Thermal Resistance at Smooth-Sphere/Rough-Flat Contacts: Theoretical Analysis

2021 ◽  
Vol 8 ◽  
pp. 45-58
Author(s):  
Guoqing Yu ◽  
Hongzhi Liu ◽  
Wei Zhao ◽  
Gaojie Yang

The PV/T collectors realize the simultaneous output of electricity and thermal energy, which are more efficient than the separated photovoltaic (PV) or solar thermal collectors. In this paper, the electricity generation and thermal collection performances of tube-sheet PV/T collector are studied. The main research contents are as follows: an experimental test system of PV/T collector was built to test the electricity generation and thermal collection performances of tube-sheet PV/T at an inlet water temperature of 30°C. Moreover, the flow resistance test was carried out. In addition, the theoretical heat transfer model was established, and the thermal performance was calculated by theoretical analysis. The experimental data showed that the daily average temperature difference between the PV panel and the inlet water temperature was about 22.5°C. The daily average electrical efficiency was about 9.25%, and the daily average thermal efficiency was about 28.67%. The theoretical analysis of the tube-sheet PV/T model was carried out, and the calculated results were close to the experimental results. The main reason for the large temperature difference between the PV panel and water temperature was that the combined thermal resistance between the PV panel and the absorber plate was large, and reducing the combined thermal resistance could reduce the temperature of the PV panel. The effects of solar irradiance, ambient temperature and spacing of row tubes on the performance of thermal collection were analyzed to optimize the PV/T performance.


2013 ◽  
Vol 684 ◽  
pp. 261-264
Author(s):  
Ru Chun Li ◽  
Xin Zhang ◽  
Qi Zheng

The high power light emitting diode (LED) array integrated with the microchannel heat sink is designed. Detailed theoretical analysis of the thermal resistance for the microchannel heat sink is obtained. The thermal resistance minimum is achieved by the heat sink structure optimization, the result of theoretical analysis is simulated by MATLAB software. The result shows that: the system acquired the best heat dissipation effect, when the total size of the radiator is fixed, the width of the cooling channel is 0.1mm, and the cooling water flow rate is 1 m/s, the minimum of thermal resistance is 0.019w/°C.


2013 ◽  
Vol 456 ◽  
pp. 278-281 ◽  
Author(s):  
Li Fei Pang

There was a thermal model established for the packaged power IC chip which is usually used in the design of a class amplifier. After the theoretical analysis of the equivalent chip thermal resistance model carried out on the basis of thermal resistance theory, the optimization and calculation of the baseboard's material and thickness were simulated with Icepak. The acceptable thermal structure of was showed as suggestions for the reliability of chip with discussions of the simulation.


Author(s):  
J E R Coney ◽  
H Kazeminejad ◽  
C G W Sheppard

A theoretical analysis of the performance of a cooling and dehumidifying vertical rectangular fin has been carried out. Conventional fin theory based on the assumption of a uniform and known sensible heat-transfer coefficient was extended by incorporating the condensate thermal resistance and fin thickness into the analysis for gravity-controlled flow during dehumidification. The fin and the condensate layer equations were solved numerically and evaluated for both insulated and uninsulated fin tip boundary conditions, by assuming a Biot number at the fin tip. Numerical results are presented for various psychrometric and flow conditions and compared with those of a dry fin.


Author(s):  
A. Gómez ◽  
P. Schabes-Retchkiman ◽  
M. José-Yacamán ◽  
T. Ocaña

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.


2001 ◽  
Vol 84 (7) ◽  
pp. 27-36
Author(s):  
Aki Yuasa ◽  
Daisuke Itatsu ◽  
Naoki Inagaki ◽  
Nobuyoshi Kikuma

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