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Measurement of boiling heat transfer coefficient in liquid nitrogen bath by inverse heat conduction method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第5期10卷 691-696页

作者： Tao JIN Jian-ping HONG Hao ZHENG Ke TANG Zhi-hua GAN institute of {1. and cryogenics Zhejiang University Hangzhou 310027 China

Inverse heat conduction method (IHCM) is one of the most effective approaches to obtaining the boiling heat transfer coefficient from measured results. This paper focuses on its application in cryogenic boiling heat transfer. Experiments were conducted on the heat transfer of a stainless steel block in a liquid nitrogen bath, with the assumption of a 1. conduction condition to realize fast acquisition of the temperature of the test points inside the block. With the inverse-heat conduction theory and the explicit finite difference model, a solving program was developed to calculate the heat flux and the boiling heat transfer coefficient of a stainless steel block in liquid nitrogen bath based on the temperature acquisition data. Considering the oscillating data and some unsmooth transition points in the inverse-heat-conduction calculation result of the heat-transfer coefficient, a two-step data-fitting procedure was proposed to obtain the expression for the boiling heat transfer coefficients. The coefficient was then verified for accuracy by a comparison between the simulation results using this expression and the verifying experimental results of a stainless steel block. The maximum error with a revised segment fitting is around 6%, which verifies the feasibility of using IHCM to measure the boiling heat transfer coefficient in liquid nitrogen bath.

关键词： Inverse heat conduction method (IHCM) Liquid nitrogen bath Boiling heat transfer coefficient

Research on the chemical adsorption precursor state of CaCl_2-NH_3 for adsorption refrigeration

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Science China(Technological Sciences) 2005年第1期48卷 70-82页

作者： WANG Liwei WANG Ruzhu WU Jingyi WANG Kai institute of {1. and cryogenics Shanghai Jiao Tong University Shanghai 200030 China Institute of Refrigeration and Cryogenics Shanghai Jiao Tong University Shanghai 200030 China Institute of Refrigeration and Cryogenics Shanghai Jiao Tong University Shanghai 200030 China Institute of Refrigeration and Cryogenics Shanghai Jiao Tong University Shanghai 200030 China

As a type of chemical adsorption working pair, the physical adsorption occurs first for CaCl2-NH3 because the effective reaction distance for van der Waals force is longer than that for chemical reaction force, and this physical adsorption state is named the precursor state of chemical adsorption. In order to get the different precursor states of CaCl2-NH3, the different distances between NH3 gas and Ca2+ are realized by the control of different phenomena of swelling and agglomeration in the process of adsorption. When the serious swelling exists while the agglomeration does not exist in the process of adsorption, experimental results show that the activated energy consumed by adsorption reaction increases for the reason of longer distance between Ca2+ and NH3, and at the same time the performance attenuation occurs in the repeated adsorption cycles. When the agglomeration occurs in the process of adsorption, the activated energy for the transition from precursor state to chemical adsorption decreases because the distance between NH3 gas and Ca2+ is shortened by the limited expansion space of adsorbent, and at the same time the performance attenuation does not occur. The adsorption refrigeration isobars are researched by the precursor state of chemical adsorption; results also show that the precursor state is a key factor for isobaric adsorption performance while the distribution of Ca2+ does not influence the permeation of NH3 gas in adsorbent.

关键词： refrigeration, chemical adsorption, precursor state of chemical adsorption, attenuation, activated energy.

Adsorption performances and refrigeration application of adsorption working pair of CaCl_2-NH_3

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Science China(Technological Sciences) 2004年第2期47卷 173-185页

The adsorption performance of CaCl2?NH3 is studied under the condition of different expansion spaces for adsorbent, and the relationships between adsorption performance of CaCl2?NH3 and the phenomena of swelling and agglomeration during adsorption are researched. It is found that the performance stability is related to the ratio of expansion space to the volume of adsorbent r as, and the performance attenuation is serious in the case of large r as. Severe adsorption hysteresis exists in the process of adsorption and desorption at the same evaporating and condensing temperatures, which is related to the stability constant of chemical reaction. This phenomenon cannot be explained by the theory of physical adsorption. Moderate agglomeration will be beneficial to the formation of ammoniate complex; the magnitude of expansion space will affect adsorption performance. Analysis shows that the activated energy needed in the process of adsorption for the sample with r as. of 2∶1.is less than that for the sample with r as of 3∶1. The refrigeration performance of CaCl2?NH3 is predicted from experiments. The cooling capacity of one adsorption cycle is about 945.4 kJ/kg for the adsorbent with an r as of 2∶1.at the evaporating temperature of 0°C. Keywords chemical adsorption - attenuation - adsorption hysteresis - ammonia - activated carbon - refrigeration

关键词： chemical adsorption, attenuation, adsorption hysteresis, ammonia, activated carbon, refrigeration.

Bioinspired Double-stranded Yarn with Alternating Hydrophobic/Hydrophilic Patterns for High-efficiency Fog Collection

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Chinese Journal of Polymer Science 2024年第7期42卷 968-975,I0008页

作者： Lan-Lan Hou Meng-Na Qiu Ya-Qiong Wang Tong-Hua Bai Zhi-Min Cui Jing-Chong Liu Ying-Qun Qi Nü Wang Yong Li Yong Zhao Beijing institute of Graphic Communication Beijing102600China Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education Beijing Key Laboratory of Bioinspired Energy Materials and DevicesSchool of ChemistryBeijing Advanced Innovation Center for Biomedical EngineeringBeihang UniversityBeijing100191China Key Laboratory of cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing100190China Beijing Key Laboratory for Bioengineering and Sensing TechnologyDaxing Research InstituteSchool of Chemistry and Biological EngineeringUniversity of Science and Technology BeijingBeijing100083China

Efforts to develop innovative water harvesting strategies offer powerful solutions to alleviate the water crisis,especially in remote and arid *** by the hydrophobic/hydrophilic pattern of desert beetles and water self-propulsion property of spider silks,a double-strand hydrophobic PVDF-HFP/hydrophilic PAN nanofibers yarn is proposed by electrospinning and twisting *** double-strand cooperation approach allows for water deposition on hydrophobic PVDF-HFP segment and transport under the asymmetric capillary driving force of hydrophilic PAN segment,thus speeded up the aggregation and growth of *** effects of the composition and the diameter ratio of the two primary yarns were studied and optimized for boosting fog collection *** double-strand anisotropic yarn not only provide an effective method for water harvesting,but also hold the potential to inspire innovative design concepts for fog collection materials in challenging environments.

关键词： Fog collection Wettability Electrospinning Nanofibers Spider silk

Experimental observation on a small-scale thermoacoustic prime mover

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第2期8卷 205-209页

作者： JIN Tao ZHANG Bao-sen TANG Ke BAO Rui CHEN Guo-bang institute of {1. and cryogenics Zhejiang University Hangzhou 310027 China

A miniature thermoacoustic prime mover, consuming heat to radiate sound, may be considered as a potential way of heat management in microcircuits because of its simplicity and stability. A prototype with variable resonant tube length of 1. to 25 cm was built, and experiments were carried out to observe its performance, such as onset temperature, oscillation amplitude and operating frequency. The results with atmospheric air showed that proper structures and operating conditions can make the system start an oscillation at a temperature lower than 1.0 ℃, which proves the feasibility of potential usage in electronic units. The influences of stack position, heat input power or tube inclination on the oscillation amplitude, onset temperature and operating frequency are also presented.

关键词： Thermoacoustics Miniaturization Onset temperature

Experimental study on a cryosurgery apparatus

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第2期11卷 128-131页

作者： Shao-zhi ZHANG Dong-bo WU Ge YANG Guang-ming CHEN institute of {1. and cryogenics Zhejiang University Hangzhou 310027 China

Cryosurgery is an effective way of curing many diseases including tumors and cancers. It can be applied using a variety of systems and cryogens. Cheap, convenient, reliable equipment still needs to be developed so that cryotherapy may be accepted by surgeons and hospitals. This paper presents a cryosurgery apparatus that utilizes an auto-cascade refrigeration system. Refrigerant mixture R50/R23/R600a was selected as the working fluid. The mixture composition was altered to achieve lower temperatures and higher capacity. The lowest temperature at the cryoprobe could be as low as -1.0℃, and 8 W refrigeration capacity could be obtained at -80 ℃. An ice ball of 1..6 mm diameter could be formed when the cryoprobe was immersed in a water bath at 37 ℃.

关键词： Cryosurgery Cryoprobe Auto-cascade refrigeration system Refrigerant mixture

Liquid metal biomaterials: translational medicines,challenges and perspectives

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National Science Review 2024年第2期11卷 264-284页

作者： Hanchi Xu Jincheng Lu Yikuang Xi Xuelin Wang Jing Liu Department of Biomedical Engineering School of Medicine Tsinghua University Beijing Tsinghua Changgung Hospital School of Clinical Medicine Tsinghua University Shanghai World Foreign Language Academy Beijing Advanced Innovation Center for Biomedical Engineering School of Engineering MedicineBeihang University Beijing Key Lab of Cryo-Biomedical Engineering and Key Lab of cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences

Until now, significant healthcare challenges and growing urgent clinical requirements remain incompletely addressed by presently available biomedical materials. This is due to their inadequate mechanical compatibility, suboptimal physical and chemical properties, susceptibility to immune rejection, and concerns about long-term biological safety. As an alternative, liquid metal(LM) opens up a promising class of biomaterials with unique advantages like biocompatibility, flexibility, excellent electrical conductivity,and ease of functionalization. However, despite the unique advantages and successful explorations of LM in biomedical fields, widespread clinical translations and applications of LM-based medical products remain limited. This article summarizes the current status and future prospects of LM biomaterials, interprets their applications in healthcare, medical imaging, bone repair, nerve interface, and tumor therapy, *** to translate LM materials into medicine and obstacles encountered in practices are *** that, we outline a blueprint for LM clinics, emphasizing their potential in making new-generation artificial organs. Last, the core challenges of LM biomaterials in clinical translation, including bio-safety,material stability, and ethical concerns are also discussed. Overall, the current progress, translational medicine bottlenecks, and perspectives of LM biomaterials signify their immense potential to drive future medical breakthroughs and thus open up novel avenues for upcoming clinical practices.

关键词： liquid metal biomaterials translational medicine clinical device healthcare therapeutics

Review on cryogenic technologies for CO_(2) removal from natural gas

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Frontiers in Energy 2022年第5期16卷 793-811页

作者： Yujing BI Yonglin JU institute of {1. and cryogenics Shanghai Jiao Tong UniversityShanghai 200240China

CO_(2) in natural gas(NG)is prone to condense directly from gas to solid or solidify from liquid to solid at low temperatures due to its high triple point and boiling temperature,which can cause a block of ***,CO_(2) will also affect the calorific value of *** on the above reasons,CO_(2) must be removed during the NG liquefaction *** with conventional methods,cryogenic technologies for CO_(2) removal from NG have attracted wide attention due to their nonpolluting and low-cost *** integration with NG liquefaction can make rational use of the cold energy and realize the purification of NG and the production of byproduct liquid CO_(2).In this paper,the phase behavior of the CH_(4)-CO_(2) binary mixture is summarized,which provides a basis for the process design of cryogenic CO_(2) removal from ***,the detailed techniques of design and optimization for cryogenic CO_(2) removal in recent years are summarized,including the gas-liquid phase change technique and the gas-solid phase change ***,several improvements for further development of the cryogenic CO_(2) removal process are *** removal process in combination with the phase change and the traditional techniques with renewable energy will be the broad prospect for future development.

关键词： cryogenic CO_(2)removal purification of natural gas(NG) biogas upgrading CH_(4)-CO_(2)binary system

Simulation and experiments on cooling and power system driven a solid sorption combined by the exhaust waste heat

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Frontiers in Energy 2017年第4期11卷 516-526页

作者： Peng GAO Liwei WANG Ruzhu WANG Yang YU institute of {1. and cryogenics Shanghai Jiao Tong University Shanghai 200240 China

A solid sorption combined cooling and power system driven by exhaust waste heat is proposed, which consists of a MnCl2 sorption bed, a CaCl2 sorption bed, an evaporator, a condenser, an expansion valve, and a scroll expander, and ammonia is chosen as the working fluid. First, the theoretical model of the system is established, and the partitioning calculation method is proposed for sorption beds. Next, the experimental system is estab- lished, and experimental results show that the refrigerating capacity at the refrigerating temperature of-1.℃ and the resorption time of 30 min is 1.95 kW, and the shaft power is 1.9.2 W. The system can provide approximately 60% of the power for the evaporator fan and the condenser fan. Finally, the performance of the system is compared with that of the solid sorption refrigeration system. The refrigerating capacity of two systems is almost the same at the same operational condition. Therefore, the power generation process does not influence the refrigeration process. The exergy efficiency of the two systems is 0.076 and 0.047, respectively. The feasibility of the system is determined, which proves that this system is especially suitable for the exhaust waste heat recovery.

关键词： solid sorption exhaust waste heat combinedcooling and power system exergy efficiency