Heat Sink Technology Research Articles

A design method of thermoelectric cooler

A system design method of thermoelectric cooler is developed in the present study. The design calculation utilizes the performance curve of the thermoelectric module that is determined experimentally. An automatic test apparatus was designed and built to illustrate the testing. The performance test results of the module are used to determine the physical properties and derive an empirical relation for the performance of thermoelectric module. These results are then used in the system analysis of a thermoelectric cooler using a thermal network model. The thermal resistance of heat sink is chosen as one of the key parameters in the design of a thermoelectric cooler. The system simulation shows that there exists a cheapest heat sink for the design of a thermoelectric cooler. It is also shown that the system simulation coincides with experimental data of a thermoelectric cooler using an air-cooled heat sink with thermal resistance 0.2515°C/W. An optimal design of thermoelectric cooler at the conditions of optimal COP is also studied. The optimal design can be made either on the basis of the maximum value of the optimal cooling capacity, or on the basis of the best heat sink technology available.

High flux boiling in low flow rate, low pressure drop mini-channel and micro-channel heat sinks

Due to the need for practical cooling technologies which could dissipate high heat fluxes, an experimental study of pressure drop and CHF in mini-channel ( D = 2.54 mm) and micro-channel ( D = 510 μm) heat sinks of 1 cm heated length was performed using R-113. Test conditions included inlet subcooling ranging from 10 to 32°C and a range of low flow rates up to a maximum of 95 ml min −1. The tests yielded CHF values for both heat sinks in excess of 200 W cm −2 with the advantage of both low flow rates and low pressure drops ( ΔP < 0.32 bar) as compared to high-flux, single-phase micro-channel heat sinks. Key features of the miniature heat sinks include a lack of inlet subcooling effect on CHF and superheated outlet conditions at the lowest flow rates. A single CHF correlation was developed for both heat sinks. The paper will illustrate the use of the CHF correlation and a generalized model for pressure drop as predictive tools in assessing the merits of different channel sizes in incorporating miniature heat sink technology into high heat flux cooling schemes. Overall, the mini-channel's performance proved superior to the micro-channel due to pressure drops less than 0.01 bar for comparable CHF values as well as the reduced likelihood of clogging and the relative ease in fabricating the mini-channel.

CW performance of vapor-grown GaAs transferred electron oscillators

The CW performance of GaAs transferred electron oscillators (TEO) is described. The TEO were fabricated from n+-n-n+epitaxial structures of GaAs grown from the vapor phase. The devices consisted of single mesas, 5-6 mil in diameter, on plated silver heat sinks. Fifteen devices were fabricated from three separate wafers and the results were very uniform. The dc to RF efficiency varied between 4 and 5.7 percent for the 15 devices packaged and tested. The best results were 350 and 390 mW of RF power with a conversion efficiency of 5.4 and 5.7 percent, respectively, at approximately 17.5 GHz from single 5.5-mil mesas. These data represent new highs in performance from single-mesa TEO at this frequency. The results indicate that vapor epitaxial growth procedures combined with a device fabrication scheme based on plated heat sink technology can yield reproducible TEO with RF powers greater than 250 mW at efficiencies greater than 5 percent. The results indicate also that the plated heat sink approach will be useful for other devices, such as IMPATTS, in which thermal considerations limit device performance.