김치냉장고의 저장성능 개선을 위한 기초연구

Abstract

Kimchi is the traditional and representative fermented food in Korea which can be stored for a long time. But the acidity changes continuously with the ambient temperature and the taste of kimchi also changes with the acidity. The traditional storage methods of kimchi to preserve for a long time is to put it into the pot and to bury under the ground in winter season outside. The traditional methods have become more difficult because of the residential variation in modern form. Therefore, Kimchi refrigerator has been developed to maintain its aging and tastes for a long time. This is a new household electronics as a pure domestic technology. The technology of ripening and custody applied to the kimchi refrigerator are productive. But consumers want to keep the kimchi fresh for a long time. Therefore, fundamental research using the CFD and experiment has been carried out in this study to investigate the flow and heat transfer characteristics in the kimchi refrigerator. The research subjects of the kimchi refrigerator are chest type and stand type kimchi refrigerator. The kimchi refrigerators are classified according to Cooling system; chest type refrigerator is direct cooling of natural convection, and stand type refrigerator is indirect cooling of forced convection by fan. This research is the basic study on enhancement of performance in the kimchi refrigerator for the manufacturing. To get temperature distribution during working and to get the characteristics of the internal flow, numerical analysis and experiment have been done for the chest type and stand type kimchi refrigerators that are avaliable in real life. As a result, we confirm that the temperature difference in the wall part of kimchi box in the chest type kimchi refrigerator freezer room is mainly due to the wall height. The temperature difference at the wall of Kimchi box depends on the position of the boxes. The maximum temperature difference at the upper part of the freezer room is about 1℃ between the top and bottom. And the maximum temperature difference at the lower part of the freezer room is about 3 ℃ between the top and bottom. The internal flow due to temperature differences inside the freezer room is formed upside on the surface of the wall of kimchi box. And the down flow is formed in the space between the kimchi boxes. Numerical results about the heat transfer based on the initial value of experimental results and experimental results are consistent within -0.5 ~ 0 ℃ difference. The flow directions of each duct are not symmetrical due to the complex shape of the inlet duct of middle room and operating characteristics of the internal fan of stand type kimchi refrigerator. And the internal fluid flow in the middle room does not appear to be symmetrical. Therefore we know that it is the main reason of the temperature differences between the left and right side.