The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper stud...The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure drop.These results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.展开更多
This study deals with the high-risk shell-and-tube heat exchangers in the effluent system of hydrogenation reaction of the petrochemical industry.The process of hydroprocessing reactor effluent system is simulated in ...This study deals with the high-risk shell-and-tube heat exchangers in the effluent system of hydrogenation reaction of the petrochemical industry.The process of hydroprocessing reactor effluent system is simulated in Aspen Plus to study the distribution of corrosive medium in the three phases of oil,gas and water.The least-squares method is utilized to calculate the ammonium salt crystallization temperature.Then,the heat exchanger with risk of ammonium salt crystal corrosion is identified.Dynamic mathematical modeling of the heat exchanger is established to determine the transfer function.A temperature control system with proportional integral derivative(PID)control of the heat exchanger outlet is designed,and fuzzy logic is used to implement self-tuning of PID parameters.After MATLAB simulation,the results show the control system can achieve rapid control of the heat exchanger outlet temperature.展开更多
The size of the heat exchanger is an important factor determining the dimensions of the cold box in helium cryogenic systems. In this paper, a counter-flow multi-stream plate-fin heat exchanger is optimized by means o...The size of the heat exchanger is an important factor determining the dimensions of the cold box in helium cryogenic systems. In this paper, a counter-flow multi-stream plate-fin heat exchanger is optimized by means of a spatial interpolation method coupled with a hybrid genetic algorithm.Compared with empirical correlations, this spatial interpolation algorithm based on a kriging model can be adopted to more precisely predict the Colburn heat transfer factors and Fanning friction factors of offset-strip fins. Moreover, strict computational fluid dynamics simulations can be carried out to predict the heat transfer and friction performance in the absence of reliable experimental data. Within the constraints of heat exchange requirements, maximum allowable pressure drop, existing manufacturing techniques and structural strength, a mathematical model of an optimized design with discrete and continuous variables based on a hybrid genetic algorithm is established in order to minimize the volume. The results show that for the first-stage heat exchanger in the EAST refrigerator, the structural size could be decreased from the original2.200？×？0.600？×？0.627（m^3） to the optimized 1.854？×？0.420？×？0.340（m3）, with a large reduction in volume. The current work demonstrates that the proposed method could be a useful tool to achieve optimization in an actual engineering project during the practical design process.展开更多
This Paper has first studied the simplified model of tubular heat exchanger which is widely used in the industry and other field.On the basis of reference 2,a new pole assignment design method of pro-cess control syst...This Paper has first studied the simplified model of tubular heat exchanger which is widely used in the industry and other field.On the basis of reference 2,a new pole assignment design method of pro-cess control system with derivative control action is found.For the above system,the method and the for-mation which calculate the feedback matrix K and gain matrix L is given,and the simulation of the system is made.展开更多
Heat exchangers are widely used in industry, and analyses and optimizations of the performance of heat exchangers are important topics. In this paper, we define the concept of entropy resistance based on the entropy g...Heat exchangers are widely used in industry, and analyses and optimizations of the performance of heat exchangers are important topics. In this paper, we define the concept of entropy resistance based on the entropy generation analyses of a one-dimensional heat transfer process. With this concept, a two-stream parallel flow heat exchanger with viscous heating is analyzed and discussed. It is found that the minimization of entropy resistance always leads to the maximum heat transfer rate for the discussed two-stream parallel flow heat exchanger, while the minimizations of entropy generation rate, entropy generation numbers, and revised entropy generation number do not always.展开更多
When simulating or designing plate heat exchangers for multicomponent mixtures, most designers are often perplexed with the question on how to choose or estimate the physical property param- eters and hope to have a r...When simulating or designing plate heat exchangers for multicomponent mixtures, most designers are often perplexed with the question on how to choose or estimate the physical property param- eters and hope to have a reliable database that could be adopted. The commercial codes HYSYS supply the physical property package on over 1500 pure substances and over 16 000 binary coefficients for them. This work has briefly presented an efficient communication interface based on the Microsoft Component Object Model （COM） between inner plate heat exchanger simulation codes and the HYSYS package. The application of a custom-made HYSYS-COM interface has shown high efficiency, such as significant reduction of time needed for evaluating each process stream＇s properties. This automation method can be conveniently extended to further optimization study for any specific operation device such as heat transfers, columns, and other facilities.展开更多
Crude distillation unit(CDU)is regarded as the main energy consumer in the entire refinery process.In this paper,the process simulation software and the energy management software are used to simulate the flowsheet an...Crude distillation unit(CDU)is regarded as the main energy consumer in the entire refinery process.In this paper,the process simulation software and the energy management software are used to simulate the flowsheet and analyze the energy consumption,respectively.Stream data obtained from an existing CDU are applicable in the pinch analysis.To reduce the amount of cross-pinch heat transfer,three approaches of resequencing,repiping,and adding heat exchangers are adopted.Compared with the existing CDU,the results demonstrate that the inlet temperature of the furnace can be increased by 25.4℃,the amount of hot and cold utilities can be reduced by 15.1%and 19.6%,respectively.The economic evaluation indicates that the operating cost is saved by 8×106$/a,and the payback period is about 9 months.展开更多
Diesel hydrotreating unit(DHT)is an integral part of the refinery,and its energy-saving optimization is of great significance to the enterprise.In this paper,process simulation software and energy management software ...Diesel hydrotreating unit(DHT)is an integral part of the refinery,and its energy-saving optimization is of great significance to the enterprise.In this paper,process simulation software and energy management software are used to simulate the flowsheet and analyze the energy consumption,respectively.Stream data obtained from an existing DHT are applied in the pinch analysis for retrofitting the heat exchanger network(HEN)to achieve maximum energy utilization by using pinch analysis.Since DHT is constrained by pressure,the pressure factor is considered in the process of retrofitting.The results show that the amount of cross-pinch heat transfer is reduced,the inlet temperature of the furnace is increased by 55℃,and the amount of hot and cold utilities can be reduced by 70.25%and 50.16%,respectively.The economic evaluation indicates that the operating cost is saved by 4.39×10^(6)$/a,and the payback period is about 2 months.展开更多
As the key equipment of floating liquefied natural gas(FLNG)process,the performance of spiral wound heat exchanger(SWHE)influences operation costs and reliability of the whole system.The sea conditions destroy the fal...As the key equipment of floating liquefied natural gas(FLNG)process,the performance of spiral wound heat exchanger(SWHE)influences operation costs and reliability of the whole system.The sea conditions destroy the falling film flow state of the refrigeration and then affect the heat transfer performance of FLNG SWHE.In order to design and optimize the SWHE,a cryogenic experimental device of FLNG process and a numerical model of falling film flow have been constructed to study the effects of sea conditions on the falling film flow and heat transfer characteristics of SWHE.The cryogenic experimental results show that the pitching conditions have larger effects on the heat transfer performance than yawing.Under the pitching angle of 7°,the natural gas temperature and gaseous refrigerant temperature increase by 3.22°C and 7.42°C,respectively.The flow rates of refrigerant and feed natural gas have a great impact on the heat transfer performance of SWHE under pitching and compound sloshing conditions.When the tilt angle increases to 9°,the tube structure with outer diameter D=8 mm and pipe spacing S=4 mm is recommended to reduce the drying area of the pipe wall surface.展开更多
A study on heat transfer performance by thermal fluid coupling simulation for the fouling in a shell-tube heat exchanger used in engineering was presented. The coupling simulation was performed in a fluid and solid do...A study on heat transfer performance by thermal fluid coupling simulation for the fouling in a shell-tube heat exchanger used in engineering was presented. The coupling simulation was performed in a fluid and solid domains under three different fouling conditions: fouling inside the tube, fouling outside the tube, and fouling inside the shell. The flow field, temperature, and pressure distributions in the heat exchanger were solved numerically to analyze the heat transfer performance parameters, such as thermal resistance. It is found that the pressure drop of the heat exchanger and the thermal resistance of the tube wall increase by nearly 30% and 20%, respectively, when the relative fouling thickness reaches 10%. The fouling inside the tube has more impact on the heat transfer performance of the heat exchanger, and the fouling inside the shell has less impact.展开更多
To simultaneously improve the quantity and quality of heat recovery in a heat exchanger network(HEN),this study conducts a theory analysis based on the first and second laws of thermodynamics.Under the premise of maxi...To simultaneously improve the quantity and quality of heat recovery in a heat exchanger network(HEN),this study conducts a theory analysis based on the first and second laws of thermodynamics.Under the premise of maximizing the heat recovery quantity of HEN,Ġdiss is used as an evaluation index to optimize the quality of heat recovery.Meanwhile,the total annual cost(TAC)is considered as another optimization objective to ensure the economic feasibility of the HEN.A superstructure-based multi-objective mixed integer non-linear programming approach is put forward to solve the trade-off between minimizingĠdiss and minimizing TAC.This allows for the optimum HEN structure to be obtained.A well-studied example is solved to highlight the benefits of the proposed method.展开更多
The HTS current leads of superconducting magnets for large scale fusion devices and high energy particle colliders can reduce the power consumption for cooling by 2/3 compared with conventional leads. The resistive se...The HTS current leads of superconducting magnets for large scale fusion devices and high energy particle colliders can reduce the power consumption for cooling by 2/3 compared with conventional leads. The resistive sections of high-rated current leads are usually made of a heat exchanger cooled by gas flow. The supply of the cooling mass flow incurs more than 90% of the cooling cost for the HTS leads. The mass flow rate requirement depends not only on the length and material of the resistive heat exchanger, but also on the heat transfer coefficient and HEX surface, the joint resistance at the cold end of a sheet-stack HEX with a larger specific presented in the paper. The test results of efficiency can be achieved. and its cooling approach. The design and operation surface and a much smaller hydraulic diameter are an HTS lead optimized for 8 kA show that a 98.4%展开更多
In this investigation, a novel thermally coupled reactor （TCR） containing methyl formate （MF） production in the endothermic side and methanol synthesis in the exothermic side has been investigated. The interesting...In this investigation, a novel thermally coupled reactor （TCR） containing methyl formate （MF） production in the endothermic side and methanol synthesis in the exothermic side has been investigated. The interesting feature of this TCR is that productive methanol in the exothermic side could be recycled and used as feed of endothermic side for MF synthesis. Other important advantages of the proposed system are high production rates of hydrogen and MF. The configuration consists of two thermally coupled concentric tubular reactors. In these coupled reactors, autothermal system is obtained within the reactor. A steady-state heterogeneous model is used for simulation of the coupled reactor. The proposed model has been utilized to compare the performance of TCR with the conventional methanol reactor （CMR）. Noticeable enhancement can be obtained in the performance of the reactors. The influence of operational parameters is studied on reactor performance. The results show that coupling of these reactions could be feasible and beneficial. Experimental proof-of-concept is required to validate the operation of the novel reactor.展开更多
Using the inversion of the auto correlation function Toeplitz matrix of pseudo random binary sequence (PRBS) derived in this paper and the theorem of partitioned matrix inversion, a fast multistage least squares (FM...Using the inversion of the auto correlation function Toeplitz matrix of pseudo random binary sequence (PRBS) derived in this paper and the theorem of partitioned matrix inversion, a fast multistage least squares (FMLS) method is developed. Its performances are theoretically analyzed and digital simulation is made to compare FMLS with multistage least squares (MSLS), correlation least squares(COR LS) and LS for their computer speed and identification accuracy. Finally, FMLS is applied to identifying the heat excharger dynamics. It is shown that FMLS is a good and effective identification technique.展开更多
Mathematical model of cross type multi-stream plate-fin heat exchanger is established.Meanwhile,mean square error of accumulative heat load is normalized by dimensionless,and the equations of temperature-difference un...Mathematical model of cross type multi-stream plate-fin heat exchanger is established.Meanwhile,mean square error of accumulative heat load is normalized by dimensionless,and the equations of temperature-difference uniformity factor are improved.Evaluation factors above and performance of heat exchanger are compared and analyzed by taking aircraft three-stream condenser as an example.The results demonstrate that the mean square error of accumulative heat load is common result of total heat load and excess heat load between passages.So it can be influenced by passage arrangement,flow inlet parameters as well as flow patterns.Dimensionless parameter of mean square error of accumulative heat load can reflect the influence of passage arrangement to heat exchange performance and will not change dramatically with the variation of flow inlet parameters and flow patterns.Temperature-difference uniformity factor is influenced by passage arrangement and flow patterns.It remains basically unchanged under a certain range of flow inlet parameters.展开更多
The high-pressure hydrogenation heat exchanger is an impoltmlt equipment of the refinery, but it is exposed tothe problem of leakage caused by ammonium salt corrosion. Therefore, it is very important to evaluate the o...The high-pressure hydrogenation heat exchanger is an impoltmlt equipment of the refinery, but it is exposed tothe problem of leakage caused by ammonium salt corrosion. Therefore, it is very important to evaluate the operating statusof flae hydrogenation heat exchanger. To improve flae method for evaluating the operating status of hydrogenation heat ex-chmagers by using flae traditional method, flais paper proposes a new method for evaluating the operation of hydrogenationheat exchangers based on big data. To address flae noisy data common in flae industry, this paper proposes an automatednoisy interval detection algorithm. To deal with flae problem that the sensor parameters have voluminous and mtrelateddimensions, flais paper proposes a key parameter detection algorithm based on flae Pearson correlation coefficient. Finally,this paper presents a system-based health scoring algorithm based on PCA （Principal Component Analysis） to assist site op-erators in assessing the healfla of hydrogenation heat exchangers. The evaluation of flae operating status of flae hydrorefiningheat exchange device based on big data technology will help the operators to more accurately grasp the status of flae indus-trial system mad have positive guiding significance for the early warning offlae failure.展开更多
Heat transfer enhancement is used in many applications including heat exchangers, air conditioning, and refrigeration systems; hence many researchers have conducted experimental and numerical researches on heat transf...Heat transfer enhancement is used in many applications including heat exchangers, air conditioning, and refrigeration systems; hence many researchers have conducted experimental and numerical researches on heat transfer enhancement and have developed various techniques and methods. As a passive heat transfer technique, twisted tapes are widely used in various industries for their cost savings, lower maintenance requirements and the fact that they are easily set up. This paper introduces the principle of heat transfer enhancement of twisted tapes and reviews some of the experimental works done by researchers on this technique in recent years. The variously modified twisted tape inserts are widely researched and used to enhance heat transfer efficiency for heat exchangers. Twisted tapes perform better in low Re conditions and in square tubes. However, they could also cause higher pressure drops. Twisted tapes have great potential and profound implications if they can be used in traditional heat exchangers. Besides this, some correlations between the Nusselt number and friction factors are presented in this paper.展开更多
The experimental performance of small-sized ground-coupled heat pump (GCHP) is researched intensively. However, there are little data documenting the operation performance of existing large-sized GCHP system. We prese...The experimental performance of small-sized ground-coupled heat pump (GCHP) is researched intensively. However, there are little data documenting the operation performance of existing large-sized GCHP system. We presented the actual performance measurement of a GCHP installed for apartment buildings in Wuhan, Hubei province, P. R. China. The system was constructed with a closed vertical typed ground heat exchanger with a total pipe length of 32 000 m. During one year, various operating parameters were monitored, including the outdoor temperature, the flow rate, the electrical consumption, and the water temperature. The seasonal coefficients of performances of the heat pumps and the system based on the measured data were found to be 4.01 and 2.96 in the cooling season, and 3.54 and 2.86 in the heating season, respectively. The GCHP system was more economical than the air-source room air conditioner in the energy efficiency which was increased by 29% in cooling mode and 50% in heating mode. There was an obvious heat imbalance of soil between the injection rate and the extraction rate in the residential GCHP system operation.展开更多
The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the...The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 mm.Numerical simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow features.The results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were analyzed.In calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So heat transfer deterioration should be taken seriously in the design and safe operation of vaporizer PCHE. The study of this work clarified the local heat transfer and flow feature of supercritical methane in microchannel and contributed to the deep understanding of supercritical methane flow of the vaporization process in PCHE.展开更多
Liquid hydrogen storage and transportation is an effective method for large-scale transportation and utilization of hydrogen energy. Revealing the flow mechanism of cryogenic working fluid is the key to optimize heat ...Liquid hydrogen storage and transportation is an effective method for large-scale transportation and utilization of hydrogen energy. Revealing the flow mechanism of cryogenic working fluid is the key to optimize heat exchanger structure and hydrogen liquefaction process(LH2). The methods of cryogenic visualization experiment, theoretical analysis and numerical simulation are conducted to study the falling film flow characteristics with the effect of co-current gas flow in LH2spiral wound heat exchanger.The results show that the flow rate of mixed refrigerant has a great influence on liquid film spreading process, falling film flow pattern and heat transfer performance. The liquid film of LH2mixed refrigerant with column flow pattern can not uniformly and completely cover the tube wall surface. As liquid flow rate increases, the falling film flow pattern evolves into sheet-column flow and sheet flow, and liquid film completely covers the surface of tube wall. With the increase of shear effect of gas-phase mixed refrigerant in the same direction, the liquid film gradually becomes unstable, and the flow pattern eventually evolves into a mist flow.展开更多
基金funded by the National Natural Science Foundation of China(No.51806236,No.51806239)the Fundamental Research Funds for the Central Universities(No.2015XKMS059)+1 种基金Shaanxi Postdoctoral Fund Project(No.2018BSHEDZZ56)Foundation of Key Laboratory of Thermo-Fluid Science and Engineering(Xi'an Jiaotong University),Ministry of Education(No.KLTFSE2017KF01)。
文摘The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure drop.These results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.
基金supported by the National Natural Science Foundation of China(Grant No.51876194U1909216)General Research Project of Zhejiang Provincial Department of Education(Y201942785)。
文摘This study deals with the high-risk shell-and-tube heat exchangers in the effluent system of hydrogenation reaction of the petrochemical industry.The process of hydroprocessing reactor effluent system is simulated in Aspen Plus to study the distribution of corrosive medium in the three phases of oil,gas and water.The least-squares method is utilized to calculate the ammonium salt crystallization temperature.Then,the heat exchanger with risk of ammonium salt crystal corrosion is identified.Dynamic mathematical modeling of the heat exchanger is established to determine the transfer function.A temperature control system with proportional integral derivative(PID)control of the heat exchanger outlet is designed,and fuzzy logic is used to implement self-tuning of PID parameters.After MATLAB simulation,the results show the control system can achieve rapid control of the heat exchanger outlet temperature.
基金supported by funds of the Science Foundation within the Institute of Plasma Physics,Chinese Academy of Sciences(No.Y32ETY130B)
文摘The size of the heat exchanger is an important factor determining the dimensions of the cold box in helium cryogenic systems. In this paper, a counter-flow multi-stream plate-fin heat exchanger is optimized by means of a spatial interpolation method coupled with a hybrid genetic algorithm.Compared with empirical correlations, this spatial interpolation algorithm based on a kriging model can be adopted to more precisely predict the Colburn heat transfer factors and Fanning friction factors of offset-strip fins. Moreover, strict computational fluid dynamics simulations can be carried out to predict the heat transfer and friction performance in the absence of reliable experimental data. Within the constraints of heat exchange requirements, maximum allowable pressure drop, existing manufacturing techniques and structural strength, a mathematical model of an optimized design with discrete and continuous variables based on a hybrid genetic algorithm is established in order to minimize the volume. The results show that for the first-stage heat exchanger in the EAST refrigerator, the structural size could be decreased from the original2.200？×？0.600？×？0.627（m^3） to the optimized 1.854？×？0.420？×？0.340（m3）, with a large reduction in volume. The current work demonstrates that the proposed method could be a useful tool to achieve optimization in an actual engineering project during the practical design process.
文摘This Paper has first studied the simplified model of tubular heat exchanger which is widely used in the industry and other field.On the basis of reference 2,a new pole assignment design method of pro-cess control system with derivative control action is found.For the above system,the method and the for-mation which calculate the feedback matrix K and gain matrix L is given,and the simulation of the system is made.
基金supported by the National Natural Science Foundation of China(Grant No.51106082)the Tsinghua University Initiative Scientific Research Program
文摘Heat exchangers are widely used in industry, and analyses and optimizations of the performance of heat exchangers are important topics. In this paper, we define the concept of entropy resistance based on the entropy generation analyses of a one-dimensional heat transfer process. With this concept, a two-stream parallel flow heat exchanger with viscous heating is analyzed and discussed. It is found that the minimization of entropy resistance always leads to the maximum heat transfer rate for the discussed two-stream parallel flow heat exchanger, while the minimizations of entropy generation rate, entropy generation numbers, and revised entropy generation number do not always.
基金the National High Technology Research and Development Program of China(863 Program)(2006AA05Z216)the DUT Youth Fond
文摘When simulating or designing plate heat exchangers for multicomponent mixtures, most designers are often perplexed with the question on how to choose or estimate the physical property param- eters and hope to have a reliable database that could be adopted. The commercial codes HYSYS supply the physical property package on over 1500 pure substances and over 16 000 binary coefficients for them. This work has briefly presented an efficient communication interface based on the Microsoft Component Object Model （COM） between inner plate heat exchanger simulation codes and the HYSYS package. The application of a custom-made HYSYS-COM interface has shown high efficiency, such as significant reduction of time needed for evaluating each process stream＇s properties. This automation method can be conveniently extended to further optimization study for any specific operation device such as heat transfers, columns, and other facilities.
基金This work was supported by the National Natural Science Foundation of China(Grant:21878333).
文摘Crude distillation unit(CDU)is regarded as the main energy consumer in the entire refinery process.In this paper,the process simulation software and the energy management software are used to simulate the flowsheet and analyze the energy consumption,respectively.Stream data obtained from an existing CDU are applicable in the pinch analysis.To reduce the amount of cross-pinch heat transfer,three approaches of resequencing,repiping,and adding heat exchangers are adopted.Compared with the existing CDU,the results demonstrate that the inlet temperature of the furnace can be increased by 25.4℃,the amount of hot and cold utilities can be reduced by 15.1%and 19.6%,respectively.The economic evaluation indicates that the operating cost is saved by 8×106$/a,and the payback period is about 9 months.
基金This work was supported by the National Natural Science Foundation of China(Grant:21878333).
文摘Diesel hydrotreating unit(DHT)is an integral part of the refinery,and its energy-saving optimization is of great significance to the enterprise.In this paper,process simulation software and energy management software are used to simulate the flowsheet and analyze the energy consumption,respectively.Stream data obtained from an existing DHT are applied in the pinch analysis for retrofitting the heat exchanger network(HEN)to achieve maximum energy utilization by using pinch analysis.Since DHT is constrained by pressure,the pressure factor is considered in the process of retrofitting.The results show that the amount of cross-pinch heat transfer is reduced,the inlet temperature of the furnace is increased by 55℃,and the amount of hot and cold utilities can be reduced by 70.25%and 50.16%,respectively.The economic evaluation indicates that the operating cost is saved by 4.39×10^(6)$/a,and the payback period is about 2 months.
基金supported by the National Natural Science Foundation of China(U21B2085)the Natural Science Foundation of Shandong Province of China(ZR2021QE073)+2 种基金the China Postdoctoral Science Foundation(2021M703587)the Qingdao Postdoctoral Applied Research Project(qdyy20200096)Fundamental Research Funds for the Central Universities(20CX06076A)
文摘As the key equipment of floating liquefied natural gas(FLNG)process,the performance of spiral wound heat exchanger(SWHE)influences operation costs and reliability of the whole system.The sea conditions destroy the falling film flow state of the refrigeration and then affect the heat transfer performance of FLNG SWHE.In order to design and optimize the SWHE,a cryogenic experimental device of FLNG process and a numerical model of falling film flow have been constructed to study the effects of sea conditions on the falling film flow and heat transfer characteristics of SWHE.The cryogenic experimental results show that the pitching conditions have larger effects on the heat transfer performance than yawing.Under the pitching angle of 7°,the natural gas temperature and gaseous refrigerant temperature increase by 3.22°C and 7.42°C,respectively.The flow rates of refrigerant and feed natural gas have a great impact on the heat transfer performance of SWHE under pitching and compound sloshing conditions.When the tilt angle increases to 9°,the tube structure with outer diameter D=8 mm and pipe spacing S=4 mm is recommended to reduce the drying area of the pipe wall surface.
基金National Natural Science Foundation of China (21878102)
文摘A study on heat transfer performance by thermal fluid coupling simulation for the fouling in a shell-tube heat exchanger used in engineering was presented. The coupling simulation was performed in a fluid and solid domains under three different fouling conditions: fouling inside the tube, fouling outside the tube, and fouling inside the shell. The flow field, temperature, and pressure distributions in the heat exchanger were solved numerically to analyze the heat transfer performance parameters, such as thermal resistance. It is found that the pressure drop of the heat exchanger and the thermal resistance of the tube wall increase by nearly 30% and 20%, respectively, when the relative fouling thickness reaches 10%. The fouling inside the tube has more impact on the heat transfer performance of the heat exchanger, and the fouling inside the shell has less impact.
基金The authors would like to gratefully acknowledge the financial support provided by the National Key R&D Program of China(2017YFE0116300,2019YFE0122100)the Youth Innovation Promotion Association,CAS(2017353)the DNL Cooperation Fund,CAS(DNL202023).
文摘To simultaneously improve the quantity and quality of heat recovery in a heat exchanger network(HEN),this study conducts a theory analysis based on the first and second laws of thermodynamics.Under the premise of maximizing the heat recovery quantity of HEN,Ġdiss is used as an evaluation index to optimize the quality of heat recovery.Meanwhile,the total annual cost(TAC)is considered as another optimization objective to ensure the economic feasibility of the HEN.A superstructure-based multi-objective mixed integer non-linear programming approach is put forward to solve the trade-off between minimizingĠdiss and minimizing TAC.This allows for the optimum HEN structure to be obtained.A well-studied example is solved to highlight the benefits of the proposed method.
文摘The HTS current leads of superconducting magnets for large scale fusion devices and high energy particle colliders can reduce the power consumption for cooling by 2/3 compared with conventional leads. The resistive sections of high-rated current leads are usually made of a heat exchanger cooled by gas flow. The supply of the cooling mass flow incurs more than 90% of the cooling cost for the HTS leads. The mass flow rate requirement depends not only on the length and material of the resistive heat exchanger, but also on the heat transfer coefficient and HEX surface, the joint resistance at the cold end of a sheet-stack HEX with a larger specific presented in the paper. The test results of efficiency can be achieved. and its cooling approach. The design and operation surface and a much smaller hydraulic diameter are an HTS lead optimized for 8 kA show that a 98.4%
文摘In this investigation, a novel thermally coupled reactor （TCR） containing methyl formate （MF） production in the endothermic side and methanol synthesis in the exothermic side has been investigated. The interesting feature of this TCR is that productive methanol in the exothermic side could be recycled and used as feed of endothermic side for MF synthesis. Other important advantages of the proposed system are high production rates of hydrogen and MF. The configuration consists of two thermally coupled concentric tubular reactors. In these coupled reactors, autothermal system is obtained within the reactor. A steady-state heterogeneous model is used for simulation of the coupled reactor. The proposed model has been utilized to compare the performance of TCR with the conventional methanol reactor （CMR）. Noticeable enhancement can be obtained in the performance of the reactors. The influence of operational parameters is studied on reactor performance. The results show that coupling of these reactions could be feasible and beneficial. Experimental proof-of-concept is required to validate the operation of the novel reactor.
文摘Using the inversion of the auto correlation function Toeplitz matrix of pseudo random binary sequence (PRBS) derived in this paper and the theorem of partitioned matrix inversion, a fast multistage least squares (FMLS) method is developed. Its performances are theoretically analyzed and digital simulation is made to compare FMLS with multistage least squares (MSLS), correlation least squares(COR LS) and LS for their computer speed and identification accuracy. Finally, FMLS is applied to identifying the heat excharger dynamics. It is shown that FMLS is a good and effective identification technique.
文摘Mathematical model of cross type multi-stream plate-fin heat exchanger is established.Meanwhile,mean square error of accumulative heat load is normalized by dimensionless,and the equations of temperature-difference uniformity factor are improved.Evaluation factors above and performance of heat exchanger are compared and analyzed by taking aircraft three-stream condenser as an example.The results demonstrate that the mean square error of accumulative heat load is common result of total heat load and excess heat load between passages.So it can be influenced by passage arrangement,flow inlet parameters as well as flow patterns.Dimensionless parameter of mean square error of accumulative heat load can reflect the influence of passage arrangement to heat exchange performance and will not change dramatically with the variation of flow inlet parameters and flow patterns.Temperature-difference uniformity factor is influenced by passage arrangement and flow patterns.It remains basically unchanged under a certain range of flow inlet parameters.
基金supported by the National Natural Science Foundation of China (U1534201)the open project of Science and Technology on Communication Networks Laboratorythe National Key Research and Development Program of China (2016QY01W0200)
文摘The high-pressure hydrogenation heat exchanger is an impoltmlt equipment of the refinery, but it is exposed tothe problem of leakage caused by ammonium salt corrosion. Therefore, it is very important to evaluate the operating statusof flae hydrogenation heat exchanger. To improve flae method for evaluating the operating status of hydrogenation heat ex-chmagers by using flae traditional method, flais paper proposes a new method for evaluating the operation of hydrogenationheat exchangers based on big data. To address flae noisy data common in flae industry, this paper proposes an automatednoisy interval detection algorithm. To deal with flae problem that the sensor parameters have voluminous and mtrelateddimensions, flais paper proposes a key parameter detection algorithm based on flae Pearson correlation coefficient. Finally,this paper presents a system-based health scoring algorithm based on PCA （Principal Component Analysis） to assist site op-erators in assessing the healfla of hydrogenation heat exchangers. The evaluation of flae operating status of flae hydrorefiningheat exchange device based on big data technology will help the operators to more accurately grasp the status of flae indus-trial system mad have positive guiding significance for the early warning offlae failure.
文摘Heat transfer enhancement is used in many applications including heat exchangers, air conditioning, and refrigeration systems; hence many researchers have conducted experimental and numerical researches on heat transfer enhancement and have developed various techniques and methods. As a passive heat transfer technique, twisted tapes are widely used in various industries for their cost savings, lower maintenance requirements and the fact that they are easily set up. This paper introduces the principle of heat transfer enhancement of twisted tapes and reviews some of the experimental works done by researchers on this technique in recent years. The variously modified twisted tape inserts are widely researched and used to enhance heat transfer efficiency for heat exchangers. Twisted tapes perform better in low Re conditions and in square tubes. However, they could also cause higher pressure drops. Twisted tapes have great potential and profound implications if they can be used in traditional heat exchangers. Besides this, some correlations between the Nusselt number and friction factors are presented in this paper.
基金Funded by National Natural Science Foundation of China (Grant No. 51078160)
文摘The experimental performance of small-sized ground-coupled heat pump (GCHP) is researched intensively. However, there are little data documenting the operation performance of existing large-sized GCHP system. We presented the actual performance measurement of a GCHP installed for apartment buildings in Wuhan, Hubei province, P. R. China. The system was constructed with a closed vertical typed ground heat exchanger with a total pipe length of 32 000 m. During one year, various operating parameters were monitored, including the outdoor temperature, the flow rate, the electrical consumption, and the water temperature. The seasonal coefficients of performances of the heat pumps and the system based on the measured data were found to be 4.01 and 2.96 in the cooling season, and 3.54 and 2.86 in the heating season, respectively. The GCHP system was more economical than the air-source room air conditioner in the energy efficiency which was increased by 29% in cooling mode and 50% in heating mode. There was an obvious heat imbalance of soil between the injection rate and the extraction rate in the residential GCHP system operation.
基金provided by Science and Technology Development Project of Jilin Province(No.20230101338JC)。
文摘The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 mm.Numerical simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow features.The results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were analyzed.In calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So heat transfer deterioration should be taken seriously in the design and safe operation of vaporizer PCHE. The study of this work clarified the local heat transfer and flow feature of supercritical methane in microchannel and contributed to the deep understanding of supercritical methane flow of the vaporization process in PCHE.
基金supported by the National Natural Science Foundation of China(52304067,62273213)the Natural Science Foundation of Shandong Province of China(ZR2021QE073)+1 种基金the Natural Science Foundation of Shandong Province for Innovation and Development Joint Funds(ZR2022LZH001)the China Postdoctoral Science Foundation(2023M732111)。
文摘Liquid hydrogen storage and transportation is an effective method for large-scale transportation and utilization of hydrogen energy. Revealing the flow mechanism of cryogenic working fluid is the key to optimize heat exchanger structure and hydrogen liquefaction process(LH2). The methods of cryogenic visualization experiment, theoretical analysis and numerical simulation are conducted to study the falling film flow characteristics with the effect of co-current gas flow in LH2spiral wound heat exchanger.The results show that the flow rate of mixed refrigerant has a great influence on liquid film spreading process, falling film flow pattern and heat transfer performance. The liquid film of LH2mixed refrigerant with column flow pattern can not uniformly and completely cover the tube wall surface. As liquid flow rate increases, the falling film flow pattern evolves into sheet-column flow and sheet flow, and liquid film completely covers the surface of tube wall. With the increase of shear effect of gas-phase mixed refrigerant in the same direction, the liquid film gradually becomes unstable, and the flow pattern eventually evolves into a mist flow.
