A generalized heat transfer correlation for Iouver fin geometry

Chang, Yu; Wang, Chi-Chuan

doi:10.1016/0017-9310(96)00116-0

Cited by 367 publications

(42 citation statements)

References 7 publications

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“…The effect is due the larger deviation between the lowest and highest velocities in the flow maldistribution profiles with high standard deviation. Hence, there is a larger net reduction in heat transfer capacity due to the lower heat transfer performance caused by the lower refrigerant velocities which is supported by Chang and Wang [30]. From Figure 5, D is almost equal to zero when the standard deviation approaches 0.1.…”

Section: Pressure Drop Correlationmentioning

confidence: 73%

“…The air side heat transfer coefficient was calculated using the Colburn factor, j, recommended by Chang and Wang [30] for louvered fins. The single-phase refrigerantside Nusselt number for laminar flow was calculated using the equation provided by Subramaniam [31].For single phase turbulent flow, the Nusselt number can be obtained by using the equation developed by Subramaniam [31].…”

Section: Heat Transfer Correlationmentioning

confidence: 99%

See 1 more Smart Citation

Analysis on the refrigerant (R32) flow maldistribution of microchannel heat exchanger under superheat and sub-cool

Chng¹,

Chin²,

Tang³

2017

Int. J. Automot. Mech. Eng.

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The aim of this research is to study the impact of statistical moments of probability density function such as mean, standard deviation, skew of R32 flow maldistribution profile on the thermal performance of microchannel heat exchanger under superheat, and subcooling effect. A mathematical model was developed in order to analyse the influence of the statistical moments of probability density function of R32 flow maldistribution on the thermal performance of microchannel heat exchanger under superheat and sub-cooling effect. It was found that the high standard deviation and high negative skew of R32 flow maldistribution profile gave a large impact on the D of microchannel heat exchanger and can achieve up to 10%. Moreover, it was found that the heat transfer performance of microchannel heat exchanger dropped significantly when the sub-cool increases. In short, low standard deviation, high positive skew, and superheat of a flow maldistribution profile is preferred in order to minimize the performance deterioration effect. An experiment was set up to verify the mathematical model. The results from the mathematical model agreed well within 10% of the experimental data. A performance deterioration correlation related to refrigerant maldistribution under superheat and subcool was developed to provide a faster solution to design an even flow distribution heat exchanger. The proposed correlation in this research offers a quicker and simpler way to study the R32 flow maldistribution problem.

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Section: Pressure Drop Correlationmentioning

confidence: 73%

Section: Heat Transfer Correlationmentioning

confidence: 99%

Analysis on the refrigerant (R32) flow maldistribution of microchannel heat exchanger under superheat and sub-cool

Chng¹,

Chin²,

Tang³

2017

Int. J. Automot. Mech. Eng.

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“…For condensation, the correlation given by [25] combines the influences of the forced convection Nu F and gravity controlled convection Nu B using an asymptotic expression Nu ¼ ðNu 2 F þ Nu 2 B Þ 1=2 . The correlations to calculate the heat transfer coefficients on the air side are specific to cross-flow compact heat exchangers with louvers and fins [26] and [27]. This simplifies the calibration process to identifying two multipliers, k ae,a and k ac,a , which correct the heat transfer …”

Section: Refrigerant Dynamicsmentioning

confidence: 99%

Modeling air conditioning system with storage evaporator for vehicle energy management

Zhang

Canova

2015

Applied Thermal Engineering

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h i g h l i g h t sControl-oriented modeling of storage evaporator. Demonstrate the benefits through simulations in Matlab/Simulink. Benchmark solution of optimization problem using dynamic programming. Preliminary application of hybrid optimal control problem. a b s t r a c tAutomotive Air Conditioning (A/C) system significantly affects fuel consumption and emission. Thus, Phase Change Material (PCM) is exploited in an innovative storage evaporator to improve the A/C system performance. Due to hybrid features introduced by mode switching when PCM changes its status between liquid and solid, the task of control-oriented modeling is particularly challenging. Upon the energy-based model built, an optimal control problem of an advanced A/C system with a storage evaporator is formulated as to find an optimal clutch command sequence balancing fuel consumption, cabin comfort and drivability constraints. In the scope of vehicle energy management, Dynamic Programming (DP) algorithm usually serves as a tool of obtaining benchmark optimal solution, against which results from other optimal algorithms are compared. However, a direct application of DP algorithm to the optimal control problem faces unexpected difficulty, because the discretization of state space is not feasible for an irregular multi-dimensional subspace formed by the multi-mode model. Alternatively, hybrid optimal control theory is pursued and a preliminary study is conducted to illustrate its promising application.

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“…For condensation, the correlation given by [29] combines the influences of the forced convection N u F and gravity controlled convection N u B using an asymptotic expression N u = (N u 2 F + N u 2 B ) 1/2 . On the external air side, specific heat transfer coefficients are defined for compact heat exchangers with louvers and fins, as noted by [30,31].…”

Section: Model Calibration and Validationmentioning

confidence: 99%

Modeling and output feedback control of automotive air conditioning system

Zhang

Canova

2015

International Journal of Refrigeration

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This paper presents an application of robust control theory to an automotive Air Conditioning (A/C) system. A control-oriented model built using movingboundary method is validated against experimental data collected on a vehicle chassis dynamometer, at constant engine speeds as well as on driving cycles.Next, an H ∞ controller is synthesized by formulating an optimization problem whose solution requires appropriate weighting functions selection. Singular perturbation method is utilized to remove states associated with fast dynamics in both model and controller. Both full-order and reduced-order H ∞ controllers are verified by simulation results obtained using the nonlinear A/C system model. It is demonstrated that the designed controller is capable of tracking the reference output trajectories while rejecting disturbances introduced on the boundary conditions of the heat exchangers. Furthermore, a preliminary study is performed to reveal the opportunity of designing a gain-scheduled H ∞ controller for global output tracking.

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A generalized heat transfer correlation for Iouver fin geometry

Cited by 367 publications

References 7 publications

Analysis on the refrigerant (R32) flow maldistribution of microchannel heat exchanger under superheat and sub-cool

Analysis on the refrigerant (R32) flow maldistribution of microchannel heat exchanger under superheat and sub-cool

Modeling air conditioning system with storage evaporator for vehicle energy management

Modeling and output feedback control of automotive air conditioning system

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