Nanoscale Heat Transferin

Thin Films

Thomas Prevenslik

Discovery Bay, Hong Kong, China

1ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

Background

Over the past 30 years, heat transfer in thin films has been based on classical methods.

However, for films less than about 100 nm, classical heat transfer cannot explain the reduced thermal

conductivity found in experiments.

T. Prevenslik, “Heat Transfer in Thin Films,” Third Int. Conf. on Quantum, Nano and Micro Technologies,

ICQNM 2009, February 1-6, Cancun, 2009.

ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China2

Experimental Data

Bulk Copper

0

100

200

300

400

500

10 100 1000 10000

Film Thickeness - - nm

The

rmal

Con

duct

ivity

- W

/ m

-K

.

Keff Copper FilmsElectronics Cooling, 2007

3ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

Experiment

4

Pulse Method (Thin Solid Films, Kelemen, 36 (1976) 199-203)

Thermal Diffusivity

c

K

T/Tlnt4

xx

21

21

22

K = thermal conductivity = density, c = specific heat

X1

X2

T1

T2

Wire

F

Data Shows K 0 as f 0

Substrate

Film

Problem

Diffusivity diverges as c 0 Instability requires testing with the film

combined with substrate. Davitadze, et al., App. Phys. Lett.. 89

(,2002)

S

W

ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

L

Current Approach

To explain reduced conductivity data, Fourier heat conduction theory is thought not applicable to thin films

having thickness < than the mean free paths of phonons.

Heat Transfer in thin films is modified to treat phonons as particles in the Boltzmann Transport Equation (BTE).

5ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

Purpose

6

To provide a QM explanation

for thin film heat transfer based on

QED induced EM radiation

QM = Quantum Mechanics

QED = Quantum Electro Dynamics

EM = Electromagnetic

ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

QED induced EM radiation

Classically, heat is conserved by an increase in temperature.

But at the nanoscale, QM forbids heat to be conserved by an increase in temperature because specific heat

vanishes.

QED allows heat to be conserved by the frequency up-conversion of kT energy to the EM confinement

frequency of the film which escapes by the emission of nonthermal EM radiation

7ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

Thin Film

8

QED Heat Transfer QCond = QJoule - QQED

T2 = (QJoule- QQED) (f + S ) / A Keff

QQED / QJoule = T1 / T2 -1

QQED

QCond

T Current Approach

QCond =QJoule

T1 = QJoule (f + S ) / A Keff

QJoule

ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

Effective Conductivity

Keff = [Kf / f + KS / S ] / (f + S )

EM Confinement

c

f rn2 hfEP

For << W and L, 2nr

2r2r

2r

2 n2

1

Ln2

1

Wn2

11

Photons in Rectangular cavity resonator, nr > 1

9ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

kT

3 DOF confined

3 DOF

1 DOF confined

QM Restrictions

0.00001

0.0001

0.001

0.01

0.1

1 10 100 1000

Wavelength - - microns

Pla

nck

Ene

rgy

- E -

eV

1

kT

hcexp

hc

E

10

Film

0.0285 eV

ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

Thin Film Specific Heat

3 microns0

0.2

0.4

0.6

0.8

1

1.2

0.001 0.01 0.1 1 10 100 1000

Thin Fim Thickness - nr microns

Dim

ensi

onle

ss S

peci

fic H

eat

C* EM

Emission Temp

Increase

ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

11

QED radiation in NPs

• • • Specific Heat Vanishes

No Temperature change

EM

Emission

= 2Dnr

Molecular

Collisions

Nanofluids

Room B, 2 PM

Laser/Solar/Supernovae

Photons

Residual kT Energy

Tribochemistry Joule

Heat

NP

12 ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

QED Induced Heat Transfer

CondQEDJoule QQQ

13

dt

dNEQ PPQED

Non Thermal Emission

EP = Photon Planck Energy

dNP/dt = Photon Rate

ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

QED induced Heat Transfer

14

0

100

200

300

400

500

10 100 1000 10000

Film Thickeness - - nm

The

rmal

Con

duct

ivity

- W

/ m

-K

.

0510152025303540

E(d

N/d

t) /

A (

T-T

o)

x10

9 W

/ m

2- K.

Kbulk - Keff

Keff

EMEmission

ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

Conclusions Thin film specific heat vanishes.

Film temperatures follow the substrate. PWR fuel rod cladding simulated in ANSYS by coupling clad

temperatures with substrate.

No need to modify bulk conductivity for thin films

Heat loss normal to the surface by QED emission.

QED emission can and should be measured with standard photomultipliers for 100 nm films.

15ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

Extensions Einstein’s Static Universe

Redshift in cosmic dust means Universe is not expanding and dark energy does not exist.

TribochemistryRubbing of surfaces produces NPs that produce VUV to enhance chemical reactions

Gecko walking on walls and ceilingsSpatulae under on hair tips act as NPs to produce electrostatic attraction

Unification of Static ElectricityRubbing of surfaces produces NPs that charge the surroundings.

Nanocatalysts and Chemiluminescence Gold NPs added to chemical reactants in solution enhance chemical reactions

X-rays from peeling Scotch TapeNPs that form as adhesive tears accumulates charge that at breakdown produces x-rays

Casimir forceBB thermal radiation in gap between parallel plates produces attraction

Etc…16

ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China

Questions & Papers

Email: thomas@nanoqed.net

http://www.nanoqed.org

17ASME Micro/Nanoscale Heat / Mass Transfer Int. Conf., Dec. 18-21, 2009 — Shanghai, China