Ecological adsorption technology is becoming a focus of attention by industry due to the utilization of low grade thermal energy sources for cooling production. It can be a promising part of sustainable development co...Ecological adsorption technology is becoming a focus of attention by industry due to the utilization of low grade thermal energy sources for cooling production. It can be a promising part of sustainable development concept of the global economy. Therefore, research aiming at improving their performance i.e. Coefficient of Performance(COP) by optimizing the construction of sorption beds with a built in heat exchanger system is crucial. The heat transfer characteristics between the bed of porous media(sorbent) and surface of the heat exchanger system determine the heating power of an adsorption chiller. The HP increase can be obtained by heat transfer intensification due to the increase in the thermal conductivity of the sorbent layer in the vicinity of the heat exchanger's surface. The novel modification of the sorbent layer structure is proposed in the paper in order to improve the heat transfer processes in the heat exchanger boundary layer. The analysis of desorption process conditions in the parametric model of a coated and fixed adsorption bed design is presented in the paper. The computational fluid dynamics(CFD) with conjugate heat transfer analysis is used to determine the crucial input parameters(temperature distribution in the sorbent bed) for further analytical calculations. The commercial code Ansys Fluent was used to perform numerical simulations. The developed computational model consisted of three subdomains representing heating water, heat exchanger material(copper) and sorbent(silica gel). The comparison of a novel coated design and a conventional fixed bed is discussed in the paper. The numerical analysis is based on experimental thermal conductivity measurements of the sorbent layer in different configurations, which were performed using Laser Flash Method.展开更多
Magnetohydrodynamic (MHD) effect and heat transfer are two key issues for design of dual coolant lead lithium (DCLL) blanket. Flow channel insert (FCI) has been applied to decouple the liquid metal from the walls to e...Magnetohydrodynamic (MHD) effect and heat transfer are two key issues for design of dual coolant lead lithium (DCLL) blanket. Flow channel insert (FCI) has been applied to decouple the liquid metal from the walls to efficiently decline MHD pressure drops and reduce heat losses from the liquid metal for increasing bulk exit temperatures of the blanket. However, there are still big pressure drops and a higher velocity jet located at the gap flow. Moreover, the FCI made from silicon carbide (SiC) constitutes a complex blanket structures which potentially causes special flow phenomena. In the present work, the characteristics of fluid flow and heat transfer in the DCLL blanket channel are investigated for the first wall (FW) sprayed a layer of no-wetting nano coating (NWNC) on its inner surface. The results show that the pressure drop with NWNC wall is oneorder magnitude lower than that with FCI in the general DCLL blanket. The Nusselt number on the NWNC wall is about half of that on the general wall. On this basis, a heat transfer criterion equation of DCLL channel is achieved for the NWNC wall without FCI. The results are compared with that criterion equation of general wall conditions, which indicates the criterion equation can well predict the convection heat transfer of DCLL channel.展开更多
Achieving a reasonable homogeneity of the coating deposition rate within a low-pressure plasma process is a challenge, especially in large volume chambers. The local gas flow behavior is one key parameter in the coati...Achieving a reasonable homogeneity of the coating deposition rate within a low-pressure plasma process is a challenge, especially in large volume chambers. The local gas flow behavior is one key parameter in the coating deposition. Basically, with the exception of the product geometry and the electrode design, there are two main influences on the gas flow distribution inside a large volume chamber: 1) gas feed-in system and 2) gas exhaustion system. This work focuses on the gas exhaustion system with the aim to reduce its influence on the gas flow behavior inside a large plasma coater. In this sense, a solution with a perforated plate, named “Baffle-Plate”, is created. Thereby relevant construction parameters are identified and investigated to understand their influence in respect to the homogeneity of the gas exhaustion. Number of holes, hole diameter, distance of the Baffle-Plate to the top of the chamber, gas flow and chamber volume are evaluated parameters. Computational fluid dynamics (CFD) simulations are used as a tool to determine velocity and pressure distribution inside the PECVD-chamber and, consequently, to evaluate the layout parameters of the Baffle-Plate. Additionally, practical coating experiments with and without the Baffle-Plate installed are performed. The results show a correlation between the gas flow distribution and the homogeneity of the coating deposition rate. With these results construction guidelines have been formulated. Hence in future developments correct technical layouts of the Baffle-Plate can be applied, easily.展开更多
We simulated the heat transfer phenomena of the heating module that is primarily based on the radiant energy in the near-infra-red(NIR) domain.In the module,the power emitted by the lamp filament is distributed to the...We simulated the heat transfer phenomena of the heating module that is primarily based on the radiant energy in the near-infra-red(NIR) domain.In the module,the power emitted by the lamp filament is distributed to the lamp glass,reflector,and the target medium,which are cooled by an air flow.The radiant heat transfer is simulated by using the ray-tracing scheme,in which the spectral characteristics of the emission and the materials are incorporated.The heat transport from the lamp glass to the cooling air is analyzed by using the finite volume method.As the lamp-filament temperature rises in the range of 3000-3400K,the NIR radiant power on the target medium increases.However,the lamp-glass temperature also rises,and the proportion of the NIR power to the entire radiation has a peak in the temperature range.The spectral distributions of the absorbed energies in all the components in the module are highly non-uniform,and a monochromatic model of the radiant heat transfer may result in a significant discrepancy.展开更多
The correlation between particle in-flight parameter, defect content and mechanical property of yttria-stabilized zirconia coating was systematically studied in the present work. The melting state of in-flight particl...The correlation between particle in-flight parameter, defect content and mechanical property of yttria-stabilized zirconia coating was systematically studied in the present work. The melting state of in-flight particle during spraying was simulated using computational fluid dynamics. The results suggested that, with the increase of velocity and temperature of in-flight particles in the plasma jet, the particles changed from partially melted state to fully melted one. As a result, the total defect content of as-sprayed coating gradually decreased, while elastic modulus and microhardness increased correspondingly. However, the fracture toughness of as-sprayed coating reached a maximum value when the total defect content reached approximately 9.1%.展开更多
基金the project:"The development of innovative technology of adsorption chiller NETI?,using special,glued construction of the adsorption beds"(number:POIR.01.01.01-00-1659/15)partially supported by National Science Centre of Poland (Narodowe Centrum Nauki) grant number 2017/01/X/ST8/00019granted by the Faculty of Mathematics and Natural Sciences of Jan Dlugosz University in Czestochowa.
文摘Ecological adsorption technology is becoming a focus of attention by industry due to the utilization of low grade thermal energy sources for cooling production. It can be a promising part of sustainable development concept of the global economy. Therefore, research aiming at improving their performance i.e. Coefficient of Performance(COP) by optimizing the construction of sorption beds with a built in heat exchanger system is crucial. The heat transfer characteristics between the bed of porous media(sorbent) and surface of the heat exchanger system determine the heating power of an adsorption chiller. The HP increase can be obtained by heat transfer intensification due to the increase in the thermal conductivity of the sorbent layer in the vicinity of the heat exchanger's surface. The novel modification of the sorbent layer structure is proposed in the paper in order to improve the heat transfer processes in the heat exchanger boundary layer. The analysis of desorption process conditions in the parametric model of a coated and fixed adsorption bed design is presented in the paper. The computational fluid dynamics(CFD) with conjugate heat transfer analysis is used to determine the crucial input parameters(temperature distribution in the sorbent bed) for further analytical calculations. The commercial code Ansys Fluent was used to perform numerical simulations. The developed computational model consisted of three subdomains representing heating water, heat exchanger material(copper) and sorbent(silica gel). The comparison of a novel coated design and a conventional fixed bed is discussed in the paper. The numerical analysis is based on experimental thermal conductivity measurements of the sorbent layer in different configurations, which were performed using Laser Flash Method.
基金support from the National Natural Science Foundation of China(Grants 11675077 and51576208)
文摘Magnetohydrodynamic (MHD) effect and heat transfer are two key issues for design of dual coolant lead lithium (DCLL) blanket. Flow channel insert (FCI) has been applied to decouple the liquid metal from the walls to efficiently decline MHD pressure drops and reduce heat losses from the liquid metal for increasing bulk exit temperatures of the blanket. However, there are still big pressure drops and a higher velocity jet located at the gap flow. Moreover, the FCI made from silicon carbide (SiC) constitutes a complex blanket structures which potentially causes special flow phenomena. In the present work, the characteristics of fluid flow and heat transfer in the DCLL blanket channel are investigated for the first wall (FW) sprayed a layer of no-wetting nano coating (NWNC) on its inner surface. The results show that the pressure drop with NWNC wall is oneorder magnitude lower than that with FCI in the general DCLL blanket. The Nusselt number on the NWNC wall is about half of that on the general wall. On this basis, a heat transfer criterion equation of DCLL channel is achieved for the NWNC wall without FCI. The results are compared with that criterion equation of general wall conditions, which indicates the criterion equation can well predict the convection heat transfer of DCLL channel.
文摘Achieving a reasonable homogeneity of the coating deposition rate within a low-pressure plasma process is a challenge, especially in large volume chambers. The local gas flow behavior is one key parameter in the coating deposition. Basically, with the exception of the product geometry and the electrode design, there are two main influences on the gas flow distribution inside a large volume chamber: 1) gas feed-in system and 2) gas exhaustion system. This work focuses on the gas exhaustion system with the aim to reduce its influence on the gas flow behavior inside a large plasma coater. In this sense, a solution with a perforated plate, named “Baffle-Plate”, is created. Thereby relevant construction parameters are identified and investigated to understand their influence in respect to the homogeneity of the gas exhaustion. Number of holes, hole diameter, distance of the Baffle-Plate to the top of the chamber, gas flow and chamber volume are evaluated parameters. Computational fluid dynamics (CFD) simulations are used as a tool to determine velocity and pressure distribution inside the PECVD-chamber and, consequently, to evaluate the layout parameters of the Baffle-Plate. Additionally, practical coating experiments with and without the Baffle-Plate installed are performed. The results show a correlation between the gas flow distribution and the homogeneity of the coating deposition rate. With these results construction guidelines have been formulated. Hence in future developments correct technical layouts of the Baffle-Plate can be applied, easily.
基金supported by the Korea Research Foundation Grant funded by the Korean Government(MOEHRD,Basic ResearchPromotion Fund)(KRF-2008-331-D00076)
文摘We simulated the heat transfer phenomena of the heating module that is primarily based on the radiant energy in the near-infra-red(NIR) domain.In the module,the power emitted by the lamp filament is distributed to the lamp glass,reflector,and the target medium,which are cooled by an air flow.The radiant heat transfer is simulated by using the ray-tracing scheme,in which the spectral characteristics of the emission and the materials are incorporated.The heat transport from the lamp glass to the cooling air is analyzed by using the finite volume method.As the lamp-filament temperature rises in the range of 3000-3400K,the NIR radiant power on the target medium increases.However,the lamp-glass temperature also rises,and the proportion of the NIR power to the entire radiation has a peak in the temperature range.The spectral distributions of the absorbed energies in all the components in the module are highly non-uniform,and a monochromatic model of the radiant heat transfer may result in a significant discrepancy.
基金supported by the Collaborative Innovation Center of Advanced Control Valve Project (Grant No. WZYB-XTCX-001)
文摘The correlation between particle in-flight parameter, defect content and mechanical property of yttria-stabilized zirconia coating was systematically studied in the present work. The melting state of in-flight particle during spraying was simulated using computational fluid dynamics. The results suggested that, with the increase of velocity and temperature of in-flight particles in the plasma jet, the particles changed from partially melted state to fully melted one. As a result, the total defect content of as-sprayed coating gradually decreased, while elastic modulus and microhardness increased correspondingly. However, the fracture toughness of as-sprayed coating reached a maximum value when the total defect content reached approximately 9.1%.
