Effective NTU of a counterflow heat exchanger with unbalanced flow and longitudinal heat conduction through fluid separating and outer walls

Raju, Leera; Nandi, T.K.

doi:10.1016/j.applthermaleng.2016.10.200

Cited by 15 publications

(2 citation statements)

References 12 publications

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“…Balanced flow and unbalanced flow are always considered in the number of heat transfer unit (NTU) method for heat exchanger design [11]. Balanced flow means heat capacity rates of cold flow and hot flow are the same i.e., Cc/Ch = 1.…”

Section: Effect Of Small-scale Longitudinal Heat Conduction On Balancmentioning

confidence: 99%

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A Numerical Study of Small-Scale Longitudinal Heat Conduction in Plate Heat Exchangers

Borjigin

Zeng

et al. 2018

Energies

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Abstract:Longitudinal heat conduction has a significant effect on the heat transfer performance of plate heat exchangers, but longitudinal heat conduction is usually neglected in numerical studies and the thermal design of a heat exchanger. In this paper, heat transfer models with and without longitudinal heat conduction are proposed to analyze the effect of small-scale longitudinal heat conduction in a plate heat exchanger. The performance of small-scale longitudinal heat conduction is illustrated by temperature and heat flux contours in the heat transfer models with and without longitudinal heat conduction. The results show that small-scale longitudinal heat conduction occurs in the plate and a more uniform temperature profile of the plate is obtained due to small-scale longitudinal heat conduction. In balanced flow, the contributions of longitudinal heat conduction for counter-flow, cross-flow and parallel-flow plate heat exchangers are −3.15%, −0.09% and 0, respectively, whereas, for the respective unbalanced flows they are evaluated to be −1.73%, 0.53% and 0.05%, respectively. Moreover, it is observed that small-scale longitudinal heat conduction in plates is influenced by the thermal conductivity of the plate. The higher the thermal conductivity, the larger is the reduction of thermal performance. The contribution of longitudinal heat conduction varies from −0.54% to −4.01%.

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Section: Effect Of Small-scale Longitudinal Heat Conduction On Balancmentioning

confidence: 99%

“…The performance deterioration was more severe at low mass flow rates or at high NTU operations. Later [11] they presented an expression for effective NTU considering unbalanced flows and LHC through the both inner and outer walls.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Study of Small-Scale Longitudinal Heat Conduction in Plate Heat Exchangers

Borjigin

Zeng

et al. 2018

Energies

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Modified effectiveness and linear regression based models for heat exchangers under heat gain/loss to the environment

2018

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Developing mathematical models for describing heat exchanger outlet temperatures is of great importance for the practice, since heat exchangers are unavoidable elements in any applications, where heat transfer is needed between hydraulically separated fluid parts. The conventional, well-tried physically-based E model (standing for the known effectiveness-NTU approach) is recalled. This model assumes energy balance between the two sides of a heat exchanger (without any interaction with the environment). Based on studies in the literature, mathematical models with similar simplicity and usability to that of the E model, but under heat gain/loss to the environment, are still lacking in the field. This work intends to contribute to filling this gap with two proposed models, called ME and LR models. Based on measured data, all three models are accurate enough for general engineering/modelling purposes, nevertheless, the partly physically-based, partly empirical ME model is more precise than the E model if the heat gain/loss to the environment is considerable, and the empirical (black-box type) LR model is more precise than both the E and ME models if the heat gain/loss is not negligible. Furthermore, the outlet temperatures can be explicitly expressed from the simple linear algebraic relations characterizing all models alike.

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Coupling ε-NTU method for thermal design of heat exchanger in cabinet cooling system

Borjigin

Zhang

Zeng

et al. 2019

Applied Thermal Engineering

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Effective NTU of a counterflow heat exchanger with unbalanced flow and longitudinal heat conduction through fluid separating and outer walls

Cited by 15 publications

References 12 publications

A Numerical Study of Small-Scale Longitudinal Heat Conduction in Plate Heat Exchangers

A Numerical Study of Small-Scale Longitudinal Heat Conduction in Plate Heat Exchangers

Modified effectiveness and linear regression based models for heat exchangers under heat gain/loss to the environment

Coupling ε-NTU method for thermal design of heat exchanger in cabinet cooling system

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