What is the heat transfer coefficient of radiator?
Heat transfer coefficient K of radiator (w / temperature resistance): refers to the heat transferred out per square meter of heat dissipation area per unit time when the average temperature of the heat medium in the radiator is one degree different from the indoor temperature. The product of the value and the heat dissipation area, and then the standard heat transfer temperature difference (64.5 ℃) is the standard heat dissipation of the radiator. That is to say, q = k · f · 64.5, the larger the K value is, the larger the heat dissipation capacity of the radiator will be. K value is the comprehensive coefficient of the whole heat transfer process (including convection heat transfer and radiation heat transfer), which is related to the characteristics and service conditions of the radiator itself, such as water flow, internal and external surface conditions, etc.
What is the cooling area of the radiator
Radiator cooling area f (M2): refers to the total surface area of radiator cooling elements (cooling part) contacting with indoor air. The higher the fin system is, the larger the F value is. The F value of the series fin radiator is the largest among all kinds of products. However, please note that since the heat dissipation capacity of the radiator q = k · f.t, under the same condition of Δ T, the maximum Q value of the product of K · f must be the largest, that is, a single increase of F does not necessarily increase the Q value. In addition, if you want to increase the heat dissipation, increasing the heat dissipation area is a very good way.
What are the requirements for the painting and color of the outer surface of radiator
1) Metallic paint such as silver powder should not be used, because it can reduce the heat dissipation capacity (cast iron radiator reduces about 9% )
2) White, blue, red and other colors also affect the radiator, but the range is 2% (blue is better than white).
Principle of heat dissipation
When the heat is transferred to the top of the radiator, it is necessary to dissipate the heat to the surrounding environment as soon as possible. For air-cooled radiator, it is necessary to exchange heat with the surrounding air. At this time, the heat is transferred between two different media, and the following formula is q = α x a x Δ T, where Δ t is the temperature difference between the two media, that is, the temperature difference between the radiator and the surrounding air; and α is the thermal conductivity of the fluid, which is a fixed value after the material and air composition of the radiator are determined; the most important a is the contact area between the radiator and air, in other conditions Under the same premise, for example, the volume of the radiator is generally limited, the space in the case is limited, and it will increase the difficulty of installation. However, by changing the shape of the radiator, increasing its contact area with the air, and increasing the heat exchange area, it is an effective means to improve the heat dissipation efficiency. In order to achieve this, the surface area is generally increased by fin design supplemented by surface roughening or threading.
When the heat is transferred to the air, the temperature of the air in contact with the radiator will rise rapidly. At this time, the hot air and the surrounding cold air should take away the heat through convection and other heat exchange methods. For the air-cooled radiator, the most important means is to improve the speed of air flow, and use the fan to achieve forced convection. This is mainly related to fan design and wind speed. The efficiency of radiator fan (such as flow, wind pressure) mainly depends on fan blade diameter, axial length, fan speed and blade shape. The flow of fans is mostly in CFM (British system, cubic foot / minute), and one CFM is about 0.028mm3/minute.
