학술논문
냉장고용 핀-튜브 증발기의 핀수에 따른 열전달 성능의 변화에 대한 실험 연구 / An Experimental Study on Heat Transfer Characteristics with various Fin Numbers in Fin-Tube Evaporator of Refrigerator
Document Type
Dissertation/ Thesis
Author
Source
Subject
Language
Korean
Abstract
본 연구는 가정용 냉장고 핀-튜브 증발기에 대하여 핀의 개수에 따른 증발기의 열전달 성능 변화를 실험적으로 규명하기 위한 연구이다.본 연구를 위한 증발기는 관의 외경 8mm, 관의 내경 6mm, 관의 길이 6.902m, 60x28mm의 핀423개를 가진 7열2단의 증발기와 관의 외경 8mm, 관의 길이 9.390m, 60×26mm의 핀731개를 가진 12열2단의 증발기를 이용하였다. 실제 냉장고 증발기의 관내를 유동하는 냉매 대신 물로 대체하였고, 항온수조를 이용하여 증발기 입구 측 물의 온도와 유량을 제어하였다. 공기 측의 온도는 별도의 제어방식을 적용하지 않고 실험실 내의 공기를 공급하였다. 실제 냉장고 유로와 근사한 덕트를 가진 풍동을 제작하였으며 공기 측의 속도는 관내유동을 고려하였다.제작된 증발기 성능평가 장치로 핀의 개수의 변화에 따른 열전달량, 총괄열전달계수 및 대수평균온도차의 상관관계를 정량적으로 평가하고 비교한 결과 고정된 공기측으로 인하여 핀수 75%에 비하여 100%의 열전달량이 감소했지만, 핀수가 최대인 경우에 물유량이 증가하면 열전달량도 증가하였다. 핀수가 감소하면 핀 면적이 감소하여 증발기 전열면적이 감소하고, 열전달량은 핀수 75%까지는 증가하다가 그 이후에는 감소하는 성향을 나타내었다. 핀수 75%일 때 열전달량이 가장 높은 특성을 가지고, 총괄열전달계수는 증가하는 경향성을 나타내었다.따라서 열전달량의 측면에서, 주어진 설계조건에 맞는 핀수의 최적점이 존재한다는 것을 실험을 통하여 규명하였다.
The purpose of this study is to investigate the heat transfer performance of the evaporator according to the number of fins for the refrigerator fin-tube evaporator.The evaporator for this study consisted of a 7 row 2 stage evaporator with an outer diameter of 8 mm, a tube inner diameter of 6 mm, a tube length of 6.902 m, and a width of 60 x 28 mm, and an outer diameter of 8 mm, a tube length of 9.390 m, The evaporator of 12 rows and 2 stages with 731 fins was used.Instead of the refrigerant flowing in the tube of the actual refrigerator evaporator, it was replaced with water, and the temperature and flow rate of the evaporator inlet water were controlled by using a constant temperature water tank. The temperature of the air side was supplied with air in the laboratory without applying a separate control method.A wind tunnel with a real duct and an approximate duct was fabricated.As a result of comparing the heat transfer amount, total heat transfer coefficient and logarithmic mean temperature difference according to the change of the number of fins by quantitative evaluation of the manufactured evaporator performance evaluation device, it was found that the heat transfer amount of 100% , But the heat transfer rate also increased when the water flow rate increased when the number of fins.When the number of fins decreases, the fin area decreases and the area of the heat transfer area of the evaporator decreases. The amount of heat transfer increases to 75% of the number of fins and then decreases. The heat transfer coefficient at the fin 75% was the highest, and the overall heat transfer coefficient was increased.Experimental results show that there is an optimal point of the fin number in accordance with the given design conditions in terms of the heat transfer amount.
The purpose of this study is to investigate the heat transfer performance of the evaporator according to the number of fins for the refrigerator fin-tube evaporator.The evaporator for this study consisted of a 7 row 2 stage evaporator with an outer diameter of 8 mm, a tube inner diameter of 6 mm, a tube length of 6.902 m, and a width of 60 x 28 mm, and an outer diameter of 8 mm, a tube length of 9.390 m, The evaporator of 12 rows and 2 stages with 731 fins was used.Instead of the refrigerant flowing in the tube of the actual refrigerator evaporator, it was replaced with water, and the temperature and flow rate of the evaporator inlet water were controlled by using a constant temperature water tank. The temperature of the air side was supplied with air in the laboratory without applying a separate control method.A wind tunnel with a real duct and an approximate duct was fabricated.As a result of comparing the heat transfer amount, total heat transfer coefficient and logarithmic mean temperature difference according to the change of the number of fins by quantitative evaluation of the manufactured evaporator performance evaluation device, it was found that the heat transfer amount of 100% , But the heat transfer rate also increased when the water flow rate increased when the number of fins.When the number of fins decreases, the fin area decreases and the area of the heat transfer area of the evaporator decreases. The amount of heat transfer increases to 75% of the number of fins and then decreases. The heat transfer coefficient at the fin 75% was the highest, and the overall heat transfer coefficient was increased.Experimental results show that there is an optimal point of the fin number in accordance with the given design conditions in terms of the heat transfer amount.