy saving fraction falls from 5.67% to 5.08%. In addition, when the evaporate temperature increases from 4°C to 14°C, the average COP of the absorption subsystem decreases from 0.384 to 0.365. The work of the compressor decreases from 48.2 kW to 32.8 kW and the corresponding average COP of the absorption subsystem is improved from 2.591 to 3.082.

关键词： solar absorption-subcooled compression hybrid dynamic simulation performance analysis

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Research on performance of mixed absorption refrigeration for solar air-conditioning

WAN Zhongmin, SHU Shuiming, HU Xinhua, WANG Biaohua

《能源前沿（英文）》 2008年第2卷第2期页码 222-226 doi: 10.1007/s11708-008-0017-2

摘要： A novel lithium bromide/water mixed absorption refrigeration cycle that is suitable for the utilization of solar air-conditioning and can overcome the drawbacks of low system overall efficiency of traditional solar absorption refrigeration air-condition systems is presented. The accessorial high pressure generator was added in the cycle. The lithium bromide solution flowing out from the high pressure generator was mixed with the solution from the low pressure absorber to increase lithium bromide solution concentration and decrease pressure in the high pressure absorber. The performance of a mixed absorption refrigeration cycle was analyzed. The theoretical analysis shows that the highest COP is 0.61, while the highest available temperature difference of heat resource is 33.2°C. The whole coefficient of performance of the solar air-conditioning using mixed absorption cycle is 94.5% higher than that of two-stage absorption. The advantages of solar air-conditioning can be markedly made use of by the cycle.

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ZnO nanorefrigerant in R152a refrigeration system for energy conservation and green environment

D. SENDIL KUMAR,R. ELANSEZHIAN

《机械工程前沿（英文）》 2014年第9卷第1期页码 75-80 doi: 10.1007/s11465-014-0285-y

摘要：

In this paper the reliability and performance of a vapour compression refrigeration system with ZnO nanoparticles in the working fluid was investigated experimentally. Nanorefrigerant was synthesized on the basis of the concept of the nanofluids, which was prepared by mixing ZnO nanoparticles with R152a refrigerant. The conventional refrigerant R134a has a global warming potential (GWP) of 1300 whereas R152a has a significant reduced value of GWP of 140 only. An experimental test rig is designed and fabricated indigenously in the laboratory to carry out the investigations. ZnO nanoparticles with refrigerant mixture were used in HFC R152a refrigeration system. The system performance with nanoparticles was then investigated. The concentration of nano ZnO ranges in the order of 0.1% v, 0.3% v and 0.5%v with particle size of 50 nm and 150 g of R152a was charged and tests were conducted. The compressor suction pressure, discharge pressure and evaporator temperature were measured. The results indicated that ZnO nanorefrigerant works normally and safely in the system. The ZnO nanoparticle concentration is an important factor considered for heat transfer enhancement in the refrigeration system. The performance of the system was significantly improved with 21% less energy consumption when 0.5%v ZnO-R152a refrigerant. Both the suction pressure and discharge pressure were lowered by 10.5% when nanorefrigerant was used. The evaporator temperature was reduced by 6% with the use of nanorefrigerant. Hence ZnO nanoparticles could be used in refrigeration system to considerably reduce energy consumption. The usage of R152a with zero ozone depleting potential (ODP) and very less GWP and thus provides a green and clean environment. The complete experimental results and their analysis are reported in the main paper.

关键词： ZnO nanorefrigerant reduced GWP COP pressure ratio green energy

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Phase transition regulation and caloric effect

《能源前沿（英文）》 2023年第17卷第4期页码 463-477 doi: 10.1007/s11708-023-0860-1

摘要： Solid state refrigeration based on caloric effect is regarded as a potential candidate for replacing vapor-compression refrigeration. Numerous methods have been proposed to optimize the refrigeration properties of caloric materials, of which single field tuning as a relatively simple way has been systemically studied. However, single field tuning with few tunable parameters usually obtains an excellent performance in one specific aspect at the cost of worsening the performance in other aspects, like attaining a large caloric effect with narrowing the transition temperature range and introducing hysteresis. Because of the shortcomings of the caloric effect driven by a single field, multifield tuning on multicaloric materials that have a coupling between different ferro-orders came into view. This review mainly focuses on recent studies that apply this method to improve the cooling performance of materials, consisting of enlarging caloric effects, reducing hysteresis losses, adjusting transition temperatures, and widening transition temperature spans, which indicate that further progress can be made in the application of this method. Furthermore, research on the sign of lattice and spin contributions to the magnetocaloric effect found new phonon evolution mechanisms, calling for more attention on multicaloric effects. Other progress including improving cyclability of FeRh alloys by introducing second phases and realizing a large reversible barocaloric effect by hybridizing carbon chains and inorganic groups is described in brief.

关键词： phase transition regulation caloric effect solid state refrigeration

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Pumping into a cool future: electrocaloric materials for zero-carbon refrigeration

《能源前沿（英文）》 2022年第16卷第1期页码 19-22 doi: 10.1007/s11708-022-0820-1

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A comparison of production system life cycle models

Rajesh ATTRI, Sandeep GROVER

《机械工程前沿（英文）》 2012年第7卷第3期页码 305-311 doi: 10.1007/s11465-012-0332-5

摘要：

Companies today need to keep up with the rapidly changing market conditions to stay competitive. The main issues in this paper are related to a company’s market and its competitors. The prediction of market behavior is helpful for a manufacturing enterprise to build efficient production systems. However, these predictions are usually not reliable. A production system is required to adapt to changing markets, but such requirement entails higher cost. Hence, analyzing different life cycle models of the production system is necessary. In this paper, different life cycle models of the production system are compared to evaluate the distinctive features and the limitations of each model. Furthermore, the difference between product life cycle and production life cycle is summarized, and the effect of product life cycle on production life cycle is explained. Finally, a production system life cycle model, along with key activities to be performed in each stage, is proposed specifically for the manufacturing sector.

关键词： production system life cycle model product

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Experimental and CFD analysis of nozzle position of subsonic ejector

Xilai ZHANG, Shiping JIN, Suyi HUANG, Guoqing TIAN

《能源前沿（英文）》 2009年第3卷第2期页码 167-174 doi: 10.1007/s11708-009-0001-5

摘要： The influence of nozzle position on the performance of an ejector was analyzed qualitatively with free jet flow model. Experimental investigations and computational fluid dynamics (CFD) analysis of the nozzle position of the subsonic ejector were also conducted. The results show that there is an optimum nozzle position for the ejector. The ejecting coefficient reaches its maximum when the nozzle is positioned at the optimum and decreases when deviating. Moreover, the nozzle position of an ejector is not a fixed value, but is influenced greatly by the flow parameters. Considering the complexity of the ejector, CFD is reckoned as a useful tool in the design of ejectors.

关键词： ejector nozzle position ejecting coefficient CFD

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Analysis on carbon emission reduction intensity of fuel cell vehicles from a life-cycle perspective

《能源前沿（英文）》 doi: 10.1007/s11708-023-0909-1

摘要： The hydrogen fuel cell vehicle is rapidly developing in China for carbon reduction and neutrality. This paper evaluated the life-cycle cost and carbon emission of hydrogen energy via lots of field surveys, including hydrogen production and packing in chlor-alkali plants, transport by tube trailers, storage and refueling in hydrogen refueling stations (HRSs), and application for use in two different cities. It also conducted a comparative study for battery electric vehicles (BEVs) and internal combustion engine vehicles (ICEVs). The result indicates that hydrogen fuel cell vehicle (FCV) has the best environmental performance but the highest energy cost. However, a sufficient hydrogen supply can significantly reduce the carbon intensity and FCV energy cost of the current system. The carbon emission for FCV application has the potential to decrease by 73.1% in City A and 43.8% in City B. It only takes 11.0%–20.1% of the BEV emission and 8.2%–9.8% of the ICEV emission. The cost of FCV driving can be reduced by 39.1% in City A. Further improvement can be obtained with an economical and “greener” hydrogen production pathway.

关键词： hydrogen energy life-cycle assessment (LCA) fuel cell vehicle carbon emission energy cost

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Composite adsorbents of CaCl

Huashan LI, Xianbiao BU, Lingbao WANG, Zhenneng LU, Weibin MA

《能源前沿（英文）》 2012年第6卷第4期页码 356-360 doi: 10.1007/s11708-012-0207-9

摘要： Composite adsorbents of CaCl and sawdust prepared by carbonization for adsorption refrigeration with NH as refrigerant are tested, and the effects of carbonization temperature on the sorption capacity and rate are analyzed. The results show that the amount of pores in the sawdust of the composite adsorbents carbonized, apart from the content of CaCl , is the most dominant factor influencing the NH sorption on composite adsorbents. The optimum carbonization temperature is 700°C, which gives the maximal NH sorption capacity as high as 0.774 kg of NH per kg of the composite, and the specific cooling power is approximately between 338 and 869 W/kg with the cycle duration varying from 5 to 20 minutes. The present study demonstrates that the composite absorbent of CaCl and sawdust prepared by carbonization is more promising and competitive for adsorption refrigeration application.

关键词： adsorption refrigeration composite adsorbent calcium chloride sawdust carbonization