Characteristics of Cold Storage Process of Finned Tube Radiator
According to the low heat transfer coefficient of the coil during the ice storage period, a scheme of using finned tubes
as the ice storage heat exchanger was proposed, and the experiment was carried out with a finned tube radiator with a fin distance of 12.7 mm, and the finned tube heat dissipation was obtained. The variation law of cooling capacity, the advancing process of the icing interface and the distribution of ice layer thickness in the cold storage cycle of the finned tube are of reference significance for the subsequent research on the finned tube ice storage tank.
In the ice storage air conditioning system, the heat transfer performance of the ice storage tank is very important, and it has become one of the focuses of the research on cold storage technology. Refrigerant coil direct evaporative cold storage tank has direct heat exchange between refrigerant and water without secondary heat transfer loss, so it has been widely used. However, due to the large thermal resistance of the ice layer, the heat exchange performance is not good.
In the cold storage stage of the coil direct evaporative cold storage tank, as the ice layer continues to thicken, its thermal resistance also increases. Therefore, increasing the heat exchange area outside the tube and reducing the thickness of the ice layer can improve the heat transfer performance. The key point is that simply increasing the coil density will occupy more ice storage space, resulting in too small IPF. The addition of fins outside the tube can increase the heat exchange area without reducing the effective ice storage space of the ice storage tank. Therefore, the use of finned tubes as heat exchangers for cold storage should be one of the optional technical solutions. Hengshui Xinchengxiang has carried out experimental research on the finned tube radiator with a tube diameter of 9.52mm, a tube spacing of 25.4mm, smooth aluminum fins, and a thickness of 0.2mm. The same non-finned coils were compared in experiments, and it was found that the average cooling capacity of the cold storage cycle of the cold storage system of the finned tube radiator (ignoring the heat leakage loss, that is, the cold storage capacity) increased by 15.3% (the water pump was stopped), and the ice storage capacity was 25% higher. .9% effect. At the beginning of the cold storage, the ratio of the heat transfer coefficient converted into the outer wall area of the tube is around 1.0, that is, the strengthening effect is not obvious. gradually increased, and reached 2.52 in the late stage of cold storage. In this paper, the process characteristics of cold storage in finned tube exchangers will be studied.
For the finned-tube radiator with a fin pitch of 12.7mm, the relevant cold storage experiments were carried out to reveal the variation law of the cooling capacity during the cold storage period, the advancing process of the icing interface, and the distribution of the ice layer thickness. The heat transfer coefficient of the finned tubes
radiator is relatively stable during the cold storage period, and the phenomenon of heat transfer deterioration due to the thickening of the ice layer will not occur.