Transient heat transfer in simultaneously developing channel flow with step change in inlet temperature

Guedes, Rodrigo; Özişik, M.N.

doi:10.1016/0017-9310(94)90386-7

Cited by 5 publications

(4 citation statements)

References 18 publications

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“…Thus, maintaining device operation within a certain temperature range is desired, but requires detailed knowledge about the transient heat transfer process. Several studies have been conducted to better understand transient heating at the macro and micro scales [1][2][3][4][5][6][7]. Siegel and Sparrow [1] analytically studied transient laminar heat transfer in a flat duct with a wall temperature and a heat flux step change.…”

Section: Introductionmentioning

confidence: 99%

“…Perlmutter and Siegel [2] analytically solved unsteady laminar flow heat transfer equations for fully-developed flow by applying step changes of pressure drop, wall temperature, and heat flux. The solutions to the transient laminar convection heat transfer equations were solved analytically in circular pipes [3][4][5] and in parallel plates [5][6][7] at the macro scale. For instance, Olek et al [3] used non-standard variable separation to separate the effects of the fluid and the solid, and Yan [7] analyzed the effects of variables (e.g., wall thickness, thermal diffusivity, Reynolds, and Nu number) on the time required to reach steady state.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of transient temperature response under micro jet impinging using nitrogen (N2)

Shin

Kim

2021

J Mech Sci Technol

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We studied the transient local surface temperature response that occurs when jet impinging of nitrogen gas is applied to the surface to which a pulsating heat flux is applied. After manufacturing a micro jet impinging device, which was composed of three parts--a silicon wafer, a vinyl sticker, and a Pyrex wafer--nitrogen gas was used as working fluid and the velocity was 344.8 m/s, corresponding jet Reynolds was 1467. And the amplitudes of heat fluxes varied from 5.67 to 16.17 W/cm 2 , the frequency also varied from 0.1 to 1000 Hz, then temperature response of RTDs was acquired. For example, when a heat flux, 8.5 W/cm 2 , was applied with a frequency of 0.1 Hz, the highest and lowest temperatures of RTD located on the center of the heater and under indirect jets were 30.2 °C and 20.7 °C. From the acquired results, the time constant of the device was estimated between 17 ms and 32 ms, and this result shows the conjugated mode of conduction and convection of heat transfer. To understand the dominant heat transfer, we decoupled the conduction mode and the convective heat transfer mode through analytical calculations and confirmed that the time constants were 11 μs and 128 ms, respectively. In addition, the heat transfer coefficient was inversely calculated through numerical calculation by simulating the RTD manufactured in the device, and through this, it was confirmed that the dimensionless time constant was related to the Nu number and the correlation was developed as / t τ − = ≤

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of transient temperature response under micro jet impinging using nitrogen (N2)

Shin

Kim

2021

J Mech Sci Technol

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“…Several analytical [3][4][5] and numerical studies [6][7][8][9][10][11][12][13][14][15][16] have been performed at the macroscale to understand the parametric trends governing the transient response of a thermal system to an applied unsteady boundary condition. The thermal system was either a thick walled circular pipe [3,5,7,8,11] or parallel flat plates [4,5,[12][13][14]16]. Transient boundary conditions were introduced in the form of a step change in heat flux [11] or a step change in temperature (outside wall [7] or ambient [6,10] or inlet [4,5,13]).…”

Section: Introductionmentioning

confidence: 99%

“…The thermal system was either a thick walled circular pipe [3,5,7,8,11] or parallel flat plates [4,5,[12][13][14]16]. Transient boundary conditions were introduced in the form of a step change in heat flux [11] or a step change in temperature (outside wall [7] or ambient [6,10] or inlet [4,5,13]). Yan [16] numerically investigated conjugate transient heat transfer in turbulent infinitely long channel with ambient convection.…”

Section: Introductionmentioning

confidence: 99%

Thermal behavior of a microdevice under transient heat loads

Basu

Werneke

Peles

et al. 2015

International Journal of Heat and Mass Transfer

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An experimental study was carried out to investigate the transient response of a thermal microsystem to both a step change and a square wave pulse change in heat flux. The microsystem consisted of a single microchannel etched on a silicon microdevice that was bonded to a Pyrex wafer. A thin-film titanium heater was deposited on the Pyrex substrate. The heater acted as the power source as well as the resistance temperature device. The influence of flow convection on the transient response was studied for two fluids: air and HFE-7000. The effects of heat flux, Reynolds number, fluid properties, and pulse parameters (amplitude, width, duty cycle) on the transient temperature response were identified. The temperature response consisted of an initial rapid temperature rise followed by slower convection dynamics. For longer pulse widths, the temperature of the microdevice reached steady state. Higher order dynamics were identified at the beginning of the temperature response. Convection dynamics were approximated as a first-order response, and the effects of Reynolds number and fluid properties on the time constant of the first order response were identified.

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