Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)最新文献

{"title":"Prediction of Performance for an Ejector Refrigeration Cycle Working\u0000with R245fa Using Artificial Neural Network","authors":"Mehdi Bencharif, S. Croquer, Sébastien Poncet, S. Zid, H. Nesreddine","doi":"10.11159/icffts20.120","DOIUrl":"https://doi.org/10.11159/icffts20.120","url":null,"abstract":"In this paper, an artificial neural network (ANN) model is used to predict the performance parameters of an ejector refrigeration cycle working with R245fa. Three approaches are used to achieve this objective: experimental analysis, thermodynamic modeling, and artificial neural network. Fourteen parameters were collected from eight numerical or experimental studies. The ANN input parameters include geometric features (Dcol, Dprimout, NXP, Dcas, Lcas, Dout, Ldiff) and operating conditions (Pprim, Tprim, Psec, Tsec, Tcond), while the outputs are the ejector performance metrics. A computer program has been written in MATLAB using a neural network toolbox. The mean-square error (MSE) and the linear coefficient of correlation (R) have been chosen as metrics to evaluate the performance function and accuracy of the ANN model. In terms of the limiting compression ratio (Pcr) and entrainment ratio (ω), the ANN deviates by 3.63 (%) and 1.52 (%) respectively relative to the experimental data and by -4.01 (%) and -6.17 (%) relative to the thermodynamic model predictions.","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"159 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124467549","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}

{"title":"Carbon Dioxide – Based Energy Storage System: a Thermodynamic\u0000Approach","authors":"J. Lamotte, S. Poncet","doi":"10.11159/icffts20.126","DOIUrl":"https://doi.org/10.11159/icffts20.126","url":null,"abstract":"Extended Abstract Compressed gas energy storage systems attract progressively the attention of researchers. Coupled to renewable energy sources, they enable to align the electrical energy demand with its production by overcoming their intermittency nature. They may also produce heating and cooling at the same time. They offer a green solution for remote communities but also for provinces where the price of electricity may highly vary during a day. The performances of systems working with air have been extensively evaluated thermodynamically and experimentally for decades and these technologies have already been implemented at a large scale (see the sites of Huntorf and MacIntosh). On the contrary, only few works focused on carbon dioxide as energy transfer medium. With the development of carbon dioxide capture and transport technologies, it appears as a nice way to massively revaluate CO2 and by the way to limit its emissions and climate change. After an exhaustive literature review on the capture, transport and utilization of carbon dioxide in energy storage systems, a thermodynamic model based on real fluid properties is developed. It evaluates the thermodynamic performances of an innovative cycle proposed recently by Liu et al. (2020). The influences of the turbine inlet pressure and temperature, compressor inlet and outlet pressures, charging/discharging times, the CO2 mass flowrate and isentropic efficiencies are quantified in details. Some improvements are then proposed to both diminish the price of the system and reduce the throttling losses by integrating transcritical ejectors. The integration of vortex tubes could be also beneficial for cooling and heating production.","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125813305","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}

{"title":"Experiments on supercritical flow instability in two vertical parallel\u0000channels","authors":"I. Singh, V. Chatoorgoon","doi":"10.11159/icffts20.125","DOIUrl":"https://doi.org/10.11159/icffts20.125","url":null,"abstract":"Very limited experimental data on supercritical flow instability is present in the literature. To enrich this limited database and to further the understanding of supercritical flow instability, an experimental study was conducted using two vertical parallel channels with supercritical CO2. A total of 7 experimental cases were performed with a system pressure range of 8.25 – 9.1MPa and inlet temperatures 0.5 – 10.05 °C. The channel inlet temperature and system pressure were held constant and the input power was increased gradually until mass flow oscillations commenced. The distribution of mass flow rate in the channels with input power increase was examined. Initially, at low input power, the flow rate in the channels was almost equal, with an increase in input power, it got distributed in channels and become asymmetric, and with the further input power increase, it started oscillating 180 °out-of-phase. The results for seven experimental cases are presented and these would be useful for code validation purposes.","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132584272","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}

{"title":"2D Frost Growth and Densification Model in Counterflow\u0000Heat Exchanger","authors":"Alexandre Coulombe, H. Fellouah, Sébastien Poncet","doi":"10.11159/icffts20.121","DOIUrl":"https://doi.org/10.11159/icffts20.121","url":null,"abstract":"When a heat recovery ventilator is operating under winter conditions, the water vapor present in the exhaust airflow can lead to frost formation. The outside temperature at which frost formation occurs depends on many variables such as the heat exchanger plate temperature, the exhaust air humidity ratio, the exhaust airflow and the plate spacing. In this study, a new 2D frost formation model is proposed and applied to counterflow parallel plate heat exchangers. The method is based on a frost growth and densification model. The frost densification depends on the square root of the time and the ratio of supercooling and supersaturation degree. An energy balance equation for the heat conduction through the frost layer and the heat and mass transfer from the moist air to the frost layer is used as a convergence criterion on the frost surface temperature prediction. The proposed 2D model showed that the airflow from a 2.5 mm parallel plate spacing heat exchanger can be reduced as much as 33% over a 25 minutes period. While a larger plate spacing, such as a 4.0 mm spacing, is less prone to airflow reduction due to frost growth, less than 5% reduction over the same time period, the 2.5 mm spacing is still more efficient than the 4.0 mm spacing at the end of the 25 minutes period, with efficiencies of 77% and 55% respectively.","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115359288","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}

{"title":"Droplet Heating and Evaporation: Recent Developments of Simple\u0000Models of Complex Processes","authors":"S. Sazhin","doi":"10.11159/icffts20.05","DOIUrl":"https://doi.org/10.11159/icffts20.05","url":null,"abstract":"Extended Abstract The most recent and important developments in the modelling of heating and evaporation of mono- and multi-component droplets since the publication of the author’s monograph [1] and review paper [2] are reviewed. In contrast to the models used in most engineering applications, the effects of temperature and species mass fraction gradients within spherical droplets are considered based on the analytical solution to the one-dimensional heat transfer and species diffusion equations, assuming that the heating process is also spherically symmetrical. It is shown that this approach is particularly useful for practical applications in CFD codes. The models were implemented into the ANSYS Fluent CFD code using User-Defined Functions (UDF). The predictions of this code, inclusive of the new models, were verified against the results predicted by the in-house research code [3]. In the case of hydrocarbon fuels with large numbers of components a multi-dimensional quasi-discrete model has been developed. In this model, the contributions of individual components are replaced by the contributions of groups of components with close transport and thermodynamic properties, called quasi-components [2]. A new, relatively simple, approach to the modelling of heating and evaporation of suspended droplets that can be applied to water sprays for fire suppression [4], and the modelling of heating and evaporation of multi-component liquid films are discussed [5]. Simplified approaches to the modelling of micro-explosions for automotive applications are presented. These approaches are based on analytical solutions to the heat conduction equation in a composite droplet with Dirichlet and Robin boundary conditions at the droplet surface, and continuity conditions at the fuel-water interface [6,7]. In the latter model, the time instant when the temperature at the water-fuel interface is equal to the water nucleation temperature is associated with the start of puffing/micro-explosion.","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126080626","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}

{"title":"Theoretical and Experimental Investigations for the Virtual Mass of a\u0000Taylor Bubble","authors":"A. Kendoush, Warren E. Overton","doi":"10.11159/icffts20.122","DOIUrl":"https://doi.org/10.11159/icffts20.122","url":null,"abstract":"An exact theoretical analysis was presented for the virtual mass of the Taylor bubble. The present theoretical results were validated experimentally and proved the earlier results of Kendoush [1] were grossly approximate. An experiment was designed, installed, and tested for the purpose of obtaining the virtual mass by using a 3-D manufactured polymeric Taylor bubble.","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122212567","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}

{"title":"The Impact of the Location of Temperature Sensors on the Accuracy of\u0000Transient-State Temperature Distribution Identification","authors":"M. Konieczny","doi":"10.11159/icffts20.124","DOIUrl":"https://doi.org/10.11159/icffts20.124","url":null,"abstract":"Extended Abstract Many structures in various technical applications operate under strong thermal conditions. Steadyor transient-state heat transfer phenomena can create substantial temperature differences which should not exceed the allowable limit. The common problem of calculating the temperature field is the difficulty in accessing some of the thermal boundary conditions in operated elements. This usually concerns internal surfaces, where the fluid is in contact with the element. Numerical analysis of phenomena taking place in a flowing fluid is very time-consuming. Another way to determine the temperature distribution is to find the solution of the inverse heat conduction problem (IHCP) in the device under analysis [1-4] and verify it experimentally [5]. Despite the unknown boundary condition, the proposed method makes it possible to determine the temperature field using “measured” temperature histories determined in easily accessible points on the component outer surface, using energy balance equations. Unfortunately, the accuracy of the method is strongly dependent on the distance between the temperature sensors and the unknown boundary. The second factor creating the final error is the uncertainty of the thermocouple input data. For bigger distances, e.g. in a thick-walled pressure component burdened with measurement errors, oscillations appear in the solutions and the solution error can rise to unacceptable values. Information about the error size is crucial in determining the potential use of specific applications. As a result of a series of transient-state numerical analyses, the final error value was determined as a function of the wall thickness and measurement inaccuracy. “Measurement” errors of ±0.25, ±0.5, and ±1°C were assumed and implemented in the analysis as disturbance. Numerical tests were conducted for two types of a thick-walled pipe with the inner diameter of 160 mm and the wall thickness values of 40 and 60 mm, respectively. It is assumed that the pipe with a uniform initial temperature distribution is partially flooded by the hot medium, which simulates the system heating process. The outer surface is exposed to ambient air. Additionally, in order to overcome instabilities, the influence of smoothing digital filters was investigated. It may be stated that the expected standard deviation σ < 2 (relative error measure RE < 0.5%) of the final result can be achieved for the input error of ±0.5°C for the 40-mm-thick wall, but the input data acceptable error for the wall thickness of 60 mm should be ±0.25°C and smoothing filters must be used additionally. Both levels of temperature measurement accuracy are achievable for industrial thermocouples. For the wall thickness of 60 mm and the input error of ± 0.5°C (no filters applied), the standard deviation value is much higher: σ ≈ 5.1 (RE ≈ 36%). The algorithm is stable even for thick walls. However, for thicknesses over 50mm, it becomes more sensitive to input errors and require","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114306308","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}

{"title":"Two Approaches to Mathematical Modelling of Heating/Evaporation of\u0000a Multi-component Liquid Film","authors":"S. Sazhin, M. Jia, Yanzhi Zhang, O. Rybdylova","doi":"10.11159/icffts20.130","DOIUrl":"https://doi.org/10.11159/icffts20.130","url":null,"abstract":"- Two numerical algorithms for modelling multi-component liquid film heating/evaporation are compared. Both algorithms are based on the solutions of one-dimensional heat transfer/species diffusion equations describing the processes in the liquid film. One of these algorithms is based on the fully numerical solutions of these equations, while the second one is based on their analytical solutions at each time step. The predictions of both algorithms are compared for the case of a 50%/50% hexadecane/heptane film under typical Diesel engine conditions. The agreement between the time evolution of thickness and surface/average temperatures of the film, predicted by both algorithms, appears to be rather close. This allows us to recommend both algorithms for practical engineering applications.","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124869033","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}

{"title":"Simulation of Water Vapor Adsorption in a Fixed-bed Column with\u0000Silica Gel Material for Thermal Energy Storage Applications","authors":"Y. Carrier, C. Strong","doi":"10.11159/icffts20.128","DOIUrl":"https://doi.org/10.11159/icffts20.128","url":null,"abstract":"Extended Abstract In order to reduce the environmental impact of fossil fuels and transition to a low-carbon economy, researchers around the world have been investing heavily in the development of renewable energy technologies. However, the renewable energy sources (e.g. wind power and solar energy) have the major constraint of intermittency and lack of consistency. Therefore, energy storage technologies play an important role in balancing the misalignment between the energy supply and demand, and creating a more flexible and reliable energy system [1]. Water vapor adsorption in porous materials in a fixed bed column can be used in the thermal energy storage (TES) systems for space heating applications. Various adsorbent materials have been tested and evaluated for their thermal energy storage abilities by our research group [2]-[6]. Silica gel has proven to be one of the better adsorbents with high energy storage density using low regeneration temperatures [5]. To gain a better understanding of this exothermic adsorption process, a mathematical model has been developed in this study, to simulate the water vapor adsorption process of silica gel material from humid air. The model included the mass and energy balances with equations to take into account the adsorption isotherms, the pressure-drop in the system, the heat of adsorption released during the process and the heat loss to the surroundings. The validated model can be used to optimize the TES system design and predict the TES system’s performance under operating conditions that we are not able to create in our laboratories.","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124286346","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}

{"title":"Salt Impregnated Matrices for Water-Vapour Adsorption-Based Thermal\u0000Energy Storage","authors":"C. Strong, Suboohi Shervani, Y. Carrier, F. Tezel","doi":"10.11159/icffts20.127","DOIUrl":"https://doi.org/10.11159/icffts20.127","url":null,"abstract":"","PeriodicalId":104107,"journal":{"name":"Proceedings of the International Conference on Fluid Flow and Thermal Science (ICFFTS'20)","volume":"711 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116124321","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}