Abstract A mathematical model was constructed to estimate the performance of an MFI-membrane reactor used for Fischer–Tropsch synthesis to produce a mixture of liquid hydrocarbons. In order to accurately evaluate the reactor’s performance a parametric study was performed. Under certain operational conditions, such as the total initial pressure in the reaction zone (1–4 MPa) and the hydrogen/carbon monoxide ratio (H2/CO: 1 to 2) on the performance of the studied reactor. The selectivity (productivity) of the hydrocarbon products (S i ), the quantity of hydrocarbons permiated (θ i ) and the separation factors of each space (α i ) were predicted. With increasing pressure, it is observed that θ CO and θ H 2 ${theta }_{{H}_{2}}$ are decreasing from 0.62 to 0.45 and from 0.55 to 0.49 respectively. However, as the H2/CO ratio rises, this measurement shows a slight increase. Aside from, the separation factors of the majority of the current species are unaffected by the H2/CO ratio increasing, while the separation factors of carbon monoxide and hydrogen are increasing. Similarly the selectivity of water, methane, carbon dioxide and ethane increases with increasing H2/CO ratio. Based on these findings it is revealed that the membrane can enable permeability for all species present in the products mixture with varying separation factors, and that the ability to separate species other than water from the reaction side is essentially non-existent.
摘要 建立了一个数学模型，以估算用于费托合成生产液态烃混合物的 MFI 膜反应器的性能。为了准确评估反应器的性能，进行了参数研究。在特定的操作条件下，如反应区的总初始压力（1-4 兆帕）和氢气/一氧化碳比率（H2/CO：1 至 2），会对所研究的反应器的性能产生影响。预测了碳氢化合物产物的选择性（生产率）（S i ）、碳氢化合物的过氧化量（θ i ）和各空间的分离系数（α i ）。随着压力的增加，θ CO 和 θ H 2 ${theta }_{H}_{2}}$ 分别从 0.62 降至 0.45 和从 0.55 降至 0.49。不过，随着 H2/CO 比值的上升，这一测量值略有增加。除此以外，当前大多数物种的分离因数不受 H2/CO 比率增加的影响，而一氧化碳和氢气的分离因数却在增加。同样，水、甲烷、二氧化碳和乙烷的选择性也随着 H2/CO 比率的增加而增加。根据这些发现，膜可以使产品混合物中存在的所有物质都具有不同的渗透性，分离因子也各不相同，而从反应侧分离水以外物质的能力基本上不存在。
{"title":"Mathematical modeling and evaluation of permeation and membrane separation performance for Fischer–Tropsch products in a hydrophilic membrane reactor","authors":"Dounia Alihellal, Sabrina Hadjam, Lemnouer Chibane","doi":"10.1515/cppm-2023-0016","DOIUrl":"https://doi.org/10.1515/cppm-2023-0016","url":null,"abstract":"Abstract A mathematical model was constructed to estimate the performance of an MFI-membrane reactor used for Fischer–Tropsch synthesis to produce a mixture of liquid hydrocarbons. In order to accurately evaluate the reactor’s performance a parametric study was performed. Under certain operational conditions, such as the total initial pressure in the reaction zone (1–4 MPa) and the hydrogen/carbon monoxide ratio (H2/CO: 1 to 2) on the performance of the studied reactor. The selectivity (productivity) of the hydrocarbon products (S i ), the quantity of hydrocarbons permiated (θ i ) and the separation factors of each space (α i ) were predicted. With increasing pressure, it is observed that θ CO and θ H 2 ${theta }_{{H}_{2}}$ are decreasing from 0.62 to 0.45 and from 0.55 to 0.49 respectively. However, as the H2/CO ratio rises, this measurement shows a slight increase. Aside from, the separation factors of the majority of the current species are unaffected by the H2/CO ratio increasing, while the separation factors of carbon monoxide and hydrogen are increasing. Similarly the selectivity of water, methane, carbon dioxide and ethane increases with increasing H2/CO ratio. Based on these findings it is revealed that the membrane can enable permeability for all species present in the products mixture with varying separation factors, and that the ability to separate species other than water from the reaction side is essentially non-existent.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139211953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Gas sweetening with an aqueous solution of diethanolamine is a crucial and common process in natural gas processing. However, the process, particularly in the solvent regeneration section, consumes a substantial amount of energy, significantly escalating the cost of gas. This paper presents a simulation and optimization of an existing natural gas refinery plant using a lean vapor compression method. The simulation results indicate that the current process requires 2.73 GJ/tacid gas for solvent regeneration, with exergy destruction of 14,120.59 kW in the solvent regeneration section. The total annualized cost for the current process is 11.68 M$. A modified scheme is proposed to address the issue of high energy consumption and the associated costs. The proposed scheme demonstrates significant improvements in the aforementioned parameters. Specifically, energy for solvent regeneration, exergy destruction in the solvent regeneration section, total annualized cost, and cost of gas are reduced by 16.12 %, 25.04 %, 20.97 %, and 20 % compared to the current process, respectively. These improvements enhance the thermoeconomic indexes, making the proposed scheme a viable and cost-effective alternative to the current process.
{"title":"Energy, exergy, economic, and environmental analysis of natural gas sweetening process using lean vapor compression: a comparison study","authors":"Xiujun Sun, Lizhi Yuan","doi":"10.1515/cppm-2023-0040","DOIUrl":"https://doi.org/10.1515/cppm-2023-0040","url":null,"abstract":"Abstract Gas sweetening with an aqueous solution of diethanolamine is a crucial and common process in natural gas processing. However, the process, particularly in the solvent regeneration section, consumes a substantial amount of energy, significantly escalating the cost of gas. This paper presents a simulation and optimization of an existing natural gas refinery plant using a lean vapor compression method. The simulation results indicate that the current process requires 2.73 GJ/tacid gas for solvent regeneration, with exergy destruction of 14,120.59 kW in the solvent regeneration section. The total annualized cost for the current process is 11.68 M$. A modified scheme is proposed to address the issue of high energy consumption and the associated costs. The proposed scheme demonstrates significant improvements in the aforementioned parameters. Specifically, energy for solvent regeneration, exergy destruction in the solvent regeneration section, total annualized cost, and cost of gas are reduced by 16.12 %, 25.04 %, 20.97 %, and 20 % compared to the current process, respectively. These improvements enhance the thermoeconomic indexes, making the proposed scheme a viable and cost-effective alternative to the current process.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139243050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Spontaneous condensation occurs due to high steam speeds, leading to droplets in the stream that not only decrease performance but also hazard the security of the nozzle. This study aims to predict the position and size of suitable injected water droplets due to reduced losses due to liquid mass fraction. Firstly, the model of steam flow has been confirmed by experimental data using the Eulerian–Eulerian approach in Moore’s nozzle B. Then, the flow turbulence caused by phase change is modelled by k–w sst model. Then, the injection has applied in three sizes (coarse, medium, and fine) at four different positions of the nozzle and has analysed, which according to the findings of fine droplet size, has led to an enhancement in Mach number and on the other hand, injection in nucleation zone has resulted in a 7 % and 3 % reduction in wetness losses for the radius of coarse and fine droplets, respectively. It is predicted that the nucleation rate will decrease the smaller the injected droplets are in the nucleation region. Injection with a number droplet of 1.015 × 1018 and a radius of 0.013 (μm) in the nucleation zone of 10 mm after the throat increased by 4.5 % of Mach number.
{"title":"Numerical investigation of liquid mass fraction and condensation shock of wet-steam flow through convergence-divergence nozzle using strategic water droplets injection","authors":"Yijun Xu, Xuan Zhang, Yu Bai, Xin Li","doi":"10.1515/cppm-2023-0043","DOIUrl":"https://doi.org/10.1515/cppm-2023-0043","url":null,"abstract":"Abstract Spontaneous condensation occurs due to high steam speeds, leading to droplets in the stream that not only decrease performance but also hazard the security of the nozzle. This study aims to predict the position and size of suitable injected water droplets due to reduced losses due to liquid mass fraction. Firstly, the model of steam flow has been confirmed by experimental data using the Eulerian–Eulerian approach in Moore’s nozzle B. Then, the flow turbulence caused by phase change is modelled by k–w sst model. Then, the injection has applied in three sizes (coarse, medium, and fine) at four different positions of the nozzle and has analysed, which according to the findings of fine droplet size, has led to an enhancement in Mach number and on the other hand, injection in nucleation zone has resulted in a 7 % and 3 % reduction in wetness losses for the radius of coarse and fine droplets, respectively. It is predicted that the nucleation rate will decrease the smaller the injected droplets are in the nucleation region. Injection with a number droplet of 1.015 × 1018 and a radius of 0.013 (μm) in the nucleation zone of 10 mm after the throat increased by 4.5 % of Mach number.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139254537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Unstable processes are challenging to control because they have one or more positive poles that produce unrestrained dynamic activity. Controlling such unstable plants becomes more challenging with the occurrence of the delay. This article presents a novel direct synthesis based sliding mode controller design for unstable second order plus dead-time processes. A sliding surface with three parameters has been considered. The continuous control law, which is responsible for maintaining the system mode to the desired sliding surface mode, has been obtained using the direct synthesis approach. The discontinuous control law parameters have been obtained using the differential evolution optimization technique. A desired reference model is considered for the direct synthesis method, and an objective function is constituted in terms of performance measure (integral absolute error) and control effort measure (total variation of controller output) for the optimization approach. Illustrative examples show the superiority of the proposed controller design method over recently reported literature, especially in terms of load rejection. The proposed controller approach is further extended to control the temperature of a nonlinear chemical reactor. Furthermore, the robustness of the proposed controller is also investigated for plant parametric uncertainty.
{"title":"Direct synthesis based sliding mode controller design for unstable second order with dead-time processes with its application on continuous stirred tank reactor","authors":"Mohammed Hasmat Ali, Md. Nishat Anwar","doi":"10.1515/cppm-2023-0062","DOIUrl":"https://doi.org/10.1515/cppm-2023-0062","url":null,"abstract":"Abstract Unstable processes are challenging to control because they have one or more positive poles that produce unrestrained dynamic activity. Controlling such unstable plants becomes more challenging with the occurrence of the delay. This article presents a novel direct synthesis based sliding mode controller design for unstable second order plus dead-time processes. A sliding surface with three parameters has been considered. The continuous control law, which is responsible for maintaining the system mode to the desired sliding surface mode, has been obtained using the direct synthesis approach. The discontinuous control law parameters have been obtained using the differential evolution optimization technique. A desired reference model is considered for the direct synthesis method, and an objective function is constituted in terms of performance measure (integral absolute error) and control effort measure (total variation of controller output) for the optimization approach. Illustrative examples show the superiority of the proposed controller design method over recently reported literature, especially in terms of load rejection. The proposed controller approach is further extended to control the temperature of a nonlinear chemical reactor. Furthermore, the robustness of the proposed controller is also investigated for plant parametric uncertainty.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139271602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Microfluidic technology has garnered growing interest in diverse domains. The efficacy and precision of microfluidic devices are significantly influenced by micromixing processes. Micromixers, comprising microchannels designed to blend fluids within a confined space and limited flow pathway, constitute indispensable components of microfluidic systems. Among these components, the micromixer stands out as a critical element, tasked with achieving maximal mixing efficiency while imposing minimal pressure drop. This paper focusses on the numerical and experimental study the baffle-based split and recombine chamber (B-SARC) micromixers. The models of a curved wavy micromixer (without baffle) and the baffle-based split and recombine chamber (B-SARC) micromixers with three baffles such as square, triangular and teardrop shaped baffles been developed using COMSOL Multiphysics software. The mixing performance analysis has been carried out by studying the mixing index and pressure drop. The influence of baffle shapes i.e. square, triangular and teardrop shaped baffles of aspect ratio 1, 1.5 and 2 on mixing performance analysis has been investigated numerically, for widespread assortment of Reynolds numbers (Re) lies between 0.1 and 90. The polydimethylsiloxane (PDMS) baffle-based split and recombine chamber (B-SARC) micromixers have been fabricated. Further, the experimental analysis has been carried out. The experimental analysis for pressure drop as well as mixing index has been performed. A good agreement has been observed between experimental and computational results which leads to validation of the computational results. The results revel the role of diffusion at lower Reynolds numbers and the production of derivative flows owing to advection at higher Reynolds numbers within the considered range of Re.
{"title":"Numerical and experimental study of the baffle-based split and recombine chamber (B-SARC) micromixers","authors":"Sanjay A. Pawar, Vimal Kumar Chouksey","doi":"10.1515/cppm-2023-0053","DOIUrl":"https://doi.org/10.1515/cppm-2023-0053","url":null,"abstract":"Abstract Microfluidic technology has garnered growing interest in diverse domains. The efficacy and precision of microfluidic devices are significantly influenced by micromixing processes. Micromixers, comprising microchannels designed to blend fluids within a confined space and limited flow pathway, constitute indispensable components of microfluidic systems. Among these components, the micromixer stands out as a critical element, tasked with achieving maximal mixing efficiency while imposing minimal pressure drop. This paper focusses on the numerical and experimental study the baffle-based split and recombine chamber (B-SARC) micromixers. The models of a curved wavy micromixer (without baffle) and the baffle-based split and recombine chamber (B-SARC) micromixers with three baffles such as square, triangular and teardrop shaped baffles been developed using COMSOL Multiphysics software. The mixing performance analysis has been carried out by studying the mixing index and pressure drop. The influence of baffle shapes i.e. square, triangular and teardrop shaped baffles of aspect ratio 1, 1.5 and 2 on mixing performance analysis has been investigated numerically, for widespread assortment of Reynolds numbers (Re) lies between 0.1 and 90. The polydimethylsiloxane (PDMS) baffle-based split and recombine chamber (B-SARC) micromixers have been fabricated. Further, the experimental analysis has been carried out. The experimental analysis for pressure drop as well as mixing index has been performed. A good agreement has been observed between experimental and computational results which leads to validation of the computational results. The results revel the role of diffusion at lower Reynolds numbers and the production of derivative flows owing to advection at higher Reynolds numbers within the considered range of Re.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135776661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Extensive research has been done to provide energy from renewable sources due to climate change, global warming and limited fossil resources. Due to its low energy density, biomass is one of the renewable energy sources that is not used directly. Biomass is a clean, renewable energy source with a zero carbon dioxide release rate. Gasification is a chemical process that converts carbonaceous materials like biomass into gaseous fuels or useful chemical raw materials for gasification to occur in an oxygen-deficient environment with a requirement for heat which needs mediators for the reaction, like air, oxygen, superheated steam, or a combination of these. This study has been conducted to investigate the impact of the type of biomass feed on the production of syngas using the steam gasification method. Therefore, rice husk, wood chip, wood residue, coffee bean and green waste are considered, and the impact of gasification temperature and steam to biomass ratio (S/B) is investigated. According to the results, wood residue produces the most hydrogen compared to other feeds. With the increase of gasification temperature, an increase-decrease trend in the mass flow rate of hydrogen and an increase trend in the mass flow rate of carbon monoxide can be seen. The hydrogen produced in wood residue is 855 kg/h at S/B of 0.2 as well as a gasification temperature of 1200 °C. The lowest mass flow rate of hydrogen and carbon monoxide is related to green waste feed.
{"title":"Numerical investigation of different biomass feedstock on syngas production using steam gasification and thermodynamic analysis","authors":"Hao Wu, Liping Zhang, Bing Xiao","doi":"10.1515/cppm-2023-0056","DOIUrl":"https://doi.org/10.1515/cppm-2023-0056","url":null,"abstract":"Abstract Extensive research has been done to provide energy from renewable sources due to climate change, global warming and limited fossil resources. Due to its low energy density, biomass is one of the renewable energy sources that is not used directly. Biomass is a clean, renewable energy source with a zero carbon dioxide release rate. Gasification is a chemical process that converts carbonaceous materials like biomass into gaseous fuels or useful chemical raw materials for gasification to occur in an oxygen-deficient environment with a requirement for heat which needs mediators for the reaction, like air, oxygen, superheated steam, or a combination of these. This study has been conducted to investigate the impact of the type of biomass feed on the production of syngas using the steam gasification method. Therefore, rice husk, wood chip, wood residue, coffee bean and green waste are considered, and the impact of gasification temperature and steam to biomass ratio (S/B) is investigated. According to the results, wood residue produces the most hydrogen compared to other feeds. With the increase of gasification temperature, an increase-decrease trend in the mass flow rate of hydrogen and an increase trend in the mass flow rate of carbon monoxide can be seen. The hydrogen produced in wood residue is 855 kg/h at S/B of 0.2 as well as a gasification temperature of 1200 °C. The lowest mass flow rate of hydrogen and carbon monoxide is related to green waste feed.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135776660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Partial Least Squares (PLS) is a supervised multivariate statistical/machine learning technique, which is used for classification and identification/authentication of a variety of operating conditions in tomato juice concentrator/evaporator, yeast fermentation bioreactor and fluid catalytic cracking process plants. Data for the three processes were generated pertaining to different operating conditions (for each of them) including faulty ones by simulating their mechanistic models over 25 h. The simulated data at transient conditions were chosen for further processing. They were divided into training and testing data pools. After training, the developed PLS model could classify various process operating conditions 100 % accurately and identify unknown process operating conditions (simulated using training pool with certain degree of variations in them) pertaining to the processes.
{"title":"Classification and authentication of operating conditions in different processes using Partial Least Squares","authors":"Rubal Chandra, Madhusree Kundu","doi":"10.1515/cppm-2023-0074","DOIUrl":"https://doi.org/10.1515/cppm-2023-0074","url":null,"abstract":"Abstract Partial Least Squares (PLS) is a supervised multivariate statistical/machine learning technique, which is used for classification and identification/authentication of a variety of operating conditions in tomato juice concentrator/evaporator, yeast fermentation bioreactor and fluid catalytic cracking process plants. Data for the three processes were generated pertaining to different operating conditions (for each of them) including faulty ones by simulating their mechanistic models over 25 h. The simulated data at transient conditions were chosen for further processing. They were divided into training and testing data pools. After training, the developed PLS model could classify various process operating conditions 100 % accurately and identify unknown process operating conditions (simulated using training pool with certain degree of variations in them) pertaining to the processes.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135217524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The generator energy consumption in the renewable refrigeration cycles is supplied by solar energy, geothermal energy and waste heat. The thermal energy of low grade can be utilized to superheat the vapour in a generator of the refrigeration cycle. The effect of primary flow superheating was examined on the renewable refrigeration cycle performance using the wet steam model in the ejector. The vapour’s degree of superheating was selected in the 0–100 K range. The superheating level effects were investigated on parameters (wet steam, entrainment ratio, energy consumption, COP, second law efficiency and exergy destruction). The aim of this study is a comprehensive evaluation of the effect of superheat on the ejector refrigeration cycle and the flow behavior in the steam ejector simultaneously. The results represented that superheating the inlet steam in the primary nozzle weakens the spontaneous condensation intensity and delays the condensation shock, the combining process between the secondary flow and the primary flow is improved, and the entrainment ratio is increased, the generator energy consumption and the efficiency of the second law are decreased, the exergy destruction in the ejector is reduced, and the total exergy destruction of the refrigeration cycle is increased. Considering the second law efficiency, COP, the entrainment ratio and the energy consumption, a temperature of 40° of the superheat was achieved as the best degree of the superheat in this cycle that in comparison to the state without superheating, the entrainment ratio and COP are increased by 4.4 % and 1 %, the second law efficiency and the generator energy consumption are reduced by 19.5 % and 1.6 %, respectively.
{"title":"Energy and exergy analysis of primary steam superheating effects on the steam ejector applied in the solar renewable refrigeration cycle in the presence of spontaneous nucleation","authors":"Han zhang Wang","doi":"10.1515/cppm-2023-0038","DOIUrl":"https://doi.org/10.1515/cppm-2023-0038","url":null,"abstract":"Abstract The generator energy consumption in the renewable refrigeration cycles is supplied by solar energy, geothermal energy and waste heat. The thermal energy of low grade can be utilized to superheat the vapour in a generator of the refrigeration cycle. The effect of primary flow superheating was examined on the renewable refrigeration cycle performance using the wet steam model in the ejector. The vapour’s degree of superheating was selected in the 0–100 K range. The superheating level effects were investigated on parameters (wet steam, entrainment ratio, energy consumption, COP, second law efficiency and exergy destruction). The aim of this study is a comprehensive evaluation of the effect of superheat on the ejector refrigeration cycle and the flow behavior in the steam ejector simultaneously. The results represented that superheating the inlet steam in the primary nozzle weakens the spontaneous condensation intensity and delays the condensation shock, the combining process between the secondary flow and the primary flow is improved, and the entrainment ratio is increased, the generator energy consumption and the efficiency of the second law are decreased, the exergy destruction in the ejector is reduced, and the total exergy destruction of the refrigeration cycle is increased. Considering the second law efficiency, COP, the entrainment ratio and the energy consumption, a temperature of 40° of the superheat was achieved as the best degree of the superheat in this cycle that in comparison to the state without superheating, the entrainment ratio and COP are increased by 4.4 % and 1 %, the second law efficiency and the generator energy consumption are reduced by 19.5 % and 1.6 %, respectively.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135216076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this paper, a thermodynamic study of the combination of Concentrated Photovoltaic Thermal (CPVT) and Multi Effect Desalination (MED) system was conducted. CPVT produces electricity, and the heat produced in CPVT is used for the MED system. Engineering Equation Software (EES) was utilized to simulate this system. The effect of CPVT parameters (area, concentration ratio, and average solar radiation) and MED parameters (effect number and temperature of heating steam) were investigated on the produced heat, produced power, exergy destruction, total mass flow rate (FR) of desalinated water, total FR of feed water, heating steam FR and total brine FR. The range of changes for CPVT surface, concentration ratio, and average solar radiation was considered from 2000 m 2 to 20000 m 2 , from 5 to 15 and from 400 W/m 2 to 1100 W/m 2 , respectively. Based on obtained results, as the surface area of the solar panel, the ratio of concentration, and average solar radiation increase, the heat produced increases. Transferring this heat to the MED unit increases the total FR of desalinated water. But it has no significant effect on the Gain ratio (GOR). As the surface area of the solar panel increases from 10000 m 2 to 12000 m 2 , the average radiation intensity increases from 800 W/m 2 to 1000 W/m 2 , and the concentration ratio increases from 10 to 12 in effect the number of 4 and steam temperature of 70 °C, the total mass FR of desalinated water increases by 29 %, 23 %, and 20 %, respectively.
{"title":"Solar driven desalination system for power and desalination water production by concentrated PVT and MED system","authors":"Xiaochuan Zhang","doi":"10.1515/cppm-2023-0044","DOIUrl":"https://doi.org/10.1515/cppm-2023-0044","url":null,"abstract":"Abstract In this paper, a thermodynamic study of the combination of Concentrated Photovoltaic Thermal (CPVT) and Multi Effect Desalination (MED) system was conducted. CPVT produces electricity, and the heat produced in CPVT is used for the MED system. Engineering Equation Software (EES) was utilized to simulate this system. The effect of CPVT parameters (area, concentration ratio, and average solar radiation) and MED parameters (effect number and temperature of heating steam) were investigated on the produced heat, produced power, exergy destruction, total mass flow rate (FR) of desalinated water, total FR of feed water, heating steam FR and total brine FR. The range of changes for CPVT surface, concentration ratio, and average solar radiation was considered from 2000 m 2 to 20000 m 2 , from 5 to 15 and from 400 W/m 2 to 1100 W/m 2 , respectively. Based on obtained results, as the surface area of the solar panel, the ratio of concentration, and average solar radiation increase, the heat produced increases. Transferring this heat to the MED unit increases the total FR of desalinated water. But it has no significant effect on the Gain ratio (GOR). As the surface area of the solar panel increases from 10000 m 2 to 12000 m 2 , the average radiation intensity increases from 800 W/m 2 to 1000 W/m 2 , and the concentration ratio increases from 10 to 12 in effect the number of 4 and steam temperature of 70 °C, the total mass FR of desalinated water increases by 29 %, 23 %, and 20 %, respectively.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135365751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Nowadays, the use of equipment with little pollution is essential due to the increase in the planet’s temperature. Ejectors are considered one of the equipment with no pollution, and their failure rate is low due to the lack of moving parts. Also, scholars have recently focused on improving the efficiency of industrial equipment. The use of accurate modeling is required to improve steam ejector performance. In a steam ejector, non-equilibrium condensation creates a two-phase flow situation. The wet steam model, used in this study, characterizes this two-phase flow. The study’s objective was to compare this wet steam model with the dry gas model. In the wet steam model, the liquid mass fraction is 0.25, and its calculated entrainment ratio is lower than the dry gas model, closely matching experimental observations. The dry gas model reaches a maximum Mach number of about 5, while the wet steam model approximates 4. A significant temperature difference exists between the two models, with the dry gas model indicating lower temperatures compared to the wet steam model. Diagonal shocks and expansion waves are evident in the mixing chamber, fixed cross-section, and diffuser. These phenomena occur with greater intensity and a slight delay in the wet steam model compared to the dry gas model.
{"title":"Numerical investigation of the effects of dry gas model and wet steam model in solar-driven refrigeration ejector system","authors":"Honglun Cong, Jiao Zhang","doi":"10.1515/cppm-2023-0042","DOIUrl":"https://doi.org/10.1515/cppm-2023-0042","url":null,"abstract":"Abstract Nowadays, the use of equipment with little pollution is essential due to the increase in the planet’s temperature. Ejectors are considered one of the equipment with no pollution, and their failure rate is low due to the lack of moving parts. Also, scholars have recently focused on improving the efficiency of industrial equipment. The use of accurate modeling is required to improve steam ejector performance. In a steam ejector, non-equilibrium condensation creates a two-phase flow situation. The wet steam model, used in this study, characterizes this two-phase flow. The study’s objective was to compare this wet steam model with the dry gas model. In the wet steam model, the liquid mass fraction is 0.25, and its calculated entrainment ratio is lower than the dry gas model, closely matching experimental observations. The dry gas model reaches a maximum Mach number of about 5, while the wet steam model approximates 4. A significant temperature difference exists between the two models, with the dry gas model indicating lower temperatures compared to the wet steam model. Diagonal shocks and expansion waves are evident in the mixing chamber, fixed cross-section, and diffuser. These phenomena occur with greater intensity and a slight delay in the wet steam model compared to the dry gas model.","PeriodicalId":9935,"journal":{"name":"Chemical Product and Process Modeling","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136078259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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