An experimental investigation on the boiling heat transfer and frictional pressure drop of R245fa in a 7 mm horizontal micro-fin tube was performed.The results show that in terms of flow boiling heat transfer characte...An experimental investigation on the boiling heat transfer and frictional pressure drop of R245fa in a 7 mm horizontal micro-fin tube was performed.The results show that in terms of flow boiling heat transfer characteristics,boiling heat transfer coefficient(HTC)increases with mass velocity of R245fa,while it decreases with the increment of saturation temperature and heat flux.With the increase of vapor quality,HTC has a maximum and the corresponding vapor quality is about 0.4,which varies with the operating conditions.When vapor quality is larger than the transition point,HTC can be promoted more remarkably at higher mass velocity or lower saturation temperature.Among the four selected correlations,KANDLIKAR correlation matches with 91.6%of experimental data within the deviation range of±25%,and the absolute mean deviation is 11.2%.Also,in terms of frictional pressure drop characteristics of flow boiling,the results of this study show that frictional pressure drop increases with mass velocity and heat flux of R245fa,while it decreases with the increment of saturation temperature.MULLER-STEINHAGEN-HECK correlation shows the best prediction accuracy for frictional pressure drop among the four widely used correlations.It covers 84.1%of experimental data within the deviation range of±20%,and the absolute mean deviation is 10.1%.展开更多
Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the su...Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed. However, it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing. In this paper, a special multi-tooth tool composed of a row of triangular tiny teeth is designed. The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting. As a result, several stainless steel fibers with periodic micro-fins are produced simultaneously. Morphology of periodic micro-fins is found to be diverse and can be classified into three categories： unilateral plane, unilateral tapering and bilateral. There are two forming mechanisms for the micro-fins. One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth; the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached. Influence of cutting conditions on formation of micro-fins is investigated. Experimental results show that cutting depth has no significant effect on micro-fin formation, high cutting speed is conducive to micro-fin formation, and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins. This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.展开更多
Using brighten white and modified PET chips, fine denier hollow fibres (dpf=0.5～1.5) were prepared on a Fuji Filter MSTC-400 and VC-443A drawn machine, whose structure and properties were tested by X-ray diffraction ...Using brighten white and modified PET chips, fine denier hollow fibres (dpf=0.5～1.5) were prepared on a Fuji Filter MSTC-400 and VC-443A drawn machine, whose structure and properties were tested by X-ray diffraction mater, SOM-II sonic velocity meter and Instron-1122 Tensile tester, electron and light microscopy etc,. The results show: fine denier hollow taken-up yarns prepared at low spinning velocity have radial orientation, higher strength and elongation at rupture because radial stress is higher than normal stress. Fine denier hollow drawn yarns with hollow degree up to 18～35％ and high tenacity, together with high crystalline degree and small crystal and amorphous domains, can be empolyed as products.展开更多
This paper is a part of studies on the silk-like polyester filaments.This paper studiesthe structural characteristics of fine denier PET undrawn filaments and mechanical proper-ties on the spinning line by mcans of in...This paper is a part of studies on the silk-like polyester filaments.This paper studiesthe structural characteristics of fine denier PET undrawn filaments and mechanical proper-ties on the spinning line by mcans of infra-red spectra,X-ray diffraction,birefringence,density gradient colum,tension testing and calculating.The results show that the solidificat-ing stress is larger than 10 dyn/cm,orientation and crystallinity incrcase,thestress-crystallization is larger than the effects of cooling velocity,and the boiling watershringkage behaves limited value.It is confirmed that the forming conditions of undrawnfilaments is mainly kinetic control by the methods of X-ray analysis as well as other testingand calculating.展开更多
Using near-azeotropic refrigerant R410A as the working fluid, the experimental studies on the horizontal micro-fin tubes were conducted. Several factors affecting heat transfer coefficients were analyzed, and the char...Using near-azeotropic refrigerant R410A as the working fluid, the experimental studies on the horizontal micro-fin tubes were conducted. Several factors affecting heat transfer coefficients were analyzed, and the characteristics of flow boiling of the refrigerant in the horizontal micro-fin tubes were discussed. The local heat transfer coefficients increase with mass flux, heat flux and quality. And the heat transfer enhancement factor of those testing tubes is about 1.6 to 2.2.展开更多
Micro-finance is providing financial services to poor people, who traditionally lack access to banking and related services. In India, the population of Muslims is about 180 million and the majority of them live below...Micro-finance is providing financial services to poor people, who traditionally lack access to banking and related services. In India, the population of Muslims is about 180 million and the majority of them live below poverty line. The regions where poor Muslims are in majority are marked as negative for providing loans by the banks. Study on interest-free （Islamic） micro-finance for implementation in a country like India can be very helpful in eradicating poverty and developing micro-enterprises together with sustainable development of poor and country as a whole. The primary aim of Islamic teachings （economics） is social justice to all irrespective of caste, creed, race, colour, and religion. Due to this reason, interest （riba） is prohibited not only in Islam but also in Christianity. This paper studies an Islamic micro-finance institution （Anjuman Islahul Muslemeen） situated in Bhopal （Madhya Pradesh）, India. The institution was registered in 1918 by a group of Muslims to help the poor. Today, about 98 years have passed by and all group members have changed but the organization is still growing with the aim of the well-being of poor people, not only Muslims but non-Muslims as well and is serving the humanity.展开更多
The primariy application of rare - earth spin finishes on PET/PA composite super - fine denier fiber has been studied in this paper. It results in the improvement of fi-ber’s properties, such as increased whiteness, ...The primariy application of rare - earth spin finishes on PET/PA composite super - fine denier fiber has been studied in this paper. It results in the improvement of fi-ber’s properties, such as increased whiteness, brightness and brilliance, effective and uniform spliting of compos-ite fiber into super - fine denier fiber and enhanced dye-ing effect.展开更多
基金Project(51606162)supported by the National Natural Science Foundation of ChinaProject(2018JJ2399)supported by the Natural Science Foundation of Hunan Province,China
文摘An experimental investigation on the boiling heat transfer and frictional pressure drop of R245fa in a 7 mm horizontal micro-fin tube was performed.The results show that in terms of flow boiling heat transfer characteristics,boiling heat transfer coefficient(HTC)increases with mass velocity of R245fa,while it decreases with the increment of saturation temperature and heat flux.With the increase of vapor quality,HTC has a maximum and the corresponding vapor quality is about 0.4,which varies with the operating conditions.When vapor quality is larger than the transition point,HTC can be promoted more remarkably at higher mass velocity or lower saturation temperature.Among the four selected correlations,KANDLIKAR correlation matches with 91.6%of experimental data within the deviation range of±25%,and the absolute mean deviation is 11.2%.Also,in terms of frictional pressure drop characteristics of flow boiling,the results of this study show that frictional pressure drop increases with mass velocity and heat flux of R245fa,while it decreases with the increment of saturation temperature.MULLER-STEINHAGEN-HECK correlation shows the best prediction accuracy for frictional pressure drop among the four widely used correlations.It covers 84.1%of experimental data within the deviation range of±20%,and the absolute mean deviation is 10.1%.
基金Supported by National Natural Science Foundation of China(Grant No.51375176)Guangdong Provincial Natural Science Foundation of China(Grant No.2014A030313264)Fundamental Research Funds for the Central Universities,SCUT,China(Grant No.2013ZZ017)
文摘Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed. However, it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing. In this paper, a special multi-tooth tool composed of a row of triangular tiny teeth is designed. The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting. As a result, several stainless steel fibers with periodic micro-fins are produced simultaneously. Morphology of periodic micro-fins is found to be diverse and can be classified into three categories： unilateral plane, unilateral tapering and bilateral. There are two forming mechanisms for the micro-fins. One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth; the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached. Influence of cutting conditions on formation of micro-fins is investigated. Experimental results show that cutting depth has no significant effect on micro-fin formation, high cutting speed is conducive to micro-fin formation, and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins. This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.
文摘Using brighten white and modified PET chips, fine denier hollow fibres (dpf=0.5～1.5) were prepared on a Fuji Filter MSTC-400 and VC-443A drawn machine, whose structure and properties were tested by X-ray diffraction mater, SOM-II sonic velocity meter and Instron-1122 Tensile tester, electron and light microscopy etc,. The results show: fine denier hollow taken-up yarns prepared at low spinning velocity have radial orientation, higher strength and elongation at rupture because radial stress is higher than normal stress. Fine denier hollow drawn yarns with hollow degree up to 18～35％ and high tenacity, together with high crystalline degree and small crystal and amorphous domains, can be empolyed as products.
文摘This paper is a part of studies on the silk-like polyester filaments.This paper studiesthe structural characteristics of fine denier PET undrawn filaments and mechanical proper-ties on the spinning line by mcans of infra-red spectra,X-ray diffraction,birefringence,density gradient colum,tension testing and calculating.The results show that the solidificat-ing stress is larger than 10 dyn/cm,orientation and crystallinity incrcase,thestress-crystallization is larger than the effects of cooling velocity,and the boiling watershringkage behaves limited value.It is confirmed that the forming conditions of undrawnfilaments is mainly kinetic control by the methods of X-ray analysis as well as other testingand calculating.
基金Shanghai Leading Academic Discipline Project(No.T0503)
文摘Using near-azeotropic refrigerant R410A as the working fluid, the experimental studies on the horizontal micro-fin tubes were conducted. Several factors affecting heat transfer coefficients were analyzed, and the characteristics of flow boiling of the refrigerant in the horizontal micro-fin tubes were discussed. The local heat transfer coefficients increase with mass flux, heat flux and quality. And the heat transfer enhancement factor of those testing tubes is about 1.6 to 2.2.
文摘Micro-finance is providing financial services to poor people, who traditionally lack access to banking and related services. In India, the population of Muslims is about 180 million and the majority of them live below poverty line. The regions where poor Muslims are in majority are marked as negative for providing loans by the banks. Study on interest-free （Islamic） micro-finance for implementation in a country like India can be very helpful in eradicating poverty and developing micro-enterprises together with sustainable development of poor and country as a whole. The primary aim of Islamic teachings （economics） is social justice to all irrespective of caste, creed, race, colour, and religion. Due to this reason, interest （riba） is prohibited not only in Islam but also in Christianity. This paper studies an Islamic micro-finance institution （Anjuman Islahul Muslemeen） situated in Bhopal （Madhya Pradesh）, India. The institution was registered in 1918 by a group of Muslims to help the poor. Today, about 98 years have passed by and all group members have changed but the organization is still growing with the aim of the well-being of poor people, not only Muslims but non-Muslims as well and is serving the humanity.
文摘The primariy application of rare - earth spin finishes on PET/PA composite super - fine denier fiber has been studied in this paper. It results in the improvement of fi-ber’s properties, such as increased whiteness, brightness and brilliance, effective and uniform spliting of compos-ite fiber into super - fine denier fiber and enhanced dye-ing effect.
