1 / 9

Convective heat exchange within a compact heat exchanger

Convective heat exchange within a compact heat exchanger. EGEE 520 Instructor: Dr. Derek Elsworth Student: Ana Nedeljkovic-Davidovic 2005. 1. Introduction. Characterised mainly by a high heat transfer area per unit volume; Optimization between heat exchange and pressure drop;

ayoka
Download Presentation

Convective heat exchange within a compact heat exchanger

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Convectiveheat exchange within a compact heat exchanger EGEE 520 Instructor: Dr. Derek Elsworth Student: Ana Nedeljkovic-Davidovic 2005

  2. 1.Introduction • Characterised mainly by a high heat transfer area per unit volume; • Optimization between heat exchange and pressure drop; • Parallel flow compact heat exchangers d=2[mm]

  3. 2.1Governing Equations • Analytical expression describing parabolic velocity distribution u=16Umax(y-y0) (y1-y) (x-x0) (x1-x0) / [(y1-y0)2(x1-x0)2] • Energy balance equation • Boundary condition Twall=500[K] T inlet=300[K]; Convective flow-outlet;

  4. 2.2Solution using FEMLABTemperature distribution • Air: • k=0.0505 (w/m K) • c= 1529 (J/kg K) • ρ= 0.8824 (kg/m3) • Velocity: • U max = 2.2 (m/s) • Twall=500[K] • Tinlet=300[K] • Aluminum: • k=155 (w/m K) • c= 895 (J/kg K) • ρ= 2730 (kg/m3)

  5. 3.1Validation FEMLAB results: ∫T2dA=0.001528 [Km2]; ∫WdA=3.168e-6 [m/s m2] Mass and heat flow rate: Average heat transfer coefficient: a=89.21 [W/m2K] Average value of the Nusselt number: Nu= aD/k=3.18 Thermally fully developed flow with constant wall temperature Nu=2.976 ( A.F. Mills, 1999, Heat transfer)

  6. 3.2 Validation • Re= 68 <2300 • Tm=400[K] • Thermally developing, hydraulically developed flow for Re <2300 and constant wall temperature (Housen)

  7. 4. Parametric study

  8. 5.Section of the heat exchanger

  9. 6. Conclusion • Average value of the Nusselt number Nu= aD/k=3.18 • Convective heat transfer coefficient increases with an increase in velocity and with an increase in wall temperature • To calculate more precise value of a and Nu , local heat transfer coefficient is necessary to be determined.

More Related