Thermal simulation becomes conventional in thermal design for all electronic devices including automotive electronic control unit (ECU). The thermal resistance of semiconductor package is important for predicting temperature rise by self-heating or heat receiving precisely, but it is difficult to obtain the quantity of thermal resistance from semiconductor makers directly due to several reasons such as industrial secrets. Recently, JEDEC standardized “Transient Dual Interface Test Method (TDI)” to measure thermal resistance of junction-to-case (θJC) for power devices with higher accuracy and more easily than traditional test method. We have developed newly TDI which can improve the credibility of TDI. In this method, three kinds of θJC are extracted separately as follows: 1. Branch point of two transient thermal resistances (conventional TDI), 2. Calculate the heat capacity of thermal path in the package and read structure function at that point, 3. Knick point of structure function. The range value where the exact θJC exists can be determined by comparing each θJC. It is very valuable for both semiconductor makers and assembly makers to standardize high reliable measurement of θJC and this method is expected to be essential in order to strengthen competitiveness in global market.
Agricultural crop plants, vegetable and flower and ornamental plants, have an optimum growth temperature range that concentrates within 15-25 °C. A seasonal temperature change has strong influence on growing of agricultural products. The soil warming for plant husbandry is one of the effective growth promotion methods for agricultural crop plant. Generally, the ridge warming is performed by warm water circulation of underground. Moreover, there is another research which observed the growth process of the Welsh onion using an electrically heated wire for soil warming. These studies showed that the soil warming brings growth promotion of agricultural products. But all passed studies are carried out by using the heavy oil or electric power for soil warming as fuel. The experimental result of this study is shown that the relationship between heat amount of soil warming for plant husbandry by ground heat and the growth promoting effect. The underground 2-4m ground heat as a heat source keeps temperature range 15-25 °C through a year. However, the heat amount of this study is very smaller than other researches, so that the growth promoting effect is necessary to examine. The growth promoting effect is proved by the Japanese-mustard-spinach cultivation experiment by using the ground heat at an actual ridge. The growth promoting effect, weight, height and number of leaves, is evaluated in 10 times actual experiment for three years. This paper describes the relationship between growth promoting effect and the amount of ground heat transport for soil warming by heat pipe on the cold season.
The boiling cooling performance of high heat generating devices is examined experimentally. Influence of various minute surface structures on the boiling heat transfer from the surface of dummy CPU is investigated. Surfaces used are smooth type, two pyramid types and two grid types. By using the minute surface structures, nucleate boiling heat transfer is enhanced. When pyramid 0.5mm type is used as the surface structure, improvement of the heat transfer is largest among the test surfaces; it is about three times of smooth surface at equal heat flux condition on the projected surface area basis. Boiling heat transfer is further enhanced when surfactant (sodium myristate) solution is used. When pyramid 0.5mm type is used with the surfactant solution of 0.1wt%, improvement is about five times of smooth surface with pure water at equal heat flux condition on the projected surface area basis.
In this study，a new experimental apparatus was developed to investigate the effect of surface orientation on heat transfer characteristics of spray cooling. The distributions of heat transfer characteristics were investigated varying the volumetric droplet flow rate with the horizontal upward facing surface，the vertical surface and the horizontal downward facing surface. Experimental results showed that the surface orientation affected the heat transfer characteristics of spray cooling according to the behavior of the liquid film. In the case of the vertical surface the heat transfer characteristics in the transition region increases in the downside of spray and decreases in the upside of the spray. In the case of the horizontal downward facing surface the heat transfer characteristics in the transition region decreases near end of the region of the first liquid film.