Experimental Study on Heat Transfer Enhancement of Natural Circulation Liquid Cooling System for Electronic Component

The present research is an experimental study on heat transfer characteristics of a natural circulation cooling system for electronic components. A smooth chip and two micro-pin-finned chips were tested. The chip is mounted on the base of a rectangular horizontal duct located at the bottom of 250 mm high natural circulation loop.FC-72 is used as a coolant. The test conditions are set that the operation pressure of experimental system is 1. 013× 105 Pa, the flow rate of FC-72 is 150 g/min and the subcoolings are 10 K, 25 K and 35 k, respectively. Effect of the subcooling on nucleate boiling and critical heat flux(CHF) were investigated. The results show that subcoolingis found to significantly affect CHF for all chips and micro-pin-finned chips sharply enhanced the boiling heat transfer, CHF of micro-pin-finned chips are 2.5～3 times as large as that of smooth chip at the same subcooling.

Obsolescence optimization of electronic and mechatronic components by considering dependability and energy consumption

Nowadays, rapid technological progress influences the dependability of equipments and also causes rapid obsolescence. The mechatronic and electronic equipment components are mostly affected by obsolescence. A new challenger unit possesses identical functionalities, but with higher performances. This work aims to find the optimal number of components which should be replaced by new-type units, under budgetary constraints. In this work, the new challenger unit is characterized by lower energy consumption and the optimization steps are based on genetic algorithm (GA). The result shows the importance of this type of replacement in order to economize energy consumption and to deal with obsolescence.

Design of Assembled PCB Imaging System Based on Laser Triangulation

With the increasing miniaturisation and integration of electronic products and the increase of heat, it is necessary to design and introduce heat sinks and install fans. The volume of electronic components, especially the height, is very important for the structural and thermal design of electronic devices. This paper presents a design scheme of an online height measurement device based on laser triangulation and commercial charge coupled device(CCD). It analyzes the principles of electronic component height measurement, and expounds the composition and working principle of the laser measurement system. In addition, the commonly used methods to determine the center position are compared and analysed. These methods include circle fitting, gray centroid and extension method or Gaussian fitting. These methods usually lead to different results. The experimental results show that the fitting speed of the gray centroid is faster. The 3 D model of components is given through measurement, and the error factors affecting measurement are analysed.

Thermal Analysis of a Phase Change Material Based Heat Sink for Cooling Protruding Electronic Chips

This work aims to numerically study the melting natural convection in a rectangular enclosure heated by three discreet protruding electronic chips. The beat sources generate heat at a constant and uniform volumetric rate. A part of the power generated in the heat sources is dissipated to a phase change material （PCM, n-eicosane with melting temperature, Tm = 36℃）. Numerical investigations were carded out in order to examine the effects of the plate thickness on the maximum temperature of electronic components, the percentage contribution of plate heat conduction on the total removed heat and temperature profiles in the plate. Con＇elations for the dimensionless secured working time （time to reach the threshold temperature, Tcr = 75℃） and the corresponding liquid fraction were derived.

Surface activity and cleaning performance of rosin-based quaternary ammonium salt type asymmetric Gemini surfactants

Rosin,a renewable and abundant resource,has been extensively processed and chemically modified to endow it with special properties,especially in the surfactant industry.In this study,four rosin-based quaternary ammonium asymmetric gemini surfactants(RGS-2-n)with different alkyl chain lengths(n=12,14,16,18)were synthesized using a simple two-step method based on dehydroabietylamine as the raw material.The feasibility of these surfactants for cleaning purposes was comprehensively evaluated,suggesting that the surfactants own high surface activity and good cleaning performance.Furthermore,by successfully introducing the amine group of dehydroabietylamine into the hydrophilic group of the surfactants,we avoided its potential harm to the environment and water pollution.Density functional theory proves rosin-based gemini surfactants with asymmetric structure can further improve cleaning efficiency.Overall,our findings suggests that RGS-2-n surfactants are promising and sustainable candidates for cleaning electric plates,and provide new opportunities for rosin application in the electric industry.