Experimental Study on Heat Transfer and Pressure Drop Characteristics of Four Types of Plate Fin－and－TUbe Heat Exchanger Surfaces

ＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｙｏｎＨｅａｔＴｒａｎｓｆｅｒａｎｄＰｒｅｓｓｕｒｅＤｒｏｐＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＦｏｕｒＴｙｐｅｓｏｆＰｌａｔｅＦｉｎ－ａｎｄ－ＴＵｂｅＨｅａｔＥｘｃｈａｎｇｅｒＳｕｒｆａｃｅｓ￥Ｈ．Ｊ．Ｋａｎｇ；Ｗ．Ｌ...     

Heat and Mass Transfer Enforcement of Vibrating Fluidized Bed

ＨｅａｔａｎｄＭａｓｓＴｒａｎｓｆｅｒＥｎｆｏｒｃｅｍｅｎｔｏｆＶｉｂｒａｔｉｎｇＦｌｕｉｄｉｚｅｄＢｅｄ￥ＣｈｕＺｈｉｄｅ；ＹａｎｇＪｕｎｈｏｎｇ；ＬｉＸｕｈｕｉ；ＳｏｎｇＹａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＴｈｅｒｍａｌＥｎｅｒｇｙＥｎｇｉｎｅｅｒ...     

On Effectiveness and Entropy Generation in Heat Exchanger

ＯｎＥｆｆｅｃｔｉｖｅｎｅｓｓａｎｄＥｎｔｒｏｐｙＧｅｎｅｒａｔｉｏｎｉｎＨｅａｔＥｘｃｈａｎｇｅｒＯｎＥｆｆｅｃｔｉｖｅｎｅｓｓａｎｄＥｎｔｒｏｐｙＧｅｎｅｒａｔｉｏｎｉｎＨｅａｔＥｘｃｈａｎｇｅｒ￥ＸｉｏｎｇＤａｘｉ；ＬｉＺｈｉｘｉｎ；ＧｕｏＺｅ...     

Application of Exergoeconomics to the Analysis and Optimization of Process Systems

ＡｐｐｌｉｃａｔｉｏｎｏｆＥｘｅｒｇｏｅｃｏｎｏｍｉｃｓｔｏｔｈｅＡｎａｌｙｓｉｓａｎｄＯｐｔｉｍｉｚａｔｉｏｎｏｆＰｒｏｃｅｓｓＳｙｓｔｅｍｓＡｐｐｌｉｃａｔｉｏｎｏｆＥｘｅｒｇｏｅｃｏｎｏｍｉｃｓｔｏｔｈｅＡｎａｌｙｓｉｓａｎｄＯｐｔｉｍｉｚａｔ...     

Analysis of Entropy Generation of Combined Heat and Mass Transfer in Internal and External Flows with the Assumption of Local Thermodynamic Equilibrium

ＡｎａｌｙｓｉｓｏｆＥｎｔｒｏｐｙＧｅｎｅｒａｔｉｏｎｏｆＣｏｍｂｉｎｅｄＨｅａｔａｎｄＭａｓｓＴｒａｎｓｆｅｒｉｎＩｎｔｅｒｎａｌａｎｄＥｘｔｅｒｎａｌＦｌｏｗｓｗｉｔｈｔｈｅＡｓｓｕｍｐｔｉｏｎｏｆＬｏｃａｌＴｈｅｒｍｏｄｙｎａｍｉｃＥｑｕｉｌｉ...     

Use of Computational Fluid Dynamics to Simulate the Effects of Design and Operating Parameters on the Overall Performance

ＵｓｅｏｆＣｏｍｐｕｔａｔｉｏｎａｌＦｌｕｉｄＤｙｎａｍｉｃｓｔｏＳｉｍｕｌａｔｅｔｈｅＥｆｆｅｃｔｓｏｆＤｅｓｉｇｎａｎｄＯｐｅｒａｔｉｎｇＰａｒａｍｅｔｅｒｓｏｎｔｈｅＯｖｅｒａｌｌＰｅｒｆｏｒｍａｎｃｅ￥Ｖ．Ｎａｓｓｅｒｚａｄｅｈ；Ｊ．Ｓｗｉｔ...     

Investigation of Enhanced Boiling Heat Transfer from Porous Surfaces

ＳｕｒｆａｃｅｓＩｎｖｅｓｔｉｇａｔｉｏｎｏｆＥｎｈａｎｃｅｄＢｏｉｌｉｎｇＨｅａｔＴｒａｎｓｆｅｒｆｒｏｍＰｏｒｏｕｓＳｕｒｆａｃｅｓ￥ＬｉｎＺｈｉｐｉｎｇ；ＭａＴｏｎｇｚｅ；ＺｈａｎｇＺｈｅｎｇｆａｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＥｎｇｉｎｅｅｒｉｎ...     

Research and Development on PFBC—CC in China and Jiawnag Pilot plant Project

ＲｅｓｅａｒｃｈａｎｄＤｅｖｅｌｏｐｍｅｎｔｏｎＰＦＢＣ－ＣＣｉｎＣｈｉｎａａｎｄＪｉａｗａｎｇＰｉｌｏｔＰｌａｎｔＰｒｏｊｅｃｔＮｉｎｇｓｈｅｎｇＣａｉ；ＭｉｎｇｙａｏＺｈａｎｇ；ＤａｎＬｉ；ＷｅｎｔｉｎｇＦｕ（ＴｈｅｒｍａｌＥｎｅｒｇｙＥｎｇｉｎ...     

The Numerical Study of Marangoni Flow and Its Stability in Czochralski Crystal Growth

ＴｈｅＮｕｍｅｒｉｃａｌＳｔｕｄｙｏｆＭａｒａｎｇｏｎｉＦｌｏｗａｎｄＩｔｓＳｔａｂｉｌｉｔｙｉｎＣｚｏｃｈｒａｌｓｋｉＣｒｙｓｔａｌＧｒｏｗｔｈＸｉｎｏ－ＢｏＷｕ；ＸｕＧｅｎｇ；Ｚｅｎｇ－ＹｕａｎＧｕｏ（Ｄｅｐｔ．ｏｆＥｎｇｉｎｅｅｒｉｎｇＭｅｃｈ...     

Effects of NH＿3 on N＿2O Formation and Destruction in Fluidized Bed Coal Combustion

ＥｆｆｅｃｔｓｏｆＮＨ＿３ｏｎＮ＿２ＯＦｏｒｍａｔｉｏｎａｎｄＤｅｓｔｒｕｃｔｉｏｎｉｎＦｌｕｉｄｉｚｅｄＢｅｄＣｏａｌＣｏｍｂｕｓｔｉｏｎ￥ＪｉａｎＷｅｉＹｕａｎ；ＢｏＦｅｎｇ；ＪｉａｎｘｉｎＬｕ；ＨａｏＬｉｕ；ＤｅｃｈａｎｇＬｉｕ（Ｎａｔｉｏｎａ...     

Heat and mass transfer in a non-isothermal fixed bed solid adsorbent reactor: a uniform pressure-non-uniform temperature case

A uniform pressure model is presented to describe the heat and mass transfer in a fixed bed of solid adsorbent in a finned reactor. This model neglects the resistance to mass diffusion but takes into account the resistances to heat diffusion through two coefficients: the heat conductivity of the adsorbent bed and the heat transfer coefficient between the adsorbent bed and the fins. An experiment has been conducted to validate this model and the two heat transfer coefficients are obtained by an identification technique. When the temperature of the closed reactor is modified on one side of the reactor, large temperature inhomogeneities inside the reactor are observed and mass transfer occurs through a heat pipe effect: the model explains that effect which is observed experimentally. That uniform pressure model is more adapted to describe the history of solid adsorbent reactors used in thermal processes than uniform temperature models proposed by other authors.     

A dimensionless analysis of heat and mass transport in an adsorber with thin fins; uniform pressure approach

A numerical study on heat and mass transfer in an annular adsorbent bed assisted with radial fins for an isobaric adsorption process is performed. A uniform pressure approach is employed to determine the changes of temperature and adsorbate concentration profiles in the adsorbent bed. The governing equations which are heat transfer equation for the adsorbent bed, mass balance equation for the adsorbent particle, and conduction heat transfer equation for the thin fin are non-dimensionalized in order to reduce number of governing parameters. The number of governing parameters is reduced to four as Kutateladze number, thermal diffusivity ratio, dimensionless fin coefficient and dimensionless parameter of Γ which compares mass diffusion in the adsorbent particle to heat transfer through the adsorbent bed. Temperature and adsorbate concentration contours are plotted for different values of defined dimensionless parameters to discuss heat and mass transfer rate in the bed. The average dimensionless temperature and average adsorbate concentration throughout the adsorption process are also presented to compare heat and mass transfer rate of different cases. The values of dimensionless fin coefficient, Γ number and thermal diffusivity ratio are changed from 0.01 to 100, 1 to 10^− 5 and 0.01 to 100, respectively; while the values of Kutateladze number are 1 and 100. The obtained results revealed that heat transfer rate in an adsorbent bed can be enhanced by the fin when the values of thermal diffusivity ratio and fin coefficient are low (i.e., α^? = 0.01, Λ = 0.01). Furthermore, the use of fin in an adsorbent bed with low values of Γ number (i.e. Γ = 10^− 5) does not increase heat transfer rate, significantly.     

新型固体吸附制冷吸附床的结构比较研究

参考国内外现有的固体吸附床结构 ,利用相似原理比较了气 -液、气 -气、液 -液换热器结构的传热特点 ,得出板翅式和翅片管式固体吸附床比管壳式固体吸附床具有传热系数高和传热面积大的优点。本文提出在逐渐解决固体填充和加工工艺困难的前提下 ,板翅式和翅片管式固体吸附床具有很好的应用前景     

Design and Investigation of Heat Transfer in a New Adsorbent Bed With CPC for Solar Adsorption Refrigeration Systems

This article presents the design and the heat transfer study in a novel adsorbent bed with compound parabolic concentrator (CPC) for solar adsorption chillers. The objectives of the study were to investigate the heat transfer in the adsorbent bed experimentally, and to verify the fins layout through finite-element analysis (FEA) simulation. CPCs with different concentration ratios were experimentally tested and an appropriate design of CPC was selected for a prototype. The prototype was designed with the objective of improving the heat and mass transfer ability of the adsorbent bed. Fins were placed in the transverse direction under the receiver area of each CPC. Spaces were provided from three sides of the adsorbent for easy movement of the refrigerant. FEA software was used to study the effect of the fins layout and fins pitch. The experimental results showed that the heat was efficiently transferring up to the end and extended parts of the bed. Simulation results indicated that the present strategy of placing the fins in a transverse direction gives uniform heat distribution compared to a fins layout with fins placed in a longitudinal direction. The proposed design scheme will be helpful to improve the system performance by increasing the heat and mass transfer ability of an adsorbent bed.     

A three-dimensional non-equilibrium model for an intermittent adsorption cooling system

Intermittent adsorption cycles, driven by low temperature heat, like solar heat, instead of electricity or natural gas, can achieve substantial fossil energy savings. In this paper, the mathematical model for the coupled heat and mass transfer in the adsorber of an intermittent adsorption cooling system is set up. The model includes four submodels: heat transfer in heating/cooling fluids, heat transfer in the metal tube, heat transfer in the fins, and heat and mass transfer in the adsorbent. The model for the heat and mass transfer in the adsorbent is a three-dimensional non-equilibrium model which takes into account both the internal and the external mass transfer resistance in the adsorbent. An experiment has been done to validate the model. With some modifications, the model can be used in system optimization and design of adsorption cycles driven by solar energy or waste heat.     

Experimental investigation of contact resistance in adsorber of solar adsorption refrigeration

The key component of a solar adsorption refrigeration unit is the adsorber packed with an adsorbent such as zeolite, active carbon and CaCl₂. One essential problem faced is the poor heat transfer in adsorbers, which strongly influences the performance of the system. Poly-aniline, with the advantage of superior thermal conduction, was introduced into an adsorber to increase the thermal conductivity of the adsorbents. As the thermal conductivity coefficient of adsorbent in the adsorber is enhanced, the thermal contact resistance of the interface becomes a significant proportion and needs to be improved. The heat transfer of solid interfaces, particularly the effects of the adsorbent granule or block with rough surfaces, is studied in this paper. Methods for decreasing the contact resistance using spreading adhesive or exerting pressure on the interface are presented and analysed. A test facility and relevant procedure are developed to measure the effects of different interfaces on the contact resistance. The heat transfer at the interface between the copper surface and the adsorbent granule or block is investigated, and its effect in improving the thermal performance of the adsorber in solar adsorption refrigeration is compared. The experimental results show that exerting pressure or spreading adhesive on the interface can reduce the contact resistance significantly without affecting the mass transfer of the adsorbent in an adsorber.     

A zeolite-coated bed for air conditioning adsorption systems: parametric study of heat and mass transfer by dynamic simulation

In this paper the heat and mass transfer properties of a new zeolite-coated adsorbent bed to be employed in sorption air conditioning systems are investigated by a modelling approach. It consists of a dynamic model which allows to calculate the exchanged energies, the cycle time and, thus, the specific power of the bed. The analysis of the model results, has shown that the proposed configuration (in which the heat transfer enhancement is mainly related to the good adhesion between metal and adsorbent) is very interesting if compared with the traditional beds. Furthermore, to determine the conditions which allow to obtain the most effective heat and mass transfer in the new adsorbent bed, an optimisation study has been carried out.     

Study and optimization of the thermal performances of the offset rectangular plate fin absorber plates, with various glazing

The low thermophysical characteristics of air used as a heat transfer fluid in the solar collectors with thermal conversion require a fully developed turbulent flow. This increases the thermal heat transfer between the absorber plate and the fluid, which clearly improves the thermal performances of the solar collector with obstacles arranged into the air channel duct. In the present work, we introduce, in solar collector, the offset rectangular plate fins, which are used in heat exchangers. An experimental investigation carried out showed the generated enhancement of thermal performance. The offset rectangular plate fins, mounted in staggered pattern, are oriented parallel to the fluid flow and are soldered to the underside of absorber plate. They are characterized by high heat transfer area per unit volume. High thermal performances are obtained with low pressure losses and in consequence a low electrical power consumption by the fan in comparison to the flat plate collector. The experimental results are all so compared by using two types of transparent cover; double and triple.     

Convective heat transfer and pressure drop of annular tubes with three different internal longitudinal fins

Pressure drop and heat transfer characteristics of air in three annular tubes with different internal longitudinal fins were investigated experimentally at uniform wall heat flux. The tested tubes have a double‐pipe structure with the inner blocked tube as an insertion. Three different kinds of fins, plain rectangle fin, plain rectangle fin with periodical ridges and wave‐like fin, were located peripherally in the annulus. The friction factor and Nusselt number can be corrected by a power‐law correction in the Reynolds number range tested. It was found that the tube with periodical ridges on the plain fin or with wave‐like fin could augment heat transfer; however, the pressure drop was increased simultaneously. In order to evaluate the comprehensive heat transfer characteristics of the tested tubes, two criteria for evaluating the comprehensive thermal performance of tested tubes were adopted. They are: 1) evaluating the comprehensive heat transfer performance under three conditions: identical mass flow, identical pumping power, and identical pressure drop; 2) the second law of thermodynamics, i.e., the entropy generation. According to the two different evaluating methods, it was found that the tube with wave‐like fins provided the most excellent comprehensive heat transfer performance among the three tubes, especially when it was used under higher Reynolds number conditions. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(1): 29–40, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20186     

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In this study, fully developed laminar flow and convective heat transfer in an internally finned tube heat exchanger are investigated numerically. The flow is assumed to be both hydrodynamically and thermally developed with uniform outside wall temperature. Parameters of the thickness, length, and number of fins and thermal conductivity ratio between fin and working fluid are varied to obtain the friction factor as well as Nusselt number. The results show that the heat transfer improves significantly if more fins are used; however, the pressure drop turns out to be large in this heat exchanger. In addition, it is found that the emergence of closed-loop isotherms between the areas of two neighboring fins leads to heat transfer enhancement in the internally finned tube. When the fin number is smaller than 14, there appears a maximum Nusselt number at about 0.8 of the dimensionless fin length. Finally, an experiment is conducted to verify the numerical results.