I need to find the heat dissipation area; please help everyone
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This post was last edited by 42806073 on 2010-12-20 at 15:14. The flue gas temperature is 800 degrees; it needs to be reduced to 500 degrees, and a set of multi-tube air-cooled radiators is intended for cooling, with a tube diameter of 1. Given a flue gas flow rate of 50,000 cubic meters per hour, a flue diameter of 1 meter, and a radiator tube diameter of 100 mm, what is the required heating surface area? That is, how many heat dissipation tubes are needed? How long is the tube? In other words, at 800 degrees and with a flue gas flow rate of 50,000 cubic meters per hour, how many 100 mm diameter pipes are needed, and what length should they be, in order to reduce the temperature to below 500 degrees? Could everyone please help calculate this? I don’t have any professional books available for reference regarding other parameters
Missing conditions: It is necessary to know parameters such as the mass flow rate of the flue gas, its heat capacity, and the wind speed inside the pipe.
The idea is good; everyone who can help should do so, otherwise we won’t be able to complete the task
This post was last edited by aben1981 on 2010-12-20 at 14:41. The idea is actually quite simple: it’s based on the principle of conservation of energy. That is, flue gas heat dissipation = the heat carried away by the air. The heat dissipation of flue gas can be estimated using the formula Q=CM△t, while the amount of heat carried away by the air is calculated using Newton’s cooling law, namely: Q=hA△t. In this formula, A represents the heat exchange area, and h is the heat transfer coefficient. However, determining the value of h is somewhat complex; you can refer to the manual for heat exchangers, as it contains relevant information on this topic. A reminder: the meaning of △t in the two formulas is different; in the first one it refers to the temperature drop of the flue gas, while in the second one it refers to the temperature rise of the ambient air. As for what the appropriate increase in air temperature should be, it depends on requirements related to environmental protection and other factors. You can first assume a value for the calculation.
The wind speed inside the tubes is dependent on the number of tubes. The tube diameter is 100 mm, the flow rate of flue gas is 50,000 m³/h, and the temperature of the flue gas is 800 degrees. The flue gas can be considered as air. What values should the number of tubes and the tube length have?
Air temperature rise? The radiator is cooled by a fan; temperature rise is not a concern. What is the method for calculating the fan speed?
How is the heat transfer coefficient calculated? Is it related to the pipe material? The pipe should be Q235 with a wall thickness of 3 mm.
Under these calculation conditions, it is necessary to assume an increase in air temperature; otherwise, it would be equivalent to having two unknowns in one equation, making it impossible to find a solution.
Can the air temperature rise be calculated? Given the wind speed of the cooling blower
The mass flow rate of cold air is required to calculate the temperature rise