Search

Smooth and rough porous copper fiber sintered sheets, employed here as wicks for loop heat pipes for the first time, were fabricated using a low-temperature solid-phase sintering method. The capillary performance of these porous copper fiber sintered sheets were analyzed and discussed. The influence of the surface morphology, filling ratio, and working fluid on the thermal resistance, evaporator wall temperature, and start-up time of the loop heat pipes were investigated. The results showed that the capillary pumping amount of working fluid for both smooth and rough porous copper fiber sintered sheets initially increases rapidly, and then gradually attains a stable state. The curve of the capillary pumping amount of working fluid can be described as a function that increases exponentially over time. When rough porous copper fiber sintered sheets are used as wicks and deionized water is used as the working fluid, the capillary pumping amount is maximized. Compared to smooth porous copper fiber sintered sheets, loop heat pipes with rough porous copper fiber sintered sheets exhibit a shorter start-up time, lower thermal resistance, and lower evaporator wall temperature. For a filling ratio in the range of 15–45%, loop heat pipes with rough porous copper fiber sintered sheets and a 30% filling ratio show lower thermal resistance and a lower evaporator wall temperature. Ultimately, the use of deionized water as the working fluid with a 30% filling ratio enables loop heat pipes with rough porous copper fiber sintered sheets to be stably operated at a heat load of 200 W. [ABSTRACT FROM AUTHOR]

A novel porous copper fiber sintered felt (PCFSF) as catalyst support is fabricated to construct the methanol steam reforming microreactor for hydrogen production. In this study, the heat and mass transfer properties of PCFSF with different porosities is experimentally investigated. The results show that the PCFSF with different porosities exhibits good uniform heat transfer. The thermal conductivity is decreased with increasing porosity in the porosity range of 70–90%. With lower gas feed rate, no great change of the pressure drop is observed. However, larger pressure drop is produced with the higher gas feed rates. Moreover, we found that the resident time in the PCFSF is gradually decreased with increasing porosity. Much longer resident time is obtained when the lower gas feed rate is selected. The PCFSF with 80% porosity as catalyst support presents better reaction performance because of the enhancement of heat and mass transfer resulting from the unique porous structure. [ABSTRACT FROM AUTHOR]

Highlights: [•] We used the sessile drop method to measure the static contact angle. [•] Wettability mechanism of various metal foams and PCFSS was analyzed. [•] Contact angle was increased firstly and then was decreased with increasing porosity. [•] The effect of sintering parameters on the contact angle of PCFSS was also discussed. [•] The PCFSS with maximum static contact angle was obtained. [ABSTRACT FROM AUTHOR]

Abstract: Novel porous metal fiber sintered sheets (PMFSSs) with different porosities were fabricated by sintering copper fibers. Using four-point probe method, comparative study was conducted to investigate the effects of probe spacing, porosity, and sintering condition on the electrical conductivity of PMFSS. Our experimental results showed that probe spacing plays an important role in determining the electrical conductivity. Uniform probe spacing was adopted in order to reduce the error caused by non-uniformity of probe spacing. The measured electrical conductivity was found to decrease with increasing porosity ranging from 70% to 90% for the PMFSS produced under the same sintering condition. Our experimental results were found to agree well with the theoretical prediction by Liu’s model for the PMFSS with different porosities. The effect of sintering condition on electrical conductivity was also investigated. It was revealed that higher sintering temperature or longer holding time yields higher electrical conductivity of PMFSS. [Copyright &y& Elsevier]

Abstract: A novel porous metal fiber sintered sheet (PMFSS) with three-dimensional reticulated structure was fabricated by using solid-state sintering method of copper fibers. Uniaxial compressive test was carried out to investigate the effects of porosity and manufacturing parameters on the compressive properties of PMFSS. During the compressive process, it was found that the PMFSS initially exhibited short-term elastic deformation, and then quickly entered into the compact densification deformation stage. The stress–strain plots showed no obvious yield stage in the whole uniaxial compressive process. Under given stress, the PMFSS with higher porosity exhibited higher strain, hence implying lower effective stiffness. Additionally, our results showed that higher sintering temperature or longer sintering time would soften the PMFSS. [Copyright &y& Elsevier]