Second law analysis of counter flow cryogenic heat exchangers in presence of ambient heat-in-leak and longitudinal conduction through wall

Gupta, Prabhat K.; Kush, P.K.; Tiwari, Ashesh

doi:10.1016/j.ijheatmasstransfer.2007.03.035

Cited by 27 publications

(4 citation statements)

References 12 publications

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“…The design of a cryogenic heat exchanger is concerned with quantifying the relation between the pressure and temperatures at the inlet and exit of the heat exchanger as influenced by the complex heat and mass transfer inside of the heat exchanger [1,2] to just name a few. Assuming a balanced heat exchanger, including a simple model for the effect of the heat leak and conduction heat transfer, one can obtain a relation between the temperature at the inlet and exit of the heat exchanger [5,6].…”

Section: Exergy Based Model For Fom Of Heat Exchangersmentioning

confidence: 99%

Exergy-based figure of merit for regenerative and recuperative heat exchangers with application to multistage cryocoolers

Razani¹,

Dodson²,

Fraser³

2012

AIP Conference Proceedings

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One of the major losses in cryogenic refrigerators operating on oscillating regenerative cycles or steady state recuperative cycles is due to regenerative or recuperative heat exchangers in the cycles, respectively. Accurate numerical modeling of these losses requires extensive numerical simulation of coupled mass, energy, and momentum conservation equations. In this study, a unified model based on exergy flow is developed to define the Figure of Merit (FOM) for heat exchangers with application to multistage cryogenic refrigerators. It is shown that the conventional definition of exergetic efficiency used for heat exchangers is not convenient for their performance evaluation in their application to multistage cryocoolers. It is shown that a rational definition of exergy input to the heat exchanger component is necessary for proper definition of the FOM. The result of the first order model of the regenerator is compared to the results of computational fluid dynamics using REGEN 3.2. The effect of intermediate cooling on the FOM of recuperative heat exchangers is presented. The exergy destruction in the heat exchangers due to heat transfer and fluid flow are presented and discussed.

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Section: Exergy Based Model For Fom Of Heat Exchangersmentioning

confidence: 99%

Exergy-based figure of merit for regenerative and recuperative heat exchangers with application to multistage cryocoolers

Razani¹,

Dodson²,

Fraser³

2012

AIP Conference Proceedings

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“…Gupta et al investigated the second law analysis for counter current cryogenic heat exchangers in the presence of ambient heat inleak and longitudinal heat conduction through wall. They cited the importance of considering the effect of longitudinal heat conduction in the design of cryogenic heat exchangers.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of recuperative tube‐in‐tube heat exchanger operating in cryogenic refrigeration process: simulation‐based transient study

Saberimoghaddam

Abadi

2016

Asia-Pacific J Chem Eng

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Heat exchangers are the critical components of refrigeration and liquefaction processes. In the current paper, thermal behavior of Joule‐Thomson refrigeration system, including counter current helically coiled tube‐in‐tube heat exchanger and expansion valve, is studied in unsteady state conditions. According to obtained results, heat inleak let to longer cooldown time and lower liquefaction efficiency. Moreover, there was a critical length for a tube‐in‐tube heat exchanger operating in the Joule‐Thomson cooling system. A heat exchanger with a length shorter than the critical length could not liquefy the high‐pressure gas. This critical length was named as cooldown length (LCD) here. Increasing the heat exchanger length up to LCD led to increase in cooldown time, while increasing the length higher than LCD had no considerable effect on cooldown time. The simulations indicated that longitudinal heat conduction did not have considerable effect on the performance of heat exchanger in unsteady state conditions. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

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“…The effects on heat transfer, friction factor, and dimensionless exergy loss were investigated experimentally by mounting helical wires of different pitch in the inner pipe in a double pipe heat exchanger by Akpinar [12]. Gupta et al [13] defined the fractional exergy loss differently by dividing the irreversibility by maximum heat that can be transferred ideally so that one can get a better understanding about the quantitative values of exergy loss in respect to maximum heat transferred. San [14] considered the exergy change rate in an ideal gas flow or an incompressible flow to analyze a heat exchanger.…”

Section: Introductionmentioning

confidence: 99%

Second Law Efficiency Analysis of Heat Exchangers

Manjunath

Kaushik

2013

Heat Trans. Asian Res.

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Analytical analysis of unbalanced heat exchangers is carried out to study the second law thermodynamic performance parameter through second law efficiency by varying length-to-diameter ratio for counter flow and parallel flow configurations. In a single closed form expression, three important irreversibilities occurring in the heat exchangers-namely, due to heat transfer, pressure drop, and imbalance between the mass flow streams-are considered, which is not possible in first law thermodynamic analysis. The study is carried out by giving special influence to geometric characteristics like tube length-to-diameter dimensions; working conditions like changing heat capacity ratio, changing the value of maximum heat capacity rate on the hot stream and cold stream separately and fluid flow type, i.e., laminar and turbulent flows for a fully developed condition. Further, second law efficiency analysis is carried out for condenser and evaporator heat exchangers by varying the effectiveness and number of heat transfer units for different values of inlet temperature to reference the temperature ratio by considering heat transfer irreversibility. Optimum heat exchanger geometrical dimensions, namely length-to-diameter ratio can be obtained from the second law analysis corresponding to lower total entropy generation and higher second law efficiency. Second law analysis incorporates all the heat exchanger irreversibilities.

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Second law analysis of counter flow cryogenic heat exchangers in presence of ambient heat-in-leak and longitudinal conduction through wall

Cited by 27 publications

References 12 publications

Exergy-based figure of merit for regenerative and recuperative heat exchangers with application to multistage cryocoolers

Exergy-based figure of merit for regenerative and recuperative heat exchangers with application to multistage cryocoolers

Evaluation of recuperative tube‐in‐tube heat exchanger operating in cryogenic refrigeration process: simulation‐based transient study

Second Law Efficiency Analysis of Heat Exchangers

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