Cross/counter flow types of heat exchanger seem likely to have superior characteristics in regard to design a large heat transfer surface area per unit volume by alternately laminating the elements. In this paper, a cross flow type of heat exchanger are examined by experiment, and inserted plate with/without slit holes setting in ducts are proposed to be up the exchanging heat performance from the view point of the enhancement of heat transfer coefficient and pressure loss decreasing, substituting the conventional heat transfer surface increasing technique. Experimental results for 4 cases (CFHE without inserted plate, and inserted plate with/without slit holes) are discussed as a relation of temperature effectiveness and number of heat transfer unit and exergy transfer, referred to the numerical results taking the effect of the inserted plate with/without slit holes on flow, heat transfer behaviors and pressure decreasing into consideration.

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This paper described the result that executed the optimization calculation of a parallel slit fin to improve the performance of a plate-finned tube heat exchanger for air-conditioning. The optimization calculation was executed by combining a multi objective genetic algorithm (MOGA) with a computational fluid dynamics. As a result, the optimized slit fin that was able to improve the heat transfer rate about 14% against the parallel slit fin that had already existed was extracted. Moreover, we found the heat transfer rate became the maximum when the angle of the slit was about 20 degrees.

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Recent years, a fluidized bed is utilized in power plants or chemical reaction equipments, but few studies for relation between the heat transfer coefficients and the suspension density of solid particles in the cross-section are performed, especially in the range from the turbulent to fast fluidized circulating beds. In this study, heat transfer characteristics such as heat transfer coefficients (h) of a circulating fluidized bed (CFB) are basically examined when a single vertical tube is immersed in the riser. The h is measured with a heat radiation from the part of a vertical tube to the test section.

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This present paper attempts to numerically estimate heat transfer enhancement and pressure drop decrease on a duct flow system of heat exchanger. Inserted plates inside the duct flow are proposed in order to enhance heat transfer coefficient, however the inserted plates cause a significant pressure drop, In order to decrease the pressure drop, the inserted plates with slits were employed. Numerical calculations of two-dimensional, laminar, and steady state conditions of duct flow with and without inserted plates were carried out. Air, as a heated media, with range of velocities 0.5m/s-1.5m/s and ambient temperature 20℃ was heated by using 50℃ isothermal duct wall. The calculation results show that the setting of inserted plates enhances the heat transfer coefficient significantly but pressure drop also increase. The presence of slits hole in the inserted plates decreases the pressure drop significantly but the heat transfer coefficient decrease slightly. The calculated streamlines, isotherms, vector velocity, local and average heat transfer coefficient, total heat transfer, and required fan power (pressure drop) are presented.

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A method to making ice slurry is one of key technology for cold-energy storage system. This study has been performed to study the use of ultrasonic wave to remove the crystal-ice layer formed around cooled cylinder in a circular tube continuously. In the experiments, ethylene glycol solution was used. It was found that the dendritic ice layers whose adhesion areas were small formed in the ultrasonic field. They were slided along the surface, and removed by flowing solution. The crystal growth and removal condition in the ultrasonic field were discussed in relation to ultrasonic power, surface temperature, flow velocity and irradiation cycle.

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As a part of space heating system, a heat storage element is intensively investigated here to elevate thermal performance of the system using solar heat as its heat source. Adopted heat storage material is polyethylene glycol #4000 having melting temperature of around 55〜60℃. The material is filled up in spherical thin stainless capsule, which is used as heat storage element. A lot of the elements packed in a tank are heated and cooled mutually by using air, namely, heat transfer medium. Detected thermal performances related to the elements and the tank are checked theoretically to confirm proprieties of the testing results. The present investigation offers useful information for practical application of the system, including matters of system improvement.

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Rock-Beds are generally considered to be the most suitable storage units for heating systems combined with air heated type of solar collector in cold regions. Thermal characteristics of rock bed storage tanks were investigated by experiments using inline and stagger brick's arrangement for storage units of sub-scale model and by numerical analysis for basic models corresponding to experimental condition. The effect of bricks aligned/stagger arrays and it's dimensions on thermal storage and convection behavior in charging/discharging process were discussed, and the stagger arrangement of the bricks was cleared to be the most effective in storage performance due to the convective heat transfer enhancement and the area increasing.

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