Results Of Heat Transfer Analysis Research Articles

Modeling evaluation for fire resistance design of rail car floor assembly

This paper is prepared to report the engineering practice by a Chinese railcar manufacture in a railcar design process for a Metro system in U.S. The fire resistance of rail car floor systems is considered as one of the important fire protection features on the railcars operated in U.S., which provides fire separation between the equipment installed under the floor and the passengers insider railcar. In this study, a pragmatic approach was developed to numerically evaluate the fire resistance of rail car floor assemblies and provide insights for necessary design modifications. Finite element analysis (FEA) was applied to assess the fire resistance performance of a rail car floor assembly designed for a metro railway system in the U.S. An optimization algorithm was applied to obtain the thermal properties of intumescent coating. FEA analysis results were applied to assist the design modifications so that the floor assembly successfully satisfies the current requirement and passes the ASTM E119 fire resistance test. The FEA modeling details and heat transfer analysis results are presented. It is also shown that the model predictions agree conservatively well with the full-scale fire resistance test data.

Numerical analysis-based structural behavior assessment of a cable-stayed bridge under tanker fire

Recently, preparation and preventive measures against disasters that can affect the public infrastructure have emerged as a major issue worldwide. Cable-stayed bridges are one of the important infrastructures, damage to which may lead to significant casualties and economic loss in the event of a disaster. Fire accidents involving cable-stayed bridges can cause considerable damage to the structures. In this study, numerical analysis was performed to evaluate the effects of fire on cable-stayed bridges. In previous studies, a fire intensity model (FIM) was proposed to simulate cable-stayed bridges’ fire that is an open environment. Heat transfer analysis (HTA) and structural analysis were performed using the proposed model. Although the results of HTA presented that higher temperature rises were observed in cables with smaller cross-sections, the structural behavior of the bridge demonstrated vulnerability when a fire occurred near any cable locations that would greatly affect the behavior of the bridge in the event of damage. Based on fire analysis conducted in this study, it is expected that the findings will enable indirect evaluations of fire damage to cable-stayed bridges.

Coupled transient heat and moisture transfer investigation of facade panel connections

PurposeThe purpose of this study is to investigate the effect of panel connections on the hygrothermal performance of facade panels using a coupled, transient heat and moisture transfer analysis.Design/methodology/approachA coupled, transient heat and moisture transfer analysis has been conducted to investigate the effect of panel connections in the hygrothermal behavior of facade panels. Governing partial differential equations for the coupled heat and moisture transfer were formulated. Four panel connections proposed by pre-cast/pre-stressed concrete institute were modeled for the ultra-high performance fiber-reinforced concrete facade panel as illustrations and a finite element method was used to solve the numerical models.FindingsThe results of heat transfer analysis showed that steel connections could significantly reduce the thermal resistivity of facade panels by converging heat fluxes and acting as thermal bridges within facade panels. The results also showed that the maximum heat flux in the steel connector of the panel to foundation connection was 10 times higher compared to the other connections. Also, the results of moisture transfer showed that air gaps between the panels had higher moisture flux compared to the other layers in the models. The results show the significant importance of panel connections in the energy performance analysis of facade systems. They also highlight the importance of devising novel connection designs and materials that consider the transient, coupled heat and moisture transfer in the connections to effectively exploit the potential opportunities provided by innovative facade systems to improve building energy efficiency.Originality/valueThis paper, for the first time, investigates the effect of panel connections in the hygrothermal performance of building facade systems using a coupled, transient heat and moisture transfer analysis.

Receiver tube heat transfer analysis of a CCP collector designed based on branched fractals geometry

For the development of systems related to renewable energy and specifically for thermo-solar energy, it is essential to study and analyze the different thermal phenomena of heat transfer, in search of the best conditions that allow strengthening the designs. Phenomena such as radiation, convection, and conduction are highly studied, from the field of materials to the field of infrastructure, finding day to day optimal solutions that guarantee a great use of the solar resource available on the earth's surface. This study presented the results of heat transfer analysis on a receiver pipe in a CCP; designed using the theory of branched fractal geometry to improve the heat transfer associated with concentrating solar capture systems. A fractal structure as a branch or arboreal fractal type network, influenced thermal and electrical parameters, as electrical resistance, thermal resistance, and convective heat transfer, so increasing the level branch heat transfer can be enhancement along of the pipe. The use of renewable energies in agriculture benefits the industrial processes that require a continuous power system, due to climatic conditions and geographical location is not a guarantee in food production fields, which reason solar capture systems contribute to food dehydration processes, water heating, refrigeration, and energy production. Keywords: heat transfer, fractal geometry, solar collector, fractality, fractal dimension, parabolic cylindrical concentrator, DOI: 10.25165/j.ijabe.20201305.4733 Citation: Palacios A, Amaya D, Ramos O. Receiver tube heat transfer analysis of a CCP collector designed based on branched fractals geometry. Int J Agric & Biol Eng, 2020; 13(5): 56–62.

Receiver tube heat transfer analysis of a CCP collector designed based on branched fractals geometry

For the development of systems related to renewable energy and specifically for thermo-solar energy, it is essential to study and analyze the different thermal phenomena of heat transfer, in search of the best conditions that allow strengthening the designs. Phenomena such as radiation, convection, and conduction are highly studied, from the field of materials to the field of infrastructure, finding day to day optimal solutions that guarantee a great use of the solar resource available on the earth's surface. This study presented the results of heat transfer analysis on a receiver pipe in a CCP; designed using the theory of branched fractal geometry to improve the heat transfer associated with concentrating solar capture systems. A fractal structure as a branch or arboreal fractal type network, influenced thermal and electrical parameters, as electrical resistance, thermal resistance, and convective heat transfer, so increasing the level branch heat transfer can be enhancement along of the pipe. The use of renewable energies in agriculture benefits the industrial processes that require a continuous power system, due to climatic conditions and geographical location is not a guarantee in food production fields, which reason solar capture systems contribute to food dehydration processes, water heating, refrigeration, and energy production. Keywords: heat transfer, fractal geometry, solar collector, fractality, fractal dimension, parabolic cylindrical concentrator, DOI: 10.25165/j.ijabe.20201305.4733 Citation: Palacios A, Amaya D, Ramos O. Receiver tube heat transfer analysis of a CCP collector designed based on branched fractals geometry. Int J Agric & Biol Eng, 2020; 13(5): 56–62.

Interface oscillation of droplets upon impact on a heated surface in the Leidenfrost state

When a droplet impacts on a heated surface above the dynamic Leidenfrost temperature, it bounces off the surface by levitating on a vapour layer. The vapour layer is of great importance for impact morphology and heat transfer. In this study, by focusing on the vapour layer, we identify that the bottom interface of the droplet, rather than remaining stable, may oscillate rapidly during the rebounding stage of the droplet in the Leidenfrost state. The interface oscillation refers to repeated formation and discharge of dimple depression at the bottom of the droplet. The results of heat transfer analysis confirm that the interface oscillation can remarkably affect the flow in the vapour layer and the heat transfer between the droplet and the heated surface. The effects of important dimensionless numbers controlling the process are analysed, including the Jakob number, the Ohnesorge number, and the Weber number.

Cryogenic Compressive Strength and Thermal Deformation of Reinforced Polyurethane Foam Material for Membrane Type LNG Carrier

LNG carrier is purposed to transport a liquefied LNG cargo which is reduced to 1/600 of volume in temperature condition of -163°C. In the context of structural performance on LNG cargo hold, the mechanical and thermal behaviors of insulation material under cryogenic temperature are considered as one of the critical factors for the hold design. This paper deals with the thermal deformation and the compressive strength of the reinforced polyurethane foam (RPUF) adapted for the insulation material of membrane type LNG carrier via both material tests and numerical simulations realizing the cryogenic condition. The material tests related to the thermal deformation are carried out to investigate the characteristics for thermal transfer on the actual RPUF specimen. The heat transfer simulations based on finite element analysis (FEA) are carried out using forced convection theory. The results of heat transfer analyses are compared to the material test results. Reasonable cryogenic conditions on RPUF are reviewed from both the analyses and the test results. In the regard of static material strength for the RPUF, the compressive material tests are carried out. The cryogenic temperature effect on the compressive strength of RPUF is evaluated by comparing to the room temperature material test results. From the compressive material tests, the effect of temperature on the ultimate compressive strength is investigated with variation of elongation.

Numerical verification of hyporheic zone depth estimation using streambed temperature

Summary The hyporheic zone is the active region of groundwater and surface water mixing, and consequently, through which the contaminants released to surface water are transferred to groundwater. Because of the high energy demand and expense associated with the remediation of contaminated groundwater, it has become a matter of primary concern to find an efficient and cost-effective way to restore the contaminated groundwater. Therefore delineating the hyporheic zone is of vital importance for the prevention and management of groundwater contamination. This paper proposes a method to estimate the depth of the hyporheic zone using heat transfer analysis for a streambed. In order to assess the adequacy of the proposed method, the sensitivity of the results of heat transfer analyses to the hyporheic flux was evaluated. Due to the high sensitivity to the hyporheic zone depth, the heat transfer analysis was determined to be appropriate to delineate the hyporheic zone depth. The depth estimated from the heat transfer analysis was comparable with that from a conventional tracer test. The proposed method has an advantage over existing methods of determining the hyporheic zone depth due to the fact that it only requires field temperature measurements.

멤브레인 LNG 선박용 강화 폴리우레탄폼의 극저온 거동 연구

In the context of the structural performance of an LNG hold, the mechanical characteristics of the insulation material are considered to be a critical design factor under cryogenic temperatures. This paper presents the thermal elasto-plastic behavior of the reinforced polyurethane foam (RPUF) adapted for the insulation material of a membrane-type LNG carrier via both experiments and numerical simulations realizing the cryogenic condition. The experiments are carried out to investigate the thermal transfer and thermal elasto-plastic deformation characteristics of an actual RPUF specimen. The heat transfer simulations based on the finite element method (FEM) include a forced convection analysis. The results of heat transfer analyses are compared with the experimental results. Reasonable cryogenic conditions for RPUF are reviewed based on both the analysis and experimental results

Heat transfer characteristics of oscillating flow regenerators in cryogenic temperature range below 20 K

Linearized thermoacoustic model considering temperature oscillation in the solid wall is applied to analyze the heat transfer characteristics of compressible oscillating flow in parallel-plate and circular-tube regenerators. In particular, the study focus results of heat transfer analysis are applicable in lower cryogenic temperature ranges (<20 K). Complete expression for Nusselt number is derived and it is shown to be the function of six nondimensional parameters when the shape of the regenerator is fixed. These parameters are discussed, respectively. Simplified expressions of the Nusselt numbers for both parallel plates and circular tubes structured regenerators are derived. Heat transfer characteristics can be evaluated via these simple expressions. Possible approaches of enhancing heat transfer in a thermoacoustic regenerator are discussed.

Design, materials and R&amp;D issues of innovative thermal contact joints for high heat flux applications

Abstract Plasma facing components in fusion machines are designed with a layer of sacrificial armour material facing the plasma and a high-conductivity material in contact with the coolant. One of the most critical issues associated with making the proposed design concept work, from a power handling point of view, is achieving the necessary contact conductance between the armour and the heat sink. This paper presents a novel idea for the interface joint between the sacrificial armour and the actively cooled permanent heat sink. It consists of a thermal bond layer of a binary or more complex alloy, treated in the semi-solid region in such a way as to lead to a fine dispersion of a globular solid phase into a liquid matrix (rheocast process). The alloy in this “mushy state” exhibits a time-dependent, shear rate-dependent viscosity, which is maintained reversibly when the material is solidified and heated again in the semi-solid state. The function of the thermal bond layer is to facilitate heat transfer between the replaceable armour and the permanent heat sink without building up excessive thermal stresses, as in conventional brazed joints, and allow an easy replacement whenever needed without disturbing the coolant system. No contact pressure is required in this case to provide the desired heat transfer conductance, and the reversible thixotropic properties of the rheocast material should guarantee the stability of the layer in the semi-solid conditions. Key design, material and testing issues are identified and discussed in this paper with emphasis on specific needs for future research and development work. Examples of suitable material options which are being considered are reported together with some initial heat transfer analysis results.