Effect of Header on Latent Heat Recovery Heat Exchanger

The most part of energy losses in heat & power system is due to the heat released by the exhaust gas to atmosphere. The exhaust gas consists of non-condensable gas and steam with sensible and latent heat. As a lot of latent heat is included in the exhaust gas, its recovery is very important to improve the system efficiency. Based on the previous basic studies, a thermal hydraulic prediction method for latent heat recovery exchangers was proposed. Two kinds of compact heat exchanger with staggered banks of large and small diameter tubes were designed and fabricated based on the prediction method. In the calculations varying the various parameters, approximately the same heat recovery rate was obtained with both the heat exchangers. The more compactness was obtained with the small tubes at a desired heat recovery rate. The pressure loss in gas side was slightly smaller and that in water side was significantly larger incase of the small tube. By adapting the single header instead of conventional multi header, the pressure loss in the water side could be significantly reduced but the reduction rate of heat recovery was only between 40 to 10%.