Analysis of a screen heat exchanger

Journal Article · Sun Nov 01 04:00:00 EST 1992 · Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States)

DOI:https://doi.org/10.1115/1.2911897· OSTI ID:5546531

Jones, G F ^[1]; Prenger, F C ^[2]

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1. Villanova Univ., PA (United States)
2. Los Alamos National Lab., NM (United States)

Heat transfer in a fluid-to-fluid screen heat exchanger is analyzed from first principles. The screens are treated as an ensemble of pin fins and an empirical heat transfer coefficient accounts for convection heat transfer at the fin surface. Pressure drop and simultaneous axial conduction in the screen matrix and the wall separating the fluid streams are modeled. Expressions are obtained that relate dimensionless length ratios to exchanger effectiveness antipressure drop. The [open quotes]mesh ratio, [open quotes]defined as the ratio of fin diameter (d) to spacing (s), prevails throughout the results. The key findings are: (1) the existence of an optimal ratio of fin length (a) to fin diameter that maximizes thermal performance (arising from the competition between the fin-length dependent heat transfer coefficient and fin surface area), (2) increasing and greater than optimal increases exchanger length and reduces pressure drop, for and less than optimal heat transfer is depressed antipressure drop increased, and (3) the pressure drop is linear with overall Ntu and varies as d[sup [minus]2], (1 + d/s)[sup 6], and approximately the square of the mass flow rate per width of exchanger. An exact solution for axial conduction is presented that is valid in the limit of large Ntu and equal fluid capacity rates. Axial conduction is seen to decrease with increasing Ntu and mass flow rates and reduced fin and ratio. Predictions from the model are validated by comparing with published effectiveness and pressure-drop data. 18 refs., 5 figs.

• OSTI ID: 5546531
• Journal Information: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States), Journal Name: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States) Vol. 114:4; ISSN 0022-1481; ISSN JHTRAO
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
CONVECTION
ENERGY TRANSFER
FINS
FLOW RATE
FLUID FLOW
HEAT EXCHANGERS
HEAT TRANSFER
MASS TRANSFER
PERFORMANCE
PRESSURE DROP
SURFACE AREA
SURFACE PROPERTIES
THERMAL ANALYSIS
THERMAL CONDUCTION