Archives of Thermodynamics最新文献_第7页

Numerical study of flow maldistribution in plate heat exchangers used for evaporation process 蒸发用板式换热器内流动不均匀的数值研究

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ather.2019.129994

Paweł Płuszka, Arkadiusz Brenk, Z. Malecha

引用次数: 1

Irreversible energy degradation in heat transfer between two fluids – analysis on manifolds 两种流体之间热传递中的不可逆能量退化——歧管分析

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ather.2020.135858

Z. Drożyński

{"title":"Irreversible energy degradation in heat transfer between two fluids – analysis on manifolds","authors":"Z. Drożyński","doi":"10.24425/ather.2020.135858","DOIUrl":"https://doi.org/10.24425/ather.2020.135858","url":null,"abstract":"Thermodynamics deals with irreversible transformations of substances. Every thermodynamic property of a substance, as a function of two parameters describing its state, can be illustrated as a simply connected manifold. The term manifold stands for the Methods of Geometrical Representation of Thermodynamic Properties of Substances by Means of Surfaces. Generally, every transformation of a substance changes its energy (or enthalpy) by heat transfer and work done on it. All such changes (transformations) are considered to be irreversible and can be described using appropriate manifolds. Studies show that every transformation is associated with the degradation of energy. Such relations (between heat, work and other forms of energy or enthalpy) can be described by the Pfaff formulas and their integrations. This article discusses the issue of irreversible energy degradation in heat transfer between two fluids. Irreversible heat transfer between separated fluids most often occurs through surface heat exchangers. All such processes are determined by convective heat transfer in thermal boundary layers and conduction through the wall. Consequently, entropy changes of fluids in heat and mass transfer can be observed in these layers. While the entropy rate of the heating fluid is negative and that of the heated medium is positive, the sum of entropy changes of all substances involved in the heat transfer process is always positive. These sums, known as entropy increase (entropy generation), can be interpreted as the measure of irreversible degradation of energy in heat transfer processes. The consequence of this degradation is that an arbitrary engine powered by the degraded (lower-temperature) heat flux will operate at a lower efficiency. The significance of this discussion relates especially to cases in power plants and cooling systems where ∗Corresponding Author. Email: drozd@imp.gda.pl","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43014538","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}

引用次数: 0

Generalized thermal microstretch elastic solid with harmonic wave for mode-I crack problem 具有谐波的广义热微拉伸弹性固体I型裂纹问题

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ATHER.2020.133626

K. Lotfy, A. El-Bary, M. Allan, M. H. Ahmed

引用次数: 2

An experimental study of solar air heater using arc shaped wire rib roughness based on energy and exergy analysis 基于能量和火用分析的弧形丝肋粗糙度太阳能空气加热器实验研究

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ather.2021.138112

Harish Kumar Ghritlahre

{"title":"An experimental study of solar air heater using arc shaped wire rib roughness based on energy and exergy analysis","authors":"Harish Kumar Ghritlahre","doi":"10.24425/ather.2021.138112","DOIUrl":"https://doi.org/10.24425/ather.2021.138112","url":null,"abstract":"In the present study, energy and exergy analysis has been evaluated for roughened solar air heater (SAH) using arc shaped wire ribs. To achieve this aim, two diﬀerent types of ﬂow arrangement have been considered. These arrangements are: apex upstream ﬂow and apex downstream ﬂo. In addition to this, a smooth duct SAH has been used for comparative study. The experiments were performed using the mass ﬂow rate of 0.007– 0.022 kg/s on outdoor condition at Jamshedpur city of India. The absorber plate roughness geometry has been designed with relative roughness height 0.0395, rib size 2.5 mm, relative roughness pitch 10 and arc angle 60 ◦ . The energetic and exergetic performances have been examined on the basis of the ﬁrst and second law of thermodynamics. According to the results, there is observed to be the maximum thermal eﬃciency and exergy eﬃciency as 73.2% and 2.64%, respectively, for apex upstream ﬂow SAH at 0.022 kg/s, while, at same mass ﬂow rate the maximum thermal eﬃciency and exergy ef-ﬁciency is obtained as 69.4% and 1.89%, respectively, for apex downstream ﬂow SAH. In addition to this, results reported that the maximum outlet temperature and temperature diﬀerence observed at lower mass ﬂow rate. Also examined the outlet air temperature of SAH with various mass ﬂow rates is very important for both analysis.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47027594","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}

引用次数: 3

Research on oxy-fuel combustion power cycle using nitrogen for turbine cooling 利用氮气进行涡轮冷却的全氧燃烧动力循环研究

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ather.2020.135859

V. Kindra, Rogalev, O. Zlyvko, A. Zonov, M. Smirnov, Ilya

引用次数: 4

Partially transient one-dimensional thermal-flow model of a heat exchanger, upwind numerical solution method and experimental verification 换热器部分瞬态一维热流模型、迎风数值求解方法及实验验证

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ather.2022.144406

D. Kardaś, Izabela WARDACH-ŚWIĘCICKAa, Artur Grajewski, A. Grajewski

{"title":"Partially transient one-dimensional thermal-flow model of a heat exchanger, upwind numerical solution method and experimental verification","authors":"D. Kardaś, Izabela WARDACH-ŚWIĘCICKAa, Artur Grajewski, A. Grajewski","doi":"10.24425/ather.2022.144406","DOIUrl":"https://doi.org/10.24425/ather.2022.144406","url":null,"abstract":"Shell and tube heat exchangers are commonly used in a wide range of practical engineering. The key issue in such a system is the heat exchange between the hot and cold working media. An increased cost of production of these devices has forced all manufacturing companies to reduce the total amount of used materials by better optimizing their construction. Numerous studies on the heat exchanger design codes have been carried out, basically focusing on the use of fully time-dependent partial diﬀerential equations for mass, momentum, and energy balance. They are very complex and time-consuming, especially when the designers want to have full information in a full 3D system. The paper presents the 1D mathematical model for analysis of the thermal performance of the counter-current heat exchanger comprised of mixed time-dependent and time-independent equations, solved by the upwind numerical solution method, which allows for a reduction in the CPU time for obtaining the proper solution. The comparison of numerical results obtained from an in-house program called Upwind Heat Exchanger Solver written in a Fortran code, with those derived using commercial software package ASPEN, and those obtained experimentally, shows very good agreement in terms of the temperature and pressure distribution predictions. The proposed method for fast designing calculations appears beneﬁcial for other tube shapes and types of heat exchangers.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48068674","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}

引用次数: 0

Passive cooling through the atmospheric window for vehicle temperature control 通过大气窗进行被动冷却以控制车辆温度

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ather.2021.138108

U. Khan, R. Zevenhoven

{"title":"Passive cooling through the atmospheric window for vehicle temperature control","authors":"U. Khan, R. Zevenhoven","doi":"10.24425/ather.2021.138108","DOIUrl":"https://doi.org/10.24425/ather.2021.138108","url":null,"abstract":"One of the most energy-intensive activities for a vehicle is space air conditioning, for either cooling or heating. Considerable energy savings can be achieved if this can be decoupled from the use of fuel or electricity. This study analyzes the opportunities and eﬀectiveness of deploying the concept of passive cooling through the atmospheric window (i.e. the 8– 14 µ m wavelength range where the atmosphere is transparent for thermal radiation) for vehicle temperature control. Recent work at our institute has resulted in a skylight (roof window) design for passive cooling of building space. This should be applicable to vehicles as well, using the same materials and design concept. An overall cooling eﬀect is obtained if outgoing (long wavelength greater than 4 µ m) thermal radiation is stronger than the incoming (short wavelength less than 4 µ m) thermal radiation. Of particular interest is to quantify the passive cooling of a vehicle parked under direct/indirect sunlight equipped with a small skylight, designed based on earlier designs for buildings. The work involved simulations using commercial computational ﬂuid dynamics software implementing (where possible) wavelength-dependency of thermal radiation properties of materials involved. The ﬁndings show that by the use of passive cooling, a temperature diﬀerence of up to 7–8 K is obtained with an internal gas ﬂow rate of 0.7 cm/s inside the sky-light. A passive cooling eﬀect of almost 27 W/m 2 is attainable for summer season in Finland. Comparison of results from Ansys Fluent and COMSOL models shows diﬀerences up to about 10 W/m 2 in the estimations.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49517077","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}

引用次数: 2

Heat and mass transfer mechanism on three-dimensional flow of inclined magneto Carreau nanofluid with chemical reaction 具有化学反应的倾斜磁Carreau纳米流体三维流动的传热传质机理

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ather.2020.133630

引用次数: 2

Energetic and exergetic analysis of a triple-pressure reheat combined cycle power using different primary movers 使用不同原动机的三压再热联合循环动力的能量和运动分析

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ather.2019.129543

A. Almutairi, Hamad Alhajeri, A. Alenezi

引用次数: 0

A universal model for solar radiation exergy accounting: Case study of Tunisia 太阳辐射火用计算的通用模型:以突尼斯为例

IF 0.9

Archives of Thermodynamics Pub Date : 2023-07-20 DOI: 10.24425/ather.2022.141980

D. Lounissi, N. Bouaziz

{"title":"A universal model for solar radiation exergy accounting: Case study of Tunisia","authors":"D. Lounissi, N. Bouaziz","doi":"10.24425/ather.2022.141980","DOIUrl":"https://doi.org/10.24425/ather.2022.141980","url":null,"abstract":"The global solar radiation is the origin for all environmental processes on the earth and the majority of energy sources are derived from it. The data of solar radiation are required for the design and the study of solar application systems. The more important is the quality of the solar radiation which is deﬁned by the maximum work can be provided by the solar radiation. This quality is measured by the exergy content of a solar radiation. In the present work, a universal pattern has been built to provide a prediction of solar exergy dependently to the geographic location. Fitting models have been developed for exergy account depending on geographic location, based on the linear, quadratic, cubic, logarithmic, exponential, power regression. The Petela model is adopted from literature for exergetic eﬃciency accounting of solar radiation. The global solar radiation according to ASHRAE model is expressed dependently of the cosine of zenith angle. The developed model is applied on Tunisia regions to predict exergy solar potential. The studied regions are classiﬁed regarding the exergy account, high, medium and low solar exergy locations. Results show that generally the solar radiation shows a low degree of exergy content, about 7% of diﬀerence.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43652475","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}

引用次数: 5