空冷器的设计(英文)

I don't know who will be interested with my topic. Any way I’ll try my best to squeeze out my time to write more.
Today’s topic: Air-cooled Heat Exchanger Design
Highly recommended Technical Paper: “Effectively Design Air-cooled Heat Exchangers”, by R. Mukherjee, published on CHEMICAL ENGINEERING PROCESS / FEB 1997 Page 26 to 46. Abstract: This primer discusses the thermal design of ACHEs and the optimization of the thermal design, and offers guidance on selecting ACHEs for various applications. API 661—Petroleum, petrochemical and natural gas industries—Air –Cooled heat exchangers Applications:
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Forced and induced draft air cooled heat exchangers Recirculation and shoe-box air cooled heat exchangers Hydrocarbon process and steam condensers Large engine radiators Turbine lube oil coolers Turbine intercoolers Natural gas and vapor coolers Combustion pre-heaters Flue gas re-heaters Lethal service Unique customizations
Recommend Vendor: Hudson Products Corporation GEA Rainey Corporation Jord International Korea Heat Exchanger Ind. Co., Ltd. FBM Hudson Italiana SpA Air Cooler Design Heat Transfer Basics Air cooled heat exchangers rely on thermodynamic properties of heat transfer. Specifically, heat transfer is energy released over time. Two standard formulas used to calculate heat transfer are as follows:
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Duty=Fluid Mass Flow * Cp * Delta T The overall heat-transfer coefficient, U, is determined as follows:

1/U=1/airside heat transfer coefficient+1/tubeside heat transfer+tubeside fouling resistance + airside fouling resistance+ tube wall resistance
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Duty=U * Area * LMTD o U is the inverse of sum resistance to heat transfer (defined as above) o Area is the cooler’s total finned heat transfer area o LMTD is the Log Mean Temperature Difference, or the driving force of heat transfer
Given the above graph, recommending an absolute minimum of 10°C Delta T for most applications based on economies of scale. Of course smaller Delta T’s, such as 5°F, have been designed. Keep in mind as the ambient increases, the LMTD goes down reducing cooling ability. The optimum temperature is around 15°C-20°C more than the design ambient temperature. Flow Pattern & LMTD Effects There are three main types of flow patterns used in air cooled heat exchangers; countercurrent flow, co-current flow and cross current flow. Counter-Current Flow – By far the most common in the process industry, counter-current flow cools the hottest fluid with the warmest air, and the coldest fluid with the coldest air. In other words, the process fluid enters the heat exchanger and passes through the finned tubes at the top of the bundle. These top tubes are exposed to air warmed by the lower tube rows. As the process fluid cools and passes through the lower tube rows, the air temperature is lower as it has been exposed to less and less tube rows.