Experimental Study on Comprehensive Performance of Sintering Biporous Wicks Prepared by Salt Dissolution and Cold Pressing Process

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Chunsheng Guo ◽  
Cheng Jiang ◽  
Jun Ma ◽  
Yingwen Cao ◽  
Yong Zou ◽  
...  
Keyword(s):  
Resistance Testing ◽  
Pressing Pressure ◽  
Long Distance ◽  
Capillary Suction ◽  
Cold Pressing ◽  
Testing Platform ◽  
Loop Heat Pipes ◽  
Porous Wick ◽  
Salt Dissolution ◽  
Total Suction

Abstract Porous wicks are a key component of loop heat pipes (LHPs). In order to enhance the antigravity and long-distance operation ability of the LHP, a porous wick is required to have the characteristics of high permeability and high capillary suction capability. In this paper, biporous wicks were prepared by salt dissolution pore-forming technology, and a gas resistance testing platform and a capillary suction testing platform were setup to test the samples. The current research studies the effects of different pore-forming agent mass ratios (10%, 30%, and 40%) and different cold pressing pressures (30 kN, 40 kN, 50 kN, and 60 kN) on the porosity, permeability, and the suction speed. The study finds that the porosity, permeability, and the total suction mass of the porous wicks all increase when the NaCl mass increases; the increase of the suction speed is proportional to the increase of the porosity and the permeability, and hence, proportional to the increase of NaCl mass. The total suction mass and suction speed is inversely proportional to cold pressing pressure.

Experimental Study On Preparation and Heat Transfer of Nickel-Based Ammonia LHP

2021 ◽  
Author(s):  
Wenjing Ning ◽  
Jun Ma ◽  
Cheng Jiang ◽  
Yingwen Cao ◽  
Chunsheng Guo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Pore Size ◽  
Thermal Load ◽  
Physical Property ◽  
Variable Load ◽  
Pressing Pressure ◽  
Cold Pressing ◽  
Porous Wick ◽  
Start Up

Abstract The loop heat pipe (LHP) is a passive heat sink used in aerospace and electronic devices. As the core component of the LHP, the physical property parameters of porous wick directly affect the overall performance of the LHP. In this paper, the performance of the porous wick is improved by adjusting the pore size, thereby improving the performance of the LHP. The nickel-based double-pore porous wicks are prepared by T225 nickel powder and NaCl particles, and the pore size of the porous wicks can be changed by different cold pressing pressures (30KN, 40KN, 50KN, 60KN). The effects of different cold pressing pressures on the porosity, permeability, and other physical property parameters are studied when the ratio of pore former is 20wt%. In the end, we select the cold pressing pressure of 30KN to prepare the porous wick of the LHP. Then the effects of constant load and variable load of the heat transfer performance under different placement angles are studied. The results show that the heat load range is 10W-100W, the minimum evaporator thermal resistance is 0.424K/W, and the minimum LHP thermal resistance is 0.598K/W. When ß=0°, there is a "backflow" phenomenon at the initial stage of low thermal load. With the increase of thermal load, the "backflow" duration decreases until it disappears, and the start-up time becomes shorter. The thermal resistances of the evaporator and LHP decrease and then increase. When ß= -90°, the LHP appears "reverse start-up" phenomenon.

Modulated porous wick evaporator for loop heat pipes: Experiment

2014 ◽  
Vol 72 ◽  
pp. 163-176 ◽  
Author(s):  
Jinliang Xu ◽  
Xianbing Ji ◽  
Wolong Yang ◽  
Ziwei Zhao
Keyword(s):  
Heat Pipes ◽  
Loop Heat Pipes ◽  
Porous Wick

Development of nickel bi-porous wicks for miniature loop heat pipe applications

2019 ◽  
Vol 16 (2) ◽  
pp. 331-339
Author(s):  
Yogesh Mahulkar ◽  
Chetankumar Sedani
Keyword(s):  
Particle Size ◽  
Nickel Powder ◽  
Standard Procedure ◽  
Electronics Cooling ◽  
Heat Pipes ◽  
Content Type ◽  
Loop Heat Pipes ◽  
Porous Wick ◽  
Carbonyl Nickel ◽  
Powder Type

PurposeMiniature loop heat pipes (MLHPs) are highly efficient passive heat transfer devices, which have considerable advantages over conventional heat pipes. Currently, miniature LHPs with ammonia and water as working fluids have been developed and utilized in electronics cooling within temperature range of 50°C-70°C at any orientation in 1-g conditions.Design/methodology/approachThe authors studied the standard procedure for the development of bi-porous nickel wicks and their characterization. Three different shaped nickel powders were studied, and best fitting nickel powder for electronics cooling application was reported. The manufacturing of bi-porous wick structures was analyzed with parameters such as porosity, permeability, capillary pressure and effective thermal conductivity for efficient performance of MLHP.FindingsThe study investigated the sintering process for number of samples to identify effective sample for the particular application. It is found that carbonyl nickel powder (type 287) with particle size of 2.6-3.3 µm gives promising results. Permeability and porosity were found to be highest in this case.Originality/valueIt is found that carbonyl nickel powder type with particle size gives promising results. Permeability and porosity was found to be highest in this case.

A personalised medicine drug sensitivity and resistance testing platform and utilisation of acoustic droplet ejection at the Institute for Molecular Medicine Finland

Synergy ◽  
2014 ◽  
Vol 1 (1) ◽  
pp. 78 ◽  
Author(s):  
Jani Saarela ◽  
Evgeny Kulesskiy ◽  
Karoliina Laamanen ◽  
Tea Pemovska ◽  
Vilja Pietiäinen ◽  
...  
Keyword(s):  
Drug Sensitivity ◽  
Personalised Medicine ◽  
Molecular Medicine ◽  
Resistance Testing ◽  
Testing Platform ◽  
Droplet Ejection

scholarly journals Experimental Study of a Loop Heat Pipe with Direct Pouring Porous Wick for Cooling Electronics

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1332
Author(s):  
Bing Cai ◽  
Weizhong Deng ◽  
Tong Wu ◽  
Tingting Wang ◽  
Zhengyuan Ma ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Heat Load ◽  
Load Test ◽  
Vapor Flow ◽  
Loop Heat Pipes ◽  
Load Matching ◽  
Porous Wick ◽  
Start Up ◽  
Compensation Chamber ◽  
And Performance

A pouring silicate wick was manufactured to explore the influence of process and physical properties on the production and performance of loop heat pipes (LHP). This paper theoretically analyzed the advantages of pouring porous wick and introduced the technology of pouring silicate directly on evaporator. Based on this, the heat transfer performance of copper-methanol LHP system with pouring porous wick was tested under different positions. The results showed that with the input of multiple heat sources, the LHP could start up and maintain a stable temperature from 40 W to 160 W. When the vapor grooves were located above the compensation chamber, it was difficult to start up positively. By adding gravity assistance, the system could obtain more stable liquid supply and vapor flow, so as to realize start up. In the variable heat load test, the LHP showed good adaptability to the change of heat load. The thermal resistance of the system decreased with the increase of heat load. The thermal resistance of the evaporator almost unchanged and was always lower than 0.05 °C/W, which indicated that the pouring porous wick in the evaporator had good heat load matching.

Freeze–Thaw Durability and Salt Scaling Resistance Assessment of Portland Cement Concrete Composite Pavement

2012 ◽  
Vol 2290 (1) ◽  
pp. 76-83
Author(s):  
Mary Vancura ◽  
Derek Tompkins ◽  
Lev Khazanovich
Keyword(s):  
United States ◽  
Portland Cement ◽  
The United States ◽  
Resistance Testing ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Capillary Suction ◽  
Freeze Thaw ◽  
Salt Scaling ◽  
Scaling Resistance

The SHRP 2 R21 project on composite pavement investigated the durability of various mixtures of portland cement concrete (PCC) used in the construction of a two-layer composite PCC pavement. Project consultants in Europe, where composite PCC over PCC pavement was more common than in the United States, advised the R21 research team to consider using the CIF (capillary suction, internal damage, and freeze–thaw) standard of the International Union of Laboratories and Experts in Construction Materials, Systems, and Structures (RILEM), Paris, rather than the familiar ASTM standards. As a result, the R21 project adopted the RILEM CIF standard to evaluate the freeze–thaw durability and salt scaling resistance of concretes. The research also explored a modified RILEM CIF test (using pure water instead of a sodium chloride solution in scaling tests) alongside the standard RILEM CIF tests. The paper describes this experience to expose other institutions and agencies in the United States to the RILEM standards for the freeze–thaw durability and salt scaling resistance testing of concretes.

scholarly journals Optimization of bonding parameters of laminated wood using a novel bio-based RPF adhesive

2019 ◽  
Vol 275 ◽  
pp. 01025
Author(s):  
Xueyong Ren ◽  
Yinlan Shen ◽  
Ying Gao ◽  
Derong Zhang ◽  
Jianmin Chang
Keyword(s):  
Process Parameters ◽  
Phenol Formaldehyde ◽  
Green Manufacturing ◽  
Pressing Pressure ◽  
Curing Agent ◽  
Pyrolysis Oil ◽  
Cold Pressing ◽  
Bonding Parameters ◽  
Pressing Time ◽  
Wood Bonding

Adhesive is the key component and factor for the manufacture of glulam, affected both the properties and cost of glulam product. Bio-based resorcinol-phenol-formaldehyde (BRPF) resin was developed by partly replacing the expensive resorcinol and phenol with the cheap biomass derived pyrolysis oil. The press process parameters and the dosage of adhesive and corresponding curing agent were selected as the factors and extensively studied. BRPF resin was successfully used to bond the laminas to produce glulam, and the optimized process parameters for the cold-pressing adhesion of BRPF resin with pine wood were obtained as follows: the cold-pressing pressure 1.4 MPa, the cold-pressing time 9 h, the amount of adhesive coating 320 g/m2, and the proportion of curing agent (poly-formaldehyde) 17%. The mechanical performances of laminated wood bonding with BRPF resin under the optimal condition were further verified. It is believed that the results obtained here will promote the use of bio-based resin in the bonding of laminated wood, and then contribute to the green manufacturing of glulam with lower cost.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

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